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Although omnipresent in Russian, then Soviet, and finally post-Soviet agrarian history, the village plot has often been described as a residue of the past, destined for impending disappearance. However, it is still alive, especially in the Ukrainian countryside where it sustains five million rural households while ensuring a significant share of national agricultural production. After recalling the place of the plot in Soviet agriculture, within the kolkhoz structure, and its evolution in the aftermath of decollectivisation, this article analyses its contemporary modes of operation, as well as the diversity within household plots. The authors demonstrate, based on extensive fieldwork conducted in five raions (districts), that the economic performance of these micro-farms is far from negligible and that they play a decisive role in regional production. [ABSTRACT FROM AUTHOR]

Abstract: Background: Myocardial wall thickness (WT) in patients with a prior myocardial infarction has been used to indicate scarring. However, the correlation of WT with sites critical to ventricular tachycardia (VT) has not been previously investigated. The purpose of this study was to correlate electroanatomic mapping data obtained during VT ablation with WT determined by cardiac computed tomography (CT). Methods and results: Cardiac CTs were performed in 15 consecutive patients (mean age 63 ± 10 years, 86% male, left ventricular ejection fraction 27 ± 12%) with a prior infarct referred for VT ablation. The CTs were registered to the electroanatomic maps obtained during the mapping procedure. Pacing was performed throughout the scar at sites with fractionated electrograms and isolated potentials. Ablation sites were identified by pace‐mapping or entrainment‐mapping and these sites were correlated with WT. Bipolar and unipolar voltage amplitude and bipolar electrogram width correlated with WT (correlation coefficient: 0.63, 0.65, and 0.41, respectively, P < 0.001). Ablation target sites were identified for 58 of 113 inducible VTs. The ablation target sites were located on CT‐defined ridges (WT: 4.2 ± 1.2 mm) bordered by areas of thinning (WT: 2.6 ± 1.1 mm, P < 0.0001) in 14 of 15 patients. Ablation targets were found on ridges in 49 of 58 VTs (84%) for which target sites were identified. A total of 70 ridges were localized in the 15 patients. VT became noninducible postablation in 11 of 15 patients (73%). Conclusion: WT measured by CT identifies ridges of myocardial tissue that often are critical for postinfarction VT and that can be appropriate target sites for ablation. [ABSTRACT FROM AUTHOR]

Large-scale agricultural projects, which are based on land ownership concentration and agricultural specialization, are currently being promoted in developing countries. Considered as the way to a modernized agriculture, they are expected to actively contribute to increasing production, growth and employment, especially in African wetland areas. The present article examines the Cameroon part of lake Chad and provides a comparison, rarely addressed, of two dramatically different forms of exploitation: multi-use of space through recession agriculture, pastoralism and fishing (currently practiced by small-scale farmers) and large-scale specialized cropping (agropole project currently promoted by the state). We first critically examine the arguments in favour of the agropole project by a brief reviewing of the current literature. We then describe the two forms of exploitation of lake Chad environment. Lastly we compare the family farming systems to the maize specialized agricultural firm in terms of economic performance. Stemming from basics such as (1) the careful examination of cropping, pastoral herding and fishing practices, and (2) the analysis of how added-value is created, our study shows that the wealth produced by family farming systems based on multi-use of space equals the one expected to be produced by the agricultural firm, while creating three times more employment. This result is of particular importance in the current context in which the Boko Haram crisis seems to have renewed the arguments in favour of large-scale agricultural projects. [ABSTRACT FROM AUTHOR]

Aims The mechanisms underlying persistent atrial fibrillation (AF) in patients with atrial fibrosis are poorly understood. The goal of this study was to use patient-derived atrial models to test the hypothesis that AF re-entrant drivers (RDs) persist only in regions with specific fibrosis patterns. Methods and results Twenty patients with persistent AF (PsAF) underwent late gadolinium-enhanced MRI to detect the presence of atrial fibrosis. Segmented images were used to construct personalized 3D models of the fibrotic atria with biophysically realistic atrial electrophysiology. In each model, rapid pacing was applied to induce AF. AF dynamics were analysed and RDs were identified using phase mapping. Fibrosis patterns in RD regions were characterized by computing maps of fibrosis density (FD) and entropy (FE). AF was inducible in 13/20 models and perpetuated by few RDs (2.7 + 1.5) that were spatially confined (trajectory of phase singularities: 7.6 + 2.3 mm). Compared with the remaining atrial tissue, regions where RDs persisted had higher FE (IQR: 0.42-0.60 vs. 0.00-0.40, P < 0.05) and FD (IQR: 0.59-0.77 vs. 0.00-0.33, P < 0.05). Machine learning classified RD and non-RD regions based on FD and FE and identified a subset of fibrotic boundary zones present in 13.8 + 4.9% of atrial tissue where 83.5 + 2.4% of all RD phase singularities were located. Conclusion Patient-derived models demonstrate that AF in fibrotic substrates is perpetuated by RDs persisting in fibrosis boundary zones characterized by specific regional fibrosis metrics (high FE and FD). These results provide new insights into the mechanisms that sustain PsAF and could pave the way for personalized, MRI-based management of PsAF. [ABSTRACT FROM AUTHOR]

Atrial Fibrosis on MRI in Patients Introduction We studied the extent and distribution of left atrial (LA) fibrosis on delayed-enhanced (DE) MRI in a general cardiology population. Methods and Results One hundred ninety consecutive patients referred for cardiac MRI underwent DE imaging using a free breathing method. The population comprised 60 AF patients and 130 patients without AF, including 75 with structural heart disease (SHD). DE was quantified using histogram thresholding, expressed in % of the wall. Regression analysis was performed to identify predictors of DE. Additionally, DE was registered on a template to study its distribution in subpopulations. In the total population, age, AF, and SHD were independently associated with DE. DE was increasingly observed from 11.1 ± 4.7% in patients with no SHD nor AF, 18.8 ± 7.8% in SHD and no AF history, 22.9 ± 7.8% in paroxysmal AF, to 27.8 ± 7.7% in persistent AF. Among non-AF patients, age and SHD were independently associated with DE. Among AF patients, female gender and AF persistence were independently associated with DE. DE was variably distributed but more frequently detected in the posterior wall. Conclusion Age, history of AF, and SHD are the most powerful predictors of atrial fibrosis, as detected by MRI, in a general cardiology population. Atrial fibrosis predominates in the posterior LA wall. [ABSTRACT FROM AUTHOR]

Atrial Function After Persistent AF Ablation Introduction The atrial outcome after extensive ablation is unknown. We sought to quantify atrial structure and function years after successful ablation for persistent atrial fibrillation (PsAF). Methods and Results We studied after 80 ± 15 months 26 patients (54 ± 8 years, 1 woman) with PsAF successfully treated by ablation (2.2 ± 0.7 stepwise approach procedures, cumulative RF duration 126 ± 37 minutes). At follow-up atrial scar burden and atrial outflows were quantified using delayed-enhanced and velocity-encoded MRI, respectively. Cine imaging was used to quantify atrial conduit function (CF), active emptying fraction (AEF), expansion index (EI), and the inter-appendage mechanical activation delay. Patients underwent exercise testing at baseline and follow-up. LA and RA scar extent were 29 ± 6 and 4.3 ± 2.8%, respectively. LA and RA AEF were 10.0 ± 5.3 and 30 ± 8%. Mean inter-appendage delay was 83 ± 47 ms [42-217]. Complete LAA isolation was found in 3 patients. A wave was absent in 9/26 patients. LA scar extent related to the number of procedures (R = 0.58, P = 0.002) and total RF duration (R = 0.56, P = 0.003). Among follow-up characteristics, LA scar extent related to LAAEF (R = −0.73, P < 0.0001), LAEI (R = −0.64, P = 0.0003), A-wave peak (R = −0.72, P < 0.0001), and inter-appendage mechanical delay (R = 0.47, P = 0.02). At multivariable analysis, LA scar extent was independently related to LAAEF and LAEI. LAAEF and LA scar extent correlated with exercise capacity at follow-up (R = 0.44, P = 0.02, and R = −0.40; P = 0.04). Conclusion LA contractility and compliance are markedly impaired years after successful PsAF ablation. LA dysfunction is closely related to scar burden. [ABSTRACT FROM AUTHOR]

This article examines the role of coffee in the agriculture of southwest Ethiopian highlands, a context characterized by recent huge private coffee estate developments, coffee certification projects and smallholdings. The analysis shows that smallholder farmers prioritize staple crops, and allocate land and labor to coffee only once food production objectives have been reached. It also underscores the diversity of the local peasantry, often treated as a homogeneous group in development projects designed to boost farmers' income through coffee production. Based on this analysis, the article evaluates the effects of recent coffee-oriented development policies: state forest concessions for coffee investment, and two coffee certification projects (UTZ-Certified and Fair-Trade/Organic). Because they omit the differentiated farmers' strategies, these certification initiatives fail to improve local populations' livelihoods and accelerate incipient socioeconomic inequalities. Moreover, when applied to big private plantations, they participate in farmers' dispossession from critical forest resources essential to households' food self-sufficiency. [ABSTRACT FROM PUBLISHER]

