INTRODUCTION:While very high-power short-duration (vHPSD) ablation has been shown to be safe and effective for ablation of atrial fibrillation, the utility of vHPSD ablation for targeting premature ventricular complexes (PVCs) remains unclear. We aimed to describe our experience of PVC ablation using vHPSD ablation targeting areas with suboptimal catheter contact. METHODS AND RESULTS:We included 8 patients (mean age 66.5 ± 11.3 years, 77% female gender, mean LV ejection fraction 52.8 ± 8.2%, baseline PVC burden 23.3 ± 10.1% [range 9-41%]) with PVCs originating from intracavitary structures [LV papillary muscle(s) (n = 7), RV papillary muscle (n = 1)] which were successfully eliminated with vHPSD ablation using a temperature-controlled ablation catheter (QDOT-MICRO; Biosense Webster, Irvine, California, USA) with lesions delivered at 90 W for 4 seconds using QMODE+ mode. Mean QMODE+ lesions delivered in each patient was 28 ± 15.1 with a mean total QMODE+ RF time of 112 ± 60.4 seconds. There were no procedural complications. Durable PVC suppression was confirmed on post-ablation monitoring in all patients (mean post-ablation PVC burden < 1% [range 0-2.3%]). CONCLUSION:Ablation with vHPSD using a temperature-controlled radiofrequency ablation catheter can be safe and effective for PVC ablation in regions with poor catheter stability such as RV and LV papillary muscles.

Background Obesity is a prevalent risk factor for recurrent atrial fibrillation (AF) after catheter ablation. Experimental and observational studies suggest that metformin may reduce the risk of AF. Objective To determine the effect of metformin on recurrent atrial arrhythmias after catheter ablation for AF. Methods In this single-center, randomized, open-label trial, patients undergoing AF ablation with body mass index (BMI) > 25 kg/m2 and without diabetes were randomized (1:1) to metformin or usual care before ablation. Metformin was titrated to the maximum tolerated dose and continued for 1 year after ablation. All patients received handheld electrocardiogram monitors in addition to usual clinical monitoring. The primary endpoint was freedom from recurrent atrial arrhythmia assessed at 12 months after ablation with a 3-month blanking period. Results Of 99 participants (mean age 63 ± 9.5 years, 70% men, BMI 32 ± 5.4 kg/m2, A1c 5.7 ± 0.5, 46% paroxysmal, and 22% prior ablation), 49 were randomized to metformin and 50 to usual care. At 12 months, the primary endpoint occurred in 38 (78%) of the metformin group and 29 (58%) of the usual care group (HR: 0.5; 95% CI: 0.2-0.9; P = 0.04). In the year after ablation, AF burden was lower in the metformin group (IQR: 0%-0%; median 0%) compared with usual care (IQR: 0%-25%; median 0%) (P = 0.03). Antiarrhythmic drugs were used in 4 of 49 patients (8%) in the metformin group and in 9 of 50 patients (18%) in the control group after ablation. Conclusions In patients with AF, elevated BMI, and without diabetes, treatment with metformin may reduce recurrent atrial arrhythmias after ablation. These findings require confirmation in larger trials.

BACKGROUND:Unsuccessful defibrillation therapy in patients with implantable cardiac defibrillators (ICDs) and ventricular tachytherapies may occur due to patient and/or device-related factors; appropriate management strategies after failed defibrillation therapy have been incompletely described. OBJECTIVES:To report on the management and outcomes of patients with implantable cardiac devices and unsuccessful defibrillation therapies. METHODS:A single-center cohort of patients with ICDs was examined, patients with unsuccessful ICD therapies were included. Demographic and device features, and survival free from recurrent unsuccessful device therapy was examined among patients undergoing operative vs. non-operative management. RESULTS:Among 1449 patients with ICDs, 40 patients (2.8%) were identified with unsuccessful defibrillation therapies (mean age 59 ± 15 years, ejection fraction 29% ± 16%, ischemic cardiomyopathy n = 27, 67.5%, secondary prevention device placement n = 22, 55%, transvenous ICD n = 34, 85%, subcutaneous ICD n = 6, 15%). Nonoperative management strategies included device reprogramming (n = 8), addition of a class III anti-arrhythmic (n = 7), or conservative therapy (n = 5). Operative management included addition of a transvenous lead (n = 10), addition of subcutaneous array (n = 8), or change in pulse generator (n = 2). A single-coil device was present in 18/20(90%) patients undergoing operative management compared to 10/20 (50%) with non-operative management (p = 0.16). There were no demographic or device differences between the two groups. After 2.4 ± 2.1 years follow up, repeat VT occurred in 22 patients (55%) including 6 patients (15%) with a repeat failed defibrillator therapy. There was no differences in the risk of recurrent failed shocks among patients with operative vs non-operative management (log rank p = 0.14). CONCLUSIONS:Among a large cohort of patients with ICD, the incidence of failed defibrillator therapy was 2.8%. With appropriate patient selection, both operative and non-operative management led to similar long-term outcomes; however, the overall incidence of repeat failed defibrillation therapy remained high at 15%.

