Search

ABSTRACT Background Objective Methods Results Primary outcome Secondary outcomes Conclusion Low‐to‐zero fluoroscopic navigation systems lower radiation exposure which improves health outcomes. Conventional x‐ray fluoroscopy (CF) has long been the standard to guide to catheter location for cardiac ablation. With advancements in technology, alternative safety navigation systems have been developed. Three primary modalities commonly utilized are three‐dimensional electroanatomic mapping (3D‐EAM), magnetic navigation system (MNS), and intracardiac echocardiography (ICE), all of which can reduce radiation exposure during the procedure.We aim to compare the efficacy and safety among ICE, EAM, MNS, and CF in ablation of atrioventricular nodal reentrant tachycardia (AVNRT).This is a meta‐analysis consisting of observational studies and randomized controlled trials, which evaluated the performance of navigation systems of catheter ablation in AVNRT patients. Primary endpoint was to access the AVNRT recurrence after the procedure during follow‐up periods. Secondary endpoints were technical success, fluoroscopic time, fluoroscopic dose area product, radiofrequency ablation time, and adverse events. Random‐effect model was applied for pooled estimated effects of included studies.A total of 21 studies (21 CF, 2 ICE, 9 EAM, 11 MNS) including 1716 patients who underwent catheter ablation for AVNRT treatment were analyzed. Of these, 16 were observational studies and 5 were randomized controlled trials.Point estimation of AVNRT recurrence showed ICE exhibited a pooled odds ratio (ORs) of 1.06 (95% confidence interval [CI]: 0.064–17.322), MNS with ORs of 0.51 (95% CI: 0.214–1.219], and EAM with ORs of 0.394 (95% CI: 0.119–1.305) when compared to CF.EAM had significant higher technical success with ORs of 2.781 (95% CI: 1.317–5.872) when compared to CF. Regarding fluoroscopy time, EAM showed the lowest time with mean differences (MD) of −10.348 min (95% CI: −13.385 to −7.3101) and P‐score of 0.998. It was followed by MNS with MD of −3.712 min (95% CI: −7.128 to −0.295) and P‐score of 0.586, ICE with MD of −1.150 min (95% CI: −6.963 to 4.662) with a P‐score of 0.294 compared to CF, which has a P‐score of 0.122. There were insignificant adverse events across the procedures.AVNRT ablation navigated by low‐to‐zero fluoroscopic navigation systems achieves higher efficacy and comparable safety to conventional fluoroscopywhile also reducing risk of radiation exposure time. [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]

Key Clinical Message: This case illustrates the safety and efficacy of pulse field ablation (PFA) in the short and medium term. It could be used to isolate extra pulmonary sites including the posterior wall. PFA could be used in the treatment of atrial tachycardias both focal and reentrant in combination with ultrahigh density electroanatomic mapping. It is also important to understand that different catheter shapes are available and their use can be tailored to the targeted anatomical site. [ABSTRACT FROM AUTHOR]

Introduction: Peak frequency (PF) mapping is a novel method that may identify critical portions of myocardial substrate supporting reentry. The aim of this study was to describe and evaluate PF mapping combined with omnipolar voltage mapping in the identification of critical isthmuses of left atrial (LA) atypical flutters. Methods and Results: LA omnipolar voltage and PF maps were generated in flutter using the Advisor HD‐Grid catheter (Abbott) and EnSite Precision Mapping System (Abbott) in 12 patients. Normal voltage was defined as ≥0.5 mV, low‐voltage as 0.1−0.5 mV, and scar as <0.1 mV. PF distributions were compared with ANOVA and post hoc Tukey analyses. The 1 cm radius from arrhythmia termination was compared to global myocardium with unpaired t‐testing. The mean age was 65.8 ± 9.7 years and 50% of patients were female. Overall, 34 312 points were analyzed. Atypical flutters most frequently involved the mitral isthmus (58%) or anterior wall (25%). Mean PF varied significantly by myocardial voltage: normal (335.5 ± 115.0 Hz), low (274.6 ± 144.0 Hz), and scar (71.6 ± 140.5 Hz) (p < .0001 for all pairwise comparisons). All termination sites resided in low‐voltage regions containing intermediate or high PF. Overall, mean voltage in the 1 cm radius from termination was significantly lower than the remaining myocardium (0.58 vs. 0.95 mV, p < .0001) and PF was significantly higher (326.4 vs. 245.1 Hz, p < .0001). Conclusion: Low‐voltage, high‐PF areas may be critical targets during catheter ablation of atypical atrial flutter. [ABSTRACT FROM AUTHOR]

In patients with premature ventricular contractions (PVCs), non-invasive mapping could locate the PVCs' origin on a personalized 3-dimensional (3D) heart model and, thus, facilitate catheter ablation therapy planning. The aim of our report is to evaluate its accuracy compared to invasive mapping in terms of assessing the PVCs' early activation zone (EAZ). For this purpose, non-invasive electrocardiographic imaging (ECGI) was performed using the Amycard 01C system (EP Solutions SA, Switzerland) in three cases. In the first step, a multichannel ECG (up to 224 electrodes) was recorded, and the dominant PVCs were registered. Afterward, a cardiac computed tomography (in two cases) or magnetic resonance imaging (in one case) investigation was carried out acquiring non-contrast torso scans for 8-electrode strip visualization and contrast heart acquisition. For the reconstructed epi/endocardial meshes of the heart, non-invasive isochronal maps were generated for the selected multichannel ECG fragments. Then, the patients underwent an invasive electrophysiological study, and the PVCs' activation was evaluated by a 3D mapping system (EnSite NavX Precision, Abbott). Finally, using custom-written software, we performed 3D fusion of the non-invasive and invasive models and compared the resulting isochronal maps. A qualitative analysis in each case showed the same early localization of the dominant PVC on the endocardial surface when comparing the non-invasive and invasive isochronal maps. The distance from the EAZ to the mitral or tricuspid annulus was comparable in the invasive/non-invasive data (36/41 mm in case N1, 73/75 mm in case N2, 9/12 mm in case N3). The area of EAZ was also similar between the invasive/non-invasive maps (4.3/4.5 cm2 in case N1, 7.1/7.0 cm2 in case N2, 0.4/0.6 cm2 in case N3). The distances from the non-invasive to invasive earliest activation site were 4 mm in case N1, 7 mm in case N2, and 4 mm in case N3. Such results were appropriate to trust the clinical value of the preoperative data in these cases. In conclusion, the non-invasive identification of PVCs before an invasive electrophysiological study can guide clinical and interventional decisions, demonstrating appropriate accuracy in the estimation of focus origin. [ABSTRACT FROM AUTHOR]

Although implantable cardioverter defibrillators offer the best protection against sudden cardiac death, catheter ablation for ventricular arrhythmias (VAs) can modify or prevent this event from occurring. In order to achieve a successful ablation, the correct identification of the underlying arrhythmogenic substrate is mandatory to tailor the pre-procedural planning of an ablative procedure as appropriately as possible. We propose that several of the imaging modalities currently used could be merged, including echocardiography (also intracardiac), cardiac magnetic resonance, cardiac computed tomography, nuclear techniques, and electroanatomic mapping. The aim of this state-of-the-art review is to present the value of each modality, that is, its benefits and limitations, in the assessment of arrhythmogenic substrate. Moreover, VAs can be also idiopathic, and in this paper we will underline the role of these techniques in facilitating the ablative procedure. Finally, a hands-on workflow for approaching such a VA and future perspectives will be presented. [ABSTRACT FROM AUTHOR]

During catheter ablation (CA) of tachycardia, conventional point‐by‐point mapping may be hindered due to hemodynamic instability. We performed open‐window mapping (CARTO, Biosense Webster, USA) in a patient who developed hemodynamic instability during orthodromic atrioventricular reciprocating tachycardia (AVRT) and unwarranted induction of AVRT during attempts to map accessory pathway (AP) with ventricular pacing. With over 11,000 points acquired rapidly, the system accurately identified AP at the mitral valve (MV) annulus where the application of single radiofrequency (RF) lesion promptly eliminated AP's conduction. Our case illustrates the utility of open‐window mapping for the ablation of AVRT. [ABSTRACT FROM AUTHOR]