Cet article présente une méthode originale d'analyse d'impact d'un projet de développement agricole complexe, le projet SOGUIPAH (projet de palmier à huile et hévéa) en Guinée forestière. En faisant appel conjointement à l'analyse systémique à l'échelle des unités de production (systèmes de production) et à l'évaluation économique incluant un scénario contrefactuel, la démarche proposée permet de quantifier l'impact du projet sur le revenu des agriculteurs et de mettre en évidence le caractère hétérogène de cet impact. Cette comparaison révèle un impact des plus limités à l'échelle globale et de très forts contrastes selon les catégories de producteurs. [ABSTRACT FROM AUTHOR]

Objectives: This study sought to evaluate the relationship between fibrosis imaged by delayed-enhancement (DE) magnetic resonance imaging (MRI) and atrial electrograms (Egms) in persistent atrial fibrillation (AF). Background: Atrial fractionated Egms are strongly related to slow anisotropic conduction. Their relationship to atrial fibrosis has not yet been investigated. Methods: Atrial high-resolution MRI of 18 patients with persistent AF (11 long-lasting persistent AF) was registered with mapping geometry (NavX electro-anatomical system (version 8.0, St. Jude Medical, St. Paul, Minnesota)). DE areas were categorized as dense or patchy, depending on their DE content. Left atrial Egms during AF were acquired using a high-density, 20-pole catheter (514 ± 77 sites/map). Fractionation, organization/regularity, local mean cycle length (CL), and voltage were analyzed with regard to DE. Results: Patients with long-lasting persistent versus persistent AF had larger left atrial (LA) surface area (134 ± 38 cm2 vs. 98 ± 9 cm2, p = 0.02), a higher amount of atrial DE (70 ± 16 cm2 vs. 49 ± 10 cm2, p = 0.01), more complex fractionated atrial Egm (CFAE) extent (54 ± 16 cm2 vs. 28 ± 15 cm2, p = 0.02), and a shorter baseline AF CL (147 ± 10 ms vs. 182 ± 14 ms, p = 0.01). Continuous CFAE (CFEmean [NavX algorithm that quantifies Egm fractionation] <80 ms) occupied 38 ± 19% of total LA surface area. Dense DE was detected at the left posterior left atrium. In contrast, the right posterior left atrium contained predominantly patchy DE. Most CFAE (48 ± 14%) occurred at non-DE LA sites, followed by 41 ± 12% CFAE at patchy DE and 11 ± 6% at dense DE regions (p = 0.005 and p = 0.008, respectively); 19 ± 6% CFAE sites occurred at border zones of dense DE. Egms were less fractionated, with longer CL and lower voltage at dense DE versus non-DE regions: CFEmean: 97 ms versus 76 ms, p < 0.0001; local CL: 153 ms versus 143 ms, p < 0.0001; mean voltage: 0.63 mV versus 0.86 mV, p < 0.0001. Conclusions: Atrial fibrosis as defined by DE MRI is associated with slower and more organized electrical activity but with lower voltage than healthy atrial areas. Ninety percent of continuous CFAE sites occur at non-DE and patchy DE LA sites. These findings are important when choosing the ablation strategy in persistent AF. [ABSTRACT FROM AUTHOR]

MRI Predictors of Reverse Remodeling After CRT Introduction Response rate after cardiac resynchronization therapy (CRT) remains suboptimal. We sought to identify pre- and intraprocedural predictors of response using MRI. Methods and Results Sixty patients underwent MRI before CRT. Left ventricular (LV) volumes and ejection fraction were assessed on cine images. Intra-LV dyssynchrony was defined as the maximal delay between first peaks of radial wall motion over 20 segments. Myocardial scar extent was quantified using delayed-enhanced MRI. After CRT, the paced LV segment was characterized on preprocedural MRI with respect to presence of scar and mechanical delay, the latter being quantified using time to first peak of wall motion, expressed in percentage of the total LV activation. Echocardiography was performed before and 6 months after CRT to quantify reverse remodeling (RR). Mean RR at 6 months was 30 ± 29% of baseline LV end-systolic volume. At univariate analysis, RR related to baseline LV end-diastolic and end-systolic volumes (R2 = 0.101, P = 0.01; R2 = 0.072, P = 0.04), intra-LV mechanical dyssynchrony (R2 = 0.351, P < 0.0001), scar extent (R2 = 0.273, P < 0.0001), and presence of scar at pacing site (R2 = 0.100, P = 0.01). QRS duration and mechanical delay at pacing site were not found related to RR (R2 = 0.041, P = 0.12 and R2 = 0.012, P = 0.4, respectively). At multivariate analysis intra-LV mechanical dyssynchrony, scar extent, and LV end-diastolic volume were independent predictors of RR (R2 = 0.307, P = 0.001; R2 = 0.096, P = 0.002, R2 = 0.078, P = 0.005, respectively). Conclusion Intra-LV dyssynchrony and scar extent are independent predictors of RR after CRT. Scar at pacing site is associated to a lesser response to CRT. Mechanical delay at this site has no impact on the response. [ABSTRACT FROM AUTHOR]

MDCT/MRI Fusion for the Guidance of VT Ablation. Background: Delayed enhancement (DE) MRI can assess the fibrotic substrate of scar-related VT. MDCT has the advantage of inframillimetric spatial resolution and better 3D reconstructions. We sought to evaluate the feasibility and usefulness of integrating merged MDCT/MRI data in 3D-mapping systems for structure-function assessment and multimodal guidance of VT mapping and ablation. Methods: Nine patients, including 3 ischemic cardiomyopathy (ICM), 3 nonischemic cardiomyopathy (NICM), 2 myocarditis, and 1 redo procedure for idiopathic VT, underwent MRI and MDCT before VT ablation. Merged MRI/MDCT data were integrated in 3D-mapping systems and registered to high-density endocardial and epicardial maps. Low-voltage areas (<1.5 mV) and local abnormal ventricular activities (LAVA) during sinus rhythm were correlated to DE at MRI, and wall-thinning (WT) at MDCT. Results: Endocardium and epicardium were mapped with 391 ± 388 and 1098 ± 734 points per map, respectively. Registration of MDCT allowed visualization of coronary arteries during epicardial mapping/ablation. In the idiopathic patient, integration of MRI data identified previously ablated regions. In ICM patients, both DE at MRI and WT at MDCT matched areas of low voltage (overlap 94 ± 6% and 79 ± 5%, respectively). In NICM patients, wall-thinning areas matched areas of low voltage (overlap 63 ± 21%). In patients with myocarditis, subepicardial DE matched areas of epicardial low voltage (overlap 92 ± 12%). A total number of 266 LAVA sites were found in 7/9 patients. All LAVA sites were associated to structural substrate at imaging (90% inside, 100% within 18 mm). Conclusion: The integration of merged MDCT and DEMRI data is feasible and allows combining substrate assessment with high-spatial resolution to better define structure-function relationship in scar-related VT. (J Cardiovasc Electrophysiol, Vol. 24, pp. 419-426, April 2013) [ABSTRACT FROM AUTHOR]

Objectives: To characterise the effects of high-salt diet (HSD) on left ventricular (LV) mass, systolic function and coronary reserve in living mice using cardiac magnetic resonance imaging (MRI). Methods: Thirty C57BL/6 1-month-old female mice were fed either a control ( n = 15) or an HSD ( n = 15). After 3 months, LV volumes, ejection fraction and mass were assessed using time-resolved three-dimensional (3D) black-blood manganese-enhanced MRI, and coronary flow velocity reserve (CFVR) was assessed using dynamic MR angiography at rest and during adenosine-induced hyperaemia. Hearts were excised to assess LV wet mass and micro-vascular remodelling at histology. Results: Micro-vascular remodelling was found at histology in all investigated hearts from the HSD group and none from the control group. No difference between the HSD and control groups was found in terms of heart weight, LV volumes and ejection fraction. Heart to body weight ratio was higher in the HSD group (4.39 ± 0.24 vs 4.02 ± 0.16 mg/g, P < 0.001), because of lower body weight (22.3 ± 0.9 vs 24.0 ± 1.4 g, P < 0.001). CFVR was lower in the HSD group (1.73 ± 0.11 vs 1.94 ± 0.12, P < 0.001). Conclusions: Phenotyping of hypertensive heart disease is feasible in living mice using dynamic MR angiography and time-resolved 3D black-blood manganese-enhanced MRI. HSD is associated with early impairment of coronary reserve, before the onset of significant hypertrophy. Key Points: • In vivo phenotyping of hypertensive heart disease is feasible in mice using MRI • HSD in mice is associated with early impairment of coronary reserve • Dietary salt in mice alters coronary reserve before the onset of ventricular hypertrophy [ABSTRACT FROM AUTHOR]