BACKGROUND:Ventricular arrhythmias from the aortic cusps (ACs) represent a subset of left ventricular outflow tract arrhythmias. Although ablation in this region can be highly effective, concerns persist regarding aortic valve injury and iatrogenic aortic regurgitation (AR). Contemporary data on AR incidence after AC mapping/ablation remain limited. OBJECTIVES:This study sought to determine the incidence, severity, and clinical significance of AR in a multicenter cohort after mapping and/or radiofrequency ablation in the ACs or commissures. METHODS:We retrospectively analyzed patients at 4 high-volume centers (2015-2024) who underwent AC/commissural mapping and/or ablation for ventricular arrhythmia and had paired preprocedural and postprocedural transthoracic echocardiograms (TTEs). AR was graded by using standardized criteria; procedure-related AR was defined as ≥2-grade worsening or new ≥moderate AR. RESULTS:Among 290 patients, 208 (218 procedures) had complete paired TTEs. Baseline AR was absent in 81% and mild in 18%. Retrograde aortic access was used in 94%, and 77% underwent radiofrequency ablation within the cusps. Clinically significant AR (≥2-grade worsening or new moderate AR) occurred in 2 procedures (0.9%), both representing progression from preexisting mild-to-moderate AR, with one of the patients having a bicuspid valve. New mild AR (1-grade increase from none to mild) occurred in 26 procedures (11.9%). Among 14 with additional follow-up imaging (median 320 days after first postprocedural TTE), AR resolved in 8 (57%) and remained mild in 6 (43%). No patient required valve intervention. CONCLUSIONS:Significant AR occurred in approximately 1% after AC mapping/ablation. New mild AR developed in 12.5% and improved in more than one-half during follow-up. No valve interventions were required, supporting the safety of cusp and commissural ablation at experienced centers.

Background:Sex-specific differences in the clinical outcome of pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) remain controversial. The impact of body mass index (BMI) on sex-based variation in the outcome of PVI is not well understood. Objective:We sought to investigate the impact of BMI with associated atrial conduction indices (ACIs) on sex-specific differences in AF recurrence after PVI. Methods:All consecutive patients who underwent their first PVI for AF from 2014 to 2019 were included. ACIs were measured on the surface electrocardiogram and intracardiac electrogram. Data were collected and analyzed based on BMI and sex. Results:The study included 387 patients with AF (121 women and 266 men; mean age 66 years; 49.2% with a BMI of ≥30 kg/m2). Women were older at the time of the procedure (median age 67 vs 62 years; P < .001). AF recurrence was more common in women (57% vs 44.4%) during a mean 5 ± 3 years' follow-up (P = .027). All-cause mortality was similar in men and women after PVI, irrespective of AF recurrence (P > .05). Post-PVI atrial flutter (AFL) occurred more often in women (21.5% vs 10.9%; P = .009). Female sex, enlarged left atria, prolonged ACI, and post-PVI AFL were predictors of AF recurrence (P < .05). High BMI and prolonged left ACI were associated with AF recurrence in women. Conclusion:Female sex was associated with a higher risk of AF recurrence after PVI and post-PVI AFL. Women with high BMI and prolonged left ACI had the highest rate of AF recurrence. This highlights the importance of weight management.

