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Background: The transesophageal echocardiogram (TEE) is the standard imaging modality for confirming the presence or absence of patent foramen ovale. PFO is a flap valve depending on the pressure change between the left and right atrium, which can help determine whether to open. 3D‐TEE was shown to optimize the visualization of PFO. There is a causal association between PFO and unexplained stroke. It seems that 3D‐TEE can present a high‐risk PFO morphological feature, which seems to show more than just being easier to open. Methods: In total, 134 consecutive patients with cryptogenic stroke or migraine who had suspected PFO and underwent c‐TCD, TTE, and c‐TEE were included in this study. TEE confirmed the PFO. The right‐to‐left shunt (RLS) grade of PFO at rest and abdominal compression Valsalva maneuver was detected by c‐TEE. Results: The long diameter of FO (1.74 ± 0.3 vs. 1.60 ± 0.4, p = 0.039), the short diameter of FO (1.12 ± 0.3 vs. 1.00 ± 0.3, p = 0.036), perimeter of FO (4.62 ± 0.7 vs. 4.22 ± 1.0, p = 0.026), and area (1.80 ± 0.8 vs. 1.35 ± 0.8, p = 0.05) of the FO were significantly larger in the larger RLS group. In group of CS, a larger proportion of Eustachian valve or a Chiari's network (14.3% vs. 3.5%, p = 0.036), a larger proportion of in the left funnelform (55.1% vs. 16.3%, p < 0.001), a longer length of the PFO tunnel (13.4 ± 4.4 vs. 7.8 ± 2.5, p < 0.001), a lower IVC‐PFO angle (16.4 ± 3.4 vs. 20.3 ± 7.7, p = 0.001), a higher proportion of LA multiple exits of the tunnel (46.9% vs. 14.3%, p < 0.001). Multivariate regression analysis showed that male gender (HR: 4.026, 95% CI: 0.883–18.361, p = 0.072), age (HR: 1.076, 95% CI: 1.002–1.155, p = 0.045), the left funnelform (HR: 7.299, 95% CI: 1.585–33.618, p = 0.011), a longer length of the PFO tunnel (HR: 1.843, 95% CI: 1.404–2.418, p < 0.001) and multiple exits of the tunnel of LA (HR: 8.544, 95% CI: 1.595–45.754, p = 0.012) increased the risk of cerebral infarction. The cut‐off value calculated by ROC for the diagnosis of high‐risk PFO was that the length of the PFO tunnel was 12 mm and the left funnelform combined with multiple exits of the left atrial (sensitivity was 92%, specificity was 90%). The area under the curve of the combined index versus PoPE score (0.932 vs. 0.736) relative to the RoPE score was statistically significant. Conclusions: TEE has shown outstanding advantages in displaying the specific morphological characteristics of PFO. The left funnelform, a longer length of the PFO tunnel, and multiple exits of the tunnel of LA are associated with an increasing risk of CS in anatomical PFO respect. [ABSTRACT FROM AUTHOR]

Introduction: Typical atrial flutter (AFL) is a macroreentrant tachycardia in which intracardiac conduction rotates counterclockwise around the tricuspid annulus. Typical AFL has specific electrocardiographic characteristics, including a negative sawtooth‐like wave in the inferior lead and a positive F wave in lead V1. This study aimed to analyze the origin of the positive F wave in lead V1, which has not been completely understood. Methods: This study enrolled 10 patients who underwent radiofrequency catheter ablation for a typical AFL. Electroanatomical mapping was performed both during typical AFL and entrainment from the right atrial appendage (RAA). The 12‐lead electrocardiogram (ECG) and three‐dimensional (3D) electroanatomical maps were analyzed. Results: The positive F wave in lead V1 changed during entrainment from the RAA in all the cases. The 3D map during entrainment from the RAA revealed an area of antidromic capture around the RAA, which collided with the orthodromic wave in the anterior right atrium. This area of antidromic capture around the RAA was the only difference from the 3D electroanatomical map of AFL and is considered the cause of the change in the F wave in lead V1 during entrainment. Conclusion: The analysis of the differences in the 12‐lead ECG and 3D maps between tachycardia and entrainment from the RAA clearly demonstrated that activation around the RAA is responsible for the generation of the positive F wave in lead V1 of typical AFL. [ABSTRACT FROM AUTHOR]

Introduction: The novel cryoballoon with 28 mm or 31 mm adjustable diameters, aims to achieve a wide antral pulmonary vein isolation (PVI). However, the distribution of antral lesions and their variations based on left atrial (LA) remodeling require further clarification. Methods: We evaluated 22 patients (67 [59.5–74.8] years, 19 males) who underwent PVI of atrial fibrillation (AF) (13 paroxysmal AF [PAF] and 9 non‐PAF) using size‐adjustable cryoballoons. LA electro‐anatomical mapping was performed post‐PVI with three‐dimensional mapping systems. We assessed the shapes of the LA and pulmonary veins (PVs) and the distribution of isolated areas (IAs), comparing the results between PAF and non‐PAF patients. Results: In the left PVs (LPVs), the distance between the PV orifice and IA edge (PVos‐IA) was larger on the roof and posterior segments (~15 mm) but relatively smaller on the anterior segment near the PV ridge (<10 mm). For the right PVs (RPVs), it was more extensive in the posterior segment (10–15 mm). Comparing PAF and non‐PAF, there were no significant differences in the PVos‐IA except for the right posterior‐carina segment, antrum IA (LPVs: 5.9 ± 1.6 vs. 5.8 ± 0.8 cm², p =.81; RPVs: 4.8 ± 2.3 vs. 4.8 ± 1.2 cm², p =.81), distances between the right and left IAs on the LA posterior wall (LAPW), and un‐isolated LAPW area (9.0 ± 4.9 vs. 9.9 ± 2.5 cm², p =.62). No individual PVIs were observed in either group. Two patients exhibited overlapping IAs on the roof, and one patient who underwent 31 mm balloon applications for all PVs exhibited an LAPW isolation. Conclusion: The size‐adjustable cryoballoon achieved a wide antral PVI even in non‐PAF patients. [ABSTRACT FROM AUTHOR]

Aims Estimation of left ventricular (LV) filling pressures in patients with a history of atrial fibrillation (AF) is challenging due to lack of reliable parameters. This study investigates the association between cardiac structure and function and invasive mean left atrial pressure (LAP). Methods and results This is a multi-centre prospective study enrolling patients undergoing transcatheter ablation for AF. The invasive measurement of LAP was performed at the time of the procedure while the echocardiography within the previous 24 h. A mean LAP ≥ 15 mmHg was considered as increased. Overall, 101 patients were included (mean age 65.8 ± 8.5 years, 68% male, mean LV ejection fraction 56.6 ± 8.0%). No significant differences regarding clinical characteristics were detected between the group of patients with normal (n = 47) or increased LAP (n = 54). The latter showed lower values of LV global longitudinal strain, larger left atrial volumes (LAVs) and worse right ventricular (RV) function. After multivariable adjustment, higher E/e′ ratio (P = 0.041) and minimal LAV index (LAVI min) (P = 0.031), lower peak atrial longitudinal strain (P = 0.030), and RV free wall longitudinal strain (P = 0.037), but not maximal LAV index (LAVI max) (P = 0.137), were significantly associated with mean LAP. The associations were not modified by cardiac rhythm. Overall, LAVI min showed the best diagnostic accuracy to predict elevated LAP (area under the curve 0.703). Conclusion LA structure and function assessment well correlates with mean LAP in patients with a history of AF. These measures may be used in the assessment of filling pressure in these patients. [ABSTRACT FROM AUTHOR]