Globalization induces changes in the combinations of productions and activities within farming systems in all parts of the world. These changes can only be apprehended through an in-depth understanding of the mechanisms and diversity of these farming systems. Labor, as a major technical determinant of differences in competitiveness, is central in these transformations. The technical and economic analysis of labor in Andean dairy production in this paper illustrates this issue. Combining various scales of analysis of labor and productivity highlights the technical obstacles faced by Andean dairy farmers, demonstrates the technical and economic principles of these production systems, and puts them in a competitive context. This analysis also discusses the benefits of a labor-centered approach of farming systems. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusion Scar substrate in nonischemic cardiomyopathy (NICM) patients is often difficult to identify. Advances in cardiac imaging, especially using late iodine‐enhanced computed tomography (LIE‐CT), allow better characterization of scars giving rise to ventricular tachycardia (VT). Currently, there are limited data on clinical correlates of CT‐derived scar substrates in NICM. We sought assess the relationship between scar location on LIE‐CT and outcomes after radiofrequency catheter ablation (RFCA) in NICM patients with VT.From 2020 to 2022, consecutive patients with NICM undergoing VT RFCA with integration of cardiac CT scar modeling (inHeart, Pessac, France) were included at two US tertiary care centers. The CT protocol included both arterial‐enhanced imaging for anatomical modeling and LIE‐CT for scar assessment. The distribution of substrate on CT was analyzed in relation to patient outcomes, with primary endpoints being VT recurrence and the need for repeat ablation procedure.Sixty patients were included (age 64 ± 12 years, 90% men). Over a median follow‐up of 120 days (interquartile range [IQR]: 41–365), repeat ablation procedures were required in 32 (53%). VT recurrence occurred in 46 (77%), with a median time to recurrence of 40 days (IQR: 8–65). CT‐derived total scar volume positively correlated with intrinsic QRS duration (r = .34, p = 0.008). Septal scar was found on CT in 34 (57%), and lateral scar in 40 (7%). On univariate logistic regression, septal scar was associated with increased odds of repeat ablation (odds ratio [OR]: 2.9 [1.0–8.4]; p = 0.046), while lateral scar was not (OR: 0.9 [0.3–2.7]; p = 0.855). Septal scar better predicted VT recurrence when compared to lateral scar, but neither were statistically significant (septal scar OR: 3.0 [0.9–10.7]; p = 0.078; lateral scar OR: 1.7 [0.5–5.9]; p = 0.391).In this tertiary care referral population, patients with NICM undergoing VT catheter ablation with septal LIE‐CT have nearly threefold increased risk of need for repeat ablation. [ABSTRACT FROM AUTHOR]

Introduction: Bicuspid aortic valves (BAV) are the most common congenital heart defects and the extent of ventricular arrhythmias (VA) in patients with BAV is unclear. The objective of this study is to describe VAs and late gadolinium enhancement cardiac magnetic resonance imaging (LGE‐CMR) in patients with BAV. Methods: A total of 19 patients with BAV (18 males, age: 58 ± 13 years) were referred for VA ablation procedures. Ten patients had BAVs at the time of ablation, nine patients had prior aortic valve replacement for a BAV. All but one patient had LGE‐CMR and all patients underwent programmed ventricular stimulation at the time of the ablation. Results: Frequent PVCs were the targeted VAs in 17/19 patients and VT in 2/19 patients. Monomorphic ventricular tachycardia (VT) was inducible in 6 patients. A total of 15 VTs were inducible (2.5 ± 1.0 VTs per patient with a mean cycle length of 322 ± 83 msec). LGE was present in 13 patients. Patients with inducible VT had larger borderzone and core scar compared to non‐inducible patients (7.8 ± 2.1 cm3 vs. 2.5 ± 3.1 cm3 and 5.1 ± 2.6 cm3 vs. 1.9 ± 3.0 cm3, p‐value <.05 for both). PVCs and VTs were mapped to the periaortic valve area in 12 patients and 4 patients, respectively. The PVC burden was reduced from 27 ± 13 to 3 ± 6 (p <.001) and the ejection fraction improved from 49 ± 13% to 55 ± 9% (p =.005). Conclusions: VAs in patients with BAV often originate from the perivalvular area and patients often have LGE and inducible VT. LGE may be due to ventricular remodeling secondary to the presence of BAV and harbors the arrhythmogenic substrate for VT. [ABSTRACT FROM AUTHOR]

Joint bright- and black-blood MRI techniques provide improved scar localization and contrast. Black-blood contrast is obtained after the visual selection of an optimal inversion time (TI) which often results in uncertainties, inter- and intra-observer variability and increased workload. In this work, we propose an artificial intelligence-based algorithm to enable fully automated TI selection and simplify myocardial scar imaging. The proposed algorithm first localizes the left ventricle using a U-Net architecture. The localized left cavity centroid is extracted and a squared region of interest ("focus box") is created around the resulting pixel. The focus box is then propagated on each image and the sum of the pixel intensity inside is computed. The smallest sum corresponds to the image with the lowest intensity signal within the blood pool and healthy myocardium, which will provide an ideal scar-to-blood contrast. The image's corresponding TI is considered optimal. The U-Net was trained to segment the epicardium in 177 patients with binary cross-entropy loss. The algorithm was validated retrospectively in 152 patients, and the agreement between the algorithm and two magnetic resonance (MR) operators' prediction of TI values was calculated using the Fleiss' kappa coefficient. Thirty focus box sizes, ranging from 2.3mm2 to 20.3cm2, were tested. Processing times were measured. The U-Net's Dice score was 93.0 ± 0.1%. The proposed algorithm extracted TI values in 2.7 ± 0.1 s per patient (vs. 16.0 ± 8.5 s for the operator). An agreement between the algorithm's prediction and the MR operators' prediction was found in 137/152 patients (κ = 0.89), for an optimal focus box of size 2.3cm2. The proposed fully-automated algorithm has potential of reducing uncertainties, variability, and workload inherent to manual approaches with promise for future clinical implementation for joint bright- and black-blood MRI. [ABSTRACT FROM AUTHOR]

Introduction: Intramural scarring is a risk factor for sudden cardiac death. The objective of this study was to determine the value of scar quantification for risk stratification in patients with nonischemic cardiomyopathy (NICM) undergoing ablation procedures for ventricular arrhythmias (VA). Methods and Results: Cardiac late gadolinium‐enhanced magnetic resonance imaging was performed in patients with NICM referred for ablation of premature ventricular complexes or ventricular tachycardia (VT). Only patients with intramural delayed enhancement were included. Scar volume was measured and correlated with immediate and long‐term outcomes. Receiver operator curves, Wilcoxon signed‐rank testing, and logistic regression were used to compare patient characteristics. The study consisted of 99 patients (74 males, mean age: 59.6 [54.0‐68.1] years, ejection fraction [EF]: 46.0 [35.0‐60.0]%). Patients without clinical VT or inducible VT had smaller total and core scar size compared to patients with a history of VT or inducible VT (total scar 1.12 [0.74‐1.79] cm3 vs 7.45 [4.16‐12.21] cm3, P <.001). A total scar volume of greater than or equal to 2.78 cm3 was associated with inducibility of VT (AUC 0.94, 95% CI [0.89‐0.98], sensitivity 85%, specificity 90%). Scar volume was associated with VT inducibility independent of a prior history of VT or the preprocedure EF (adjusted OR 1.67 [1.24‐2.24]/cm3, P <.01). Conclusion: Quantification of scar size in patients with intramural scarring is useful for risk stratification in patients with NICM and VA independent of the EF or a prior history of VT. Scar characteristics of patients without a history of VT who have inducible VT are similar to patients with a history of VT. [ABSTRACT FROM AUTHOR]

Introduction: Variants of cardiomyopathy genes in patients with nonischemic cardiomyopathy (NICM) generate various phenotypes of cardiac scar and delayed enhancement cardiac magnetic resonance (DE‐CMR) imaging which may impact ventricular tachycardia (VT) management. Methods: The objective was to compare the findings of cardiomyopathy genetic testing on DE‐CMR imaging and long‐term outcomes among patients with NICM undergoing VT ablation procedures. Image phenotyping and genotyping were performed in a consecutive series of patients referred for VT ablation and correlated to survival free of VT. Scar depth index (SDI) (% of scar at 0‐3 mm, 3‐5 mm and >5 mm projected on the closest endocardial surface) was determined. Results: Forty‐three patients were included (11 women, 55 ± 14 years, ejection fraction (EF) 45 ± 16%) and were followed for 3.4 ± 2.9 years. Pathogenic variants (PV) were identified in 16 patients (37%) in the following genes: LMNA (n = 5), TTN (n = 5), DSP (n = 2), AMLS1 (n = 1), MYBPC3 (n = 1), PLN (n = 1), and SCN5A (n = 1). A ring‐like septal scar (RLSS) pattern was more often seen in patients with pathogenic variants (66% vs 15%, p =.001). RLSS was associated with deeper seated scars (SDI >5 mm 30.6 ± 22.6% vs 12.4 ± 16.2%, p =.005), and increased VT recurrence (HR 5.7 95% CI[1.8‐18.4], p =.003). After adjustment for age, sex, EF, and total scar burden, the presence of a PV remained independently associated with worse outcomes (HR 4.7 95% CI[1.22‐18.0], p =.02). Conclusions: Preprocedural genotyping and scar phenotyping is beneficial to identify patients with a favorable procedural outcome. Some PVs are associated with an intramural, deeper seated scar phenotype and have an increase of VT recurrence after ablation. [ABSTRACT FROM AUTHOR]

