BACKGROUND:The subcutaneous implantable cardioverter defibrillator (S-ICD) offers protection from sudden cardiac death without transvenous leads. Although contemporary techniques and programming have reduced inappropriate shocks, high rates persist in certain populations. The objective of this study was to evaluate the impact of a novel quantitative vector screening (QVS) protocol on the incidence of sensing-related complications and inappropriate shocks in patients undergoing S-ICD implantation. METHODS:We analyzed 223 consecutive patients who underwent S-ICD implantation at the Hospital of the University of Pennsylvania from December 2018 to July 2025. Traditional vector screening was used before 2023. In 2023, we implemented QVS, which incorporated quantitative sensing scores for each candidate and raised the threshold for S-ICD implantation. The primary end point was time to first inappropriate shock or under-sensed ventricular arrhythmia. Secondary outcomes included SMART Pass deactivation and need for device revision. Outcomes were reported as survival analyses. RESULTS:During preimplant screening, the QVS protocol reduced patient eligibility from 96% to 83%. The median follow-up after implant was 42 months (interquartile range, 48) in the traditional vector screening arm and 18 months (interquartile range, 15) in the QVS arm. The primary end point of time to first inappropriate shock or under-sensed ventricular arrhythmia was longer in the QVS arm (log-rank, P=0.02). There were 23 primary end point events among 145 patients in the traditional vector screening arm (5.2 per 100 patient-years [95% CI, 3.1-7.4]) and 2 primary end point events among 78 patients in the QVS arm (1.8 per 100 patient-years [95% CI, 0.01-4.38]). CONCLUSIONS:Implementation of a novel S-ICD screening protocol with stricter eligibility thresholds reduced sensing-related complications, particularly inappropriate shocks.

Background Pulmonary veins (PVs) are major sources of atrial fibrillation (AF) triggers, but patients may also have non-PV (NPV) triggers. Data on the impact of targeting NPV triggers on AF ablation outcomes are limited. Objectives This study aimed to assess the outcome of patients undergoing AF ablation based on their NPV trigger status. Methods Patients undergoing first-time AF ablation using radiofrequency energy between 2018 and 2023 who received trigger provocative maneuvers were included. The provocative maneuvers consisted of cardioversion of AF, incremental isoproterenol infusion (3, 6, 12, and 20-30 μg/min) and/or an atrial burst pacing protocol. NPV triggers were defined as ectopic foci initiating AF, sustained focal atrial tachycardia (AT), or atrioventricular nodal reentrant tachycardia. Recurrence was defined as AF/AT >30 seconds after a 90-day blanking period. Results Of 2,315 patients included, 2,046 (88.4%) did not have NPV triggers, 233 (10.1%) had NPV triggers that were ablated, and 36 (1.6%) had NPV triggers that were not targeted or failed localization/ablation attempts. One-year recurrence rate was 29.5% in patients without NPV triggers, 38.2% in those with ablated NPV triggers (adjusted HR: 1.35; 95% CI: 1.08-1.69), and 72.2% in those with untreated NPV triggers (adjusted HR: 3.71; 95% CI: 2.48-5.54). This response pattern remained consistent regardless of NPV trigger subtype (AF vs focal AT) or provocation method (spontaneous vs induced triggers). Conclusions Failure to ablate induced NPV triggers is associated with a high risk of recurrence. Although the ablation of NPV triggers reduces recurrence rates to levels approaching those without such triggers, their presence indicates a modestly worse prognosis.

BACKGROUND:Identifying critical isthmuses in macro-re-entrant atrial tachycardia (MRAT) is challenging. Omnipolar Technology Near Field mapping with the Peak Frequency (PF) tool holds promise for identifying critical regions sustaining re-entry, though PF signal characteristics and the algorithm's clinical value need further exploration. OBJECTIVES:This study sought to analyze properties of PF in MRAT critical isthmuses and evaluate the value of Omnipolar Technology Near Field PF mapping in guiding ablation. METHODS:Consecutive patients undergoing MRAT ablation procedures with fully mapped circuits (using EnSite-X and HD-Grid) and termination during ablation were included. PF values were analyzed globally across the atrium and compared to the ablation termination site (within 5-mm diameter). The absolute maximum PF at and the number of ablation lesions required for termination were recorded. RESULTS:The study involved 21 MRATs (12 left, 9 right atrial) from 17 patients (age 63.9 ± 18.3 years). Termination typically required a median of 1 (Q1-Q3: 1-7) ablation lesion, with 48% terminating after the initial lesion. Maximum PF values at termination sites were significantly higher (615.2 ± 85.7 Hz) than global PF values (317.6 ± 45.4 Hz; P < 0.01) and PF within the 5-mm termination diameter (499.6 ± 115.4 Hz; P < 0.01). Voltage at termination sites (0.39 ± 0.56) was significantly lower than the global average (0.73 ± 0.57; P < 0.01). PF values above 363 Hz differentiated isthmus regions from global atrial PF, with values >530 Hz indicating maximum PF at termination sites. CONCLUSIONS:Peak frequencies at MRAT termination sites are substantially higher than global atrial PFs, supporting the potential of PF mapping as an effective tool for identifying critical isthmuses in MRAT ablation procedures.