The study aimed to standardize the cryodehydration technique for bovine fetal hearts, focusing on optimizing protocols for each developmental stage to preserve morphological characteristics. We analyzed 29 bovine fetal hearts categorized into early, middle, and late developmental stages. These hearts underwent cryodehydration until a 60%–70% reduction in original fluid volume was achieved. Biometric data were recorded and statistically analyzed using Pearson correlation tests for age versus weight and age versus number of cryodehydration sessions. Morphometric comparisons before and after cryodehydration were performed using paired t‐tests. In Group I, hearts exhibited well‐defined structures, including the atrium cordis, ventriculus cordis, auricula atrii, aorta, truncus pulmonalis, and ramus coronaries arteria, which were preserved in Groups II and III. Additionally, in Group I the heart had a conical or flat apex cordis, whereas those in Groups II and III had a more pronounced apex. The average number of cryodehydration sessions required was 9.38 (±1.2) days for Group I, 12.37 (±1.4) days for Group II, and 15 days for Group III. A positive correlation was found between age and sample weight, indicating that more developed hearts were heavier. Similarly, there was a positive correlation between gestational age and the number of cryodehydration sessions, suggesting that more advanced stages required more cryodehydration sessions. Paired t‐tests demonstrated high statistical significance in the morphometric parameters before and after cryodehydration, indicating a loss of mass during dehydration. However, there was no alteration in the macroscopic structure of the hearts, which remained morphologically preserved. In conclusion, cryodehydration shows promise for preserving and analyzing the external morphological characteristics of bovine fetal cardiac development. It also provides lightweight, odorless, and easy‐to‐handle specimens ideal for detailed morphological studies and offers a unique perspective for investigating cardiac morphology in biological research contexts. [ABSTRACT FROM AUTHOR]

Purpose: Right atrial volume (RAV) and function have proven prognostic value in the assessment of cardiac disease and may be more accurately assessed using three‐dimensional echocardiography (3DE). Normal 3DE reference values for the right atrial (RA) volume and function in healthy children have not yet been published. Furthermore, current methods of indexing cardiac measurements to body surface area (BSA) alone may be insufficient. We aimed to develop reference values for 3DE‐derived RAV and function in the pediatric population, to provide a comparison of regression methods using BSA, height, weight, and sex, and to compare 3DE values to two‐dimensional echocardiography (2DE) derived volumes. Methods: We retrospectively analyzed 187 3DE datasets acquired for a multi‐center study on healthy children at two international centers. 3DE volumes were measured with vendor‐agnostic software (Tomtec), and 2DE endo‐diastolic volume (EDV) using the area‐length single‐plane approach. Regression curve‐fitting of height (Ht), weight (Wt), BSA, and sex were explored to optimize Pearson coefficient and homoscedasticity. Results: The relationship of 3DE RAVs to BSA alone was heteroscedastic, with a residual positive relationship on indexing (R2 = 0.2506). Optimal regression of Ln (Volume) = b0 + x*Ln (Ht) + y*Ln (Wt) + z*Sex was homoscedastic. Total RA emptying fraction (EF) did not vary across age or sex, however active and passive emptying was best fit by a spline curve with a knot at approximately BSA = 1 m2. Strong agreement with 2DE‐derived EDV was present (r2 = 0.83). Conclusion: We provide reference values for RA size and function in the pediatric population and provide a comparison of methods for indexing these values. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Excessive stimulation of the inositol (1,4,5)-trisphosphate (IP3) signaling pathway has been linked to AF through abnormal calcium handling. However, little is known about the mechanisms involved in this process. We expressed the fluorescence resonance energy transfer (FRET)-based cytosolic cyclic adenosine monophosphate (cAMP) sensor EPAC-SH187 in neonatal rat atrial myocytes (NRAMs) and neonatal rat ventricular myocytes (NRVMs). In NRAMs, the addition of the α1-agonist, phenylephrine (PE, 3 µM), resulted in a FRET change of 21.20 ± 7.43%, and the addition of membrane-permeant IP3 derivative 2,3,6-tri-O-butyryl-myo-IP3(1,4,5)-hexakis(acetoxymethyl)ester (IP3-AM, 20 μM) resulted in a peak of 20.31 ± 6.74%. These FRET changes imply an increase in cAMP. Prior application of IP3 receptor (IP3R) inhibitors 2-aminoethyl diphenylborinate (2-APB, 2.5 μM) or Xestospongin-C (0.3 μM) significantly inhibited the change in FRET in NRAMs in response to PE. Xestospongin-C (0.3 μM) significantly inhibited the change in FRET in NRAMs in response to IP3-AM. The FRET change in response to PE in NRVMs was not inhibited by 2-APB or Xestospongin-C. Finally, the localization of cAMP signals was tested by expressing the FRET-based cAMP sensor, AKAP79-CUTie, which targets the intracellular surface of the plasmalemma. We found in NRAMs that PE led to FRET change corresponding to an increase in cAMP that was inhibited by 2-APB and Xestospongin-C. These data support further investigation of the proarrhythmic nature and components of IP3-induced cAMP signaling to identify potential pharmacological targets. NEW & NOTEWORTHY: This study shows that indirect activation of the IP3 pathway in atrial myocytes using phenylephrine and direct activation using IP3-AM leads to an increase in cAMP and is in part localized to the cell membrane. These changes can be pharmacologically inhibited using IP3R inhibitors. However, the cAMP rise in ventricular myocytes is independent of IP3R calcium release. Our data support further investigation into the proarrhythmic nature of IP3-induced cAMP signaling. [ABSTRACT FROM AUTHOR]

A 51‐year‐old woman presented with recurring palpitations. Electrocardiography revealed narrow QRS tachycardia with short RP configuration. Computed tomography showed coronary sinus (CS) ostial atresia along with a small persistent left superior vena cava (PLSVC). Electrophysiological study identified the retrograde earliest atrial activation site (EAAS) at the CS ostium without decremental properties, and para‐Hisian pacing suggested retrograde atrioventricular nodal conduction. Using a 1.6‐Fr microelectrode catheter distally placed in the CS via the PLSVC, EAAS was confirmed within the left atrium, not the CS ostium. Transseptal approach revealed a left lateral accessory pathway, which was successfully eliminated. [ABSTRACT FROM AUTHOR]