Background: The impact of filtering on bipolar electrograms (EGMs) has not been systematically examined. We tried to clarify the optimal filter configuration for ventricular tachycardia (VT) ablation. Methods: Fifteen patients with VT were included. Eight different filter configurations were prospectively created for the distal bipoles of the ablation catheter: 1.0–250, 10–250, 100–250, 30–50, 30–100, 30–250, 30–500, and 30–1000 Hz. Pre‐ablation stable EGMs with good contact (contact force > 10 g) were analyzed. Baseline fluctuation, baseline noise, bipolar peak‐to‐peak voltage, and presence of local abnormal ventricular activity (LAVA) were compared between different filter configurations. Results: In total, 2276 EGMs with multiple bipolar configurations in 246 sites in scar and border areas were analyzed. Baseline fluctuation was only observed in the high‐pass filter of (HPF) ≤ 10 Hz (p <.001). Noise level was lowest at 30–50 Hz (0.018 [0.012–0.029] mV), increased as the low‐pass filter (LPF) extended, and was highest at 30–1000 Hz (0.047 [0.041–0.061] mV) (p <.001). Conversely, the HPF did not affect the noise level at ≤30 Hz. As the HPF extended to 100 Hz, bipolar voltages significantly decreased (p <.001), but were not affected when the LPF was extended to ≥100 Hz. LAVAs were most frequently detected at 30–250 Hz (207/246; 84.2%) and 30–500 Hz (208/246; 84.6%), followed by 30–1000 Hz (205/246; 83.3%), but frequently missed at LPF ≤ 100 Hz or HPF ≤ 10 Hz (p <.001). A 50‐Hz notch‐filter reduced the bipolar voltage by 43.9% and LAVA‐detection by 34.5% (p <.0001). Conclusion: Bipolar EGMs are strongly affected by filter settings in scar/border areas. In all, 30–250 or 30–500 Hz may be the best configuration, minimizing the baseline fluctuation, baseline noise, and detecting LAVAs. Not applying the 50‐Hz notch filter may be beneficial to avoid missing VT substrate. [ABSTRACT FROM AUTHOR]

Goal: We present a model-based feature augmentation scheme to improve the performance of a learning algorithm for the detection of cardiac radio-frequency ablation (RFA) targets with respect to learning from images alone. Methods: Initially, we compute image features from delayed-enhanced magnetic resonance imaging (DE-MRI) to describe local tissue heterogeneities and feed them into a machine learning framework with uncertainty assessment for the identification of potential ablation targets. Next, we introduce the use of a patient-specific image-based model derived from DE-MRI coupled with the Mitchell–Schaeffer electrophysiology model and a dipole formulation for the simulation of intracardiac electrograms. Relevant features are extracted from these simulated signals which serve as a feature augmentation scheme for the learning algorithm. We assess the classifier's performance when using only image features and with model-based feature augmentation. Results: We obtained average classification scores of 97.2 $\%$ accuracy, 82.4 $\%$ sensitivity, and 95.0 $\%$ positive predictive value by using a model-based feature augmentation scheme. Preliminary results also show that training the algorithm on the closest patient from the database, instead of using all the patients, improves the classification results. Conclusion: We presented a feature augmentation scheme based on biophysical cardiac electrophysiology modeling to increase the prediction scores of a machine learning framework for the RFA target prediction. Significance: The results derived from this study are a proof of concept that the use of model-based feature augmentation strengthens the performance of a purely image driven learning scheme for the prediction of cardiac ablation targets. [ABSTRACT FROM AUTHOR]

In Sierra Leone, migration to diamond fields and the development of cash crops have contributed to the increasing integration of the peasantry in the national and global economy. Based on the study of a small northern chiefdom, Sella Limba, we describe how the labour commodification have led to the perversion of “traditional” social relations based on anteriority, and to the break‐up of large domestic groups into smaller, more precarious ones. At the same time, manual agriculture has been marginalized by massive cheap rice imports and remained very low in capital intensity. In this context, we show how low labour productivity curtails opportunities for long‐term social and economic differentiation. Farmers combine “modern” and “traditional” social relations, developing hybrid accumulation strategies that are sometimes close to mere survival. [ABSTRACT FROM AUTHOR]

The potential of cardiac magnetic resonance to improve cardiovascular care and patient management is considerable. Myocardial T1-rho (T1ρ) mapping, in particular, has emerged as a promising biomarker for quantifying myocardial injuries without exogenous contrast agents. Its potential as a contrast-agent-free ("needle-free") and cost-effective diagnostic marker promises high impact both in terms of clinical outcomes and patient comfort. However, myocardial T1ρ mapping is still at a nascent stage of development and the evidence supporting its diagnostic performance and clinical effectiveness is scant, though likely to change with technological improvements. The present review aims at providing a primer on the essentials of myocardial T1ρ mapping, and to describe the current range of clinical applications of the technique to detect and quantify myocardial injuries. We also delineate the important limitations and challenges for clinical deployment, including the urgent need for standardization, the evaluation of bias, and the critical importance of clinical testing. We conclude by outlining technical developments to be expected in the future. If needle-free myocardial T1ρ mapping is shown to improve patient diagnosis and prognosis, and can be effectively integrated in cardiovascular practice, it will fulfill its potential as an essential component of a cardiac magnetic resonance examination. [ABSTRACT FROM AUTHOR]

Success rates for catheter ablation of persistent atrial fibrillation patients are currently low; however, there is a subset of patients for whom electrical isolation of the pulmonary veins alone is a successful treatment strategy. It is difficult to identify these patients because there are a multitude of factors affecting arrhythmia susceptibility and maintenance, and the individual contributions of these factors are difficult to determine clinically. We hypothesised that the combination of pulmonary vein (PV) electrophysiology and atrial body fibrosis determine driver location and effectiveness of pulmonary vein isolation (PVI). We used bilayer biatrial computer models based on patient geometries to investigate the effects of PV properties and atrial fibrosis on arrhythmia inducibility, maintenance mechanisms, and the outcome of PVI. Short PV action potential duration (APD) increased arrhythmia susceptibility, while longer PV APD was found to be protective. Arrhythmia inducibility increased with slower conduction velocity (CV) at the LA/PV junction, but not for cases with homogeneous CV changes or slower CV at the distal PV. Phase singularity (PS) density in the PV region for cases with PV fibrosis was increased. Arrhythmia dynamics depend on both PV properties and fibrosis distribution, varying from meandering rotors to PV reentry (in cases with baseline or long APD), to stable rotors at regions of high fibrosis density. Measurement of fibrosis and PV properties may indicate patient specific susceptibility to AF initiation and maintenance. PV PS density before PVI was higher for cases in which AF terminated or converted to a macroreentry; thus, high PV PS density may indicate likelihood of PVI success. [ABSTRACT FROM AUTHOR]

After percutaneous implantation of a cardiac occluder, a complex healing process leads to the device coverage within several months. An incomplete device coverage increases the risk of device related complications such as thrombosis or endocarditis. We aimed to assess the device coverage process of atrial septal defect (ASD) occluders in a chronic sheep model using micro-computed tomography (micro-CT). After percutaneous creation of an ASD, 8 ewes were implanted with a 16-mm Nit-Occlud ASD-R occluder (PFM medical, Cologne, Germany) and were followed for 1 month (N = 3) and 3 months (N = 5). After heart explant, the device coverage was assessed using micro-CT (resolution of 41.7 μm) and was compared to histological analysis. The micro-CT image reconstruction was performed in 2D and 3D allowing measurement of the coverage thickness and surface for each device. Macroscopic assessment of devices showed that the coverage was complete for the left-side disk in all cases. Yet incomplete coverage of the right-side disk was observed in 5 of the 8 cases. 2D and 3D micro-CT analysis allowed an accurate evaluation of device coverage of each disk and was overall well correlated to histology sections. Surface calculation from micro-CT images of the 8 cases showed that the median surface of coverage was 93±8% for the left-side disk and 55±31% for the right-side disk. The assessment of tissue reactions, including endothelialisation, after implantation of an ASD occluder can rely on in vitro micro-CT analysis. The translation to clinical practice is challenging but the potential for individual follow-up is shown, to avoid thrombotic or infective complications. [ABSTRACT FROM AUTHOR]

Goal: In this paper, we used in silico patient-specific models constructed from three-dimensional delayed-enhanced magnetic resonance imaging (DE-MRI) to simulate intracardiac electrograms (EGM). These included electrically abnormal EGM as these are potential radiofrequency ablation (RFA) targets. Methods: We generated signals with distinguishable macroscopic normal and abnormal characteristics by constructing MRI-based patient-specific structural heart models and by solving the simplified biophysical Mitchell–Schaeffer model of cardiac electrophysiology (EP). Then, we simulated intracardiac EGM by modeling a recording catheter using a dipole approach. Results: Qualitative results show that simulated EGM resemble clinical signals. Additionally, the quantitative assessment of signal features extracted from the simulated EGM showed statistically significant differences (p $<$ 0.0001) between the distributions of normal and abnormal EGM, similarly to what is observed on clinical data. Conclusion: We demonstrate the feasibility of coupling simplified cardiac EP models with imaging data to generate intracardiac EMG. Significance: These results are a step forward in the direction of the preoperative and noninvasive identification of ablation targets to guide RFA therapy. [ABSTRACT FROM AUTHOR]

