Dual-Chamber Pacing for Patients with Hypertrophic Obstructive Cardiomyopathy: Prospective Randomized, Double-Blind Crossover Trial

Implantation of dual-chamber permanent pacemaker (PPM) has recently been proposed as therapeutic alternative for patients with hypertrophic obstructive cardiomyopathy (HOCM). To objectively determine the short-term benefit of PPM, we entered 11 patients with severely symptomatic HOCM (mean age, 53 ± 13 years; 7 males, 4 females) into prospective randomized, double-blind crossover trial with 2 months of continuous atrial synchronous pacing (DDD) and 2 months of backup pacing (VVI). All medications were continued throughout the study. Clinical symptoms, oxygen consumption treadmills, and Doppler echocardiography were performed at baseline and after each of the two arms. During the DDD arm, 62% experienced subjective symptomatic improvement and 37% admitted to symptomatic improvement in the VVI arm. The dat at baseline and after each of the two arms for maximum treadmill time (TMET-max), maximum oxygen consumption (VO2-max), and Doppler outflow tract gradient (GRAD) are shown: Conclusion: PPM for patients with HOCM provides subjective improvement and decrease in gradient for select group of patients. However, not all patients will respond to PPM, and there is no overall statistically significant improvement in objective exercise parameters on short-term follow-up. DDD PPM should not be routinely implanted in all patients with HOCM until further results of larger prospectively randomized trials are available.