Introduction: Pulsed‐field ablation (PFA) is a novel nonthermal energy that shows unique features that can be of use beyond pulmonary vein ablation, like tissue selectivity or proximity rather than contact dependency. Methods and Results: We report three cases of right focal atrial tachycardias arising from the superior cavoatrial junction and the crista terminalis, in close relationship with the phrenic nerve, effectively ablated using a commercially available PFA catheter designed for pulmonary vein isolation without collateral damage. Conclusion: PFA can be useful for treating right atrial tachycardias involving sites near the phrenic nerve, avoiding the need for complex nerve‐sparing strategies. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to investigate the occurrence, type and correlation of early and late atrial arrhythmias following mitral valve repair in patients with no preoperative history of atrial arrhythmias. Methods: Patients undergoing mitral valve (MV) repair for degenerative disease were included. Early and late postoperative electrocardiograms were evaluated for the incidence and type of atrial arrhythmia (atrial fibrillation [AF] or atrial tachycardia [AT]). Results: The 192 patients were included. Early atrial arrhythmias occurred in 100/192 (52.1%) patients; AF in 61 (31.8%) patients, early AT in 15 (7.8%) and both in 24 (12.5%). In total 89% of patients were discharged in sinus rhythm. During a follow‐up time of 7.3 years, 14 patients (7.3%) died and 49 (25.5%) patients developed late atrial arrhythmias. At 10 years, the cumulative incidence of any late atrial arrhythmia, with death as competing risk, was 64% (95% confidence interval [CI] = 55%–72%). On Fine‐Gray model analysis, only early postoperative AF lasting >24 h was related to the development of late AF (hazard ratio 5.99, 95% CI = 1.78%–20.10%, p =.004). Early postoperative ATs were related to the development of late tachycardias, independent of their duration (<24 h hazard ratio 4.25, 95% CI = 1.89–9.57, p =.001 and >24 h hazard ratio 3.51, 95% CI = 1.65–7.46, p =.001). Conclusions: Early and late atrial arrhythmias were common after MV repair surgery. Only early postoperative AF lasting >24 h was a risk factor for the occurrence of late AF. Conversely, any postoperative AT was correlated to the development of late ATs. [ABSTRACT FROM AUTHOR]

The Japanese Catheter Ablation (J‐AB) registry, started in August 2017, is a voluntary, nationwide, multicenter, prospective, observational registry, performed by the Japanese Heart Rhythm Society (JHRS) in collaboration with the National Cerebral and Cardiovascular Center. From January 2022, the data registration system was changed from Research Electronic Data Capture (REDCap) system to Fountayn system. The purpose of this registry was to collect the details of target arrhythmias, the ablation procedures, including the type of target arrhythmias, outcomes, and acute complications in the real‐world settings. During the year of 2022, we have collected a total of 90,042 procedures (mean age of 66.7 years and 65.9% male) from 614 participant hospitals. Detailed data were shown in Figures and Tables. [ABSTRACT FROM AUTHOR]

Background: CARTONET® enables automatic ablation site classification and reconnection site prediction using machine learning. However, the accuracy of the site classification model and trends of the site prediction model for potential reconnection sites are uncertain. Methods: We studied a total of 396 cases. About 313 patients underwent pulmonary vein isolation (PVI), including a cavotricuspid isthmus (CTI) ablation (PVI group) and 83 underwent PVI and additional ablation (i.e., box isolation) (PVI+ group). We investigated the sensitivity and positive predictive value (PPV) for automatic site classification in the total cohort and compared these metrics for PV lesions versus non‐PV lesions. The distribution of potential reconnection sites and confidence level for each site was also investigated. Results: A total of 29,422 points were analyzed (PV lesions [n = 22 418], non‐PV lesions [n = 7004]). The sensitivity and PPV of the total cohort were 71.4% and 84.6%, respectively. The sensitivity and PPV of PV lesions were significantly higher than those of non‐PV lesions (PV lesions vs. non‐PV lesions, %; sensitivity, 75.3 vs. 67.5, p <.05; PPV, 91.2 vs. 67.9, p <.05). CTI and superior vena cava could not be recognized or analyzed. In the potential reconnection prediction model, the incidence of potential reconnections was highest in the posterior, while the confidence was the highest in the roof. Conclusion: The automatic site classification of the CARTONET®R12.1 model demonstrates relatively high accuracy in pulmonary veins excluding the carina. The prediction of potential reconnection sites feature tends to anticipate areas with poor catheter stability as reconnection sites. [ABSTRACT FROM AUTHOR]

Aims Standard methods of heart chamber volume estimation in cardiovascular magnetic resonance (CMR) typically utilize simple geometric formulae based on a limited number of slices. We aimed to evaluate whether an automated deep learning neural network prediction of 3D anatomy of all four chambers would show stronger associations with cardiovascular risk factors and disease than standard volume estimation methods in the UK Biobank. Methods and results A deep learning network was adapted to predict 3D segmentations of left and right ventricles (LV, RV) and atria (LA, RA) at ∼1 mm isotropic resolution from CMR short- and long-axis 2D segmentations obtained from a fully automated machine learning pipeline in 4723 individuals with cardiovascular disease (CVD) and 5733 without in the UK Biobank. Relationships between volumes at end-diastole (ED) and end-systole (ES) and risk/disease factors were quantified using univariate, multivariate, and logistic regression analyses. Strength of association between deep learning volumes and standard volumes was compared using the area under the receiving operator characteristic curve (AUC). Univariate and multivariate associations between deep learning volumes and most risk and disease factors were stronger than for standard volumes (higher R 2 and more significant P- values), particularly for sex, age, and body mass index. AUCs for all logistic regressions were higher for deep learning volumes than standard volumes (P < 0.001 for all four chambers at ED and ES). Conclusion Neural network reconstructions of whole heart volumes had significantly stronger associations with CVD and risk factors than standard volume estimation methods in an automatic processing pipeline. [ABSTRACT FROM AUTHOR]

Simple Summary: Contrast-enhanced computed tomography (CT) is the standard radiologic examination for evaluating mediastinal tumors. In equivocal cases, cine magnetic resonance imaging (cine-MRI) and magnetic resonance imaging (MRI)/T1-weighted spin echo sequences (T1TSE) may be additionally performed. We retrospectively analyzed patients undergoing surgical resection of mediastinal tumors (benign and malignant) with prior CT, cine-MRI, and T1TSE for (re-)evaluation and comparison to the intraoperative findings and postoperative histology reports, which were defined as a gold standard. Unclear CT cases were further investigated. A total of 47 patients were included in the study. Cine-MRI is of crucial benefit in unclear CT findings compared with T1TSE, especially when infiltration into the large central vessels and atria is suspected. Background/Objectives: Contrast-enhanced computed tomography (CT) is the standard radiologic examination for evaluating the extent of mediastinal tumors. If tumor infiltration into the large central thoracic vessels, the pericardium, or the myocardium is suspected, cine magnetic resonance imaging (cine-MRI) can provide additional valuable information. Methods: We conducted a retrospective study of patients with mediastinal tumors who were staged with CT, cine-MRI, and a T1-weighted turbo spin echo (T1TSE) prior to surgical resection. Imaging was re-evaluated regarding tumor infiltration into the pericardium, myocardium, superior vena cava, aorta, pulmonary arteries, and atria and compared with intraoperative findings and postoperative histopathological reports (gold standard). Unclear CT findings were further investigated. Results: Forty-seven patients (29 female and 18 male patients; median age: 58 years) met the inclusion criteria. Cine-MRI was able to predict infiltration of the aorta in 86%, pulmonary arteries in 85%, and atria in 80% of unclear CT cases. Aortic tumor infiltration in unclear CT cases was significantly more often correctly diagnosed with cine-MRI than with T1TSE sequence. Conclusions: Additional cine-MRI is of crucial benefit in unclear CT cases. We recommend performing cine-MRI if infiltration into the large central vessels and atria is suspected. T1TSE sequence is of very limited additional value. [ABSTRACT FROM AUTHOR]

