Very late effects of dual chamber pacing therapy for obstructive, hypertrophic cardiomyopathy

Abstract

Background: The very long-term effects of dual chamber pacing as a primary treatment for hypertrophic obstructive cardiomyopathy (HOCM) are poorly known and controversial. Objective: To examine the intermediate- and long-term clinical and hemodynamic effects of permanent, dual chamber pacing in patients presenting with HOCM. Methods: Between 1991 and 2007, 51 patients (mean age = 59±14 years) presenting with HOCM and New York Heart Association (NYHA) functional class ≥ 2 despite optimal medical therapy, underwent implants of DDD pacemakers with or without defibrillator and were followed for 11.5 years (range 0.4 - 21.8). Results: During follow-up, no patient underwent myectomy or septal alcohol ablation. NYHA functional class and other disease manifestations decreased significantly between 1 and 2 years of follow-up and remained stable thereafter. The left intraventricular (LV) gradient decreased by a mean of 78% between 1 and 2 years, to reach 89% at the end of follow-up, along with the disappearance of systolic anterior motion of the mitral valve. Mean LV ejection fraction decreased from a mean of 64±8% before pacing to 56±9% at the end of follow-up (P=0.05), while LV end-diastolic diameter did not change significantly. The 5- and 10-year actuarial survival rates were 90 and 65%, respectively. Among 22 deaths, 10 were due to cardiovascular and 12 to non-cardiovascular causes; 2 patients underwent cardiac transplantation after 8 and 13 years of DDD pacing, respectively. Conclusions: In this sample of patients suffering from HOCM, DDD pacing alleviated symptoms and improved hemodynamic function over the very long term. The merits of this treatment should be revisited in a controlled trial.