Gurukripa Narayan Kowlgi

Aims: Pulsed field ablation (PFA) has emerged as a novel ablation modality for the treatment of cardiac arrhythmias and has rapidly reshaped contemporary electrophysiology practice. This article provides a comprehensive analysis on the mechanisms underlying the specific effects of PFA on myocardial, neural tissue structures, and the cardiac conduction system, integrating biophysical principles with preclinical and clinical evidence relevant to contemporary electrophysiology practice. Methods and results: This document provides an exhaustive mechanistic explanation for the preferential effects of PFA on myocardium and the limits of the ‘tissue-selectivity’ concept. The complex interplay between cellular and tissue-level biophysics, biological responses, and tissue regenerative capacity that determines differential susceptibility to electroporation across tissues is analysed. Distinct patterns of lesion formation and maturation following PFA are also reviewed, highlighting the temporal and histopathological differences compared with radiofrequency ablation. Additionally, lesion formation in heterogeneous substrates is analysed, including fibrotic and adipose-rich myocardium, where local electric field distribution critically influences lesion durability. Conclusion: The article further examines the interaction between pulsed electric fields and neural tissue, with emphasis on the phrenic nerve and intrinsic cardiac autonomic nervous system. While nerve stimulation and transient reversible conduction disturbances produced by reversible electroporation can occur during ablation, permanent neural injury appears extremely rare in current clinical experience. Finally, this manuscript examines current understanding regarding the specific effects of PFA on the cardiac conduction system, which according to the limited available evidence appear strongly dependent on electric field dose and anatomical proximity.

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.

Ischemic events after contemporary percutaneous coronary intervention (PCI) are uncommon but carry high morbidity/mortality. Identifying patients at highest risk is critical to guide dual antiplatelet therapy (DAPT) intensity while minimizing bleeding. Current machine learning (ML) model‐developed risk scores do not incorporate pharmacogenetic data. To develop and externally validate ML models that integrate clinical, demographic, and CYP2C19 genetic information to predict 1‐year ischemic outcomes post‐PCI to refine clinical decision making. We analyzed 8317 patients from TAILOR‐PCI trial ( n = 4572) and the Precision PCI registry ( n = 3745). The outcome was a composite of cardiovascular death, myocardial infarction, stroke, and stent thrombosis at 1 year. Boruta feature selection identified 11 predictors. Multiple ML algorithms were trained in TAILOR‐PCI and validated in Precision PCI using cross‐validation and synthetic minority oversampling (SMOTE). Model performance was assessed by area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. The best external performance was achieved with a support vector machine (SVM, polynomial kernel) (AUC 0.667; sensitivity 0.871; specificity 0.282), while XGBoost provided a more balanced profile (AUC 0.619; sensitivity 0.442; specificity 0.688). Variable importance for the SVM polynomial model demonstrated that all 11 included Boruta feature selected predictors had relatively high importance (> 75). ML models trained on large clinical trial and real‐world registry datasets can help identify the small subset of patients at high ischemic risk after PCI. This distinction is of relevance because ischemic events are rare, and most patients may safely de‐escalate DAPT to reduce bleeding risk while maintaining ischemic protection through a multimodal approach to risk stratification. Trial Registration: TAILOR‐PCI URL: https://clinicaltrials.gov/ct2/show/NCT01742117

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.

Background: Atrial fibrillation (AF) is common in patients with hypertrophic cardiomyopathy (HCM) and is associated with increased morbidity, heart failure (HF) exacerbations, and adverse long‐term outcomes. Although catheter ablation is an established rhythm‐control strategy, data comparing its long‐term clinical outcomes with anti‐arrhythmic drug (AAD) therapy in patients with HCM remain limited. Objective: To compare long‐term clinical outcomes of catheter ablation versus medical therapy with AADs in patients with HCM and AF. Methods: We conducted a retrospective cohort study using the TriNetX Research Network, a global federated database of electronic health records. Adult patients with HCM and AF between January 2010 and December 2020 were identified and stratified according to treatment with catheter ablation or AAD therapy. Outcomes included all‐cause mortality, HF exacerbations, AAD‐related adverse events, all‐cause hospitalization, ischemic stroke, repeat ablation, need for cardioversion, need for long‐term AAD use, and atrioventricular nodal ablation. A 1:1 propensity score matching (PSM) analysis was performed to balance baseline characteristics. Kaplan–Meier survival analysis and Cox proportional hazards models were used to estimate hazard ratios (HRs). Results: After PSM, 3144 patients were included (1572 in each cohort) with a mean follow‐up of approximately 3.4 years. Catheter ablation was associated with lower all‐cause mortality compared with AAD therapy (9.5% vs. 14.8%; HR: 0.60; 95% CI: 0.49–0.74; p < 0.001). Ablation was also associated with reduced risk of HF exacerbations (38.4% vs. 43.3%; HR: 0.79; 95% CI: 0.71–0.88; p < 0.001) and fewer AAD‐related adverse events (8.4% vs. 11.2%; HR: 0.71; 95% CI: 0.55–0.93; p = 0.011). Rates of all‐cause hospitalization (HR: 0.93; p = 0.11) and ischemic stroke (HR: 0.78; p = 0.10) were similar between groups. Conclusion: In this large real‐world cohort of patients with HCM and AF, catheter ablation was associated with lower mortality, reduced HF hospitalizations, and decreased AAD therapy‐related adverse events, as compared with medical therapy. These findings suggest that catheter ablation may provide meaningful clinical benefits in selected patients with HCM and AF, although prospective studies are needed to confirm these observations.