Background: Mapping of atypical atrial arrythmias arising in the left atrium is often challenging. The Local Activation Time (LAT) Histogram, a new function of the 3D color mapping system CARTO version 7, may help improve identification of atrial tachycardia circuits. We aimed to assess the effectiveness of the LAT Histogram for identification of left atrial tachycardia circuits. Methods: This retrospective study compared 25 consecutive cases of left atrial tachycardia that were treated before use of LAT Histogram (unused group) and 25 consecutive cases that were treated after introduction of LAT Histogram (used group) at Nagano Chuo Hospital. We evaluated whether we could identify the circuit of left atrial tachycardia from the electrophysiology lab data during ablation and the CARTO system data and whether we could perform effective ablation. Results: Door‐to‐door time, skin‐to‐skin time, and fluoroscopy time (p ≤.011) were all shorter in the LAT Histogram used group versus unused group, while mapping analysis times were longer in the used group (p ≤.019). A significantly greater number of cases in the LAT Histogram used compared with the unused group had ablation for entrance or exit points (19 vs. 10 cases; p =.001 for first map). Ablation resulted in a return to sinus rhythm and changed cycle length at the first mapping in 20 cases (80%) in the LAT Histogram unused group and in 24 cases (96%) in the used group. Conclusions: LAT Histogram may provide a simple and effective method to identify entrance and exit locations in left atrial tachycardia. [ABSTRACT FROM AUTHOR]

Background: Endless loop tachycardia (ELT) is the commonest pacemaker mediated tachycardia (PMT) encountered among patients with cardiac implantable electronic devices (CIEDs). Despite being enabled with various preventive algorithms, we encountered several cases having recurrent, long, and symptomatic ELT. Materials and Methods: We retrospectively analyzed consecutive device checkups at device clinic at a single center of eastern India between January 2019 to March 2023. Results: There were 20 cases of confirmed and sustained ELT among 4520 device checks. Although mostly benign, in two cases ELT led to clinical worsening in patients having left ventricular (LV) systolic dysfunction. Even with good ventricular function, ELT resulted in improper atrioventricular (AV) synchrony leading to disabling symptom in one case. The differentiation of ELT from sinus tachycardia and atrial tachycardia (AT) was not always easy. Magnet application is certainly useful to differentiate. The situations that provoked ELT in this study were—long AV delays, VIP (ventricular intrinsic preferences)/MVP (managed ventricular pacing), atrial non‐capture, atrial under/over sensing, premature ventricular contractions (PVCs)/couplets, premature atrial contractions (PAC) and slower ventriculo‐atrial (VA) conduction. Rate responsive shortening of post‐ventricular atrial refractory period (PVARP) also promoted its occurrence and hindered troubleshooting. When ELT occurred despite post‐PVC extension of PVARP, lowering the atrial sensitivity, switching to bipolar sensing and manual setting of longer PVARP after measuring VA conduction time were useful. "Rate responsive PVARP" had to be turned off in a few cases to prevent ELT. On the contrary, an over aggressive prolongation of PVARP led to repetitive non‐reentrant ventriculo‐atrial synchrony (RNRVAS) in two cases. Checking VA conduction during implantation and noninvasive program stimulation (NIPS) during follow up were useful to check the tendency for ELT. Conclusion: Clinically significant ELT is rare but not uncommon among devices having in‐built preventive algorithms. Manual adjustments are often useful to troubleshoot the same. [ABSTRACT FROM AUTHOR]

The majority of the cavotricuspid isthmus (CTI) region consists of discretely arranged muscle bundles separated by connective tissue. Heterogeneity in the anatomic arrangement of the muscle bundles results in differences in the endocardial and epicardial activation patterns. We present a case of recurrent atrial flutter (AFL) despite the presence of a complete endocardial CTI block. We found epicardial‐endocardial breakthrough (EEB) sites on the right atrial high septum. In addition, the epicardial excitation confirmed by endocardial activation mapping was detected as far‐field potentials. Radiofrequency ablation was performed at the EEB site. No AFL has recurred for 12 months after the present procedure. [ABSTRACT FROM AUTHOR]

A 60‐year‐old male patient suffered from frequent episodes of atrial tachycardia (AT), after the index procedure of catheter ablation for paroxysmal atrial fibrillation. During the repeat procedure, the activation map showed that the earliest activation site was located at the roof of left atrium. Multiple ablations at the earliest activation site on the roof failed to terminate the AT; however, ablation within the pulmonary artery at an adjacent anatomical site successfully eliminated the AT, even without recording distinct near‐field potential. [ABSTRACT FROM AUTHOR]

The article examines a clinical case of narrow complex tachycardia with alternating atrial activation in a 50-year-old male undergoing evaluation for a redo ablation procedure. Topics include the diagnostic considerations for alternating atrial activation; the electrophysiology study findings, including pre-excitation and narrow complex tachycardia with a VAHV response; and the challenges in managing arrhythmias complicated by prior ablation attempts and associated comorbidities.

Introduction: Atrial remodelling (AR) is the persistent change in atrial structure and/or function and contributes to the initiation, maintenance and progression of atrial fibrillation (AF) in a reciprocal self‐perpetuating relationship. Left atrial (LA) size, geometry, fibrosis, wall thickness (LAWT) and ejection fraction (LAEF) have all been shown to vary with pathological atrial remodelling. The association of these global remodelling markers with each other for differentiating structural phenotypes in AF is not well investigated. Method: Patients referred for first‐time AF ablation and controls without AF were prospectively recruited to undergo cardiac computed tomographic angiography (CCTA) and magnetic resonance imaging (MRI) with 3D atrial late‐gadolinium enhanced (LGE) sequences. LAWT, atrial myocardial mass, LA volume and sphericity were calculated from CT. Biplane LA EF and LA fibrosis burden were derived from atrial MRI. Results were compared between patients with AF and controls. Results: Forty two AF patients (64.3% male, age 64.6 ± 10.2 years, CHA2DS2‐VASc 2.48 ± 1.5, 69.0% paroxysmal AF, 31% persistent AF, LVEF 57.9 ± 10.5%) and 37 controls (64.9% male, age 56.6 ± 7.2, CHA2DS2‐VASc 1.54 ± 1.1, LVEF 60.4 ± 4.9%) were recruited. Patients with AF had a significantly higher LAWT (1.45 ± 0.52 mm vs 1.12 ± 0.42 mm, p = 0.003), tissue mass (15.81 ± 6.53 g vs. 12.18 ± 5.01 g, p = 0.011), fibrosis burden (9.33 ± 8.35% vs 2.41 ± 3.60%, p = 0.013), left atrial size/volume (95.68 ± 26.63 mL vs 81.22 ± 20.64 mL, p = 0.011) and lower LAEF (50.3 ± 15.3% vs 65.2 ± 8.6%, p < 0.001) compared to controls. There was no significant correlation between % fibrosis with LAWT (p = 0.29), mass (p = 0.89), volume (p = 0.49) or sphericity (p = 0.79). LAWT had a statistically significant weak positive correlation with LA volume (r = 0.25, p =.041), but not with sphericity (p = 0.86). LAEF had a statistically significant but weak negative correlation with fibrosis (r = −0.33, p = 0.008) and LAWT (r = −0.24, p = 0.07). Conclusion: AF is associated with significant quantifiable structural changes that are evident in LA size, tissue thickness, total LA tissue mass and fibrosis. These individual remodelling markers do not or only weakly correlate with each other suggesting different remodelling subtypes exist (e.g. fibrotic vs hypertrophic vs dilated). If confirmed, such a detailed understanding of the structural changes observed has the potential to inform clinical management strategies targeting individual mechanisms underlying the disease process. [ABSTRACT FROM AUTHOR]