Introduction: To investigate whether the current standard voltage cut‐off of <0.5 for dense scar definition on endocardial bipolar voltage mapping (EBVM), using a high‐resolution multipoint mapping catheter with microelectrodes (HRMMC), correctly identifies the actual scar area described on CT with myocardial thinning (CT MT). Methods: Forty patients (39 men; 67.0 ± 9.0 y/o) with a history of transmural myocardial infarction (mean time interval since MI 15.0 ± 7.9 years) and sustained ventricular tachycardia (VT) were consecutively enrolled. A CT MT was performed in each patient before VT ablation. The CT MT 3D anatomical model, including MT layers, was merged with the 3D electroanatomical and EBVM. Different predefined cut‐off settings for scar definition on EBVM were used to identify the optimal ones, which showed the best overlap in terms of scar area with the different MT layers. Results: A cut‐off value of <0.2 mV demonstrated the best correlation in terms of scar area with the 2 mm thinning on CT MT (p =.04) and a cut‐off of <1 mV best overlapped with the 5 mm thinning (p =.003). The currently used <0.5 mV cut‐off for scar definition on EBVM proved to be the best area correlation with 3 mm thinning (p =.0002). Conclusion: In order to better identify the real extent of scar areas after transmural MI as described on preprocedural CT MT, higher cut‐off values for scar definition should be applied if the EBVM is performed using a HRMMC. [ABSTRACT FROM AUTHOR]

Introduction: Systematic and quantitative descriptions of vein of Marshall (VOM)‐induced tissue ablation are lacking. We sought to characterize the distribution of low voltage observed in the left atrium (LA) after VOM ethanol infusion. Methods and Results: The distribution of ethanol‐induced low voltage was evaluated by comparing high‐density maps performed before and after VOM ethanol infusion in 114 patients referred for atrial fibrillation ablation. The two most frequently impacted segments were the inferior portion of the ridge (82.5%) and the first half of the mitral isthmus (pulmonary vein side) (92.1%). Low‐voltage absence in these typical areas resulted from inadvertent ethanol infusion in the left atrial appendage vein (n = 3), initial VOM dissection (n = 3), or a "no branches" VOM morphology (n = 1). Visible anastomosis of the VOM with roof or posterior veins more frequently resulted in low‐voltage extension beyond typical areas, toward the entire left antrum (19.0% vs. 1.9%, p =.0045) or the posterior LA (39.7% vs. 3.8%, p <.001) but with a limited positive predictive value ranging from 29.4% to 43.5%. Ethanol‐induced low voltage covered a median LA surface of 3.6% (1.9%–5.0%) and did not exceed 8% of the LA surface in 90% of patients. Conclusion: VOM ethanol infusion typically locates at the inferior ridge and the adjacent half of the mitral isthmus. Low‐voltage extensions can be anticipated but not guaranteed by the presence of visible anastomosis of the VOM with roof or posterior veins. [ABSTRACT FROM AUTHOR]

The mechanisms responsible for perpetuation of human persistent atrial fibrillation (AF) are controversial and probably vary between individuals. A wide spectrum of mechanisms have been described in experimental studies, ranging from a single localized stable (focal/reentrant) source, to multiple sources, up to diffuse bi-atrial wavelets. We characterized AF drivers in patients with persistent AF (lasting less than 1 year) using novel high resolution mapping, imaging and modelling approaches with the objective of evaluating their relationship to atrial structural heterogeneities. Using panoramic non-invasive mapping in humans, focal or reentrant sources driving AF waves were identified, originating from multiple distinct regions and exhibiting short lifespans and periodic recurrences in the same locations. The reentrant driver regions harboured long, fractionated electrograms covering most of the fibrillatory cycle lengths with varying beat-to-beat sequences suggestive of unstable trajectories attached to slow conducting heterogeneous tissue. MRI atrial imaging demonstrated that such drivers preferentially clustered at the borders of fibrotic atrial regions. In patient-specific computer simulations, sustained AF was shown to be driven by meandering transitory reentries attached to fibrosis borders expressing specific metrics in density and extent. Finally, random microstructural alterations devoid of cellular electrical changes were modelled, showing that a percolation mechanism could also explain atrial reentries and complex fractionated electrograms. These data from clinical, imaging and computational studies strongly suggest that intermittent and spatially unstable drivers anchoring to structural heterogeneities are a major pathophysiological mechanism in human persistent atrial fibrillation. [ABSTRACT FROM AUTHOR]

Introduction: The optimal strategy after a failed ablation for persistent atrial fibrillation (perAF) is unknown. This study evaluated the value of an anatomically guided strategy using a systematic set of linear lesions with adjunctive ethanol infusion into the vein of Marshall (Et‐VOM) in patients referred for second perAF ablation procedures. Methods and Results: Patients with perAF who underwent a second procedure were grouped according to the two strategies. The first strategy was an anatomically guided approach using systematic linear ablation with adjunctive Et‐VOM, with bidirectional blocks at the posterior mitral isthmus (MI), roof, and cavotricuspid isthmus (CTI) as the procedural endpoint (Group I). The second one was an electrophysiology‐guided strategy, with atrial tachyarrhythmia termination as the procedural endpoint (Group II). Arrhythmia behavior during the procedure guided the ablation strategy. Groups I and II consisted of 96 patients (65 ± 9 years; 71 men) and 102 patients (63 ± 10 years; 83 men), respectively. Baseline characteristics were comparable. In Group I, Et‐VOM was successfully performed in 91/96 (95%), and procedural endpoint (bidirectional block across all three anatomical lines) was achieved in 89/96 (93%). In Group II, procedural endpoint (atrial tachyarrhythmia termination) was achieved in 80/102 (78%). One‐year follow‐up demonstrated Group I (21/96 [22%]) experienced less recurrence compared to Group II (38/102 [37%], Log‐rank p =.01). This was driven by lower AT recurrence in Group I (Group I: 10/96 [10%] vs. Group II: 29/102 [28%]; p =.002). Conclusion: Anatomically guided strategy with adjunctive Et‐VOM is superior to an electrophysiology‐guided strategy for second procedures in patients with perAF at 1‐year follow‐up. [ABSTRACT FROM AUTHOR]

Background: Focal ventricular arrhythmias (VAs) originating from the intramural myocardium of the basal septum are difficult to localize and ablate. Proximal septal veins emptying into the great cardiac vein can reach close to the origin of intramural arrhythmias. Objective: To assess characteristics of proximal septal coronary veins in patients with intramural VAs. Methods and Results: Among 84 consecutive patients with intramural VAs, 29 patients (age 60 ± 11years, 16 males, ejection fraction 47 ± 13%) underwent preprocedural cardiac computed tomographic angiography (CTA). In 14 of these patients, the intramural site of origin (SOO) was identified with multipolar catheters. The intramural SOO could not be accessed with mapping catheters in the other 15 patients while mapping the coronary venous system. The CTA identified sizable proximal septal veins in all patients in whom the SOO could be accessed with mapping catheters. In the patients in whom the intramural SOO was not identified, the proximal septal veins were often either small (<2 mm at the branching site) or non‐existent (n = 9, p =.001). The proximal septal veins in patients in whom the SOO was identified were larger than in the patients in whom the SOO could not be identified (3.0 ± 0.6 mm vs. 2.1 ± 0.9 mm, p =.01). Conclusions: Preprocedural imaging with CTAs can be beneficial in identifying the anatomy of proximal septal coronary veins that allow adequate mapping of patients with suspected intramural VAs. [ABSTRACT FROM AUTHOR]

Background: Intramural ventricular arrhythmias (VAs) can originate in patients with or without structural heart disease. Electrogram (EGM) recordings from intramural sources of VA have not been described thoroughly. Objective: We hypothesized that the presence of scar may be linked to the site of origin (SOO) of focal, intramural VAs. Methods: In a series of 21 patients (age: 55 ± 11 years, 12 women, mean ejection fraction 43 ± 14%) in whom the SOO of intramural VAs was identified, we analyzed bipolar EGM characteristics at the SOO and compared the findings with the endocardial breakout site. The patients were from a pool of 86 patients with intramural VAs referred for ablation. Results: In 16/21 patients intramural scarring was detected by cardiac magnetic resonance (CMR) imaging In patients in whom the intramural SOO was reached, intramural bipolar EGMs showed a lower voltage and had broader EGMs compared to the endocardial breakout sites (0.97 ± 0.56 vs. 2.28 ± 0.15 mV, p =.001; and 122.3 ± 31.6 vs. 96.5 ± 26.3 ms, p <.01). All intramural sampled sites at the SOO had either low voltage or broad abnormal EGMs. The activation time was significantly earlier at the intramural SOO than at breakout sites (−36.2 ± 11.8 vs. −23.2 ± 9.1 ms, p <.0001). Conclusions: Sites of origin of intramural VAs with scar by CMR display EGM characteristics of scarring, supporting that scar tissue localizes to the SOO of intramural outflow tract arrhythmias in some patients. Scarring identified by CMR may be helpful in planning ablation procedures in patients with suspected intramural VAs. [ABSTRACT FROM AUTHOR]

