Background: Pulsed field ablation (PFA) is a novel technique for pulmonary vein isolation in atrial fibrillation management. Notably, asystole episodes of varying durations have been observed during electroporation, but the underlying mechanisms remain unclear. Objective: This study hypothesizes that asystole during PFA is attributable to the activation of parasympathetic ganglia on the left atrium’s surface. Methods: We conducted a study with 24 patients (67% male, 62.8 ± 11.0 years, BMI: 25.3 ± 5.6) suffering from paroxysmal atrial fibrillation. The order of pulmonary veins chosen for electroporation was randomized to avoid cumulative electroporation effects. PFA was performed and the duration of cardiac pauses post-electroporation was recorded for each application. To examine the impact of electroporation on the parasympathetic nervous system, transjugular vagal stimulation (TJVS) was performed from the right internal jugular before and after isolation of each vein, during sinus rhythm and atrial pacing. Continuous data were analyzed with Student’s t-tests or Mann-Whitney U tests as appropriate; nominal data were evaluated using chi-square or Fisher exact tests. Results: Pre-PFA TJVS induced sinus pauses of 10.1 ± 2.74 seconds. A sinus block of over 3 seconds was present in 23 out of 24 patients. Post-PFA, the Right Superior Pulmonary Vein (RSPV) showed the highest decrease of TJVS-induced sinus pauses (RSPV: before 8.41 ± 4.53 vs after 3.27 ± 3.53 sec, p<0.001, RIPV: before 6.76 ± 4.54 sec vs. 6.89 ± 5.07 sec, p=0.90; LSPV: before 6.76 ± 5.25 sec vs. after 6.93 ± 4.29 sec, p=0.61; LIPV: before 7.80 ± 4.06 sec vs. after 7.88 ± 3.84 sec, p=0.91). Notably, sinus blocks over 3 seconds decreased significantly after RSPV ablation (19 before PFA, 10 after PFA, p<0.01), with less dramatic changes in other veins (RIPV: before 19, after 16, p=0.33; LSPV: before 14, after 19, p=0.11; LIPV: before 21, after 21, p=1.00). RSPV PFA also had the strongest impact on TJVS-induced AV block duration compared to the remaining veins (RSPV: before 6.49 ± 3.48 vs after 4.07 ± 3.27 sec, p<0.01, RIPV: before 6.00 ± 3.29 sec vs. 4.58 ± 3.99 sec, p=0.08; LSPV: before 5.15 ± 3.94 sec vs. after 5.14 ± 3.48 sec, p=0.93; LIPV: before 6.06 ± 3.98 sec vs. after 5.83 ± 3.44 sec, p=0.38). The incidence of AV blocks over 3 seconds was markedly reduced post-RSPV and post RIPV ablation (RSPV: before:19 vs. after: 14, p=0.11, RIPV: before:19 vs. after: 14, p=0.11), with minor changes in other veins (LSPV: before 14, after 16, p=0.55; LIPV: before 17, after 18, p=0.77). Conclusions: PFA applications during pulmonary vein isolation have acute effect on the autonomic nervous system, as evidenced by the decrease in TJVS-induced sinus and atrioventricular block at the level of the right superior pulmonary vein. PFA-induced pauses are more frequent during applications on the LSPV, and less frequent when prior isolation of the RSPV has been performed, suggesting a vagally-mediated mechanism involving the right superior and/or right posterior ganglionated plexi.