BACKGROUND:Surgical implantation of epicardial implantable cardioverter-defibrillator (ICD) is considered when transvenous ICD placement is not feasible because of congenital anomalies, venous obstruction, or prior infections. Epicardial pacemakers are well-studied but less is known about contemporary epicardial ICD systems in adults. OBJECTIVES:This case series details the indications, techniques, safety, and long-term performance of surgically implanted epicardial high voltage (HV) coils and leads in adults. METHODS:We included all patients who received epicardial HV coils or leads at the Hospital of the University of Pennsylvania between 2014 and 2025. RESULTS:Nineteen patients (14 men, median age 64 years) were identified. Indications included ICD replacement after lead extraction for endocarditis (7), placement during concomitant surgery, including for tricuspid regurgitation (6), left ventricular assist device (3), and lack of venous access (3). HV coils were used in 58%, and 42% received epicardial leads. All patients received epicardial pace-sense leads; 68% received cardiac resynchronization therapy. HV coils or leads were sewn to the epicardium: 48% on the posterior left ventricle, 16% on the anterior right ventricle, 26% on both ventricles, and 11% in the transverse sinus. Two patients had impedances > 200 Ω because of a loose set screw and a damaged connector pin, respectively. Two had impedances < 20 Ω without clinical impact. One coil fractured 1.5 years post-implant. No failed shocks or lead migrations occurred. During a median follow-up of 468 days, 26% died, largely from advanced heart failure, none were attributable to surgery. CONCLUSION:Surgical implantation of epicardial ICD systems with HV coils/leads is safe and feasible. Multidisciplinary planning and long-term monitoring are essential.

BACKGROUND:Patients undergoing first-time atrial fibrillation (AF) ablation can benefit from targeting non-pulmonary vein (PV) triggers. Preprocedural identification of high-risk individuals can guide planning of ablation strategy. This study aimed to create a preprocedural screening tool to identify patients at risk of non-PV triggers during first-time AF ablation.METHODS:All patients who underwent first-time AF ablation at the Hospital of the University of Pennsylvania between 2018 and 2022 were identified. Those who underwent non-PV trigger provocative maneuvers or had spontaneous non-PV trigger firing were included. Non-PV triggers were defined as non-PV ectopic beats triggering AF or sustained focal atrial tachycardia that occurred spontaneously, after AF cardioversion, or after standard provocative maneuvers. The provocative maneuvers included incremental isoproterenol infusion (3, 6, 12, and 20-30 mu g/min) and an atrial burst pacing protocol. Risk factors associated with non-PV triggers in a stepwise multivariable logistic regression model with backward elimination were used to create a risk score.RESULTS:A total of 163 (8.0%) of 2038 patients had non-PV triggers during first-time AF ablation. Based on the multivariable model, we created a risk score using female sex (1 point; odds ratio [OR], 1.90 [95% CI, 1.36-2.67]), sinus node dysfunction (1 point; OR, 1.84 [95% CI, 1.04-3.24]), prior cardiac surgery (1 point; OR, 2.26 [95% CI, 1.45-3.53]), moderate to severe left atrial enlargement (2 points; OR, 3.43 [95% CI, 2.46-4.79]), and cardiac sarcoidosis/amyloidosis (4 points; OR, 7.24 [95% CI, 3.03-17.33]). Internal validation using bootstrap resampling showed an optimism-adjusted C statistic of 0.715 (95% CI, 0.678-0.751). Among all first-time AF ablations, 68.1% of procedures were low-risk for non-PV triggers (scores 0-1, 4.3% risk), 17.8% were intermediate-risk (score 2, 10.5% risk), and 14.1% were high-risk (score >= 3, 22.6% risk).CONCLUSIONS:A preprocedural screening tool can classify patients based on their risk of non-PV triggers during first-time AF ablation. This risk score can guide operators to identify patients who would benefit most from adjunctive non-PV trigger testing. However, further validation is needed to confirm these findings.