Background: Intensive training efforts are associated with hemodynamic changes accompanied by increases in cardiac output and stroke volume related to higher peak oxygen consumption and better athletic performance during exercise. These hemodynamic changes induce an enlargement of cardiac chambers, but also of the atria and may result in an athletes' heart (AH). Data from large studies about atrial enlargement in AH are sparse. Methods: Competitive athletes aged ≥18 years, who presented for pre‐participation screening 04/2020–10/2021 were included in this study and stratified for AH (defined as physiologically increased heart volume >13.0 in males and >12.0 mL/kg in females). Results: Overall, 646 athletes aged ≥18 years (median age 24.0 [20.0/31.0] years; 206 [31.9%] females) were included in our study 04/2020–10/2021; among these, 118 (18.3%) had an AH. The computed absolute heart volume was 969.4 (853.1/1083.0) mL in athletes with AH and 841.3 (707.4/966.3) mL in those without AH (p < 0.001). AH was associated with larger left ventricular mass (206.6 ± 39.0 vs. 182.7 ± 44.2 g, p < 0.001). LA area (15.4 [13.7/18.2] vs. 14.3 [12.0/16.3] cm2, p < 0.001) and RA area (15.8 [13.8/18.6] vs. 14.5 [12.3/17.0] cm2, p < 0.001) were enlarged in AH versus those athletes without AH. The logistic regressions confirmed an independent association of AH on LV mass (OR 1.05 [95% CI 1.04–1.06], p < 0.001). LA area (OR 1.29 [95% CI 1.19–1.39], p < 0.001) as well as RA area (OR 1.28 [95% CI 1.19–1.38], p < 0.001) were afflicted by AH. Conclusion: An AH is accompanied by significant enlargement of the atria as well as increased cardiac muscle mass. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to assess right atrial (RA) function, including RA phase strain, via speckle‐tracking echocardiography (STE) in a cohort of systemic lupus erythematosus (SLE) patients with pulmonary arterial hypertension (PAH) and in particular to explore the relationship between RA phase strain and the occurrence of cardiovascular events. Methods: STE analyses of RA function were evaluated in patients with SLE‐PAH and in 33 healthy control subjects. Clinical associations, serum biomarkers, echocardiographic data, survival times, and adverse cardiovascular events were evaluated. Results: A total of 66 patients with SLE‐PAH were enrolled; they were divided into two groups based on the occurrence of adverse clinical events. RA phase strain was significantly reduced in patients with events than in patients without events. The endpoint was defined as the combined outcome of all‐cause mortality, right heart failure, and rehospitalization due to disease progression. During a mean follow‐up of 17.2 ± 9.9 months, 23 patients (35%) reached the endpoint. Compared with patients with RA reservoir strain (RASr) ≥33.45%, patients with RASr < 33.45% had more adverse long‐term outcomes (log rank p <.0001). RASr was independently associated with adverse clinical outcomes according to multivariate analysis (p =.010). Conclusion: Our data suggest that RA function has prognostic value for SLE‐PAH patients, and strain analysis revealed that the worse the RA function is, the worse the prognosis. [ABSTRACT FROM AUTHOR]

Background: The atrium augments ventricular function, but the significance of atrial function in hypoplastic left heart syndrome (HLHS) has not been well evaluated. Objective: We investigated the association of atrial reservoir strain (common atrial strain [CAS]) to death or need for transplantation in patients with HLHS. Methods: In this retrospective single‐center study, echocardiograms from three timepoints (pre‐stage 1 palliation [S1P], 4–8 weeks post‐S1P, and pre‐Glenn) were analyzed in infants with classic HLHS. Patients were separated based on transplant‐free survival to Fontan (survivors) versus death or heart transplant prior to Fontan (composite outcome). Echocardiographic parameters evaluated included CAS, right ventricle (RV) global longitudinal strain (RVGLS), RV fractional area change (FAC), and tricuspid annular plane systolic excursion (TAPSE). An equal variance t‐test, regression, and receiver operating characteristic (ROC) analyses were performed. Results: A total of 45 HLHS patients (25 survivors, 20 patients meeting endpoint) were included in this study. There were no significant differences in any of the functional parameters during the pre‐stage 1 or post‐stage 1 timepoints. Pre‐Glenn CAS and RVGLS were significantly worse in those meeting composite endpoint compared to survivors. CAS was significantly correlated to RVGLS during the pre‐S1P and pre‐Glenn timepoints. A pre‐Glenn CAS < 19.5 had an area under the curve of.78 and a 75% sensitivity and 83% specificity for death or need for transplantation. Conclusion: Pre‐Glenn CAS is significantly lower in patients with mortality or need for the transplantation prior to Fontan completion and may carry prognostic significance in patients with HLHS. [ABSTRACT FROM AUTHOR]

Introduction: The impact of early recurrence of atrial tachyarrhythmia (ERAT) within the 90‐day blanking period on long‐term outcomes in atrial fibrillation (AF) patients undergoing cryoballoon ablation (CBA) is controversial. This study aimed to assess the relationship between ERAT and late recurrence of atrial tachyarrhythmia (LRAT) post‐CBA. Methods: Utilizing data from a multicenter registry in Korea (May 2018 to June 2022), we analyzed the presence and timing of ERAT (<30, 30–60, and 60–90 days) and its association with LRAT risk after CBA. LRAT was defined as any recurrence of AF, atrial flutter, or atrial tachycardia lasting more than 30 s beyond the 90 days. Results: Out of 2636 patients, 745 (28.2%) experienced ERAT post‐CBA. Over an average follow‐up period of 21.2 ± 10.3 months, LRAT was observed in 874 (33.1%) patients. Patients with ERAT had significantly lower 1‐year LRAT freedom compared to those without ERAT (42.6% vs. 85.5%, p <.001). Multivariate analysis identified ERAT as a potential predictor of LRAT, with a hazard ratio (HR) of 3.98 (95% confidence interval [CI], 3.47–4.57). Significant associations were noted across all examined time frames (HR, 3.84; 95% CI, 3.32–4.45 in <30 days, HR, 5.53; 95% CI, 4.13–7.42 in 30–60 days, and HR, 4.29; 95% CI, 3.12–5.89 in 60–90 days). This finding was consistently observed across all types of AF. Conclusion: ERAT during the 90‐day blanking period strongly predicts LRAT in AF patients undergoing CBA, indicating a need to reconsider the clinical significance of this period. [ABSTRACT FROM AUTHOR]

Introduction: There is a lack of studies in the literature directly investigating the relationship between atrial tachycardia (AT) and left atrial (LA)/left atrial appendage (LAA) thrombus, and current guidelines do not provide strong recommendations regarding the use of transesophageal echocardiography (TEE) before AT catheter ablation. This study aims to elucidate the relationship between AT and the presence of LA/LAA thrombus and contribute to the literature on the use of TEE before AT catheter ablation. Methods: This single‐center retrospective observational study screened patients who underwent TEE between February 10, 2019, and February 10, 2023. Patients were assigned to the AT patient and control groups. TEE was conducted to exclude thrombus in the AT ablation group. The control group included patients who underwent TEE for interatrial septum evaluation and had LA imaging during TEE but did not have atrial arrhythmia. To mitigate bias between the AT patient group and the control group, they were randomized 1:1 using propensity‐score matching (PSM). Following randomization, each group consisted of 49 patients. Results: All analyses were conducted after PSM. There were no statistically significant differences between the AT patient and control groups in terms of baseline clinical characteristics and echocardiographic features. Additionally, no significant differences were found between the blood viscosities calculated at low and high shear rates in both groups. The study revealed a significant difference between the two groups in the presence of LA spontaneous echo contrast (SEC) (24.5% in AT group vs 0% in Control group, p =.001), but not in the presence of thrombi (8.2% in AT group vs 0% in Control group, p =.117). Conclusion: Compared to the control group, the presence of SEC was significantly higher in the AT patient group. The increased frequency of SEC in AT patients suggests the hypothesis that AT may contribute to LA stasis. The routine use of TEE before AT catheter ablation remains controversial, despite the presence of LA thrombus and SEC in the AT patient group. The clinical assessment of thrombus presence before the procedure must be conducted on a patient‐specific basis. [ABSTRACT FROM AUTHOR]

