Catheter Ablation for Ventricular Tachycardia in Patients With Hypertrophic Cardiomyopathy: Electrophysiological Characteristics and Long-Term Outcomes.

BACKGROUND

Studies on catheter ablation of hypertrophic cardiomyopathy (HCM)- ventricular tachycardia (VT) are relatively limited and mainly focused on feasibility and safety, whereas the VT distribution and electrophysiological properties remain insufficiently characterized.

OBJECTIVES

The aim of this study was to detail the site-specific electrophysiological properties and ablation outcomes in HCM-VT.

METHODS

A total of 32 patients with HCM-VT who underwent catheter ablation were included. Through endocardial and epicardial mapping, their arrhythmogenic substrate and re-entrant circuit were identified and analyzed.

RESULTS

Combined endocardial/epicardial mapping was performed in 29 of the 32 patients. Twenty-eight VTs were induced among 25 patients, including 25 scar-mediated re-entries, 2 focal origins, and one bundle branch re-entry. Twenty-five re-entries were localized to the left ventricular (LV) lateral wall (9 of 25), apical aneurysm (6 of 25), superior basal regions (8 of 25), interventricular septum (1 of 25), and papillary muscle (1 of 25), respectively. Incomplete activation sequences were recorded across regions: LV lateral wall (epicardium: 54.3% ± 11.7%; endocardium: 35.9% ± 15.5%), apical aneurysm (endocardium: 40.3% ± 25.0%; epicardium: 32.7% ± 22.6%), and superior basal regions (endocardium: 25.5% ± 7.7%; epicardium: 27.2% ± 11.4%). Over a median follow-up of 31 months, the long-term VT-free survival rate after the index procedure was 73.3% in the LV lateral wall, 83.3% in the apical aneurysm, and 0% in the LV superior basal region and septum, which was consistent with the extent of mid-myocardial involvement. The VT-free survival rate after multiple procedures was 71.9% in all patients.

CONCLUSIONS

HCM-VTs were primarily three-dimensional re-entrant circuits with mid-myocardial involvement. Procedural success largely depended on the origin and extent of intramural involvement of VT re-entry.