BACKGROUND:The intramural site of origin is a major cause of ablation failure of ventricular arrhythmias, and the optimal strategy is unclear. This study investigated the efficacy of a stepwise ablation approach for intramural outflow tract (OT) premature ventricular complexes (PVCs) guided by mapping of the septal coronary venous system. METHODS:Consecutive patients with OT PVCs were included, in whom an intramural origin was confirmed by demonstration of earliest activation in a septal coronary vein. Radiofrequency ablation was performed from the closest endocardial site in the left ventricular OT or right ventricular OT independent of the local activation time. If there was no suppression by endocardial ablation, then retrograde transvenous ethanol infusion with a single- or double-balloon technique was performed, targeting the earliest septal coronary vein. If venous anatomy was not suitable for ethanol ablation or if this failed, then bipolar ablation was performed. RESULTS:Sixty patients (age 61±12 years; 78% men) were included. The mean QRS duration of the PVC was 150.8±17.6 ms with a maximum deflection index of 0.51±0.11, and the most common ECG pattern was a left bundle branch block with inferior axis and V3 transition (63%), followed by a right bundle branch block with inferior axis and no transition (27%). Earliest ventricular activation (28.6±11.2 ms before QRS) was recorded in the left ventricular annular vein in 15 cases and a septal perforator vein in 45 cases. Acute PVC suppression at the end of the procedure was achieved in all cases. In 87% of cases (n=52), endocardial ablation from the endocardial left ventricular OT, right ventricular OT, or both was successful in eliminating the PVC. In the remaining 8 patients, the PVC was eliminated with ethanol infusion (n=7) and bipolar ablation (n=1). Complications included one case of pericardial effusion related to venous mapping. During follow-up (17±24 months), the PVC burden was reduced from 28±12% to 2.3±4.7%, and long-term success (≥80% burden reduction) was 88%. CONCLUSIONS:Most intramural OT PVCs can be successfully eliminated with endocardial ablation adjacent to the earliest intramural activation site. A high success rate is achieved when following a stepwise approach, with bailout ablation strategies required in a minority of cases.

BACKGROUND:Long-standing persistent atrial fibrillation (LSPAF) is associated with adverse atrial structural and electrical remodeling, limiting the success of catheter ablation (CA). OBJECTIVE:To determine whether temporary restoration of sinus rhythm (TRSR) can improve the single procedure efficacy of CA in patients with LSPAF. METHODS:Patients with LSPAF undergoing their first CA between 2016 and 2022 were included. TRSR was attempted using cardioversion, with or without antiarrhythmic drugs (AAD), no later than 6 months before CA. The ablation strategy included pulmonary vein isolation (PVI), non-PV trigger ablation, and linear lesions for organized atrial tachyarrhythmias (OAT). The primary study outcome was freedom from atrial arrhythmias (AA: AF and/or OAT) on/off AAD at 12 months, and the secondary outcome was freedom from AA off AAD at 12 months. RESULTS:One hundred eighty patients (median age 66 years, 24% female) were included. TRSR was attempted in 67 (37%) patients, and 17 (25%) of these presented in SR at the time of CA. Patients undergoing TRSR had more comorbidities (CHA2DS2-VASc score 3.1 vs. 2.7, p = 0.012) than those who did not. The primary and secondary outcomes were significantly better in the TRSR than the no TRSR group: AA-free survival (73% vs. 51%, p = 0.004) and AA-free survival off AAD (69% vs. 45%, p = 0.002). The primary outcome was better in the TRSR group, whether the presenting rhythm at CA was SR or AF (75% and 72%, respectively). CONCLUSIONS:TRSR within 6 months of CA was associated with improved arrhythmia-free survival in LSPAF patients undergoing CA regardless of the presenting rhythm at ablation.