Epicardial-Only VT Ablation Background Nonischemic cardiomyopathy is a heterogeneous condition providing a favorable substrate for ventricular tachycardia (VT). Objective The purpose of this study is to further characterize the substrate in a subset of postmyocarditis patients with epicardial-only scar. Methods Twelve postmyocarditis patients (11 male, 49 ± 14 years, left ventricular ejection fraction 49 ± 12%) with VT and epicardial-only scar were included for analysis comparing automatic high-amplitude normal activity (HANA) maps to manually adjusted maps of based on local abnormal ventricular activity (LAVA) electrograms when present. A combined endocardial (endo) and epicardial (epi) approach was used in 11/12 with usual bipolar/unipolar voltage thresholds and analyzed using image integration. Results A delayed enhancement MRI scar area of 52 cm2 (38, 59) and multidetector CT wall thinning area of 18 cm2 (14, 35) was found. Bipolar voltage substrate mapping (160 points [101, 239] endo, 553 points [232, 713] epi and LAVA were found only epicardially [443 LAVA points] in all) illustrated a low-voltage area of HANA: 1 cm2 (0, 10) endo, 25 cm2 (22, 39) epi and LAVA: 1 cm2 (0, 10) endo, 39 cm2 (28, 51) epi. Manual maps performed better than automatic maps for delineating low-voltage area with a higher overlap with scar area on delayed enhancement magnetic resonance imaging (DE-MRI; 76% [66, 94] vs. 45% [35, 62]; P = 0.04). In addition, manual voltage maps also showed a higher overlap with location of LAVA (LAVA in normal voltage area: 3% [0, 9] vs. 35% [32, 41]; P < 0.05). Conclusion In postmyocarditis patients with epicardial-only scar, automatic voltage mapping may miss or minimize the electrical VT substrate. DE-MRI and manual LAVA-based voltage mapping are necessary to optimize scar delineation. Epicardial access is critical for mapping and ablation in this condition. [ABSTRACT FROM AUTHOR]

The authors examine the effectiveness of electroanatomic mapping (EAM) systems and cardiac magnetic resonance imaging (CMR) techniques in delineating left atrial (LA) scar. They discuss several studies that indicate the challenges in validating the effectiveness of EAM systems over CMR. Among the challenges cited by the authors include the standardization of CMR techniques and the characterization of different lesion types, patient subsets and clinical scenarios.

Background: Late gadolinium enhancement cardiac magnetic resonance (LGE‐CMR) imaging distinguishes between intrinsic postinfarction scar and radiofrequency ablation lesion related scar (dark core lesions [DCLs]) in patients with prior ventricular tachycardia (VT) ablation procedures. Objective: To combine LGE‐CMR and electroanatomic mapping data to describe the relationship between DCLs and recurrent VT among patients undergoing repeat ablations for postinfarction VT. Methods: Consecutive patients with repeat ablation for postinfarct VT with LGE‐CMR before the repeat procedures were studied. Prior ablation procedures and implantable cardiac defibrillator electrograms were analyzed to determine new versus previously documented VT. DCLs were identified on preprocedure LGE‐CMR and registered to electroanatomic maps. A control group of patients undergoing repeat ablation procedures without imaging was included. Results: Nineteen study patients and 14 control patients were followed for 2.6 (1.6–5.6) years (31 [94%] men, age 65.8 ± 8.4 years, ejection fraction 24.7 ± 10.3, p > 0.10 for all). DCLs corresponded to unexcitable tissue during repeat procedures (area 22.4 ± 15.1 vs. 22.9 ± 16.8 cm3, correlation coefficient =.93). Most VT target sites (39/50 [78%]) were in close proximity (<1 cm) to DCLs. Most DCL related VTs 32/39 (82%) were new VTs. Patients with LGE‐CMR imaging incorporated into their ablation procedures had improved 24‐month survival from VT (64% vs. 38%, log rank p < 0.02). Conclusion: LGE‐MRI can identify prior ablation lesions corresponding to nonexcitable tissue during repeat ablation procedures for postinfarction VT. VT target sites are often located in close proximity to the DCL area that may function as a fixed border for reentry circuits. Registration of DCL from prior ablation may facilitate repeat ablation procedures. [ABSTRACT FROM AUTHOR]

Introduction: Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). The origin of VF and the success of catheter ablation to eliminate recurrent episodes in this population are poorly understood. Methods and Results: From 2010 to 2014, five patients with HCM (age 21 ± 9 years, three female) underwent invasive electrophysiological studies and ablation at our center after resuscitation from recurrent (9 ± 7) episodes of VF. Ventricular premature beats (VPBs), seen to initiate VF in certain cases, were recorded noninvasively before the ablation procedure. Postprocedural computed tomography (CT) was performed to correlate ablation sites with myocardial hypertrophy in three patients. Outcomes were assessed by clinical follow‐up and implantable cardioverter‐defibrillator interrogations. VPB triggers were localized invasively to the distal left Purkinje conduction system (left posterior fascicle [2], left anterior fascicle [1], and both fascicles [2]). All targeted VF triggers were successfully eliminated by radiofrequency ablation in the left ventricle. Among patients with postablation CT imaging, 93 ± 12% of ablation sites corresponded to hypertrophied segments. Over 50 ± 38 months, four of five patients were free from primary VF without antiarrhythmic drug therapy. One patient who had 13 episodes of VF before ablation had a single recurrence. Conclusion: In our study of patients with HCM and recurrent VF, VF was not initiated from the myocardium but rather from Purkinje arborization. These sources colocalized with the hypertrophic substrate, suggesting electromechanical interaction. Focal ablation at these sites was associated with a marked reduction in VF burden. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular magnetic resonance T1ρ mapping may detect myocardial injuries without exogenous contrast agent. However, multiple co-registered acquisitions are required, and the lack of robust motion correction limits its clinical translation. We introduce a single breath-hold myocardial T1ρ mapping method that includes model-based non-rigid motion correction. Methods: A single-shot electrocardiogram (ECG)-triggered balanced steady state free precession (bSSFP) 2D adiabatic T1ρ mapping sequence that collects five T1ρ-weighted (T1ρw) images with different spin lock times within a single breath-hold is proposed. To address the problem of residual respiratory motion, a unified optimization framework consisting of a joint T1ρ fitting and model-based non-rigid motion correction algorithm, insensitive to contrast change, was implemented inline for fast (~ 30 s) and direct visualization of T1ρ maps. The proposed reconstruction was optimized on an ex vivo human heart placed on a motion-controlled platform. The technique was then tested in 8 healthy subjects and validated in 30 patients with suspected myocardial injury on a 1.5T CMR scanner. The Dice similarity coefficient (DSC) and maximum perpendicular distance (MPD) were used to quantify motion and evaluate motion correction. The quality of T1ρ maps was scored. In patients, T1ρ mapping was compared to cine imaging, T2 mapping and conventional post-contrast 2D late gadolinium enhancement (LGE). T1ρ values were assessed in remote and injured areas, using LGE as reference. Results: Despite breath holds, respiratory motion throughout T1ρw images was much larger in patients than in healthy subjects (5.1 ± 2.7 mm vs. 0.5 ± 0.4 mm, P < 0.01). In patients, the model-based non-rigid motion correction improved the alignment of T1ρw images, with higher DSC (87.7 ± 5.3% vs. 82.2 ± 7.5%, P < 0.01), and lower MPD (3.5 ± 1.9 mm vs. 5.1 ± 2.7 mm, P < 0.01). This resulted in significantly improved quality of the T1ρ maps (3.6 ± 0.6 vs. 2.1 ± 0.9, P < 0.01). Using this approach, T1ρ mapping could be used to identify LGE in patients with 93% sensitivity and 89% specificity. T1ρ values in injured (LGE positive) areas were significantly higher than in the remote myocardium (68.4 ± 7.9 ms vs. 48.8 ± 6.5 ms, P < 0.01). Conclusions: The proposed motion-corrected T1ρ mapping framework enables a quantitative characterization of myocardial injuries with relatively low sensitivity to respiratory motion. This technique may be a robust and contrast-free adjunct to LGE for gaining new insight into myocardial structural disorders. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular magnetic resonance T1ρ mapping may detect myocardial injuries without exogenous contrast agent. However, multiple co-registered acquisitions are required, and the lack of robust motion correction limits its clinical translation. We introduce a single breath-hold myocardial T1ρ mapping method that includes model-based non-rigid motion correction. Methods: A single-shot electrocardiogram (ECG)-triggered balanced steady state free precession (bSSFP) 2D adiabatic T1ρ mapping sequence that collects five T1ρ-weighted (T1ρw) images with different spin lock times within a single breath-hold is proposed. To address the problem of residual respiratory motion, a unified optimization framework consisting of a joint T1ρ fitting and model-based non-rigid motion correction algorithm, insensitive to contrast change, was implemented inline for fast (~ 30 s) and direct visualization of T1ρ maps. The proposed reconstruction was optimized on an ex vivo human heart placed on a motion-controlled platform. The technique was then tested in 8 healthy subjects and validated in 30 patients with suspected myocardial injury on a 1.5T CMR scanner. The Dice similarity coefficient (DSC) and maximum perpendicular distance (MPD) were used to quantify motion and evaluate motion correction. The quality of T1ρ maps was scored. In patients, T1ρ mapping was compared to cine imaging, T2 mapping and conventional post-contrast 2D late gadolinium enhancement (LGE). T1ρ values were assessed in remote and injured areas, using LGE as reference. Results: Despite breath holds, respiratory motion throughout T1ρw images was much larger in patients than in healthy subjects (5.1 ± 2.7 mm vs. 0.5 ± 0.4 mm, P < 0.01). In patients, the model-based non-rigid motion correction improved the alignment of T1ρw images, with higher DSC (87.7 ± 5.3% vs. 82.2 ± 7.5%, P < 0.01), and lower MPD (3.5 ± 1.9 mm vs. 5.1 ± 2.7 mm, P < 0.01). This resulted in significantly improved quality of the T1ρ maps (3.6 ± 0.6 vs. 2.1 ± 0.9, P < 0.01). Using this approach, T1ρ mapping could be used to identify LGE in patients with 93% sensitivity and 89% specificity. T1ρ values in injured (LGE positive) areas were significantly higher than in the remote myocardium (68.4 ± 7.9 ms vs. 48.8 ± 6.5 ms, P < 0.01). Conclusions: The proposed motion-corrected T1ρ mapping framework enables a quantitative characterization of myocardial injuries with relatively low sensitivity to respiratory motion. This technique may be a robust and contrast-free adjunct to LGE for gaining new insight into myocardial structural disorders. [ABSTRACT FROM AUTHOR]

