High-Voltage Focal Pulsed Field Ablation to Treat Scar-Related Ventricular Tachycardia: The First-in-Human VCAS Trial

Abstract

BACKGROUND: Unlike the tremendous progress made in atrial fibrillation ablation, the greatest unmet clinical need is for innovative ablation treatments for scar-related ventricular tachycardia (VT), particularly given the thick, often fibrotic tissue characteristic of the scarred substrate. A focal pulsed field ablation (PFA) catheter with a novel waveform was designed: high voltage to provide tissue penetration and low energy (using short-duration pulses) to avoid tissue overheating. We present the outcomes of VCAS (Ventricular Catheter Ablation Study), a first-in-human study of this PFA catheter to ablate scar-related VT. METHODS: An investigational 8.5F force-sensing PFA catheter was used for scar-VT ablation in ischemic or nonischemic substrates. Pulsed field lesions consisted of 5 applications, each <200 ms, of a high-voltage (>10 kV) monophasic waveform with QRS synchronization. The PFA catheter was localized by electrical impedance-based navigation. A subcohort of patients without previous cardiac surgery underwent epicardial ventricular mapping at baseline and after endocardial PFA to assess for transmurality of endocardial pulsed field lesions. Study end points included procedural efficiency, safety, and effectiveness to final follow-up of 6 months. RESULTS: At 2 centers, 26 patients underwent ablation: 66±9 years of age, 4% women, left ventricular ejection fraction 32±10%, VT storm 42%, previous VT ablation 42%. Acute procedural success, achieved in 24 (92%) patients, required 21 (interquartile range, 14–24) lesions per patient with a transpired ablation time of 31 minutes (19–42). Clinical VT was induced in 14 of 16 patients (88%) before ablation and 1 of 16 patients (6%, P <0.001) after ablation. High-density epi-endo voltage mapping was performed in 10 patients [42%]; of the 9 patients undergoing endocardial-only PFA, transmural tissue homogenization was observed in all 9 (100%) patients. Freedom from recurrent VT/ventricular fibrillation (VT/VF) or implantable cardioverter defibrillator shock was 81.8% (95% CI, 67.1–99.8). Regarding VT/VF burden, the incidence rate of postablation VT/VF significantly decreased from baseline to after PFA by 98% (median [IQR], 6 [1–11] versus 0 [0–0], respectively; P <0.001). Primary safety end points within 180 days occurred in 3 of 26 (11.5%) patients: cardiogenic shock, heart failure hospitalization, and retroperitoneal bleed. CONCLUSIONS: In this first-in-human study, the high-voltage PFA catheter efficiently delivered transmural ventricular lesions to treat scar-related VT. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT06203262.