Background: Cardiac amyloidosis (CA) is characterized by atrial myopathy, which predisposes patients to atrial fibrillation (AF) and other atrial arrhythmias (AA). Although catheter ablation of AA is effective in the general population, its efficacy and safety in patients with CA remain unclear. Objective: The study aimed to evaluate outcomes in patients with CA undergoing catheter ablation for typical atrial flutter (TAFL) and left atrial (LA) arrhythmias and to assess the presence and influence of LA low-voltage areas (LVA) in the latter. Methods: We retrospectively analyzed patients with CA undergoing first-time ablation for TAFL or LA arrhythmias (AF, atypical atrial flutter, and focal tachycardia). For the latter group, LA electroanatomical mapping (EAM) quantified LVA burden and distribution. The primary outcome was arrhythmia recurrence at 1 year. Additionally, long-term outcomes over the maximum follow-up period were assessed and correlated with LVA. Results: The cohort included 36 patients (TAFL in 11, LA arrhythmias in 25; mean age 74 ± 7 years, 81% men, 64% wild-type transthyretin amyloidosis). Recurrence of any AA after 1 year occurred in 10 patients (40%) after LA arrhythmia ablation and in 3 patients (28%) after TAFL ablation (all new AA). LVA was seen in 73% of patients undergoing LA arrhythmia, and it occupied 50.4% of the LA surface, most commonly the posterior wall (53%). However, its presence did not correlate with long-term arrhythmia-free survival (P = 0.957). Procedure-related complications, particularly heart failure decompensation (16%), were important. Conclusion: Catheter ablation provides reasonable 1-year arrhythmia control in patients with CA experiencing TAFL or LA arrhythmias. However, long-term AA recurrence rates remain high.

Importance:Atrial fibrillation (AF) ablation aims to eliminate all AF triggers. Non-pulmonary vein (PV) triggers are observed in up to 10% of patients referred for a first AF ablation procedure. However, there are limited data on sex-specific differences in non-PV triggers. Objective:To assess the sex-specific prevalence, type, and site of origin of non-PV triggers among patients referred for a first-time AF ablation procedure. Design, Setting, and Participants:This cohort study was conducted at the Hospital of the University of Pennsylvania among 2038 consecutive patients who underwent first-time AF ablation between January 1, 2018, and December 31, 2022, and received at least 1 step of the non-PV trigger provocation protocol. Statistical analysis was performed from October 2024 to May 2025. Exposures:Patients underwent a first-time AF ablation and received at least 1 step of the non-PV trigger provocation protocol: (1) cardioversion of spontaneous AF to identify any spontaneous triggers during sinus rhythm, (2) isoproterenol infusion up to 20 to 30 µg/min, and (3) rapid atrial burst pacing. Non-PV triggers were defined as non-PV ectopic beats triggering AF or sustained focal atrial tachycardia (AT). Main Outcomes and Measures:The primary end point was atrial arrhythmia recurrence within 1 year, defined as any atrial arrhythmia lasting more than 30 seconds after the 90-day blanking period. Results:A total of 2038 patients were included (mean [SD] age, 64.7 [10.5] years; 1369 men [67.2%]). The prevalence of non-PV triggers was significantly higher among women than men (72 of 669 [10.8%] vs 91 of 1369 [6.6%]; P = .001). Right atrial triggers were more common among women than men (42 of 669 [6.3%] vs 44 of 1369 [3.2%]; P = .001). Left atrial triggers were not significantly different among women compared with men (35 of 669 [5.2%] vs 50 of 1369 [3.7%]; P = .09). Although the proportion of non-PV triggers initiating AF and sustained AT was balanced among women (AF, 34 of 72 [47.2%]; AT, 36 of 72 [50.0%]; and both, 2 of 72 [2.8%]), non-PV triggers initiating AT were predominant among men (AT, 62 of 91 [68.1%]; AF, 28 of 91 [30.8%]; and both, 1 of 91 [1.1%]). Triggers from 2 or more locations were more frequent among women than men (18 of 72 [23.6%] vs 11 of 91 [12.1%]; P = .03). Among patients for whom non-PV triggers were identified (n = 163), women had a higher 1-year atrial arrhythmia recurrence rate (adjusted hazard ratio, 1.77 [95% CI, 1.02-3.08]; P = .04). Conclusions and Relevance:In this cohort study of 2038 patients, women exhibited a higher prevalence of non-PV triggers, especially from the right atrium, than men. Women with non-PV triggers were more likely to have multiple triggers and worse postablation outcomes. These findings highlight the importance of performing systematic provocation protocol with increased vigilance among women, particularly for those with additional risk factors.