OBJECTIVE: Dual chamber pacing has been recognized as an complementary therapy to reduce left ventricular outflow tract gradient (LVTOG) in patients with hypertrophic obstructive cardiomyopathy (HOCM). Although controversies still remains, most reports show the effectiveness of this novel method to reduce LVOTG, improved clinical status and increase survival in patients with HOCM refractary to clinical treatment. The aim of this study is to present the results of DDD pacemaker therapy in a group of patients with HOCM unresponsive to pharmacological management. METHOD: Forty-two patients with HOCM refractory to medical treatment and with an increasing or higher than 50 mmHg LVOTG were implanted a transvenous DDD pacemaker. The optimal atrioventricular interval was defined as that producing the lowest left ventricular outflow tract gradient without compromise of aortic or left atrial pressures. After implantation, the pacemaker was programmed with a pulse rate capable of controlling the atria and the ventricle with a reduced atrioventricular interval (equal or lower than 120 ms). Pacemaker programming was performed during ECHO evaluation to obtain the lowest LVOTG. RESULTS: The majority of patients showed hemodynamic improvement during permanent pacing. Initial pacemaker programming resulted in a reduction of the LVOTG from the mean control value of 96.50±30.55 mmHg to 41.80±22.84 mmHg (p<0,001), and in the last follow-up LVTOG decreased even further to 30.00±23.03. CONCLUSION: Dual-chamber pacing improve subjective measures of functional status in patients with symptomatic HOCM in this study, offering reduction in LVOTG and improvements in objective measures of patient symptoms and functional status.
Hypertrophic obstructive cardiomyopathy; Pacemaker, treatment