Background: Advanced 3D electroanatomic mapping (EAM) systems have revolutionized atrial fibrillation (AF) ablation by significantly reducing the use of fluoroscopy. In this study, we aimed to compare the initial experience of AF ablation procedures using the VIZIGOTM steerable sheath, which is visible on the 3D EAM, with the conventional approach involving a fixed sheath that is not visible on the 3D EAM. Methods: A total of 50 consecutive patients undergoing AF ablation were enrolled in a prospective observational study. The patient population was divided in two groups: the first group consisted of 25 consecutive patients treated with a fixed sheath that is not visualized on the mapping system (standard group), and the second group consisted of 25 consecutive patients treated using the VIZIGOTM steerable sheath (VIZIGO group). Baseline characteristics of patients, procedural, fluoroscopy, and ablation time were included in the analysis. Primary endpoints were the evaluation of procedural and fluoroscopy time. Study protocol was approved by the local ethics committee and is registered on ClinicalTrials.gov (identifier: NCT05319769). Results: No differences in baseline characteristics were present between the two groups. The median procedural and fluoroscopy time were 130 (IQR 117-181) minutes and 2.2 (IQR 0.0-8.1) minutes respectively. In the VIZIGO group, both procedural time and fluoroscopy time were significantly lower than in the standard group (118[IQR 100-120] vs. 180[IQR 132-202] minutes, p < 0.001, respectively and 0.0 [IQR 0.0-0.5] vs.8.1 [4.7-12.6] minutes, p < 0.001, respectively). At 12 months follow up, recurrences were significantly lower in the VIZIGO group compared to the group where a standard fixed sheath was used (8% vs. 32 %, p = 0.034). Conclusions: Atrial fibrillation ablation with the use of steerable sheath visible on the 3DEAM system eliminates the need of fluoroscopy and reduces procedural time without compromising safety and efficacy. [ABSTRACT FROM AUTHOR]

BACKGROUND: The circuit boundaries for reentrant ventricular tachycardia (VT) have been historically conceptualized within a 2-dimensional (2D) construct, with their fixed or functional nature unresolved. This study aimed to examine the correlation between localized lines of conduction block (LOB) evident during baseline rhythm with lateral isthmus boundaries that 3-dimensionally constrain the VT isthmus as a hyperboloid structure. METHODS: A total of 175 VT activation maps were correlated with isochronal late activation maps during baseline rhythm in 106 patients who underwent catheter ablation for scar-related VT from 3 centers (42% nonischemic cardiomyopathy). An overt LOB was defined by a deceleration zone with split potentials (≥20 ms isoelectric segment) during baseline rhythm. A novel application of pacing within deceleration zone (≥600 ms) was implemented to unmask a concealed LOB not evident during baseline rhythm. LOB identified during baseline rhythm or pacing were correlated with isthmus boundaries during VT. RESULTS: Among 202 deceleration zones analyzed during baseline rhythm, an overt LOB was evident in 47%. When differential pacing was performed in 38 deceleration zones without overt LOB, an underlying concealed LOB was exposed in 84%. In 152 VT activation maps (2D=53, 3-dimensional [3D]=99), 69% of lateral boundaries colocalized with an LOB in 2D activation patterns, and the depth boundary during 3D VT colocalized with an LOB in 79%. In VT circuits with isthmus regions that colocalized with a U-shaped LOB (n=28), the boundary invariably served as both lateral boundaries in 2D and 3D. Overall, 74% of isthmus boundaries were identifiable as fixed LOB during baseline rhythm or differential pacing. CONCLUSIONS: The majority of VT circuit boundaries can be identified as fixed LOB from intrinsic or paced activation during sinus rhythm. Analysis of activation while pacing within the scar substrate is a novel technique that may unmask concealed LOB, previously interpreted to be functional in nature. An LOB from the perspective of a myocardial surface is frequently associated with intramural conduction, supporting the existence of a 3D hyperboloid VT circuit structure. Catheter ablation may be simplified to targeting both sides around an identified LOB during sinus rhythm. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation (CA) has become safe and efficient for the treatment of patients with ventricular extrasystolic beats (VEBs). The three-dimensional electroanatomic mapping (EAM) system allows the elimination of fluoroscopy time during CA procedures. Non-fluoroscopy CA is a challenging procedure requiring intimate knowledge of cardiac anatomy in patients with VEBs. The study aimed to evaluate the efficacy and safety of the non-fluoroscopy CA using the EAM system in patients with VEBs. Methods: Completely fluoroless CA of VEBs guided by EAM was performed in 86% (94 out of 109) of consecutive patients with VEBs. The remaining 15 patients underwent conventional fluoroscopy-guided CA. Demographic and clinical baseline characteristics, procedure parameters, and following complications were obtained from the medical records. Primary outcomes were the acute procedural success rate, the permanent success rate (6-month follow-up), complications, and procedure time. Results: There were no significant differences between groups regarding baseline characteristics. Acute procedural success was achieved in 85 patients (90%) in the non-fluoroscopy group and in 14 patients (93%) in the fluoroscopy group (ns). A long-term success rate was achieved in 82 patients (87%) in the non-fluoroscopy group and in 14 (82%) patients in the fluoroscopy group (ns). The median procedure time was 85 min in the non-fluoroscopy group and 120 min in the fluoroscopy group (p = 0.029). There was only one major complication in the non-fluoroscopy group (ns). Conclusions: Completely fluoroless CA of VEBs guided by EAM is a feasible, safe, and efficient procedure. [ABSTRACT FROM AUTHOR]

Introduction: Accurate localization of septal outflow tract premature ventricular contractions (PVCs) is often difficult due to frequent mid‐myocardial or protected origin. Compared with traditional activation mapping, CARTO Ripple mapping provides visualization of all captured electrogram data without assignment of a specific local activation time and thus may enhance PVC localization. Methods: Electroanatomic maps for consecutive catheter ablation procedures for septal outflow tract PVCs (July 2018–December 2020) were analyzed. For each PVC, we identified the earliest local activation point (EA), defined by the point of maximal –dV/dt in a simultaneously recorded unipolar electrogram, and the earliest Ripple signal (ERS), defined as the earliest point at which three grouped simultaneous Ripple bars appeared in late diastole. Immediate success was defined as full suppression of the clinical PVC. Results: Fifty‐seven unique PVCs in 55 procedures were included. When ERS and EA were in the same chamber (RV, LV, or CS), the odds ratio for the successful procedure was 13.1 (95% confidence interval [CI] 2.2–79.9, p =.005). Discordance between sites was associated with a higher likelihood of needing multi‐site ablation (odds ratio [OR] 7.9 [1.4–4.6; p =.020]). Median EA‐ERS distance in successful versus unsuccessful cases was 4.6 mm (interquartile range 2.9–8.5) versus 12.5 mm (7.8–18.5); (p =.020). Conclusion: Greater EA‐ERS concordance was associated with higher odds of single‐site PVC suppression and successful septal outflow tract PVC ablation. Visualization of complex signals via automated Ripple mapping may offer rapid localization information complementary to local activation mapping for PVCs of mid‐myocardial origin. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation (CA) remains challenging due to suboptimal success rates in persistent atrial fibrillation (AF). Existing mapping technologies cannot reliably distinguish sources in this patient population. Recently, the novel electrographic flow (EGF) mapping system was developed using a modified Horn‐Schunk optical flow algorithm to detect and quantify patterns of electrical wavefront propagation in the atria. Objectives: To test the hypothesis that targeted source ablation based on EGF mapping is superior to empiric AF ablation. Methods: We included all consecutive patients undergoing EGF guided ablation for persistent AF. All patients underwent pulmonary vein isolation (PVI) and were treated with the same EAM system (CARTO). The outcome of PVI+EGF guided CA was compared with data of PVI‐only procedures (PVI‐only group) and PVI plus additional empiric adjunctive linear and substrate ablations (PVI+LINES group). 12‐months outcome as freedom from AF and atrial tachycardia/flutter (AT/AFL), procedural safety and efficiency characterized by procedure duration, fluoroscopy use, radiofrequency applications and duration, were analyzed. Both intention‐to‐treat and per protocol analysis were conducted. Results: A total number of 70 patients (39 in PVI+EGF, 16 in PVI‐only and 15 patients in PVI+LINES group) were enrolled. Intention‐to‐treat analysis showed fewer AF recurrences in PVI+EGF as compared with the PVI‐only or PVI+LINES groups at 12 months (25.6% vs. 62.5% vs. 53.3%, p =.02). There were no differences in AT/AFL recurrence (17.9% vs. 37.5% vs. 20.0%, p =.37). Procedure times were longer in PVI+EGF group (p <.01), and there were no differences in fluoroscopy use (p =.67). Conclusion: Our data suggest that patients treated with EGF‐guided CA developed fewer AF recurrences. Although the procedure times are longer, it seems to be safe and offers a more targeted, patient‐specific ablation strategy beyond PVI than adjunctive empiric lines and substrate ablation in this complex group of patients. [ABSTRACT FROM AUTHOR]