Introduction: The unique safety profile of pulsed field ablation (PFA) has made pulmonary vein isolation (PVI) + left atrial posterior wall (LAPW) ablation promising for treating persistent atrial fibrillation (PerAF). The goal of this study was to assess long‐term freedom from atrial fibrillation, atrial flutter, and atrial tachycardia (AF/AFL/AT), as well as the safety and feasibility of LAPW PFA using multipolar, pentaspline Farawave catheter. Methods: Retrospective observational study at a single institution. Data for 94 patients were collected from a prespecified intraprocedural registry. The long‐term AF/AFL/AT recurrence assessment was based on an analysis of medical history; 24‐h Holter ECGs at 3, 6, and 12 months postablation; and 12‐lead ECGs recorded during symptomatic episodes or visits. Results: Half of the patients had ls‐PerAF, and half had a history of catheter ablation—mostly RF PVI. The acute ablation success rate was 100%, and the primary safety outcome was observed in 2 patients. Fifty patients experienced AF/AFL/AT recurrence (54.3%). An increase in LAPW low‐voltage areas and AF classification were associated with arrhythmia recurrence. After a median follow‐up of 13 months, the Kaplan‒Meier estimated median time free of AF/AFL/AT after a single procedure was 14.7 months. Conclusion: PFA PVI + PWA had the best outcome in perAF patients without extensive LA fibrosis. AF recurrence was paroxysmal in significant part of the cohort. The addition of PWA to PVI using multipolar PFA was safe and did not significantly influence the transpired ablation time. [ABSTRACT FROM AUTHOR]

Left-to-right differences in the histopathologic patterns of transthyretin-derived amyloid (ATTR) deposition in the atria of older adults have not yet been investigated. Hence, this study evaluated heart specimens from 325 serial autopsy subjects. The amount of ATTR deposits in the seven cardiac regions, including both sides of atria and atrial appendages, was evaluated semiquantitatively. Using digital pathology, we quantitatively evaluated the immunohistochemical deposition burden of ATTR in the myocardium. We identified 20 sporadic ATTR cardiac amyloidosis cases (nine males). All patients had ATTR deposition in the left atrial regions of the myocardium. In the semiquantitative analysis, 14 of the 20 cases showed more severe ATTR deposition on the left atrial regions than on the right side, with statistically significant differences in the pathology grading (p < 0.01 for both the atrium and atrial appendage). Quantitative analysis further supported the difference. Moreover, six had ATTR deposition in the epineurium and/or neural fibers of the atria. Cluster analysis revealed that ATTR deposition in the myocardium was significantly more severe in males than in females. The heterogeneous distribution of amyloid deposits between atria revealed in this study may impair the orderly transmission of the cardiac conduction system and induce arrhythmias, which may be further aggravated by additional neuropathy in the advanced phase. This impairment could be more severe among males. These findings emphasize that atrial evaluation is important for individuals with sporadic ATTR cardiac amyloidosis, particularly for early detection. [ABSTRACT FROM AUTHOR]

Objective: This study evaluates the feasibility and efficacy of implanting a leadless pacemaker at the right atrial appendage (RAA) in a preclinical minipig model, aiming to address the limitations of atrial pacing with current leadless devices like the Medtronic Micra, which is typically used for right ventricular implantation. Methods: Four minipigs, each with a median body weight of 45.8 ± 10.0 kg, underwent placement of the Micra transcatheter pacing system (TPS) via the right femoral vein into the RAA apex. The pacing performance was assessed over 1‐week (short‐term) and 3‐month (long‐term) periods. Outcomes: The initial findings indicated successful implantation, with satisfactory intrinsic R‐wave amplitudes and pacing threshold. In the following period, the sensitivity, threshold, and impedance were stable with time. Notably, upon explanation at 3 months, a deep myocardial penetration by the device was observed, necessitating a redesign for safe long‐term use in a growing subject's heart. Conclusion: While initial results suggest that RAA apex placement of the Micra TPS is promising for potential inclusion in a dual‐chamber pacing system, the issue of myocardial penetration highlights the need for device redesign to ensure safety and effectiveness in long‐term applications. [ABSTRACT FROM AUTHOR]

Background: Tachycardia‐induced cardiomyopathy (TIC) is a reversible cardiomyopathy with ventricular dysfunction caused by tachyarrhythmias. Notably, atrial fibrillation (AF) is the most common causal arrhythmia leading to TIC. However, the risk factors for the development of TIC due to AF remain unclear. This study aimed to identify the associated factors of TIC due to AF. Methods: Persistent AF patients with heart rate (HR) ≥100 beats per minute who underwent initial catheter ablation were enrolled in this study. TIC was diagnosed as left ventricular ejection fraction (LVEF) < 50% during AF rhythm, which was recovered after the restoration of sinus rhythm. Non‐TIC was defined as LVEF ≥ 50% despite AF rhythm. The patient backgrounds were compared between the TIC group and the non‐TIC group to reveal the contributing factors of TIC. Results: The TIC group comprised 57 patients, while the non‐TIC group consisted of 101 patients. The TIC group was younger than the non‐TIC group (median 64 vs. 70, p = 0.006). Male sex was more frequent in the TIC group than the non‐TIC group (82.5% vs. 58.4%, p = 0.003). HR was higher in the TIC group than in the non‐TIC group (median 130 bpm vs. 111 bpm, p < 0.001). The number of smokers was significantly higher in the TIC group than in the non‐TIC group (p < 0.001). Multivariable analysis demonstrated that higher HR (odds ratio [OR]: 1.74; 95% confidence interval [CI]: 1.37–2.21; p < 0.001) and current smokers (OR: 5.27; 95% CI: 1.60–17.4; p = 0.006) were the independent factors leading to TIC. Conclusion: Higher HR and current smokers were independent risk factors for the development of TIC due to AF. [ABSTRACT FROM AUTHOR]

