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

Authors, Journal, Affiliations, Type, DOI

• Authors: Vivek Y. Reddy, Jacob S. Koruth, Petr Peichl, Jan Petru, Moritoshi Funasako, Jan Skoda, Keita Watanabe, Moritz Nies, Josef Kautzner, Petr Neuzil
• Journal: Circulation 2025;152(24):1691–1704
• Affiliations: Helmsley Electrophysiology Center, Mount Sinai Fuster Heart Hospital, New York; Homolka Hospital, Prague; Institute for Clinical and Experimental Medicine, Prague
• Type: First-in-human, prospective, multicentre, non-randomised, single-arm interventional study (VCAS; NCT06203262), with a supporting porcine study
• DOI: 10.1161/CIRCULATIONAHA.125.077025

Overview

VCAS tested a focal high-voltage pulsed field ablation (PFA) catheter designed specifically to create deep ventricular lesions for scar-related VT. The system delivers a monophasic waveform at >10 kV in five QRS-gated applications of <200 ms each, with low total energy despite the high voltage. In 12 pigs, 23 lesions measured 12.5±3.3 mm deep and 23.3±4.5 mm wide, with intact arterioles within the ablated myocardium. In 26 patients at two Czech centres — mostly post-infarction, with LVEF 32%, VT storm in 42% and prior VT ablation in 42% — acute success was 92%, clinical VT was non-inducible after ablation in 93% of tested patients, and 180-day freedom from VT/VF or ICD shock was 81.8%. In nine patients who underwent endocardial-only PFA with paired epicardial mapping, epicardial abnormal potentials disappeared in all nine, supporting transmural lesion formation. The main safety events were heart-failure-related (cardiogenic shock death, heart-failure hospitalisation) plus one retroperitoneal bleed, at a rate comparable to recent VT ablation trials.

Keywords

Pulsed field ablation; high-voltage; scar-related ventricular tachycardia; transmural ablation; post-myocardial infarction

Key Takeaways

System and waveform

• FieldForce 8.5F bidirectional, focal force-sensing, saline-irrigated catheter; compatible with commercial electroanatomic mapping but not integrated with it — localisation relied on an electrical impedance cloud.
• Each lesion = 5 applications, each <200 ms, QRS-synchronised, monophasic, >10 kV. Total joule energy is roughly an order of magnitude lower than a conventional 50 W × 10 s RF lesion.
• The catheter evolved during the study from one internalised plus two externalised electrodes (first 20 patients) to three externalised electrodes (last 6).
• An external dispersive patch is placed on the thorax; the catheter can also pace and record.

Preclinical lesion data

• 12 Yorkshire swine, 23 discrete LV lesions.
• Lesion depth 12.5±3.3 mm, width 23.3±4.5 mm; homogeneous lesions with sharply demarcated margins and intact arterioles within the ablated myocardium.
• The preclinical lesions were created in normal, not scarred, myocardium; the authors cite prior work that PFA is relatively unimpeded by scar.

Clinical cohort

• 28 patients enrolled; 2 early exits (including one screen failure) → safety set 26; 2 unsuccessful procedures → procedural set 24; 1 without post-ablation ICD interrogation → full analysis set 23.
• Age 66±9 years; 1 woman (4%); LVEF 32±10%; 92% post-MI, 8% NICM; 42% prior VT ablation; 42% VT storm within 180 days; 96% on beta-blockers; 65% on amiodarone.

Procedural results

• Acute procedural success 24/26 (92%). One failure was a PF generator malfunction requiring RF salvage; one procedure was aborted for haemodynamic decompensation.
• Median 21 lesions (IQR 14–24) per patient; transpired ablation time 31 min (19–42); skin-to-skin time 164 min (136–212); fluoroscopy 12 min (8–17).
• Clinical VT was inducible in 14/16 tested patients (88%) before ablation and 1/16 (6%) after (p<0.001); 13/14 (93%) were non-inducible after PFA.
• Endocardial-only PFA was used in 14/24 (58%); combined endocardial–epicardial mapping in 10/24 (42%).

Transmurality substudy

• In 10 patients with paired high-density epicardial mapping before and after endocardial PFA, 9 had abnormal epicardial potentials opposite the endocardial scar.
• After endocardial-only PFA, all 9 (100%) showed complete voltage abatement and disappearance of epicardial fractionated/late potentials opposite the lesions; no additional epicardial lesions were required.
• The tenth patient had a small endocardial but large inferolateral epicardial scar and received 3 endocardial lesions plus 19 single-application epicardial lesions to avoid excessive transmural ablation of normal tissue.
• The authors contrast this with a prior RF study in which endocardial ablation eliminated adjacent epicardial abnormal potentials at only 48/173 sites (28%) and in only 6/46 patients (13%).