The left ventricular epicardium is a common site of origin (SOO) among patients with idiopathic premature ventricular complexes (PVCs) undergoing catheter ablation procedures. Less is known about epicardial PVC ablation among patients with myocardial scarring. The objective of this paper is to report on the presence and impact of cardiac scar among patients with epicardial PVCs undergoing ablation procedures. In a retrospective analysis, patients with epicardial PVCs and late gadolinium enhanced cardiac magnetic resonance (LGE-CMR) imaging were included. Acute and long-term procedural outcomes were examined and stratified by the presence or absence of cardiac scar. Twenty-nine patients were included (male 17/29(59

BACKGROUND:Atrial tachycardias (AT) after radiofrequency ablation (RFA) of atrial fibrillation (AF) may utilize Bachmann's bundle (BB). Due to their epicardial location, these ATs remain poorly understood. OBJECTIVE:To describe the electrophysiologic and anatomic basis of BB-related ATs. METHODS:The region of BB was defined as the anterior left atrium (LA) immediately outside the right superior pulmonary vein. A BB-dependent AT was defined as an arrhythmia that originated from (focal) or involved the BB region (reentrant). RESULTS:Among 1611 patients with persistent AF undergoing ablation, 32 patients (2%) (age 69 ± 9, male n = 22, LA size 47 ± 6 mm, ejection fraction 55 ± 13%) with BB ATs were included. Twenty-nine (91%) had undergone prior ablation for persistent AF (average, 2.0 ± 1.3 procedures). The mechanism of BB ATs was focal (n = 7, 22%) or macro-reentry (n = 25, 78%). RFA eliminated all focal and ultimately reentrant ATs in 15 of the 32 patients; RFA was required at the right atrial (RA) projections of BB among eight of the latter patients. The electrogram at the successful site was devoid of local voltage in four patients. In nine patients with redo procedure, recurrent BB-AT was found in five (56%). After 2.3 ± 1.4 years of follow-up, 22 of the 32 patients (69%) remained free of atrial arrhythmias. CONCLUSION:The region of the BB bundle may be responsible for focal and reentrant tachycardias following RFA of persistent AF. Given its epicardial location, sequential ablation from the LA and RA may be required, even at sites that might be devoid of local voltage.

BACKGROUND:Ablation of ventricular tachycardia (VT) is often performed in patients with structural heart disease. Procedural and delayed enhancement cardiac magnetic resonance imaging (DE-CMR) characteristics among patients with very severe cardiomyopathy (CM) and without left-ventricular assist devices (LVAD) have been incompletely described. OBJECTIVES:To examine procedural and imaging characteristics of patients with very severely decreased ejection fractions undergoing VT ablation procedures. METHODS:Consecutive patients with a left ventricular ejection fraction (EF) < 20% and without LVADs who underwent VT ablation were included. A composite outcome of survival free from VT, LVAD, or transplant was examined. RESULTS:Twenty-seven patients were included (64.1 ± 7.76 years; male n = 23, 88.5%; EF 12.8 ± 3%, LV end diastolic diameter 74 ± 11 mm, ischemic CM (n = 16, 60%), Nonischemic CM (n = 9, 52%), mixed CM (n = 2, 7%)). Twenty-five (93%) patients had failed amiodarone, 9 (33%) had a prior VT ablation, and 13 (48%) underwent ablation for VT storm. Scar was present in 22/23 patients with DE-CMR (intramural [n = 13], endocardial [n = 8], epicardial [n = 2], mixed components [n = 12]). DE-CMR scar corresponded to VT sites of origin in 18/22 patients (82%), excluding one patient with right ventricular VT, two with bundle-branch-reentry VT, and one-non-inducible patient. After 22 ± 19 months, VT occurred in 15/27(56%) patients, death 8/27(30%) and the composite outcome occurred in 22/27(82%) patients. CONCLUSION:Patients with very severe cardiomyopathy undergoing VT ablation represent a high risk population, experiencing high rates of VT recurrence and death on midterm follow up. Despite severe remodeling, DE-CMR provides localizing information on the arrhythmia site of origin.

