Sugrue, Alan

ABSTRACT Background Pulsed field ablation (PFA) is an emerging non‐thermal ablation modality with proven safety in atrial arrhythmia ablation. However, data on its performance for ventricular arrhythmias (VA) remain limited. Objective To evaluate the feasibility, safety, and efficacy of PFA for complex VA in a multicenter real‐world US registry. Methods This retrospective study included consecutive patients undergoing PFA for ventricular tachycardia (VT) or premature ventricular contractions (PVCs) at three Mayo Clinic centers (April 2024 to July 2025). The primary feasibility outcome was the successful delivery of PFA lesions to the intended target substrate. Primary efficacy outcomes included acute procedural success; sustained VT recurrence requiring implantable cardioverter‐defibrillator (ICD) shocks or multiple antitachycardia pacing therapies; and ≥ 80% reduction in PVC burden. Safety outcomes included procedural complications, valvular function, thromboembolic events, renal function, and conduction disturbances. Results Twenty‐six patients were included (13 PVC, 13 VT). Acute success was achieved in all VT ablations (69.2% complete; 30.8% partial) and in 92.3% of PVC ablations. Complications occurred in 11.5% of patients (transient LBBB [ n = 1] and vascular complications [ n = 2]). No thromboembolic events, intracardiac thrombus, or acute kidney injury were observed. Lesions near the mitral valve apparatus did not worsen mitral regurgitation, including in patients with pre‐existing valve disease. After a median follow‐up of 365 days, one patient experienced VT recurrence requiring ICD shocks. Estimated recurrence‐free survival after VT ablation was 61.5% at 12 months; 58.3% of PVC patients achieved ≥ 80% burden reduction. Conclusion PFA for VA appears feasible and acutely effective, with a low rate of procedure‐related complications. While acute success was high, long‐term outcomes were acceptable for VT ablation and relatively modest for PVC ablation, highlighting the need for continued refinement of technology and energy‐delivery strategies. Larger prospective studies are warranted.

Abstract Background Vagally mediated syncope and functional bradyarrhythmias can cause recurrent symptoms, injury and a need for permanent pacing, yet standard therapies do not address the underlying autonomic reflex. Cardioneuroablation (CNA) targets this mechanism, but adoption has been limited by uncertainty about patient selection, procedural endpoints and durable outcomes. Methods We studied 95 consecutive patients with vagally mediated syncope (n=78) or functional bradyarrhythmia (n=17) who underwent CNA at a single center by a single lead operator under a uniform, prospectively maintained protocol. Extracardiac vagal stimulation (ECVS) was performed before and after ablation to confirm vagally mediated sinus or atrioventricular (AV) nodal responses and to verify their attenuation. Outcomes through 1 year included clinical recurrence, quality of life, pacing burden and pacemaker extraction. Results Before ablation, ECVS provoked sinus pauses in 95.8% of patients and AV block in 91.6%; after ablation, sinus pauses were abolished in every patient and residual AV block was present in 4.2%. One-year freedom from recurrent syncope and from bradyarrhythmia-related events was 93.8% and 94.1%. Syncope burden fell from a median of 2.7 episodes per year to none, and disease-specific quality of life improved substantially (P<0.001). Among patients with pre-existing devices, atrial pacing burden fell from a median of 22% to 0%. There were no strokes, deaths or myocardial infarctions. Conclusions In this single-center cohort, physiology-guided CNA was associated with durable symptom control, improved quality of life and reduced pacing across vagally mediated bradyarrhythmia syndromes. Multicenter controlled studies are needed to confirm these findings.

ABSTRACT Background Patients with end‐stage renal disease (ESRD) undergoing dialysis have an increased risk of pacemaker‐related complications due to limited vascular access and increased susceptibility to infection. Leadless pacemakers (LPMs) may mitigate these risks compared with conventional transvenous pacemakers (TPMs), but long‐term comparative data in this population remain limited. Methods We conducted a retrospective cohort study using the TriNetX Research Network, including adults (≥ 18 years) with ESRD on dialysis who underwent LPM or TPM implantation between May 2016 and December 2020. Propensity score matching (1:1) was performed using demographics and comorbidities. Outcomes assessed over up to 5 years included all‐cause hospitalization, heart failure hospitalization, device re‐intervention, device‐related complications, infection‐related hospitalization, pacemaker‐induced cardiomyopathy, and all‐cause mortality. Results After matching, 901 patients were included in each group with well‐balanced baseline characteristics. LPM implantation was associated with a significantly lower risk of device re‐intervention compared with TPM (4.1% vs. 9.3%; hazard ratio [HR] 0.44; 95% confidence interval [CI] 0.28–0.69; p < 0.01). There were no significant differences between groups in all‐cause hospitalization (65.5% vs. 68.3%; p = 0.22), heart failure hospitalization (26.9% vs. 30.2%; p = 0.13), all‐cause mortality (37.5% vs. 35.3%; p = 0.34), device‐related complications (14.5% vs. 14.3%; p = 0.94), infection‐related hospitalization (1.6% vs. 2.1%; p = 0.35), or pacemaker‐induced cardiomyopathy (9.0% vs. 8.6%; p = 0.66). Conclusion In a large, propensity‐matched cohort of patients with ESRD on dialysis, LPMs were associated with fewer device re‐interventions and comparable long‐term clinical outcomes compared with TPMs.