INTRODUCTION. Post-operative atrial fibrillation (POAF) represents the most common arrhythmia reported in the days following surgery. We aimed to investigate the incidence of POAF in the 28 days after surgery and determine its predictors, with a specific focus on inflammation markers. METHODS. We performed a retrospective single center cohort study that included consecutive adult patients who underwent a major surgical procedure between January 2016 to January 2020. Patients were divided into four subgroups according to the type of surgery: (I) orthopedic, (II) non-thoracic non-abdominal, (III) abdominal and esophageal, or (IV) lung and cardiovascular surgery. RESULTS. Among 53,387 included patients (48.8% male, mean age 59 ± 15.9 years), POAF occurred in 570 (1.1%) with a mean latency after surgery of 3.4±2.6 days. Ninety patients died (0.17%) after a mean of 13.7±8.4 days. The 28-day arrhythmia-free survival was lower in patients undergoing lung and cardiovascular surgery ( p<0.001). Patients who developed POAF had higher levels of C-Reactive Protein (CRP) (0.70±0.03 vs. 0.40±0.01 log10 mg/dl; p<0.0001). In the multivariable Cox regression analysis, adjusting for confounding factors (age, gender, length of hospital stay, and group of surgery), CRP was an independent predictor of POAF [HR per 1 mg/dL increase in log-scale = 1.81 (95% CI 1.18–2.79); p=0.007]. Moreover, independent predictors of POAF were also age (HR/1 year increase = 1.06 (95% CI 1.04–1.08); p<0.0001), lung and cardiovascular surgery (HR 23.62; 95% CI 5.65–98.73); p<0.0001), and abdominal and esophageal surgery (HR 6.26; 95% CI 1.48–26.49; p 0.013). CONCLUSIONS. Lung and cardiovascular surgery had the highest risk of POAF in the presented cohort. CRP was an independent predictor of POAF and post-surgery inflammation status may represent a major driver in the pathophysiology.

Introduction: Human atria comprise distinct epicardial layers, which can bypass endocardial layers and lead to downstream centrifugal propagation at the “epi-endo” connection. We sought to characterize anatomical substrates, electrophysiological properties, and ablation outcomes of “pseudo-focal” atrial tachycardias (ATs), defined as macroreentrant ATs mimicking focal ATs. Methods and Results: We retrospectively analyzed ATs showing centrifugal propagation with post-pacing intervals (PPIs) after entrainment pacing suggestive of a macroreentry. A total of 26 patients had pseudo-focal ATs consisting of 15 perimitral, 7 roof-dependent, and 5 cavotricuspid isthmus (CTI)-dependent flutters. A low-voltage area was consistently found at the collision site and co-localized with epicardial layers like the: (1) coronary sinus-great cardiac vein bundle (22%); (2) vein of Marshall bundle (15%); (3) Bachmann bundle (22%); (4) septopulmonary bundle (15%); (5) fossa ovalis (7%); and (6) low right atrium (19%). The mean missing tachycardia cycle length (TCL) was 67 ± 29 ms (22%) on the endocardial activation map. PPI was 9 [0-15] ms and 10 [0-20] ms longer than TCL at the breakthrough site and the opposite site, respectively. While feasible in 25 pseudo-focal ATs (93%), termination was better achieved by blocking the anatomical isthmus than ablating the breakthrough site [24/26 (92%) vs. 1/6 (17%); p < 0.001]. Conclusion: Perimitral, roof-dependent, and CTI-dependent flutters with centrifugal propagation are favored by a low-voltage area located at well-identified epicardial bundles. Comprehensive entrainment pacing maneuvers are crucial to distinguish pseudo-focal ATs from true focal ATs. Blocking the anatomical isthmus is a better therapeutic option than ablating the breakthrough site.

Introduction: Ultra-high-density mapping for ventricular tachycardia (VT) is increasingly used. However, manual annotation of local abnormal ventricular activities (LAVAs) is challenging in this setting. Therefore, we assessed the accuracy of the automatic annotation of LAVAs with the Lumipoint algorithm of the Rhythmia system (Boston Scientific). Methods and Results: One hundred consecutive patients undergoing catheter ablation of scar-related VT were studied. Areas with LAVAs and ablation sites were manually annotated during the procedure and compared with automatically annotated areas using the Lumipoint features for detecting late potentials (LP), fragmented potentials (FP), and double potentials (DP). The accuracy of each automatic annotation feature was assessed by re-evaluating local potentials within automatically annotated areas. Automatically annotated areas matched with manually annotated areas in 64 cases (64%), identified an area with LAVAs missed during manual annotation in 15 cases (15%), and did not highlight areas identified with manual annotation in 18 cases (18%). Automatic FP annotation accurately detected LAVAs regardless of the cardiac rhythm or scar location; automatic LP annotation accurately detected LAVAs in sinus rhythm, but was affected by the scar location during ventricular pacing; automatic DP annotation was not affected by the mapping rhythm, but its accuracy was suboptimal when the scar was located on the right ventricle or epicardium. Conclusion: The Lumipoint algorithm was as/more accurate than manual annotation in 79% of patients. FP annotation detected LAVAs most accurately regardless of mapping rhythm and scar location. The accuracy of LP and DP annotations varied depending on mapping rhythm or scar location.

