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

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 , a first-in-human study of this PFA catheter to ablate scar-related VT. Methods: An investigational 8.5-French force-sensing PFA catheter was used for scar-VT ablation in ischemic or non-ischemic substrates. PF lesions consisted of 5 applications, each <200 msec, of a high-voltage (>10 kV) monophasic waveform with QRS-synchronization. The PFA catheter was localized by electrical impedance-based navigation. A sub-cohort of patients without prior cardiac surgery underwent epicardial ventricular mapping – at baseline and after endocardial PFA – to assess for transmurality of endocardial PF lesions. Study endpoints included procedural efficiency, safety and effectiveness to final follow-up of 6 months. Results: At 2 centers, 26 patients underwent ablation: age 66 ± 9; 4% female; left ventricular ejection fraction 32 ± 10%; VT storm 42%; prior VT ablation 42%. Acute procedural success, achieved in 24 (92%) patients, required 21 [IQR 14–24] lesions per patient, with a transpired ablation time of 31 minutes [19-42]. The clinical VT was induced in 14 of 16 patients (88%) pre-ablation, and 1 of 16 patients (6%; p < 0.001) post-ablation. High-density epi-endo voltage mapping was performed in 10 patients [42%]; of the 9 patients undergoing endo cardial-only PFA, transmural tissue homogenization was observed in all 9 (100%) patients. Freedom from recurrent VT/VF or ICD shock was 81.8% [95%CI 67.1–99.8]. Regarding VT/VF burden, the incidence rate of post-ablation VT/VF significantly decreased from baseline to post-PFA by 98% (median [IQR] 6 [1–11] vs 0 [0–0], respectively; p < 0.001). Primary safety endpoints 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.