Fascicular Substrate Modification to Treat Human Ventricular Fibrillation

Background: Purkinje fibers play an important role in initiation and maintenance of ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PMVT). Fascicular substrate modification (FSM) approaches have been suggested to treat recurrent VF in case reports and small case series. Objectives: The aim of this study was to investigate outcomes of catheter-based FSM to treat VF and PMVT. Methods: Of 2,212 consecutive patients with ventricular arrhythmia undergoing catheter ablation, 18 (0.81%) underwent FSM of the Purkinje fibers as identified with high-density mapping during sinus rhythm. Fascicular substrate and VF initiation were mapped using a multipolar catheter. The endpoint of the ablation was noninducibility of VF and PMVT. In select patients, remapping revealed elimination of the targeted Purkinje potentials. Demographic, clinical, and follow-up characteristics were prospectively collected in our institutional database. Results: A total of 18 patients (mean age 56 ± 3.8 years, 22% women) were included in the study. Of those, 11 (61.1%) had idiopathic VF, 3 (16.7%) had nonischemic cardiomyopathy, and 4 (22.2%) had mixed cardiomyopathy. The average left ventricular ejection fraction was 42.5%. At least 2 antiarrhythmic drugs had failed preablation. At baseline, all patients had inducible VF or PMVT. At the end of the procedure, no patient demonstrated new evidence of fascicular block or bundle branch block. There were no procedure-related complications. After a median follow-up period of 24 months, 16 patients (88.9%) were arrhythmia free on or off drugs: 11 of 11 patients (100%) with idiopathic VF vs 5 of 7 patients (71.4%) with underlying cardiomyopathy (P = 0.06). Conclusions: Catheter ablation of human VF and PMVT with FSM is feasible and safe and appears highly effective, with high rates of acute VF noninducibility and long-term freedom from recurrent VF.