Pulmonary vein (PV) stretch is proarrhythmic for atrial fibrillation (AF). AF patients often report that a left lateral (LL) body position can trigger arrhythmia symptoms. Because the PV myocardium is thought to trigger AF, we hypothesized that the LL compared to the supine body position increases PV wall stress. Functional cardiac magnetic resonance imaging was performed in supine and LL recumbent body position in awake condition in healthy human volunteers (n = 20). Following a change from supine to LL position, the heart moved in an anterior‐LL direction in the thorax. The right superior PV diameter was increased by 19% (24.6 ± 3.1 vs. 20.7 ± 3.2 mm, p = 0.009) and left atrial (LA) volume was larger by 17% (61.7[15.4] vs. 51.0[17.8] ml, p = 0.015) in LL than supine position, respectively. The passive LA conduit fraction (normalized difference between maximum and pre‐contraction LA volume) increased by 25% in LL compared to supine position (19.6 ± 9.0 vs. 15.7 ± 7.6%, respectively, p = 0.016). Local wall stress in the PV regions increased in LL compared to supine position (overall mean: 1.01 ± 0.12 vs. 1.10 ± 0.10 arb. unit, LL vs. supine, position effect p = 0.041), whereas this was not the case in the LA walls (overall mean: 1.18 ± 0.31 vs. 1.21 ± 0.21 arb. unit, LL vs. supine, position effect p = 0.381). In conclusion, a left lateral body position increases PV myocardial stress during the atrial relaxation phase of healthy volunteers. These results have implications for the mechanisms of posture‐triggered AF. [ABSTRACT FROM AUTHOR]

Introduction: In patients with structural heart disease presenting with ventricular tachycardia (VT), detection of ventricular thrombi and subsequent management can be challenging. This study aimed to assess the value of multimodality imaging with cardiac magnetic resonance imaging (CMR), contrast‐enhanced transthoracic echocardiography (TTE), and computed tomography (CT) for thrombus detection as well as a management algorithm geared towards anticoagulation and deferred ablation for patients referred for VT ablation. Methods and results: A total of 154 consecutive patients referred for VT ablation underwent preprocedural multimodality imaging with CMR, CT, and TTE. In 9 patients (6%) a new ventricular thrombus was detected and anticoagulation was initiated. Thrombi were detected by CMR in nine patients, by CT in seven patients, and by TTE in two patients. Five patients eventually underwent endocardial VT ablation procedures 6.0 ± 2.0 months after initiation of anticoagulation with one patient also requiring an epicardial approach. Two patients died while on anticoagulation, unrelated to ventricular arrhythmia. Four of five patients were rendered non‐inducible and no testing was performed in 1/5 patients. Areas containing left ventricular thrombi were non‐excitable with pacing. Six of thirty‐two inducible VTs were mapped in close vicinity of ventricular thrombi. No clinical embolic events occurred during the ablation procedures. Conclusions: Ventricular thrombus was detected in 6% of consecutive patients with structural heart disease undergoing VT ablation. CMR was the most sensitive modality, while contrast‐enhanced TTE failed to detect the majority of thrombi. Anticoagulation followed by ablation can be safely and successfully performed in patients with ventricular thrombi. [ABSTRACT FROM AUTHOR]

Introduction: Left ventricular noncompaction (LVNC) is associated with ventricular arrhythmias (VA) including premature ventricular complexes, and ventricular tachycardia (VT). The value of imaging with delayed enhancement cardiac magnetic resonance (DE‐CMR) and programmed ventricular stimulation (PVS) for risk stratification in patients with VA and LVNC is unknown. The purpose of this study was to determine whether DE‐CMR and PVS are beneficial for risk stratification and whether CMR helps to identify VA target sites. Methods and Results: Consecutive patients with LVNC undergoing ablation for VAs were included, all patients had preprocedure DE‐CMR. A total of 23 patients (7 women, 46 ± 14 years, ejection fraction 35 ± 14) were included and followed for 2.9 ± 2.2 years. DE‐CMR scar was present in 12/23 patients (52%). PVS was performed in 20/23 patients, 8/10 patients (80%) with scar were inducible for VT compared to 0/10 (0%) patients without scar (p <.001). VA target sites in patients with scarring were located adjacent to areas of scarring in all but 1 patient and ablation was successful in 15/23 patients (65%). Patients with scar had worse survival free of VT than those without scar (log rank p =.01) and patients with inducible VT had worse survival free of VT than those who were noninducible (log rank p <.001). Conclusions: The presence of CMR defined scar in patients with LVNC was associated with inducible VT and worse outcomes. Inducibility for VT was associated with VT recurrence. Furthermore, CMR is beneficial in localizing the arrhythmogenic substrate in LVNC and therefore can aid in procedural planning. [ABSTRACT FROM AUTHOR]

Electrocardiomapping in Right Atrial Diverticulum and Accessory Pathway Combination of structural (CT-scan) and functional (3D electrocardiomapping) imaging methods helped successfully accomplish ablation of a life-threatening manifest accessory pathway in association with a complex right atrial anomaly after previous unsuccessful attempts of endo-epicardial ablation guided by the invasive electroanatomic system in an adolescent female. Such a system has a potential to facilitate the ablation procedure and impact its outcome through accurate localization of the arrhythmogenic substrate. (J Cardiovasc Electrophysiol, Vol. 24, pp. 583-585, May 2013) [ABSTRACT FROM AUTHOR]

Background: No study to date has used high‐density mapping to investigate the relationship between prior radiofrequency (RF) lesions for persistent atrial fibrillation (PsAF) ablation and subsequent atrial tachycardias (ATs). Methods: From 41 consecutive patients who underwent AT ablation at a second procedure using an ultrahigh‐density mapping system, 22 patients (38 ATs) were included as they also had complete maps with a multipolar catheter and three‐dimensional (3D) mapping system at the time of the first PsAF ablation procedure. We, therefore, compared voltage maps from the first AF ablation procedure to those from the subsequent AT ablation procedure, as well as the lesion sets used for AF ablation vs the activation patterns in AT during the second procedure. Results: In the 38 ATs, 211 of 285 analyzed atrial areas displayed low voltage area (LVA) (74%). Eighteen percent (38/211) existed before the index ablation for AF while 82% (173/211) were newly identified as LVA during the second procedure. Ninety‐nine percent (172/173) of the newly developed LVA colocalized with RF lesions delivered for PsAF. Of the 38 ATs, 89.5% (34/38) AT circuits were associated with newly developed LVA due to RF lesions whilst 10.5% (4/38) AT circuits were associated with pre‐existing LVA observed at the index procedure. No AT circuit was completely independent from index RF lesions in this series. Conclusions: Analysis of detailed 3D electroanatomical mapping demonstrates that most ATs after PsAF ablation are involving LVAs due to index RF lesions. [ABSTRACT FROM AUTHOR]

Background: Use of lesion metric indices is a proposed strategy to support pulmonary vein isolation procedures and these indices show good correlations with lesion sizes. The aim of this in silico study is to provide a detailed analysis of radiofrequency (RF) settings, including high‐power short‐duration (HPSD) settings, and resulting lesion metric indices. Methods and Results: A software program was designed which simulated virtual RF ablations. Lesion metric indices (Ablation index: AI, Lesion size index: LSI) were calculated based on underlying RF settings (contact force [CF], power, duration). In series of calculations, the applied settings were varied within defined ranges (CF: 1‐80 g, power: 1‐60 W, duration: 1‐60 seconds). Overall, n = 388 000 virtual ablations were calculated. The resulting lesion metric indices were compared with each other and analyzed in relation to respective RF settings. Increasing contact force from 1 to 10 g resulted in a 4.4‐fold LSI value, whilst increasing contact force from 10 to 20g resulted in a 1.5‐fold value (P <.01). When RF power was increased by 10 W, lesion metric indices increased between 1.3‐ and 1.6‐fold. A prolongation of RF duration by 10 seconds resulted in a 1.2‐to‐1.3‐fold increase of lesion metric indices. HPSD RF applications of 50 W, 11 to 13 seconds, and 60 W, 8 to 10 seconds resulted in equivalent lesion metric indices when compared with 30 W, 30 seconds conventional ablations. Conclusions: The findings support the clinical use of contact forces within a 10 to 20 g range. AI is more sensitive to RF duration, whereas LSI is more sensitive to contact force. HPSD RF settings can successfully be derived from lesion metric indices. [ABSTRACT FROM AUTHOR]