Introduction: The risk of typical atrial flutter (AFL) is increased proportionately to right atrial (RA) size or right atrial scarring that results in reduced conduction velocity. These characteristics result in propagation of a flutter wave by ensuring the macro re‐entrant wave front does not meet its refractory tail. The time taken to traverse the circuit would take account of both of these characteristics and may provide a novel marker of propensity to develop AFL. Our goal was to investigate right atrial collision time (RACT) as a marker of existing typical AFL. Methods: This single‐centre, prospective study recruited consecutive typical AFL ablation patients that were in sinus rhythm. Controls were consecutive electrophysiology study patients >18 years of age. While pacing the coronary sinus (CS) ostium at 600 ms, a local activation time map was created to locate the latest collision point on the anterolateral right atrial wall. This RACT is a measure of conduction velocity and distance from CS to a collision point on the lateral right atrial wall. Results: Ninety‐eight patients were included in the analysis, 41 with atrial flutter and 57 controls. Patients with atrial flutter were older, 64.7 ± 9.7 versus 52.4 ± 16.8 years (<.001), and more often male (34/41 vs. 31/57 [.003]). The AFL group mean RACT (132.6 ± 17.3 ms) was significantly longer than that of controls (99.1 ± 11.6 ms) (p <.001). A RACT cut‐off of 115.5 ms had a sensitivity and specificity of 92.7% and 93.0%, respectively for diagnosis of atrial flutter. A ROC curve indicated an AUC of 0.96 (95% CI: 0.93–1.0, p <.01). Conclusion: RACT is a novel and promising marker of propensity for typical AFL. This data will inform larger prospective studies. [ABSTRACT FROM AUTHOR]

Introduction: Fluoroscopy is traditionally used for catheter interventions in electrophysiology but carries a long-term health risk. Besides additional invasive procedures to achieve zero-fluoroscopy (ZF) interventions, electroanatomic mapping may be an alternative to fluoroscopy without the need of additional procedures. We aimed to investigate the feasibility, safety, and efficiency of a ZF approach using only electroanatomic mapping (ZF) compared to a conventional fluoroscopic (CF) approach for patients with right sided cardiac arrhythmias. Methods: We performed a single centre retrospective cohort study of consecutive patients undergoing catheter interventions for electrophysiologic procedures from January 2019 to December 2020. Patients with left-sided arrhythmias, focal cryoablation, implanted endocardial devices, or additional interventions requiring fluoroscopy were excluded. Results: 202 patients underwent a ZF and 126 patients underwent a CF approach for right-sided cardiac arrhythmias. Apart from atrial fibrillation (ZF 16% vs. CF 9%, p = 0.044), baseline demographics were similar in both groups. Acute success rate was 100% in the ZF group and 97.9% in the CF group. Mean procedure time was lower in the ZF group (70 ± 36 vs. 87 ± 44 min, p = 0.0001), while ablation time (356 ± 324 vs. 320 ± 294 s, p = 0.157) was similar. Total complication rate was low in general (1.0 % major, 2% minor complications) and without a difference between both groups. Conclusion: A ZF approach using only electroanatomic mapping without additional invasive procedures to diagnose and treat right-sided cardiac arrhythmias is feasible, efficient, and safe. [ABSTRACT FROM AUTHOR]

Introduction: Low‐voltage activity beyond pulmonary veins (PVs) may contribute to the failure of ablation of atrial fibrillation (AF) in the long term. We aimed to assess the presence of gaps (PVG) and residual potential (residual antral potential [RAP]) within the antral scar by means of an ultra‐high‐density mapping (UHDM) system. Methods: We studied consecutive patients from the CHARISMA registry who were undergoing AF ablation and had complete characterization of residual PV antral activity. The Lumipoint™ (Boston Scientific) map‐analysis tool was used sequentially on each PV component. The ablation endpoint was PV isolation (PVI) and electrical quiescence in the antral region. Results: Fifty‐eight cases of AF ablation were analyzed. A total of 86 PVGs in 34 (58.6%) patients and 44 RAPs in 34 patients (58.6%) were found. In 16 (27.6%) cases, we found at least one RAP in patients with complete absence of PV conduction. RAPs showed a lower mean voltage than PVG (0.3 ± 0.2 mV vs. 0.7 ± 0.5 mV, p <.0001), whereas the mean number of electrogram peaks was higher (8.4 ± 1.4 vs. 3.2 ± 1.5, p <.0001). The percentage of patients in whom RAPs were detected through Lumipoint™ was higher than through propagation map analysis (58.6% vs. 36.2%, p =.025). Acute procedural success was 100%, with all PVs successfully isolated and RAPs completely abolished in all study patients. During a mean follow‐up of 453 ± 133 days, 6 patients (10.3%) suffered an AF/AT recurrence. Conclusion: Local vulnerabilities in antral lesion sets were easily discernible by means of the UHDM system in both de novo and redo patients when no PV conduction was present. [ABSTRACT FROM AUTHOR]

Introduction: Multielectrode mapping (MEM) and automated point collection are important enhancements to substrate mapping in ventricular tachycardia ablation. The effects of tissue contact and respiration on electrogram voltage with differing depolarization wavefronts with MEM catheters are unclear. Methods: Bipolar and unipolar voltages were collected from control (n = 5) and infarcted (n = 7) animals with a multispline MEM catheter. Electro‐anatomic maps were created in sinus rhythm, and right and left ventricular pacing. Analysis was performed across three collections: standard settings (SS), respiratory‐phase gating (RG), and electrode‐tissue proximity (TP). Comparison was made to scar detected by cardiac MRI (cMRI). Results: Compared to SS and RG acquisition, median bipolar and unipolar voltages were higher using TP, regardless of the depolarization wavefront. In infarct animals, bipolar voltages were 30.7%–50.5% higher for bipolar and 8.7%–13.8% higher on unipolar voltages with TP, compared to SS. The effect of RG on bipolar and unipolar voltages was minimal. Percentage of local abnormal ventricular activities was not impacted by acquisition settings or wavefront direction in infarct animals. Compared with cMRI defined scar, all three acquisition settings overestimated scar area using standard voltage‐based cutoffs. RG improved the low voltage area concordance with MRI by 1.6%–5.1% whereas TP improved by 5.9%–8.4%. Conclusions: High density voltage mapping with a MEM catheter is influenced by point collection settings. Tissue contact filters reduced low voltage areas and improved agreement with cMRI fibrosis in infarcted ovine hearts. These findings have critical implications for optimizing filter settings for high density substrate mapping in the left ventricle. [ABSTRACT FROM AUTHOR]

Radiofrequency ablation is an effective and safe technique for the treatment of different types of arrhythmias. Radiofrequency ablation is performed using fluoroscopy, a standard navigation guide, which is related to radiation exposure and its well-known harmful effects on patients and laboratory staff. In the last decade, electroanatomic mapping systems have noted a steep development. Despite their indisputable advantages, they do not include information obtained by real-time fluoroscopy. This important limitation is tackled by the new CARTO-UNIVU™ module as it seamlessly combines fluoroscopy images with threedimensional (3D) electroanatomic mapping into a single accurate 3D view, enabling a pronounced reduction in radiation exposure. We report four cases of our single center first experience of the new CARTO-UNIVU™ module. [ABSTRACT FROM AUTHOR]

