Catheter Ablation of Ventricular Tachycardia in Dilated-Phase Hypertrophic Cardiomyopathy: Substrate Characterization and Ablation Outcome.

INTRODUCTION: Catheter ablation is a therapeutic option to suppress ventricular tachycardia (VT) in the setting of dilated-phase hypertrophic cardiomyopathy (DHCM). However, the characteristics of the arrhythmogenic substrate and the ablation outcome are not fully illustrated.

METHOD: A total of 23 ablation procedures for drug-refractory sustained monomorphic VTs in 13 DHCM patients (60 ± 11 years, one female, the left ventricular [LV] ejection fraction 39 ± 9%, the LV mass index 156 ± 39 g/m2 ) were performed. The distribution of VT substrate as endocardial or epicardial/intramural was based on detailed mapping and ablation response during VT.

RESULT: Two patients underwent ablation of sustained monomorphic VT that was not scar-mediated tachycardia. Of the remaining 11 patients, 8 (73%) patients had VT substrate in the basal regions, most frequently at the epicardial and/or intramural basal antero-septum. None of the patients had VT substrate located at the LV inferolateral region. Ablation at the right ventricular septum and the aortic cusps was done in 4 and 5 patients, respectively. Other approaches including bipolar and chemical ablations, were done in 3 and 2 patients, respectively. Six (55%) out of 11 patients (2 patients lost follow-up) had VT recurrence. All the six patients had basal substrate. However, anti-tachycardia pacing was sufficient for VT termination except in one patient.

CONCLUSION: Catheter ablation of VT in patients with DHCM is challenging because of the predominant basal anteroseptal epicardial/intramural location of arrhythmogenic substrate. An ablation approach from multiple sites and/or adjunctive interventional techniques are often required. This article is protected by copyright. All rights reserved.