Coronary artery injury is a rare complication of catheter ablation in the right ventricular outflow tract (RVOT). Furthermore, acute myocardial ischemia usually causes polymorphic ventricular tachycardia (VT) or ventricular fibrillation. We herein describe a case in which catheter ablation for VT originating from the RVOT provoked ischemia-related VTs due to acute occlusion of the left anterior descending artery.

Introduction. Data regarding the left atrial (LA) electroanatomical substrate in patients with hypertrophic cardiomyopathy (HCM) and atrial fibrillation (AF) are missing. In this electroanatomical mapping (EAM) study, we evaluated the extent of LA fibrosis and its impact on catheter ablation outcomes in patients with HCM and AF. Methods. High-density LA EAM was performed during AF in 28 consecutive patients with obstructive HCM and AF (42.9% displayed paroxysmal AF and 57.1% persistent AF). After propensity matching (PS), 28 non-HCM patients with AF were selected, and served as controls. Two different cut-off values of bipolar signal amplitude were investigated for fibrosis characterization (≤0.25 mV and ≤0.4 mV). HCM patients underwent pulmonary vein antral isolation (PVAI) and roof line, while non-HCM patients PVAI only. Results. After the 3-month blanking period, 10 HCM patients (35.7%) displayed atrial arrhythmia recurrence. Univariate analysis revealed that the extent of LA fibrosis was the only predictor of AF recurrence. HCM patients with arrhythmia recurrence showed significantly greater low voltage areas defined as either bipolar voltage ≤0.25 mV (22.5±10% vs. 5.5±6.4%, p=0.001) or ≤0.4 mV (32±13.9% vs. 5.9±5.1%, p<0.001). The presence of low voltage areas ≤0.4 mV greater than 14.1% of the total LA area also predicted arrhythmia recurrence with excellent sensitivity (100%) and specificity (100%). After PS matching with non-HCM patients, patients with HCM exhibited wider fibrotic regions ≤0.25 mV compared to non-HCM patients (p=0.016). Conclusions. High-density EAM reveals extensive LA fibrotic disease in patients with HCM, an event with certain implications in catheter ablation outcomes.

Background Data on the optimal location of the ECG leads for the diagnosis of drug-induced long QT syndrome (diLQTS) with Torsades de Pointes (TdP) are lacking. Methods We systematically reviewed the literature for ECGs of patients with diLQTS and subsequent TdP. We assessed T-wave morphology in each lead and measured the longest QT interval in the limb and chest leads in a standardized fashion. Results Of 84 patients, 61.9% were female and mean age was 58.8 years. QTc was significantly longer in chest versus limb leads (mean (standard deviation) 671 (102) vs 655 (97) ms, p=0.02). Using only limb leads for QT interpretation, 18 (21.4%) ECGs were non-interpretable: 10 (11.9%) due to too flat T-waves, 7 (8.3%) due to frequent, early PVCs and 1 (1.2%) due to too low ECG recording quality. In the chest leads, ECGs were non-interpretable in 9 (10.7%) patients: 6 (7.1%) due to frequent, early PVCs, 1 (1.2%) due to insufficient ECG quality, 2 (2.4%) due to missing chest leads but none due to too flat T-waves. The most common T-wave morphologies in the limb leads were flat (51.0%), broad (14.3%) and late peaking (12.6%) T-waves. Corresponding chest lead morphologies were inverted (35.5%), flat (19.6%) and biphasic (15.2%) T-waves. Conclusions Our results indicate that QT evaluation by limb leads only underestimates the incidence of diLQTS experiencing TdP and favors the screening using both limb and chest lead ECG.