A wide variety of non-invasive and invasive techniques for SCD risk stratification in non ischemic cardiomyopathy (NICM) have been proposed, including left ventricular (LV) ejection fraction, QRS duration, late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) and invasive electrophysiologic study with or without three-dimensional electroanatomic mapping (3D-EAM), to identify and characterize the arrhythmogenic substrate. There is still no clear consensus on the risk stratification in this clinical setting. The aim of our study is to characterize the 3D-EAM substrate in patients with the same clinical presentation of unexplained complex VAs and NICM using CMR, three-dimensional electranatomic mapping (3D-EAM) in association with endomyocardial biopsy (EMB) and genetic screening, as a more precise and early diagnostic assessment may provide important subsequent prognostic impact. The study was designed as a prospective multi-center observational evaluation and the patient follow-up was scheduled at 6 months interval. We enrolled 125 patients distinct into four different group by complete diagnostic work-up: myocarditis, non-dilated left ventricular cardiomyopathy, arrhythmogenic cardiomyopathy and control group. The four groups were compared in terms of clinical, imaging and 3D-EAM data. At multivariate analysis sustained VT/VF on admission [HR: 3.64 (1.79–7.4), p < 0.001], total bipolar scar area of left and right ventricle detected by 3D-EAM [HR: 2.24 (1.13–4.49), p = 0.02], histological diagnosis of myocarditis by 3D-EAM guided endomyocardial biopsy (EBM) [HR: 2.79 (1.04–7.44), p = 0.01] were independent predictors of complex VAs or death at follow-up. 3D-EAM guided EMB represent not only a valid diagnostic tool to identify the arrhythmogenic substrate in patients with NICM and ventricular arrhythmic phenotype but also an important predictor of complex Vas at long term follow-up. [Display omitted] • Given the large variety of cardiomyopathies inside the group of non-ICM, SCD risk estimation remains a clinical challenge • The early individualization of the different myocardial diseases underlying ventricular arrhythmic phenotypes may give important subsequent therapeutic and prognostic information. • Clinical data combined with 3D electroanatomic mapping (EAM) and endomyocardial biopsy guided by 3D-EAM are valuable tools in predicting ventricular arrhythmic events and worse prognosis at follow-up. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation (CA) is a safe and efficient treatment in patients with an atrioventricular accessory pathway (AP). Electroanatomical mapping (EAM) systems are useful during CA of AP, especially for reducing fluoroscopy. There are limited data about the feasibility of CA procedures performed with the use of the EAM system entirely without fluoroscopy in adults with AP. The aim of the study is to assess the feasibility, efficacy and safety of CA with the use of EAM without fluoroscopy, compared to CA with EAM and fluoroscopy in patients with AP. Methods: The study included 83 consecutive patients (age 38.25 ± 15.8 years), who were subjected to CA for AP. In 40 patients CA was performed with the use of EAM without fluoroscopy (EAM group), and in 43 patients CA was performed with EAM and fluoroscopy (control group). Baseline characteristics, procedure parameters and complications were obtained from the medical records. Data on permanent success rate was obtained after the mean follow-up time of 1 year. Primary outcomes were acute procedural success rate, long term success rate at 1-year follow-up and complications. Secondary outcomes were the procedure time and number of applications. Results: There were no statistically significant differences in baseline characteristics between the groups, except for the AP locations. Right-sided AP was more common in the EAM group, while left-sided AP was more common in the control group (p = 0.007 and p = 0.004, respectively). Acute procedural success was achieved in 38 patients (95.0%) in the EAM group and in 39 patients (90.7%) in the control group (p = 0.449). Long term success rate was achieved in 36 patients (90.0%) in the EAM group and in 36 (83.7%) patients in the control group (p = 0.399). There was one minor complication in the form of RBBB in the EAM group (p = 0.138). The mean procedure time was shorter in the EAM group compared to the control group (93.0 ± 58.3 min vs. 127.6 ± 57.5 min; p = 0.009). Conclusions: CA of both right-sided and left-sided AP completely guided by EAM without the use of fluoroscopy is feasible, safe and effective. [ABSTRACT FROM AUTHOR]

Earlier studies that investigated the relation of atrioventricular (AV) conduction system to perimembranous ventricular septal defect (pmVSD) were based on cardiopathological specimens. To study the relationship of conduction system to pmVSD using 3-dimensional electroanatomic mapping system (EAMS) in patients undergoing device closure. Fifteen consecutive cases of pmVSD from January 2014 to July 2017 (age > 2 years and weight > 8 kg) were included in the study. The course of conduction system and its relationship with the pmVSD was mapped before and after device closure, with the use of EAMS. Median age and weight of the cohort was 10 years (range 4–21 years) and 25 kg (range 13–55) respectively. Device implantation was successful in all patients except 1. The course and relation of the conduction system were posteroinferior to the pmVSD in all cases (100%), and away from the defect in 67% (10/15). In patient with baseline RBBB, the right-sided conduction system was in close proximity to the pmVSD. Two patients had part of left-sided conduction system in close proximity to pmVSD or device edges. Two patients developed RBBB following device deployment, which reverted to normal on follow up. No patient developed high grade AV block during the median follow-up of 34 months (range 24–62). This experimental study has shown the feasibility of 3D EAM of conduction system during device closure of pmVSD. This novel concept can be utilized to understand the anatomy of conduction system in other congenital heart diseases. [ABSTRACT FROM AUTHOR]

Introduction: For those cardiac resynchronization therapy (CRT) candidates who experience left-ventricular (LV) lead placement failure or underwent concomitant cardiac surgeries, surgical placement of epicardial LV lead guided by electroanatomic mapping may be a promising alternative. Methods: Electroanatomic mapping was used to guide positioning of the LV lead through a surgical approach. The LV lead was placed at the region with the latest local LV activation and normal voltage, away from the scar. Results: From April 2010 to September 2018, 10 consecutive patients (3 female) underwent surgical epicardial LV lead implantation. Among them, 3 had other surgical indications simultaneously (including 1 CRT non-responder), and 7 had failed transvenous LV lead placement. After CRT, the QRS duration was shortened from 149.3 ± 20.4 ms to 125.1 ± 15.2 ms (p = 0.01). At 6 months, the LV ejection fraction was significantly improved and remained stable in the follow-up (FU) period thereafter (baseline vs. 6 months, 31.0 ± 8.3% vs. 42.2 ± 13.4%, p = 0.006). Other parameters, including the threshold and impedance of the LV lead, were also stable at a mean FU of 755 ± 406 days, and the NYHA functional classification decreased from 2.9 ± 0.7 to 1.8 ± 0.8 (p = 0.002). Conclusions: Placement of an epicardial LV lead guided by electroanatomic mapping could be used as an adjunctive strategy in patients who were unable or refractory to conventional CRT therapy. This approach could also be applied in patients who had other surgical indications at the same time. [ABSTRACT FROM AUTHOR]

Introduction: Transseptal puncture (TSP) is widely used in clinical practice but is negatively affected by a nonneglectable rate of complications and X‐ray exposure. To address these problems, we investigated whether or not impedance mapping could correctly identify fossa ovalis (FO) and safely guide TSP. Methods and Results: Electroanatomic mapping was performed with CARTO 3 system version 7 and a ThermoCool® SmartTouch® mapping catheter was employed. In each patient, an impedance map and a bipolar voltage map of the whole interatrial septum were collected, acquiring at least 150 points with a contact force ≥2 g and using the pattern matching filter. Thirty‐five patients were enrolled. A low impedance area was clearly identified in 34 of them. In 30 patients (88%), the FO was located in the low impedance area. The map was obtained in sinus rhythm in 17 cases (50%); in 15 of these (88%), the TSP site, the patent foramen ovale, or the FO tenting area fell inside the low impedance area. The same numbers were observed when mapping during atrial fibrillation. Conclusion: To the best of our knowledge, this is the first study that provides the reliability and reproducibility of impedance mapping in identifying FO, an affordable and feasible tool that could be potentially introduced into clinical practice. [ABSTRACT FROM AUTHOR]