Background: Vein of Marshall ethanol infusion (VoMEI) may improve outcomes among patients with persistent atrial fibrillation (AF) undergoing catheter ablation procedures. Prior investigations used heterogeneous ablation strategies, limiting the understanding of VoMEI utility. Objective: The study sought to examine the safety and efficacy of a uniform ablation approach utilizing VoMEI compared with patients undergoing pulmonary vein isolation (PVI) only or PVI and posterior wall isolation (PWI). Methods: Patients undergoing first-time ablation for persistent AF utilizing VoMEI with PVI, PWI, and ablation of induced macro–re-entry arrhythmias were included. Two propensity-matched control groups (PVI only and PVI + PWI) were identified with 2:1 matching. Safety and efficacy rates between the groups were examined. Results: A total of 155 patients were included (VoMEI, n = 31; PVI, n = 62; PVI + PWI, n = 62), consisting of 98 (63%) males 66 ± 10 years of age, with left atrial diameter 49 ± 7 mm, ejection fraction 50 ± 16%, and follow-up time 3.2 ± 2.2 years, with no demographic differences between the groups (P > .05). The 1-year rate of freedom from atrial arrhythmias after a single procedure was 84%, 67%, and 54% for patients undergoing VoMEI, PVI only, and, PVI + PWI, respectively (log rank P = .021). Patients who underwent VoMEI had improved outcomes compared with patients who did not (hazard ratio 0.32, 95% confidence interval 0.12–0.78, P = .01), with fewer repeat procedures (10% vs 37%, P < .01). Procedure, radiofrequency, and fluoroscopy times were greater in the VoMEI groups (P > .05). Conclusion: Among patients with persistent AF, an ablation strategy incorporating VoMEI improved long-term ablation outcomes compared with groups of propensity-matched patients undergoing PVI only or PVI + PWI.

Background: Ventricular tachycardia (VT) induction identifies targets for ablation and is an important procedural endpoint. Ablation approaches and outcomes for patients noninducible for VT at baseline are not well described. Research question: What are the procedural characteristics and outcomes for patients presenting for VT ablation with baseline noninducibility? Methods: Patients at a single VT referral center who were noninducible at the start of a VT ablation procedure were retrospectively identified. All procedures were performed under monitored sedation. Baseline induction consisted of programmed stimulation with up to 4 extrastimuli from 2 or more ventricular sites at 2 or more drive cycles with or without isoproterenol. Ablation strategies, procedural outcomes, and long-term results were characterized. Results: A total of 27 of 160 patients referred for ablation were identified to have baseline noninducibility for VT (mean age 59 ± 13 years, 81% male, mean left ventricular ejection fraction 48 ± 16%, ischemic cardiomyopathy 41%, nonischemic cardiomyopathy 30%, Table). Prior ablation had been performed in 10/27 (37%) and 20/27 (74%) were previously treated with antiarrhythmic drugs (AADs). Mapping strategies included pace mapping of device electrograms (14/23, 61%) or prior EKGs (1/23, 4%) and pace or activation mapping of premature ventricular complexes perceived to match the clinical VT (13/23, 57%). Ablation of low voltage, fractionated, or late electrogram regions was performed in 6/27(22%). Ablation based on cardiac magnetic resonance imaging (CMR)-identified myocardial scar was performed in 7/27 (26%). VT remained noninducible in 22/23 (96%) of patients where programmed stimulation was repeated after ablation. One patient had arterial pseudoaneurysm following ablation, treated with thrombin injection. Mean follow-up was 1100 ± 967 days. VT recurred in 6/27 (22%) with a mean of 462 ± 466 days until first appropriate implantable cardioverter-defibrillator (ICD) therapy (Figure). At last follow-up, AADs were continued in 13/27 (48%) patients but had been discontinued or reduced in 16/20 (85%) prescribed AADs pre-ablation. A total of 5/27 (19%) of patients died during follow-up at a mean of 1229 ± 652 days after ablation. Conclusion: VT ablation in patients noninducible at baseline was feasible and well-tolerated with infrequent VT recurrence. Prospective studies are needed to identify optimal ablation endpoints for this population.