BACKGROUND: Radiofrequency (RF) ablation of premature ventricular complexes (PVCs) originating from the left ventricular summit may be unsuccessful, highlighting the need for alternative approaches. We aimed to assess the efficacy and safety of a novel dual-modality focal catheter in treating left ventricular summit PVCs in patients who had failed previous RF ablation. METHODS: Patients were prospectively enrolled and underwent a redo ablation procedure using an irrigated, contact-force sensing, dual-modality focal catheter (TactiFlex Duo, Abbott) under compassionate use indication. The ablation strategy, including the choice of energy modality (monopolar pulsed field [PF], RF, or both), was left to the operator’s discretion. Safety assessments included serial biomarkers, renal function, and CMR within 36 hours. Efficacy was defined as ≥80% reduction in PVC burden with symptom resolution at 3-month follow-up. RESULTS: Six consecutive patients (4 men; mean age, 53.8±15 years) with symptomatic left ventricular summit PVCs and a prior failed RF ablation (range, 1–2) were prospectively enrolled. All PVCs had an inferior axis, with a left bundle V1 morphology observed in 4 of 6 cases (mean burden, 30.1±5.3%). Acute suppression of PVCs was achieved in all cases. Acute suppression with a single PF application in the great cardiac vein-anterior interventricular vein occurred in 2 patients, while 3 patients required additional RF, PF, or combined RF+PF applications at adjacent sites. One patient with an inaccessible great cardiac vein-anterior interventricular vein was successfully treated in the left ventricular outflow tract with RF+PF application. Transient, reversible left anterior descending vasospasm was observed during PF delivery in 2 of 5 cases that underwent PF application adjacent to a coronary artery, despite pretreatment with intracoronary nitroglycerin without ECG or hemodynamic sequelae. All patients had durable suppression of PVCs at follow-up. CONCLUSIONS: In its first human application, dual-modality ablation was feasible and effective for refractory left ventricular summit PVCs. Transient coronary vasospasm occurred, though it was reversible and without acute clinical consequences.

Abstract Background The extravascular implantable cardioverter defibrillator (EV-ICD) was designed to avoid lead-related complications associated with transvenous systems and deliver features such as anti-tachycardia pacing (ATP) and reduced generator size that provide an advantage over a subcutaneous ICD (S-ICD). As such, the EV-ICD is an attractive alternative for younger patients with genetic heart diseases (GHDs) who are not in need of permanent pacing. Objective To examine the indications, complications, and the clinical outcomes of patients with GHDs who received an EV-ICD. Methods A retrospective review of the electronic record was done for all GHD patients evaluated in genetic heart rhythm and/or cardiomyopathy clinics who had an EV-ICD implanted between 1/2021 and 2/2025. Basic demographic, ICD indications, complications, and therapy data were then extracted for all study patients. Results Overall, 23 patients (35% female; mean age 39 ± 16 years; 61% with a disease-causative genetic variant; mean LVEF 57%) with an underlying GHD (hypertrophic cardiomyopathy in 9, arrhythmogenic cardiomyopathy in 8, idiopathic ventricular fibrillation in 3, dilated cardiomyopathy in 2, and long QT syndrome in 1) had an EV-ICD implanted. For the majority, an EV-ICD was implanted for primary prevention (15/23; 65%) and represented their first ICD system (21/23; 91%). The success rate of the procedure was 96% with only one abandoned procedure because of poor R-wave sensing. Inadvertent intraprocedural lead placement in the pericardial space occurred in 1 patient with previous thoracotomy and surgically placed epicardial lead without sequelae or need for revision. Over a mean follow-up of 8±9 months, the rate of complications was low (1/23; 4%) with one electrode displacement and this patient underwent defibrillation threshold testing (DFT), the device properly detected VF and emitted a successful shock 30 J. Thus far, 2 patients have received appropriate VT/VF-terminating therapies (3 ICD shocks, 0 ATP) with successful conversion to sinus rhythm. One patient died following an electrical storm. One patient had 3 inappropriate ICD shock for sinus tachycardia while exercising followed by 1 successful shock for VF. Conclusion In this early experience, EV-ICDs appear to be safe and effective in younger patients with genetic arrhythmogenic and hypertrophic cardiomyopathies. Future studies are needed to better understand the utility of EV-ICDs in patients with cardiac channelopathies and advantages of EV-ICDs over transvenous and S-ICD systems in patients with an array of sudden death-predisposing GHDs.