Electroanatomic mapping systems have become an essential tool to guide the identification and ablation of arrhythmic substrate. Recently, a novel guiding system for electrophysiology procedures was introduced that uses dielectric sensing to perform high resolution anatomical imaging. Dielectric imaging systems use electrical fields to differentiate anatomic structures based on their conductivity and permittivity. This technique enables non‐fluoroscopic, noncontact mapping of anatomic structures, assessment of pulmonary vein occlusion state during cryoballoon ablation, and has the potential to assess for additional tissue characterization including tissue thickness and tissue type. This article elaborates on the functioning and potential of dielectric imaging systems and provides two cases to illustrate the clinical impact for electrophysiology procedures. [ABSTRACT FROM AUTHOR]

Background: Post‐ablation atrial tachycardias (ATs) are characterized by low‐voltage signals that challenge current mapping methods. In this study, we analyzed common mistakes during activation mapping and delineated a mapping strategy for correct interpretation of tachycardia mechanisms in patients with challenging underlying substrate. Methods and results: Thirty‐one patients referred for AT ablation were selected for the study. Three types of incorrect activation patterns were identified, which were referred to as unrecognized block line (pseudo‐macroreentry and pseudo‐fig‐8 reentry), incorrect activation timing window of interest (WOI) (chaotic activation), and mis‐annotation of complex signals (multiple sites of "early meets late"). Pseudo‐macroreentry and chaotic activation occur in focal or localized reentry AT with the error related to the WOI selection (four cases), incorrect annotation of local activation time (six cases), or a previous line of atrial block in (seven cases). Pseudo‐fig‐8 reentry (five cases) and multiple sites of "early meets late" (nine cases) occur in macroreentrant AT with blocked areas and low‐voltage atrial substrate. All ATs were successfully eliminated at the origin site. Conclusions: We delineated a series of ATs in the setting of a disordered pattern of activation mapping encountered in patients after previous extensive ablation or atriotomy. The algorithm proposed rapidly corrects the activation map and identifies the mechanism of the AT. [ABSTRACT FROM AUTHOR]

Introduction: We report a case of a fetus with complex congenital heart disease and supraventricular tachycardia in the setting of maternal high grade atrioventricular block at 26 weeks' gestation. Methods and results: Electroanatomic mapping allowed successful implantation of a permanent pacemaker to provide adequate back‐up pacing in the mother with zero radiation exposure, thus allowing safe delivery of transplacental anti‐arrhythmic medications to reduce the fetal arrhythmia burden and optimize the fetal ventricular rate. Conclusion: This is the first reported case of using electroanatomic mapping, with zero fluoroscopy use, for pacemaker lead placement and for a novel indication. [ABSTRACT FROM AUTHOR]

Introduction: Therapies for substrate‐related arrhythmias include ablation or drugs targeted at altering conductive properties or disruption of slow zones in heterogeneous myocardium. Conductive compounds such as carbon nanotubes may provide a novel personalizable therapy for arrhythmia treatment by allowing tissue homogenization. Methods: A nanocellulose carbon nanotube‐conductive hydrogel was developed to have conduction properties similar to normal myocardium. Ex vivo perfused canine hearts were studied. Electroanatomic activation mapping of the epicardial surface was performed at baseline, after radiofrequency ablation, and after uniform needle injections of the conductive hydrogel through the injured tissue. Gross histology was used to assess distribution of conductive hydrogel in the tissue. Results: The conductive hydrogel viscosity was optimized to decrease with increasing shear rate to allow expression through a syringe. The direct current conductivity under aqueous conduction was 4.3 × 10−1 S/cm. In four canine hearts, when compared with the homogeneous baseline conduction, isochronal maps demonstrated sequential myocardial activation with a shift in direction of activation to surround the edges of the ablated region. After injection of the conductive hydrogel, isochrones demonstrated conduction through the ablated tissue with activation restored through the ablated tissue. Gross specimen examination demonstrated retention of the hydrogel within the tissue. Conclusions: This proof‐of‐concept study demonstrates that conductive hydrogel can be injected into acutely disrupted myocardium to restore conduction. Future experiments should focus on evaluating long‐term retention and biocompatibility of the hydrogel through in vivo experimentation. [ABSTRACT FROM AUTHOR]

Introduction: Technological advancement in the setting of atrial fibrillation (AF) ablation has decreased radiation exposure and complications associated with the procedure. Yet, transseptal puncture (TSP) remains a challenging step that necessitates accurate guidance. We describe our experience performing TSP under electroanatomic (EA) guidance. Methods and results: The analysis included 145 consecutive EA‐guided ablation procedures performed between June 2018 and April 2019 and 145 consecutive standard ablations performed before June 2018. EA guidance utilized the CARTO 3 three‐dimensional mapping system to reconstruct anatomic and electrical characteristics of the right atrium and fossa ovalis. Patients with a history of previous cardiac surgery were excluded. For EA‐guided procedures, the mean patient age was 60 ± 10 years, 75.2% were male, and 69.0% had paroxysmal AF. Similarly, the mean age for conventional procedures was 60 ± 11 years, 71.0% were male, and 71.7% had paroxysmal AF. The fossa ovalis was detected as a region of low voltage, <0.75 mV. EA guidance yielded shorter fluoroscopy times (EA vs. conventional, 3.6 ± 2.5 vs. 13.5 ± 10.5 min; p <.001) and a lower dose area product than conventional guidance (13 ± 11 Gy* cm2 vs. 28 ± 27 Gy* cm2; p <.001). The total procedure duration was similar between groups (146 ± 48 vs. 148 ± 54 min). There were no significant complications related to TSP. Conclusion: During AF ablation, TSP with EA guidance facilitated safe access to the left atrium while reducing radiation risk to both patients and operators. [ABSTRACT FROM AUTHOR]

Objective: Unipolar intracardiac electrograms (uEGMs) measured inside the atria during electro-anatomic mapping contain diagnostic information about cardiac excitation and tissue properties. The ventricular far field (VFF) caused by ventricular depolarization compromises these signals. Current signal processing techniques require several seconds of local uEGMs to remove the VFF component and thus prolong the clinical mapping procedure. We developed an approach to remove the VFF component using data obtained during initial anatomy acquisition. Methods: We developed two models which can approximate the spatio-temporal distribution of the VFF component based on acquired EGM data: Polynomial fit, and dipole fit. Both were benchmarked based on simulated cardiac excitation in two models of the human heart and applied to clinical data. Results: VFF data acquired in one atrium were used to estimate model parameters. Under realistic noise conditions, a dipole model approximated the VFF with a median deviation of 0.029 mV, yielding a median VFF attenuation of 142. In a different setup, only VFF data acquired at distances of more than 5 mm to the atrial endocardium were used to estimate the model parameters. The VFF component was then extrapolated for a layer of 5 mm thickness lining the endocardial tissue. A median deviation of 0.082 mV (median VFF attenuation of 49x) was achieved under realistic noise conditions. Conclusion: It is feasible to model the VFF component in a personalized way and effectively remove it from uEGMs. Significance: Application of our novel, simple and computationally inexpensive methods allows immediate diagnostic assessment of uEGM data without prolonging data acquisition. [ABSTRACT FROM AUTHOR]

The management of ventricular arrhythmias (VA) in the presence of an apparently normal heart represents a major clinical challenge and a main field of clinical research. In the past years, new imaging techniques and the spreading of new generation genetic testing have improved our knowledge of the pathogenesis of apparently idiopathic VA. However, in the absence of specific recommendations, the type and the number of noninvasive and invasive studies necessary to rule out a possible underlying cause of VA or sudden cardiac death remain extremely variable. Therefore, in many patients the underlying cardiac disease is not recognized, and a possible specific therapeutic approach cannot be initiated. Endomyocardial biopsy (EMB) can provide a significant contribution to the identification of myocardial disorders causing VA but has never been definitively included in the routine diagnostic work‐up of these patients due to the possible sampling error particularly in disorders with a focal or patchy distribution. Three‐dimensional electroanatomic mapping (EAM) may guide EMB allowing to draw myocardial samples from abnormal voltage, areas of the ventricular wall, thus reducing sampling error and increasing the sensitivity of EMB. The systematic association of EAM with EMB represents a crucial approach to characterize the pathological substrate of electroanatomic abnormalities and VA and to further clarify the arrhythmogenic mechanisms of acquired and also inherited arrhythmic disorders. [ABSTRACT FROM AUTHOR]

