Low occurrence of ventricular arrhythmias after alcohol septal ablation in high-risk patients with hypertrophic obstructive cardiomyopathy

Percutaneous alcohol septal ablation (PTSMA) is an established treatment for symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). However, there is concern of a higher risk for ventricular tachyarrhythmias and sudden death due to the myocardial scar created after PTSMA. We investigated the possibility of increased ventricular arrhythmias and risk of sudden death after PTSMA in a subgroup of patients with an already implanted ICD. Between 2009 and 2012, 239 PTSMAs were performed in 212 patients with HOCM. In 32 of those an ICD had already been implanted before PTSMA for primary (31 patients) or secondary (1 patient) prevention of sudden death. The maximum left ventricular outflow tract gradient (LVOTG) was reduced from 114 +/- 39 mmHg before PTSMA to 23 +/- 19 mmHg (P < 0.0001). Among clinical risk factors for sudden death, nonsustained ventricular tachycardia (VT), syncope and family history for sudden death were most common. After a median follow-up of 5.3 (IQR 4.3-5.7) years after PTSMA only one patient had ICD shocks (annual ICD discharge 0.6 %). In another 3 patients, with already documented nonsustained VTs as risk factor before ICD implantation, VT episodes that activated antitachycardic pacing were recorded. The annual appropriate ICD intervention including all events was 2.5 % and involved only patients with a very high estimated 5-year sudden death risk before PTSMA (> 14.3 %). In a selected high-risk patient cohort with HOCM ominous arrhythmic events seem to be rare and predominantly occur in patients with a very high estimated risk of sudden death before PTSMA.