ABSTRACT Background Transvenous lead removal (TLR) in patients with a history of mediastinal radiation poses unique challenges due to potential radiation‐induced fibrosis, vascular changes, and anatomical distortion, which may increase procedural complexity and complication risk. However, contemporary data on clinical outcomes in this population remain limited. Methods We analyzed the National Readmissions Database (2016–2021) to identify adults (≥ 18 years) undergoing TLR. Patients were stratified by prior mediastinal radiation. Baseline characteristics were compared using standard statistical tests. Multivariable logistic regression was used to evaluate the association between prior mediastinal radiation and in‐hospital outcomes, 30‐day mortality, and 30‐day readmissions after adjustment for demographics and comorbidities. Results A total of 48,985 patients underwent TLR, of whom 735 (1.5%) had a history of mediastinal radiation. Compared with patients without radiation, those with prior radiation were older (70.1 vs. 66.2 years, p < 0.01), were more frequently females (38.2% vs. 31.6%, p < 0.01), and had higher rates of valvular heart disease, atrial fibrillation, and peripheral vascular disease. Adjusted analyses demonstrated no increased risk of in‐hospital mortality (2.3% vs. 3.4%; adjusted odds ratio [aOR] 0.65, 95% confidence interval [CI] 0.41–1.18, p = 0.29) or major complications, including cardiac arrest, pericardial complications, vascular injury, pulmonary complications, or embolic events. Similarly, (3.6% vs. 5.3%; aOR 0.76, 95% CI 0.48–1.43, p = 0.35) and 30‐day all‐cause readmissions (8.7% vs. 9.1%; aOR 0.81, 95% CI 0.64–1.28, p = 0.70) were not significantly different between groups. Subgroup analyses by indication for TLR (infection vs. mechanical complication) revealed no differences in outcomes. Conclusion Despite theoretical concerns, prior mediastinal radiation was not associated with excess procedural risk or worse short‐term outcomes after TLR. These findings may inform procedural planning and risk counseling in clinical practice.

Background: Dofetilide, a commonly prescribed class III antiarrhythmic for atrial fibrillation (AF), currently requires a 3-month amiodarone washout period per FDA guidelines. We evaluated the safety of initiating dofetilide within this 3-month washout period. Methods: We performed a retrospective cohort study across all Mayo Clinic sites and identified patients using centralized datamart that were transitioned from amiodarone to dofetilide in less than 90 days. Patients were included and confirmed by manual chart review if they had been on amiodarone for ≥ 12 weeks and if available amiodarone level >0.3 mg/ml at the time of dofetilide initiation. Serial ECGs were assessed during the hospitalization for dofetilide initiation and at 3-, 6-, and 12-months follow-up to evaluate QT interval. Primary safety end point was torsade de pointes. Results: The final cohort included 66 patients with a mean age of 65 ±14 years; 71.0% were male; and the average BMI was 29.6 ±5.1 kg/m 2 . Of the 66 patients, 65 had a history of AF: 31.8% paroxysmal, 54.5% persistent, and 12.1% long-standing persistent. Permanent pacemakers and ICDs were present in 27.3% and 22.7% of patients. Patients received amiodarone for a median of 7.8 months at a mean daily dose of 187.1±48.3 mg (range: 100 – 400 mg), with a mean transition period of 44.2±20.3 days. Of 66 patients, 16 (24 %) transitioned within 30 days of stopping amiodarone—including 5 (8 %) within 14 days—while the remaining 50 (76 %) was between 30 and 90 days. A total of 24.2% (16/66) patients required dofetilide dose reduction due to QT prolongation and 10.6% of patients (7/66) required drug discontinuation. There was no difference in either discontinuation rate or dose reduction rate in patients with a transition period ≤30 days vs > 30 days [6.25% vs. 12% (p=0.85) and 12.5% vs. 28% (p=0.36), respectively]. No cases of torsades de pointes were observed during dofetilide initiation or follow up. Conclusion: In this cohort, dofetilide initiation less than 90 days after amiodarone discontinuation was not associated with increased torsades de pointes risk. These data challenge and support reconsideration of the blanket 3-month washout and suggest that a monitored, expedited rhythm-control transition is feasible and safe.