Background: Ventricular arrhythmias (VAs) have never been systematically investigated in patients with myocarditis at different stages.Objectives: The purpose of this study was to compare baseline and follow-up characteristics of VAs in patients with active myocarditis (AM) versus previous myocarditis (PM).Methods: A total of 185 consecutive patients (69% males, age 44 ± 15 years, left ventricular ejection fraction 49 ± 14%) with myocarditis and VA at index hospitalization, including ventricular fibrillation, ventricular tachycardia (VT), nonsustained ventricular tachycardia (NSVT), and Lown's grade ≥2 premature ventricular complexes, were enrolled. AM and PM groups were defined based on endomyocardial biopsy and cardiac magnetic resonance findings. A subset of patients (n = 46, 25%) also underwent electroanatomic mapping and VA transcatheter ablation.Results: At presentation, AM patients (n = 123, 66%) more commonly had ventricular fibrillation (8 cases vs. 0 cases; p = 0.053), and both irregular (61% vs. 11%; p < 0.001) and polymorphic VA (NSVT and VT: 19% vs. 2%; p = 0.002; premature ventricular complexes: 63% vs. 16%; p < 0.001). Only in PM patients with NSVT or VT, the dominant morphology (right-bundle branch block with superior axis) was 100% predictive of abnormal LV inferoposterior substrate at both cardiac magnetic resonance and electroanatomic mapping. At 27 ± 7 months prospective follow-up, 55 patients (30%) experienced malignant VA (AM vs. PM, p = 0.385). Although a prevalence of polymorphic and irregular VA was confirmed in AM patients with persistent inflammation in follow-up (58%), a predominance of monomorphic and regular VA was found in AM patients after myocarditis healing (42%), as well as in PM patients (all p < 0.001).Conclusions: In myocarditis patients, polymorphic and irregular VA are more common during the active inflammatory phase, whereas monomorphic and regular VA are associated with healed myocarditis. [ABSTRACT FROM AUTHOR]

Introduction: Minimal data exist on the Advisor HD Grid (HDG) catheter and the Precision electroanatomic mapping (EAM) system for ventricular arrhythmia (VA) procedures. Using the HDG catheter, the EAM uses the high‐density (HD) wave mapping and best duplicate software to compare the maximum peak‐to‐peak bipolar voltages within a small zone independent of wavefront direction and catheter orientation. This study aimed to summarize the procedural experience for VAs using the HDG catheter. Methods: Clinical and procedural characteristics of VA ablation procedures were retrospectively reviewed that used the HDG catheter and the Precision EAM over a 12‐month period. Results: A total of 22 patients, 18 with sustained ventricular tachycardia and 4 with premature ventricular contractions were included. Clinically indicated left and/or right ventricular (LV, RV, respectively), and aortic maps were created. LV substrate maps (n = 13) used a median 1700 points (interquartile range [IQR]25%‐75%, 1427‐2412) out of a median 18 573 (IQR25%‐75%, 15 713‐41 067) total points collected. RV substrate maps (n = 11) used a median 1435 points (IQR25%‐75%, 1114‐1871) out of a median 16 005 (IQR25%‐75%, 11 063‐21 405) total points collected. Total point utilization, used vs collected, was 9%. Mean mapping time was 43 ± 17 minutes (substrate, 34 ± 18 minutes; activation/pace mapping, 9 ± 13 minutes). Acute success was achieved in 56 (86%) and short‐term success achieved in 16 patients (73%) at a median follow‐up of 145 days (IQR25%‐75%, 62‐273 days). There were no procedural complications. Conclusion: HD wave mapping using the novel HDG catheter integrated with the Precision EAM is safe and feasible in VA procedures in the LV, RV, and aorta. Mapping times are consistent with other multielectrode mapping catheters. [ABSTRACT FROM AUTHOR]

An editorial is presented on the Automatic identification of VT substrate in the era of ultrahigh‐density mapping. Topics discussed include substrate mapping allows identification of putative VT isthmii by using surrogate markers in stable sinus or paced rhythm representing slow; and substrate mapping has improved the feasibility of VT ablation by avoiding the deleterious consequences of prolonged episodes of sustained VT to permit activation/entrainment mapping.

The article presents the discussion on late activation mapping or abrupt transition in the QRS morphology. Topics include substrate mapping being performed in sinus or paced rhythm, and comprise of annotation of abnormal electrograms showing low voltage, fractionated, and late potential; and infering critical isthmus identification by means of effective elimination resulting in clinical VT non‐inducibility.

Introduction: Point‐by‐point 3‐dimensional (3D) electroanatomic mapping (EAM) is used to guide catheter ablation of premature ventricular complexes (PVCs). Due to the differences in the spatial excursion of the cardiac chambers during cardiac cycles in PVCs vs sinus rhythm, the 3D location registration during PVCs is shifted relative to sinus rhythm. In this study, we describe our strategy to adjust for this displacement in real‐time during PVC mapping. Methods and Results: We report 21 patients who underwent catheter ablation of 23 unique PVCs using Carto 3. After mapping the earliest site for each PVC, we reregistered its 3D location to a sinus rhythm beat in real‐time, and used this to guide ablation lesion delivery. The PVC earliest location was spatially displaced from the successful ablation lesion in sinus rhythm by average 6.7 (range 3.3–13.0) mm. Offline, we subsequently analyzed 25 unique chamber maps and 606 PVC points. For each point, we reregistered the 3D location to a preceding sinus beat. The PVC points were displaced from sinus rhythm location by average 4.4 (0.3–13.7) mm. The maximally displaced point for each chamber was 7.7 (4.7–13.7) mm. The general direction of shift during PVC was leftward and inferior relative to sinus rhythm. Conclusions: During electroanatomic mapping of PVCs using the Carto 3 system, points mapped during PVCs are spatially displaced relative to their location in sinus rhythm. Electrophysiologists should recognize this phenomenon and account for the shift to guide accurate delivery of ablation lesions. [ABSTRACT FROM AUTHOR]

Multielectrode epicardial mapping during robotic implantation of cardiac resynchronization‐defibrillator system. Robotically assisted endoscopic implantation of cardiac implantable devices is well documented to be both feasible and safe, and this technique provides particular benefit in patients with limited vascular access. In a patient meeting Class I indication for cardiac resynchronization therapy with defibrillator and inaccessible vascular access, we describe in this case an optimization strategy for intraoperative left ventricular lead placement utilizing robotic epicardial electroanatomic mapping as well as the feasibility of implanting a totally epicardial biventricular cardioverter‐defibrillator system. [ABSTRACT FROM AUTHOR]

Background: Mapping and ablation of fractionated electrograms is a common treatment for scar‐based ventricular tachycardia (VT). An automated algorithm has been developed for rapid "fractionation mapping." Methods: Electroanatomic maps from 21 ablation procedures (14 scar‐based VT and seven control idiopathic VT/premature ventricular contractions with normal voltage) were retrospectively analyzed using the Ensite Precision fractionation map (fMap; Abbott Laboratories; Abbott Park, IL, USA) algorithm. For each study, voltage maps and 30 fMaps were generated using combinations of parameters: width (5, 10, 20 ms), refractory time (15, 30 ms), sensitivity (0.1, 0.2 mV), and fractionation threshold (2, 3, 5). Parameter sensitivity was assessed by overlap of fractionated areas (fArea) with successful VT ablation sites (defined by entrainment and/or pace mapping). Specificity was assessed by presence of fractionated areas in control patients. Results: Of the 30 fMap parameter sets tested, seven identified >50% of scar‐based VT ablation sites, and 26 contained <5 cm2 fractionation on control fMaps. Three combinations of fMap width/refractory/sensitivity/threshold parameters met both of the above criteria, and 20/30/0.1/2 identified the most VT ablation sites (79%) and generated 42.3 ± 28.2 cm2 of fArea on scar‐based VT maps compared with 4.9 ± 3.2 cm2 on control maps (P = .001). None of the control patients and 23% of the scar‐based VT patients had VT recurrence at mean 15 month follow‐up. Conclusion: Careful selection of signal processing parameters optimizes sensitivity and specificity of automated fractionation mapping for scar‐based VT. Real‐time use of fMap algorithms may reduce VT ablation procedure time and improve substrate modification, which may improve outcomes. [ABSTRACT FROM AUTHOR]

