Sugrue, Alan

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 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.

ABSTRACT Background Transvenous lead removal (TLR) is a Class I indication for patients with cardiac implantable electronic device (CIED) infections. However, disparities in the utilization of TLR have not been fully explored, particularly concerning demographic and socioeconomic factors. Objectives This study aims to examine whether disparities exist among patients hospitalized for CIED infections with respect to the utilization of TLR, focusing on sex, race, and income characteristics. Methods We utilized the 2019 National Inpatient Sample (NIS) to assess patients hospitalized with CIED infections and identify those who underwent TLR. Multiple logistic regression was used to examine risk factors for TLR utilization, including age, sex, race/ethnicity, and socioeconomic characteristics. Results A total of 56 709 patients were hospitalized for CIED infection in the United States in 2019, of which 9867 (17.4%) underwent TLR. On an adjusted analysis, females and Black patients were found to have lower odds of undergoing TLR compared to males and White patients (OR: 0.62; 95% CI: 0.59–0.78; p < 0.01; and OR: 0.47; 95% CI: 0.39–0.57; p < 0.01, respectively). Hispanic patients also had reduced odds of TLR (OR: 0.73; 95% CI: 0.58–0.93; p = 0.01). No significant associations were observed between income or insurance status and the likelihood of receiving TLR after adjustment. Conclusions This study identified significant disparities in the utilization of TLR among patients hospitalized for CIED infections. Female, Black, and Hispanic patients were significantly less likely to receive TLR.

AbstractIntroductionAlthough prior studies indicate that a QTc > 500 ms on a single baseline 12‐lead electrocardiogram (ECG) is associated with significantly increased risk of arrhythmic events in long QT syndrome (LQTS), less is known about the risk of persistent QT prolongation. We sought to determine QTc persistence and its prognostic effect on breakthrough cardiac events (BCEs) among pediatric patients treated for LQTS.MethodsWe performed a retrospective analysis of 433 patients with LQTS evaluated, risk‐stratified, and undergoing active guideline‐based LQTS treatment between 1999 and 2019. BCEs were defined as arrhythmogenic syncope/seizure, sudden cardiac arrest (SCA), appropriate VF‐terminating ICD shock, and sudden cardiac death (SCD).ResultsDuring the median follow‐up of 5.5 years (interquartile range [IQR] = 3–9), 32 (7%) patients experienced a total of 129 BCEs. A maximum QTc threshold of 520 ms and median QTc threshold of 490 ms were determined to be strong predictors for BCEs. A landmark analysis controlling for age, sex, genotype, and symptomatic status demonstrated models utilizing both the median QTc and maximum QTc demonstrated the highest discriminatory value (c‐statistic = 0.93–0.95). Patients in the high‐risk group (median QTc > 490 ms and maximum QTc > 520 ms) had a significantly lower BCE free survival (70%–81%) when compared to patients in both medium‐risk (93%–97%) and low‐risk (98%–99%) groups.ConclusionsThe risk of BCE among patients treated for LQTS increases not only based upon their maximum QTc, but also their median QTc (persistence of QTc prolongation). Patients with a maximum QTc > 520 ms and median QTc > 490 ms over serial 12‐lead ECGs are at the highest risk of BCE while on guideline‐directed medical therapy.

Background: Rigorous study of ventricular fibrillation (VF) is not feasible in humans. The spatiotemporal characteristics of prolonged VF remain undefined, limiting our understanding of this lethal rhythm. Methods: VF was mapped in 4 canines. The endocardial and epicardial left ventricle (LV) and right ventricle (RV) were sequentially mapped at 0 to 15, 15 to 30, 30 to 45, and 45 to 60 minutes post-induction. Ten consecutive beats were used to determine the average cycle length and regularity index of ventricular and His-Purkinje system signals in discrete regions during each time interval. Results: Average VF time was 58±12 minutes. The shortest ventricular cycle length was present in the RV apical region (70±10 msec) at 0 to 15 minutes and at 15 to 30 minutes (89±31 msec) and LV apical region at 45 to 60 minutes (242±163 msec). The His-Purkinje system cycle length was the shortest at the RV outflow tract (75±3 msec) at 0 to 15 minutes, RV inflow and free wall (89±12 msec) at 15 to 30 minutes, LV apical region (83±14 msec) at 30 to 45 minutes, and inferior and inferolateral LV (145±23 msec) at 45 to 60 minutes. Regularity index was the highest in the RV inflow and free wall (78%) at 0 to 15 minutes, RV apical region (86%) at 15 to 30 minutes, LV septum and epicardial anterior RV (80%) at 30 to 45 minutes, and anterior and anterolateral LV (75%) at 45 to 60 minutes. Conclusions: These data suggest significant regional changes in electrical activity throughout VF in canines. A transition of fastest electrical activity from RV to LV apical regions across VF was observed. These novel insights of the temporal and spatial changes of VF merit further evaluation in diseased hearts to assess for reproducibility of findings.

AbstractIntroductionTherapies 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.MethodsA 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.ResultsThe 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.ConclusionsThis 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.