Abstract Aims The increasing adoption of transcatheter tricuspid valve replacement (TTVR) offers a promising therapeutic option for patients with severe tricuspid regurgitation. However, many of these patients have pre-existing cardiac implantable electronic devices (CIEDs), raising concerns about potential lead-related complications. Despite these concerns, limited data exist on the impact of TTVR on CIED integrity and function. This study aimed to evaluate the impact of TTVR on CIED lead function, including pacing thresholds, sensing, and impedance, in patients undergoing TTVR with the EVOQUE valve system. Methods and results A retrospective observational study was conducted at Mayo Clinic Rochester, including 32 consecutive patients who underwent TTVR with pre-existing CIEDs. A total of 32 patients were included, with a mean age of 79.2 ± 8.4 years; 59% were female. A total of 62.5% had a permanent pacemaker, 12.5% had an implantable cardioverter-defibrillator, 15.6% had a cardiac resynchronization therapy pacemaker, and 9.4% had a cardiac resynchronization therapy defibrillator. Following TTVR, 10 (31%) of patients developed lead function changes during a median device follow-up of 210 days (IQR: 43–307 days). The right ventricular lead was primarily affected, with only one case involving an atrial lead. Neither the Ottawa score nor the anatomical lead position reliably predicted lead abnormality (P = 0.86 and P = 0.53, respectively). R-wave sensing changes were the most common lead change observed, affecting 55% of cases. In 67% of these cases, R-wave sensing alterations occurred as an isolated finding, with no significant change in impedance or thresholds, and were managed conservatively without any need for device reprogramming. Four patients (13%) had findings concerning for a lead insulation breach, in which one (3%) required a lead revision. Among five patients with follow-up exceeding 600 days, two patients exhibited a statistically significant gradual decline in impedance without other lead dysfunction, suggesting potential subclinical lead degradation. Conclusion Transcatheter tricuspid valve replacement with the EVOQUE system in the setting of cardiac device leads is associated with lead function changes in 31%. The majority of lead-related changes were managed conservatively, but 13% of patients had findings concerning for an insulation breach. Future studies should focus on refining implantation techniques and defining optimal strategies for managing device-lead interactions in this population.

ABSTRACT Background Valve‐in‐valve transcatheter aortic valve replacement (ViV‐TAVR) is increasingly used to treat structural valve degeneration. Permanent pacemaker implantation (PPI) following TAVR is associated with increased morbidity and mortality, yet predictors specific to ViV‐TAVR remain poorly defined. Objective To identify clinical and procedural predictors of PPI in patients undergoing ViV‐TAVR. Methods We conducted a retrospective observational study of consecutive ViV‐TAVR cases at the Mayo Clinic from 2012 to 2022. Clinical, ECG, procedural data and fluoroscopic measurements were analyzed, and propensity score matching was used to adjust for confounding. Predictors of PPI were identified using multivariable logistic regression. Results Among 261 patients, 24 (9.2%) underwent PPI. Balloon‐expandable valves were used in 66.7% and self‐expanding valves in 33.3%. Predictors of PPI included Preprocedural bifascicular block (OR 12.15, 95% CI: 2.52–68.89, p = 0.003), greater septal implantation depth (OR 1.29, 95% CI: 1.04–1.65, p = 0.019), and post‐procedural new left (OR 23.56, 95% CI: 4.91–48.52, p = 0.0004) and right bundle branch blocks (OR 24.4, 95% CI: 3.82–30.51, p = 0.001). Aortic regurgitation as the mechanism of prosthetic valve failure was associated with reduced PPI odds (OR 0.28, 95% CI: 0.10–0.76, p = 0.014). Pacing requirement—defined as > 90% ventricular pacing—increased from 25% at 3 months to 56.25% at 12 months. At a median follow‐up of 962.5 days (IQR 481.5–1555.3), adjusted mortality was significantly higher in the PPI group (aOR 9.4, 95% CI: 1.9–60.4, p = 0.028). Conclusion Bifascicular block, greater septal depth, and new bundle branch blocks predict PPI post‐ViV‐TAVR, while aortic regurgitation appears protective. Risk stratification and procedural planning are critical.