Background: The conventional method of device implantation requires fluoroscopic guidance. With the guidance of three‐dimensional (3‐D) navigation systems, devices can be implanted with minimal use of fluoroscopy. To date, this technique has been reported in several case reports in young, pregnant patients. However, this technique has not been widely utilized by electrophysiologists, despite offering several benefits, including reduced radiation exposure for the patient and the operator. Methods: In this study, we evaluated 18 patients who successfully underwent device implantation with limited use of fluoroscopy under the guidance of the EnSite Precision 3‐D mapping navigation system (Abbott, St. Paul, MN, USA). In most of the patients, the total fluoroscopy time was 1 s, accounted by a single postprocedural frame to insure appropriate lead placement. Results: A total of 19 leads were implanted in 18 patients (14 male, four female) using the electroanatomical mapping (EAM)‐guided technique. A total of 19 leads were implanted in 15 patients (10 male, five female) using the conventional method. The average length of stay was 1.20 days in the EAM group compared to 1.47 days in the conventional group (P = .10). Majority of the devices implanted in both groups were single‐chamber implantable cardiac defibrillators (VVI ICD, Abbott) implanted for cardiomyopathy with left ventricular ejection fraction persistently below 35%, including 88% (16/18) in the EAM group compared to 73% (11/15) in the conventional group. No periprocedural or immediate postprocedure complications were reported in either group. Device parameters, including impedance, capture time, and capture voltage, showed no significant difference in either group. Total radiation time and radiation dose were markedly lower in the EAM‐guided implantation group. Conclusions: In patients who meet appropriate criteria for device implantation, the use of EAM system offers a safe, practical, efficacious alternative method to device implantation, with significant reduction in radiation time and dose. [ABSTRACT FROM AUTHOR]

Key Clinical Message: The presence of a Gore‐Tex patch can create difficulty in performing transeptal puncture for atrial septal defect patients underwent atrial fibrillation ablation. The maneuverability and stability of using manually operated catheters via retrograde aortic approach could be overcome by a large‐curved catheter to form a loop facilitating approachability to all parts of left atrium. The presence of a Gore‐Tex patch can create difficulty in performing transeptal puncture for atrial septal defect patients underwent atrial fibrillation ablation. The maneuverability and stability of using manually operated catheters via retrograde aortic approach could be overcome by a large‐curved catheter to form a loop facilitating approachability to all parts of left atrium. [ABSTRACT FROM AUTHOR]

Epicardial ablation may be required to eliminate ventricular tachycardia (VT) in patients with underlying structural heart disease. The decision to gain epicardial access is frequently based on the suspicion of an epicardial origin for the VT and/or presence of an arrhythmogenic substrate. Epicardial pathology and VT is frequently present in patients with nonischemic right and/or left cardiomyopathies even in the setting of modest or no endocardial bipolar voltage substrate. In this setting, unipolar voltage mapping from the endocardium serves to help identify midmyocardial and/or epicardial VT substrate. The additional value of endocardial unipolar mapping includes its usefulness to predict the clinical outcome after VT ablation, to determine the irreversibility of myocardial disease, and to guide endomyocardial biopsy procedures to specific areas of intramural scarring. In this review, we aim to provide a guide to the use of endocardial unipolar mapping and its appropriate interpretation in a variety of clinical situations. [ABSTRACT FROM AUTHOR]

Background: Patients with systemic right ventricle (RV) often develop progressive heart failure and may benefit from cardiac resynchronization therapy (CRT); however, the optimal strategy for CRT has not been defined. Methods: A retrospective review of all the patients with systemic RV failure undergoing a hybrid transcatheter‐surgical approach was performed. Procedural technique and outcomes are reported. Results: Six patients underwent detailed electroanatomical mapping of the systemic RV followed by a new hybrid approach targeting latest endocardial activation, which was followed by focused epicardial mapping. The exact site of latest endocardial activation was variable but localized to the basolateral RV in all cases. Sites of latest activation tended to be more superior during contralateral ventricular pacing versus intact atrioventricular conduction (P = 0.06). Latest endocardial activation at the targeted site occurred at 157 ms (interquartile range [IQR] = 120‐181 ms) and corresponding epicardial activation at 174 ms (IQR = 140‐198 ms), after the onset of the QRS complex. Following the hybrid CRT, the QRS duration decreased from a median of 193 to 147 ms and the fractional area of change increased from a median of 15.5% to 30% (P < 0.001). Patients were discharged to home after a median of 4 days. Of the three patients who were initially referred for transplant evaluation, two (66%) of them no longer met the criteria following CRT. Conclusions: Whereas latest endocardial activation for the systemic RV appears to localize to the basolateral region, the optimal lead position may be variable. An approach utilizing endocardial mapping followed by a limited surgical incision and confirmation of latest activation may result in minimally invasive surgery and a favorable acute CRT response. [ABSTRACT FROM AUTHOR]

Background: The prevalence and significance of structural abnormalities in Brugada syndrome (BrS) are still largely debated.Objectives: The authors investigated the relationship between genetic background, electroanatomic abnormalities, and pathologic substrate in BrS.Methods: They performed 3-dimensional electroanatomic unipolar and bipolar mapping in 30 patients with BrS. Twenty patients underwent 3-dimensional electroanatomic unipolar and bipolar mapping-guided right ventricular outflow tract (RVOT) endomyocardial biopsy. Programmed ventricular stimulation and genetic analysis were performed in all patients.Results: Low-voltage areas (LVAs) were observed at unipolar map in 93% of patients and at bipolar map in 50% of cases. Unipolar LVAs were always larger than bipolar LVAs, were always colocalized, and in all cases included RVOT. Disease-causing mutations were detected in 10 (33%) patients. Programmed ventricular stimulation was positive in 16 cases (53%). In 75% of patients, RVOT histology showed pathologic findings with myocardial inflammation in 80% of them. Among patients with abnormal bipolar map submitted to endomyocardial biopsy, 9 (81%) showed evidence of myocardial inflammation. Conversely, bipolar map was abnormal in 83% of patients with myocardial inflammation. Myocardial inflammation was also more prevalent among inducible patients (83% vs. 25% in noninducible; p = 0.032).Conclusions: BrS is characterized by electroanatomical and structural abnormalities localized to RVOT with a gradient of the pathologic substrate from epicardium to endocardium possibly driven by myocardial inflammation. These findings reclassify BrS as a combination of structural and electrical defects opening the way to new risk stratification and therapeutic strategies. [ABSTRACT FROM AUTHOR]

This case illustrates that the condition of atrial fibrillation (AF) may harbor site(s) of regular rotational activity, reentry may be an underlying mechanism, high periodicity and wavebreak through areas of the scar may generate fibrillatory conduction, and disintegration of the "rotor" may not abolish AF. [ABSTRACT FROM AUTHOR]