Effectiveness at 180 days

• 23 patients with follow-up; median 167 days; 61% reached the 6-month interrogation.
• Freedom from recurrent VT/VF or ICD shock: 81.8% (95% CI 67.1–99.8).
• VT/VF events: median 6 (IQR 1–11) before vs 0 (0–0) after; incidence 4.2 vs 0.08 events/month, incidence rate ratio 0.02 (95% CI 0.00–0.11) — a 98% reduction.
• ATP/shock incidence fell by 97% (IRR 0.03, 95% CI 0.01–0.14).
• Results were similar for first-ever vs redo ablation and for patients with vs without VT storm.
• Antiarrhythmic therapy was unchanged in most patients (75% had no amiodarone change).

Safety

• Primary safety endpoint within 180 days: 3 patients (11.5%) — one cardiogenic shock death, one heart-failure hospitalisation, one retroperitoneal bleed.
• All three were adjudicated procedure-related; the death was possibly device/PFA-related, the other two not device/therapy-related.
• The death occurred in a 77-year-old with LVEF 35% and VT storm who decompensated during mapping, before the first PFA lesion.
• The heart-failure hospitalisation occurred in a patient with LVEF 15% and storm after a complex 33-lesion procedure.
• No stroke, TIA, phrenic nerve injury or coronary vasospasm; however, screening coronary angiography was performed in only 3 patients and almost all lesions were endocardial.
• Transient haemolysis: haemoglobin fell 16.7 g/L, haptoglobin fell 0.77 g/L, LDH rose 228 U/L and unconjugated bilirubin rose 4.6 µmol/L; all normalised by 90 days, with no haptoglobin depletion and no renal replacement therapy.
• ICD lead pacing/sensing thresholds were unchanged. One CRT-D required a software reset after PF delivery caused a pacing-configuration change; no revision was needed.

Limitations of the document

• Single-arm, no comparator. The authors explicitly state that direct comparison with RF, cryo or conventional PFA is inappropriate; randomised trials are required.
• Small sample and short follow-up. 26 patients, 23 in the effectiveness set, 6 months; the 95% CI for freedom from VT/VF (67–100%) extends into the range achieved by conventional ablation.
• Transmurality is not always desirable. Broad lesions may ablate viable midmyocardial and epicardial tissue and impair contractility; lesion depth modulation is an explicit future need.
• Transmurality assessment is indirect. Epicardial potential disappearance could reflect transient stunning rather than permanent lesion transmurality; repeat mapping was not performed.
• Preclinical lesions were in normal myocardium, not scar, and the porcine model may not reproduce human scar thickness or fat distribution.
• Safety assessment is underpowered. Coronary angiography was performed in only 3 patients and epicardial lesions were rare, so coronary spasm and phrenic injury rates in broader epicardial use are unknown.
• Sponsor involvement. Field Medical funded the study and employs/consults several authors; the authors state they had final authority over content.

Key Concepts Mentioned

• concepts/Ventricular-PFA — the energy modality and its ventricular application
• concepts/VT-Ablation — procedural context and competing technologies
• concepts/VT-Ablation-Nonischemic-Cardiomyopathy — the non-ischaemic substrate included in this cohort
• concepts/Epicardial-VT-Ablation — the epicardial mapping used to verify transmurality
• concepts/VT-Ablation-Ischemic-Cardiomyopathy — the dominant substrate in VCAS
• entities/ICD — device interrogation and interaction

Key Entities Mentioned

• Field Medical Inc. — manufacturer and sponsor (FieldForce system)
• Mount Sinai Fuster Heart Hospital, New York
• Homolka Hospital and Institute for Clinical and Experimental Medicine, Prague
• Biosense Webster / JNJ MedTech — CARTO mapping system
• Circa Scientific — PeriCross pericardial access device

Wiki Pages Updated

• Created: wiki/sources/pfa-vt-circ-2025.md
• Created: wiki/concepts/VT-Ablation.md
• Updated: wiki/concepts/Pulsed-Field-Ablation.md
• Updated: wiki/concepts/VT-Management.md
• Updated: wiki/sourceindex.md
• Updated: log.md