Background: An accurate display of scar‐related atrial tachycardia (ATs) is a key determinant of ablation success. The efficacy of ripple mapping (RM) in identifying the mechanism and critical isthmus of scar‐related ATs during coherent mapping is unknown. Methods: A total of 97 patients with complex ATs who underwent radiofrequency catheter ablation at our center between October 2018 and September 2022 were included. ATs was mapped using a multielectrode mapping catheter on the CARTO3v7 CONFIDENCE module. Coherent and RM were used to identify the reentrant circuit. Results: The mechanisms of 128 ATs were analyzed retrospectively (84 anatomic‐reentrant ATs and 44 non‐anatomic reentrant ATs). The median AT cycle length was 264 ± 25ms. The correct diagnosis was achieved in 83 ATs (68%) using only coherent mapping. Through coherent mapping plus RM, 114 ATs (84.2%) were correctly diagnosed (68% vs. 89%, p =.019). In non‐anatomical reentrant ATs, 81% of the diagnostic rate was achieved by reviewing both coherent and ripple mapping compared to reviewing coherent mapping alone (81% vs. 52%, p =.03). Reviewing coherent mapping and ripple mapping showed a higher diagnostic rate in patients who underwent cardiac surgery than those with Coherent mapping alone (64% vs. 88%, p =.04). Conclusion: Coherent mapping combined with RM was superior to coherent mapping alone in identifying the mechanism of scar‐related ATs post‐cardiac surgery and non‐anatomic reentrant ATs. [ABSTRACT FROM AUTHOR]

In the field of cardiac electrophysiology, there is a universal desire: the discovery of a flawless diagnostic maneuver for supraventricular tachycardias (SVTs). This is not merely a wish but a shared odyssey. To improve diagnostic accuracy and achieve sufficient sensitivity and specificity, numerous diagnostic maneuvers have been proposed. However, each has its limitations and prompts a search for new diagnostic techniques. This continuous cycle of discovery and refinement, which we titled "SVT Quest" is reviewed in chronological sequence. This adventure in diagnosing narrow QRS tachycardia unfolds in 3 steps: Step 1 involves differentiating atrial tachycardia from other SVTs based on the observations such as V‐A‐V or V‐A‐A‐V response, ΔAA interval, VA linking, the last entrainment sequence, and response to the atrial extrastimulus. Step 2 focuses on differentiating orthodromic reciprocating tachycardia from atrioventricular nodal reentrant tachycardia based on the observations such as tachycardia reset upon the premature ventricular contraction during His refractoriness, uncorrected/corrected postpacing interval, differential ventricular entrainment, orthodromic His capture, transition zone analysis, and total pacing prematurity. Step 3 characterizes the concealed nodoventricular/nodofascicular pathway and His‐ventricular pathway‐related tachycardia based on observations such as V‐V‐A response, ΔatrioHis interval, and paradoxical reset phenomenon. There is no single diagnostic maneuver that fits all scenarios. Therefore, the ability to apply multiple maneuvers in a case allows the operator to accumulate evidence to make a likely diagnosis. Let's embark on this adventure! [ABSTRACT FROM AUTHOR]

Infusion of fluids is one of the most common medical acts when resuscitating critically ill patients. However, fluids most often are given without consideration of how fluid infusion can actually improve tissue perfusion. Arthur Guyton's analysis of the circulation was based on how cardiac output is determined by the interaction of the factors determining the return of blood to the heart, i.e. venous return, and the factors that determine the output from the heart, i.e. pump function. His theoretical approach can be used to understand what fluids can and cannot do. In his graphical analysis, right atrial pressure (RAP) is at the center of this interaction and thus indicates the status of these two functions. Accordingly, trends in RAP and cardiac output (or a surrogate of cardiac output) can provide important guides for the cause of a hemodynamic deterioration, the potential role of fluids, the limits of their use, and when the fluid is given, the response to therapeutic interventions. Use of the trends in these values provide a physiologically grounded approach to clinical fluid management. [ABSTRACT FROM AUTHOR]

Objectives: To assess the ability of left atrial (LA) strain parameters to discriminate patients with elevated left atrial pressure (LAP) from patients with atrial fibrillation (AF). Methods and results: A total of 142 patients with non‐valvular AF who underwent first catheter ablation (CA) between November 2022 and November 2023 were enrolled in the study. Conventional and speckle‐tracking echocardiography (STE) were performed in all patients within 24 h before CA, and LAP was invasively measured during the ablation procedure. According to mean LAP, the study population was classified into two groups of normal LAP (LAP < 15 mmHg, n = 101) and elevated LAP (LAP ≥ 15 mmHg, n = 41). Compared with the normal LAP group, elevated LAP group showed significantly reduced LA reservoir strain (LASr) [9.14 (7.97–11.80) vs. 20 (13.59–26.96), p <.001], and increased LA filling index [9.60 (7.15–12.20) vs. 3.72 (2.17–5.82), p <.001], LA stiffness index [1.13 (.82–1.46) vs..47 (.30–.70), p <.001]. LASr, LA filling index and LA stiffness index were independent predictors of elevated LAP after adjusted by the type of AF, EDT, E/e′, mitral E, and peak acceleration rate of mitral E velocity. The receiver‐operating characteristic curve (ROC) analysis showed LA strain parameters (area under curve [AUC].794–.819) could provide similar or greater diagnostic accuracy for elevated LAP, as compared to conventional echocardiographic parameters. Furthermore, the novel algorithms built by LASr, LA stiffness index, LA filling index, and left atrial emptying fraction (LAEF), was used to discriminate elevated LAP in AF with good accuracy (AUC.880, accuracy of 81.69%, sensitivity of 80.49%, and specificity of 82.18%), and much better than 2016 ASE/EACVI algorithms in AF. Conclusion: In patients with AF, LA strain parameters could be useful to predict elevated LAP and non‐inferior to conventional echocardiographic parameters. Besides, the novel algorithm built by LA strain parameters combined with conventional parameters would improve the diagnostic efficiency. [ABSTRACT FROM AUTHOR]

Introduction: Ablation of scar‐related reentrant atrial tachycardia (SRRAT) involves identification and ablation of a critical isthmus. A graph convolutional network (GCN) is a machine learning structure that is well‐suited to analyze the irregularly‐structured data obtained in mapping procedures and may be used to identify potential isthmuses. Methods: Electroanatomic maps from 29 SRRATs were collected, and custom electrogram features assessing key tissue and wavefront properties were calculated for each point. Isthmuses were labeled off‐line. Training data was used to determine the optimal GCN parameters and train the final model. Putative isthmus points were predicted in the training and test populations and grouped into proposed isthmus areas based on density and distance thresholds. The primary outcome was the distance between the centroids of the true and closest proposed isthmus areas. Results: A total of 193 821 points were collected. Thirty isthmuses were detected in 29 tachycardias among 25 patients (median age 65.0, 5 women). The median (IQR) distance between true and the closest proposed isthmus area centroids was 8.2 (3.5, 14.4) mm in the training and 7.3 (2.8, 16.1) mm in the test group. The mean overlap in areas, measured by the Dice coefficient, was 11.5 ± 3.2% in the training group and 13.9 ± 4.6% in the test group. Conclusion: A GCN can be trained to identify isthmus areas in SRRATs and may help identify critical ablation targets. [ABSTRACT FROM AUTHOR]

