ABSTRACT
BACKGROUND: Hypertrophic obstructive cardiomyopathy (HOCM) is a primary cardiac disorder with a heterogeneous expression. When medical therapy fails in patients with symptomatic HOCM, three additional therapeutic strategies exist: ventricular septal myectomy, alcohol-induced percutaneous transluminal septal myocardial ablation (PTSMA) of the first septal branch of the anterior descending artery and pacemaker implantation. In this paper we present the results of seven patients in whom a dual-chamber pacemaker was implanted to reduce the gradient in the left ventricular outflow tract (LVOT) and to relieve their symptoms. METHODS: In patients with drug refractory symptomatic HOCM, not eligible for surgery, pacemaker therapy was recommended. Symptomatic HOCM was defined as symptoms of angina and dyspnoea, functional class NYHA 3-4 and a resting LVOT gradient during Doppler echocardiography of more than 2.75 m/s (30 mmHg). In these patients, a dual-chamber pacemaker was implanted with a right ventricular lead positioned in the right ventricular apex and an atrial lead positioned in the right atrial appendage. In all patients the AV setting was programmed between 50 and 100 ms, using Doppler echocardiography to determine the optimal filling and to ensure ventricular capture. RESULTS: A statistically significant reduction of the LVOT gradient was observed in all patients. The pre-implantation gradient in the LVOT measured by Doppler echocardiography varied from 3-5.8 m/s with a mean of 4.7±1.1 m/s. The post-implantation gradient varied from 1.4-2.6 m/s with a mean of 1.9±0.4 m/s (p<0.001). Symptomatic improvement was present in all patients. NYHA functional class went from 3-4 (mean 3.1±0.5) pre-implantation to 1-2 mean (1.3±0.4) after implantation (p<0.001). During a mean follow-up of 2.3±1.1 years, the improvement in functional class was maintained. CONCLUSION: Our preliminary results demonstrate that dual-chamber pacing is an effective and safe treatment for symptomatic patients with HOCM.
