Endocardial radiofrequency ablation for hypertrophic obstructive cardiomyopathy: acute results and 6 months' follow-up in 19 patients.

Objectives: The purpose of this study was to examine the efficacy and safety of endocardial radiofrequency ablation of septal hypertrophy (ERASH) for left ventricular outflow tract (LVOT) gradient reduction in hypertrophic obstructive cardiomyopathy (HOCM).

Background: Anatomic variability of the vessels supplying the obstructing septal bulge can limit the efficacy of transcoronary ablation of septal hypertrophy in HOCM. Previous studies showed that inducing a local contraction disorder without reducing septal mass results in effective gradient reduction. We examined an alternative endocardial approach to transcoronary ablation of septal hypertrophy by using ERASH.

Methods: Nineteen patients with HOCM were enrolled; in 9 patients, the left ventricular septum was ablated, and in 10 patients, the right ventricular septum was ablated. Follow-up examinations (echocardiography, 6-min walk test, bicycle ergometry) were performed 3 days and 6 months after ERASH.

Results: After 31.2 ± 10 radiofrequency pulses, a significant and sustained LVOT gradient reduction could be achieved (62% reduction of resting gradients and 60% reduction of provoked gradients, p = 0.0001). The 6-min walking distance increased significantly from 412.9 ± 129 m to 471.2 ± 139 m after 6 months, p = 0.019); and New York Heart Association functional class was improved from 3.0 ± 0.0 to 1.6 ± 0.7 (p = 0.0001). Complete atrioventricular block requiring permanent pacemaker implantation occurred in 4 patients (21%); 1 patient had cardiac tamponade.

Conclusions: ERASH is a new therapeutic option in the treatment of HOCM, allowing significant and sustained reduction of the LVOT gradient as well as symptomatic improvement with acceptable safety by inducing a discrete septal contraction disorder. It may be suitable for patients not amenable to transcoronary ablation of septal hypertrophy or myectomy.