In Ebstein’s anomaly (EA), tachycardia substrates are complex, and accessory pathway (AP) ablations are often challenging. This study demonstrates the utility of the EnSite Velocity system (St. Jude Medical, St Paul, MN) in the catheter ablation of supraventricular tachycardia in children with EA. Twenty patients [Female/Male = 8/12, median age 11.5 years (2.6-18)] with EA who underwent catheter ablation guided by the EnSite Velocity system between December 2011 and December 2016 were retrospectively evaluated. Five patients had severe EA, and two of them were at Fontan palliation pathway. The most common indications for ablations were palpitations/syncope and treatment-resistant arrhythmias. Thirty-one tachycardia substrate foci (21 manifest AP, 2 concealed AP, 4 Mahaim AP, 3 focal atrial tachycardias, and 1 typical atrioventricular nodal reentrant tachycardia) were detected in 20 patients. There were multiple tachycardia substrates in 11 patients (55%). The patient-based acute procedure success rate was 19/20 (95%), and the tachycardia-based success rate was 30/31 (97%). The mean procedure time was 170 ± 43 min (90-265). Fluoroscopy was not used in 15 (75%) patients. The mean fluoroscopy time in the remaining five patients was 3.6 ± 2.9 min (0.7-7.8). During a mean follow-up of 35.1 ± 20.3 months (6-60), tachycardia recurred in four patients (4/19, 21%). No complications were seen. Catheter ablation of arrhythmias can be performed effectively and safely in pediatric EA patients by using a limited fluoroscopic approach with the help of electroanatomical mapping systems. However, the rate of tachycardia recurrence at follow-up remains high. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Unipolar voltage mapping through its wider “field of view” can identify substrate deeper to the endocardium on the right ventricular (RV) free wall and left ventricle. The reference value(s) for normal endocardial (ENDO) unipolar voltage (UNI) for the septal aspect of the right ventricle (RV) and the effect of the aortic root that is directly opposed to the posterior septal plane of the RV outflow tract (RVOT) have not been established. Methods and results: We performed detailed (185 ± 70, range 127–342 points) RV ENDO UNI maps in 9 patients without structural heart disease; 6 had magnetic resonance (MR) imaging; 5 were males; the mean age was 49 ± 11 years. For MR analysis, the location of the aortic root was defined and its effect on unipolar voltage determined. The UNI voltage on posterior RVOT was lower (mean 6.56 ± 2.33 mV, 95% CI 6.08–7.05), compared to the rest of the septal aspect of RV (mean 8.33 ± 2.34 mV, P < 0.001, 95% CI 7.84–8.84). MR analysis confirmed that the lowest voltage region was opposite to MR‐defined aortic root. Using a cutoff for UNI abnormality of 6.0 mV for the posterior aspect of the RVOT opposite to the aortic root and 7.5 mV for the rest of the septal aspect of the RV, there was no confluent area of unipolar abnormality in any patient. Conclusion: We defined normal ENDO UNI cutoffs as 7.5 mV for the septal aspect of the RV with adjustment to 6.0 mV over the posterior RVOT opposite to the aortic root. [ABSTRACT FROM AUTHOR]

Background Organized atrial arrhythmias (OAAs) are common after orthotopic heart transplantation (OHT). Some controversies remain about their clinical presentation, relationship with atrial anastomosis and electrophysiologic features. The objectives of this retrospective study were to determine the mechanisms of OAAs after OHT and describe the outcomes of radiofrequency catheter ablation (RFCA). Methods Thirty consecutive transplanted patients (mean age 48 ± 17 years, 86.6% male) underwent 3-dimensional electroanatomic mapping and RFCA of their OAA from 2004 to 2012 at our center. Results Twenty-two patients had biatrial anastomosis and 8 had bicaval anastomosis. Macro-reentry was the arrhythmia mechanism for 96% of patients. The electrophysiologic diagnoses were: cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) in 93% of patients ( n = 28); perimitral AFL in 3% ( n = 1); and focal atrial tachycardia (FAT) in 3% ( n = 1). In 5 patients with biatrial anastomosis, a right FAT was inducible. Primary RFCA success was obtained in 93% of patients. Mean follow-up time was 39 ± 26.8 months. Electrical repermeation between recipient and donor atria, present in 20% of patients ( n = 6), did n ot account for any of the OAAs observed. Survival without OAA relapse at 12, 24 and 60 months was 93%, 89% and 79%, respectively. Conclusions CTI-dependent AFL accounted for most instances of OAA after OHT, regardless of anastomosis type. Time from transplantation to OAA was shorter with bicaval than with biatrial anastomosis. RFCA was safe and provided good long-term results. [ABSTRACT FROM AUTHOR]

The article presents the discussion on contemporary ventricular arrhythmia mapping and ablation strategies. Topics include differentiating myocardial fibrosis or scar from healthy tissue in the chambers of interest for patients with structural heart disease; and volume of point data increasing with high and now ultrahigh density mapping systems precluding real‐time manual validation from a practical standpoint.

Objectives To evaluate intra-atrial conduction delay in patients with atrial fibrillation ( AF) via calculation of conduction velocities ( CVs) of the right and left atria. Methods Electroanatomic mapping was performed during sinus rhythm, in the right atrium ( RA) in eight patients with paroxysmal AF, in 12 controls with atrioventricular nodal re-entrant tachycardia ( AVNRT) and in the left atrium ( LA) in additional 16 AF patients. Three-dimensional maps of activation sequences of the RA and LA were obtained. Local CVs were specifically calculated in the direction of wave-front propagation on the activation maps by using 3-dimensional coordinates and local activation times of triads of sites. Average CVs of each atrium and each of 8 predefined RA and LA regions were calculated. Results During sinus rhythm, the average CVs of the RA were significantly slower ( P<0·05) in the AF group (0·60 ± 0·12 m s−1) than in the controls (0·83 ± 0·13 m s−1). The average CVs of the RA basal, septal and annulus regions were significantly slower than the corresponding regions in controls ( P<0·05). In patients with AF, the average CV of the LA was 0·51 ± 0·11 m s−1, which is significantly slower than that of the RA and than that of LA as previously reported ( P<0·05). Conclusion Compared to patients with AVNRT, patients with AF are associated with conduction delay in both atria with the delay being more marked in the LA than in the RA, which suggests the involvement of conduction disturbances in the genesis and/or perpetuation of AF. [ABSTRACT FROM AUTHOR]

VT Ablation in MitraClip Patients Introduction Patients with mitral regurgitation are increasingly treated by percutaneous implantation of a MitraClip device (Abbott Park, IL, USA). We investigate the feasibility and safety of the transmitral catheter route for catheter ablation of ventricular tachycardia (VT) in these patients. Methods The mitral valve with the MitraClip in situ was crossed under transesophageal 3-dimensional echocardiographic and fluoroscopic guidance using a steerable sheath for ablation of the left ventricle. Results Five patients (all males, median age 74.0 ± 16.0 years) who had previously a MitraClip implanted were referred for catheter ablation of VT. The left ventricular ejection fraction was 29.0% ± 24.0%. One patient had both an atrial septal defect and a left atrial appendage occluder device in addition to a MitraClip. The duration between MitraClip implantation and ablation was 1019.0 ± 783.0 days. After transseptal puncture, ablation catheter was successfully steered through the mitral valve with the use of fluoroscopy. A complete high-density map of the substrate in sinus rhythm could be obtained in all patients using multipolar mapping catheters. In 1 patient, mapping was carried out using a mini-basket catheter. Procedural endpoints, noninducibility of all VTs, and abolition of all late potentials were achieved in all patients. Procedure time was 255.0 ± 52.5 minute, fluoroscopy time was 23.0 ± 7.3, and the radiation dose was 61.0 ± 37.5 Gycm2. No mitral insufficiency or worsening of regurgitation was documented after the procedure. Conclusions This is the first report demonstrating the feasibility and safety of VT ablation in patients with a MitraClip device using the anterograde transmitral catheter route. [ABSTRACT FROM AUTHOR]

Point-by-Point versus Rapid Ultra-High-Resolution Electroanatomical Mapping in AF Introduction Three-dimensional electroanatomical mapping (EAM) is an established tool facilitating catheter ablation. In this context, the novel Rhythmia system sets a new bar in fast high-resolution mapping. The aim of this study was to directly compare point-by-point versus rapid ultra-high-resolution EAM in patients scheduled for ablation of atrial fibrillation (AF) with focus on procedural data, acute success, and midterm clinical outcome. Methods and Results A total number of 74 consecutive patients (48/74 male) with symptomatic AF were scheduled to undergo pulmonary vein isolation (PVI) using either Carto or Rhythmia. The Carto-guided procedures were performed using point-by-point acquisition according to our routine approach, whereas for Rhythmia, fast anatomical mapping was utilized. Comparing Rhythmia- versus Carto-guided ablation approaches, we observed a significantly longer total mapping time (P = 0.001), longer total fluoroscopy time (P = 0.001), more delivered RF-applications (P = 0.019), and longer total RF-duration (P = 0.002). There was no difference regarding total ablation time (P = 0.707), total procedure duration (P = 0.99), and acute procedural success. During follow-up, 84.8% of patients remained free from any AF/AT-recurrence using Carto versus 88.2% when using Rhythmia (P = 0.53). From Kaplan-Meier analysis, the event rate estimations were 15% versus 13.5%, respectively. Conclusion The present study reports our first clinical experience using Rhythmia in direct comparison with the established Carto system for AF ablation. Our data clearly demonstrate that Rhythmia was proved to be effective and well applicable but more data will be mandatory before final conclusions can be drawn. [ABSTRACT FROM AUTHOR]