Introduction: Numerous P‐wave indices have been explored as biomarkers to assess atrial fibrillation (AF) risk and the impact of therapy with variable success. Objective: We investigated the utility of P‐wave alternans (PWA) to track the effects of pulmonary vein isolation (PVI) and to predict atrial arrhythmia recurrence. Methods: This medical records study included patients who underwent PVI for AF ablation at our institution, along with 20 control subjects without AF or overt cardiovascular disease. PWA was assessed using novel artificial intelligence‐enabled modified moving average (AI‐MMA) algorithms. PWA was monitored from the 12‐lead ECG at ~1 h before and ~16 h after PVI (n = 45) and at the 4‐ to 17‐week clinically indicated follow‐up visit (n = 30). The arrhythmia follow‐up period was 955 ± 112 days. Results: PVI acutely reduced PWA by 48%–63% (p <.05) to control ranges in leads II, III, aVF, the leads with the greatest sensitivity in monitoring PWA. Pre‐ablation PWA was ~6 µV and decreased to ~3 µV following ablation. Patients who exhibited a rebound in PWA to pre‐ablation levels at 4‐ to 17‐week follow‐up (p <.01) experienced recurrent atrial arrhythmias, whereas patients whose PWA remained reduced (p =.85) did not, resulting in a significant difference (p <.001) at follow‐up. The AUC for PWA's prediction of first recurrence of atrial arrhythmia was 0.81 (p <.01) with 88% sensitivity and 82% specificity. Kaplan–Meier analysis estimated atrial arrhythmia‐free survival (p <.01) with an adjusted hazard ratio of 3.4 (95% CI: 1.47–5.24, p <.02). Conclusion: A rebound in PWA to pre‐ablation levels detected by AI‐MMA in the 12‐lead ECG at standard clinical follow‐up predicts atrial arrhythmia recurrence. [ABSTRACT FROM AUTHOR]

Background: The efficacy and safety of adjunctive low‐voltage area (LVA) ablation on outcomes of catheter ablation (CA) for atrial fibrillation (AF) remains uncertain. Methods: PubMed, Embase, Cochrane Library, and ClinicalTrials.gov were searched for randomized controlled trials (RCTs) comparing CA with versus without LVA ablation for patients with AF. Risk ratios (RR) with 95% confidence intervals (CI) were pooled with a random‐effects model. Our primary endpoint was recurrence of atrial tachyarrhythmia (ATA), including AF, atrial flutter, or atrial tachycardia. We used R version 4.3.1 for all statistical analyses. Results: Our meta‐analysis included 10 RCTs encompassing 1780 patients, of whom 890 (50%) were randomized to LVA ablation. Adjunctive LVA ablation significantly reduced recurrence of ATA (RR 0.76; 95% CI 0.67−0.88; p <.01) and reduced the number of redo ablation procedures (RR 0.54; 95% CI 0.35−0.85; p <.01), as compared with conventional ablation. Among 691 (43%) patients with documented LVAs on baseline substrate mapping, adjunctive LVA ablation substantially reduced ATA recurrences (RR 0.57; 95% CI 0.38−0.86; p <.01). There was no significant difference between groups in terms of periprocedural adverse events (RR 0.78; 95% CI 0.39−1.56; p =.49). Conclusions: Adjunctive LVA ablation is an effective and safe strategy for reducing recurrences of ATA among patients who undergo CA for AF. [ABSTRACT FROM AUTHOR]

Introduction: Pulsed Field Ablation (PFA) is a novel non-thermal method for cardiac ablation, relying on irreversible electroporation induced by high-energy pulsed electric fields (PEFs) to create localized lesions in the heart atria. A significant challenge in optimizing PFA treatments is determining the lethal electric field threshold (EFT), which governs ablation volume and varies with PEF waveform parameters. However, the proprietary nature of device developer’s waveform characteristics and the lack of standardized nonclinical testing methods have left optimal EFTs for cardiac ablation uncertain. Methods: To address this gap, we introduced a laboratory protocol employing human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in monolayer format to evaluate the impact of a range of clinically relevant biphasic pulse parameters on lethal EFT and adiabatic heating (AH). Cell death areas were assessed using fluorescent dyes and confocal microscopy, while lethal EFTs were quantified through comparison with electric field numerical simulations. Results and conclusion: Our study confirmed a strong correlation between cell death in hiPSC-CMs and the number and duration of pulses in each train, with pulse repetition frequency exerting a comparatively weaker influence. Fitting of these results through machine learning algorithms were used to develop an open-source online calculator. By estimating lethal EFT and associated temperature increases for diverse pulse parameter combinations, this tool, once validated, has the potential to significantly reduce reliance on animal models during early-stage device de-risking and performance assessment. This tool also offers a promising avenue for advancing PFA technology for cardiac ablation medical devices to enhance patient outcomes. [ABSTRACT FROM AUTHOR]

The article present case study of a 52-year-old woman who had been previously diagnosed with type-A Wolff-Parkinson-White (WPW) syndrome. Topics include the diagnostic assessment of a narrow QRS tachycardia; differential diagnosis between orthodromic reciprocating tachycardia (ORT) and atrioventricular nodal reentrant tachycardia (AVNRT); and the complexities in distinguishing a posteroseptal atrioventricular pathway from a rare nodoventricular pathway.

The article focuses on a case of intermittent atrial capture loss following a cardiac defibrillator implantation. Topics include the mechanisms behind the loss of atrial capture, such as electrotonic facilitation and partial depolarization of the atrial membrane and their relationship to pacing rates; the potential causes of altered membrane excitability, like lead-tissue trauma or ischemia; and the management of the patient through adjusting the lower rate limit (LRL) for consistent capture.

We present the case of a 7-month-old female infant with a history of recurrent respiratory infections and symptoms of respiratory distress during feeding. Echocardiography isolated revealed supracardiac-type total anomalous pulmonary venous connection with a large ostium secundum atrial septal defect and severe pulmonary hypertension. Computed tomographic angiography confirmed the diagnosis and identified stenosis at the level of the venous confluence. The surgical intervention involved a novel approach using dual anastomoses between the pulmonary venous confluence and the left atrium, alongside atrial septal defect repair with a bovine pericardial patch. Postoperative recovery was uneventful, with successful weaning from mechanical ventilation on Day 9 and discharge on Day 12. The patient showed optimal venous drainage and hemodynamic stability, indicating a successful surgical outcome. This case highlights the importance of early surgical intervention in total anomalous pulmonary venous connection with complex anatomical presentations. [ABSTRACT FROM AUTHOR]

The article examines the structural and functional differences in the hearts of athletes with a physiological athletic heart (AH) compared to those without. Topics include the methodology involving echocardiography and cardiopulmonary exercise testing on 648 athletes, the significant findings of larger cardiac volumes and lower body weight in those with an AH, and the implications of atrial dilation in understanding athletic cardiac remodeling.

The pacing threshold is important for leadless pacemakers, as the pacing output has a significant impact on battery longevity. Acute pacing rate‐dependent threshold increases have also been reported with leadless pacemakers. In the present case, we experienced a case in which the threshold, which had been raised in the acute phase, once showed a tendency to improve, but then worsened again. And, as in previous reports, thresholds improved completely in the chronic phase. Repeated retrieval and reimplantation of leadless pacemakers increases the likelihood of fatal complications, so being aware of such phenomenon may prevent unnecessary procedure and complications. [ABSTRACT FROM AUTHOR]

Although ventricular capture during the atrial threshold test is possible, there are rare reports on the insulation defect and inactive leads thereof. In this case, we present a pacemaker‐dependent patient with a history of pacemaker generator replacements. The patient experienced ventricular capture induced by atrial pacing due to adhesion of the atrial and ventricular leads with an insulation defect. The atrial lead was abandoned and a new lead was implanted. However, there was a significant decrease in ventricular impedance detected shortly after the new lead was implanted. When observing the phenomenon of atrial pacing‐induced ventricular depolarization, one uncommon reason to consider is lead adhesive wear. It is important to pay attention to the contact and bending sites of the leads. [ABSTRACT FROM AUTHOR]