To assess the relationship between heart rate response and exercise tolerance in adults with systemic right ventricle (sRV) after atrial switch repair for Transposition of the Great Artery (TGA) in addition to other physiological parameters. All patients with a sRV after atrial switch repair for TGA followed in our institution between June 2015 and April 2018 who underwent cardiopulmonary exercise testing (CPET) were analyzed. Cardiac imaging performed within a six-month time period of the CPET were also collected. Chronotropic incompetence was defined as the inability to achieve 80% of age-predicted maximal heart rate reserve (HRR) and <62% on a beta-blocker regimen. Patient characteristics were assessed according to tertiles of the percentage of predicted pVO2 (%ppVO2). We studied 70 patients (mean of age 32.4 ± 7.6 years old, 51 males). Mean peak oxygen uptake was 21.5 ± 5.8 mL/kg/min, corresponding to a %ppVO2 of 57 ± 14.1% while mean VE/VCO2 slope was 37.1 ± 8.2. There was a trend toward more exaggerated hyperventilation in patient with lower pVO2. Mean age-adjusted HRR was 68.5 ± 19%. Chronotropic incompetence was observed in 65.7% and was correlated with %ppVO2 (r = 0.482; p < 0.001) as physical training evaluated with Ventilatory Anaerobic threshold (r = 0.571; p < 0.001), while no difference was found based on respiratory parameters. No echocardiographic or Magnetic Resonance Imaging parameters assessing sRV systolic function at rest were correlated with %ppVO2. Exercise limitation is related to the inability to increase cardiac output during exercise and is notably due to the degree of chronotropic incompetence. • Exercise intolerance is common in adults with TGA after atrial switch. • Chronotropic incompetence concerned the major part of the patient. • The degree of chronotropic incompetence is a major determinant of exercise intolerance. • There seems to be no association between resting systolic systemic right ventricle function and exercise capacity. [ABSTRACT FROM AUTHOR]

Background: We present a new, easily applicable approach for the guidance of cryoballoon (CB) pulmonary vein isolation (PVI) procedures that use the combination of a 3D‐mapping system image integration module and computed tomographic (CT)–derived anatomy. The aim of this retrospective, nonrandomized study was to investigate: (a) an alternative use for an established radiofrequency image integration module for cryo procedures; (b) a guidance technology for cryo PVI based on integrated CT anatomy; and (c) its clinical impact. Methods and results: CT left atrium–angiography was performed in 50 consecutive patients before a CB PVI procedure, and a 3D reconstruction of the cardiac anatomy was segmented. A total of 25 patients were treated using conventional fluoroscopy; 25 patients were treated using the 3D image integration technique. In the image integration group, the CARTO3 UNIVU (Biosense Webster) module was used for image integration of 3D anatomy and fluoroscopic imaging. Transseptal puncture and cryo PVI were guided by 3D‐overlay imaging. Procedures were feasible without complications in all patients and cryo PVI procedures were successfully guided using the image integration technique. The intraprocedural time needed to perform image integration was 37 ± 10 seconds. Fluoroscopy time was 31.7 ± 11.7 minutes in the conventional group and 20.1 ± 7.9 minutes in the image integration group (P < .001), procedure time was 116.3 ± 29.0 minutes in the conventional group vs 101.2 ± 20.9 minutes in the 3D group (P = .04). Conclusion: 3D‐overlay guidance of CB PVI is feasible, safe, and applicable in real time with minimal effort. It may significantly reduce radiation exposure by introducing 3D information, known from electroanatomic mapping systems, into cryo PVI procedures. [ABSTRACT FROM AUTHOR]

Background: Radiofrequency (RF) ablation is an established treatment for ventricular tachycardia (VT). However, the inability of current RF catheters to address deep or large substrate may explain most of the clinical failures. Objectives: The aim of this study is to assess the efficacy and safety of ablation in the left ventricle (LV) in sheep using a novel 8‐Fr deflectable ablation catheter (Sphere‐9; Affera, Inc) with a 9‐mm expandable spherical monopolar irrigated RF tip vs a standard RF irrigated catheter (Biosense Webster, Diamond Bar, CA). The impact on tissue was assessed on local bipolar electrograms (from nine uniformly distributed mini surface electrodes and an internal central reference electrode), as well as on direct lesion measurement post mortem. Methods and Results: Eleven sheep underwent LV endocardial ablation in healthy tissue using the Sphere‐9 catheter (n = 6), or a conventional irrigated RF catheter (n = 5). Twenty lesions were created with the Sphere‐9 (current limit: 2.7 A; temp. limit: 60°C; irrigation: 30 mL/min; and duration: 60‐120 seconds). Local bipolar electrograms at the surface of the catheter disappeared during RF delivery in 17 of 20 (85%) lesions. The mean lesion volume was 1707 ± 771 mm 3 (length: 15.8 ± 3.3 mm; width: 11.6 ± 4.2 mm; and depth: 10.3 ± 2.9 mm). Twenty‐five lesions were created with a standard RF irrigated catheter (power control 35 W; irrigation: 30 mL/min; duration: 60 seconds; volume 537 ± 398 mm 3; length: 8.2 ± 2.3 mm; width: 5.2 ± 1.8 mm; and depth: 5.5 ± 2.4 mm). The novel spherical RF catheter created significantly larger lesions (P < .001 for measurements in all dimensions). There were no steam pops with the novel ablation catheter vs one with the conventional catheter. Conclusions: This novel spherical monopolar irrigated RF catheter creates lesions that are twice as large and deep as a standard irrigated RF catheter. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation of atrial fibrillation using thermal energies such as radiofrequency or cryothermy is associated with indiscriminate tissue destruction. During pulsed field ablation (PFA), subsecond electric fields create microscopic pores in cell membranes-a process called electroporation. Among cell types, cardiomyocytes have among the lowest thresholds to these fields, potentially permitting preferential myocardial ablation.Objectives: The purpose of these 2 trials was to determine whether PFA allows durable pulmonary vein (PV) isolation without damage to collateral structures.Methods: Two trials were conducted to assess the safety and effectiveness of catheter-based PFA in paroxysmal atrial fibrillation. Ablation was performed using proprietary bipolar PFA waveforms: either monophasic with general anesthesia and paralytics to minimize muscle contraction, or biphasic with sedation because there was minimal muscular stimulation. No esophageal protection strategy was used. Invasive electrophysiological mapping was repeated after 3 months to assess the durability of PV isolation.Results: In 81 patients, all PVs were acutely isolated by monophasic (n = 15) or biphasic (n = 66) PFA with ≤3 min elapsed delivery/patient, skin-to-skin procedure time of 92.2 ± 27.4 min, and fluoroscopy time of 13.1 ± 7.6 min. With successive waveform refinement, durability at 3 months improved from 18% to 100% of patients with all PVs isolated. Beyond 1 procedure-related pericardial tamponade, there were no additional primary adverse events over the 120-day median follow-up, including: stroke, phrenic nerve injury, PV stenosis, and esophageal injury. The 12-month Kaplan-Meier estimate of freedom from arrhythmia was 87.4 ± 5.6%.Conclusions: In first-in-human trials, PFA preferentially affected myocardial tissue, allowing facile ultra-rapid PV isolation with excellent durability and chronic safety. (IMPULSE: A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation; NCT03700385; and PEFCAT: A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation; NCT03714178). [ABSTRACT FROM AUTHOR]

• We introduce a coordinate system for the atria based on anatomical landmarks. • We construct the coordinates from solutions to Laplace's equation. • We demonstrate the mapping of both scalar and vector data between different atria. • The coordinate system was used for registration and 2D visualisation of multimodal data. • Patient specific meshes with atrial structures and fibre direction were constructed using just five landmark points. Integrating spatial information about atrial physiology and anatomy in a single patient from multimodal datasets, as well as generalizing these data across patients, requires a common coordinate system. In the atria, this is challenging due to the complexity and variability of the anatomy. We aimed to develop and validate a Universal Atrial Coordinate (UAC) system for the following applications: combination and assessment of multimodal data; comparison of spatial data across patients; 2D visualization; and construction of patient specific geometries to test mechanistic hypotheses. Left and right atrial LGE-MRI data were segmented and meshed. Two coordinates were calculated for each atrium by solving Laplace's equation, with boundary conditions assigned using five landmark points. The coordinate system was used to map spatial information between atrial meshes, including scalar fields measured using different mapping modalities, and atrial anatomic structures and fibre directions from a reference geometry. Average error in point transfer from a source mesh to a destination mesh and back again was less than 0.1 mm for the left atrium and 0.02 mm for the right atrium. Patient specific meshes were constructed using the coordinate system and phase singularity density maps from arrhythmia simulations were visualised in 2D. In conclusion, we have developed a universal atrial coordinate system allowing automatic registration of imaging and electroanatomic mapping data, 2D visualisation, and patient specific model creation. [ABSTRACT FROM AUTHOR]