Subacute and chronic effects of DDD pacing on left ventricular diastolic function in patients with non-obstructive hypertrophic cardiomyopathy

The present study examined the ability of dual-chamber (DDD) pacing to impr ove symptoms and exercise tolerance in patients with non-obstructive hypert rophic cardiomyopathy (HNCM). Seven patients with HNCM who had failed to be nefit fi om pharmacotherapy participated in the study. The New York Heart A ssociation (NHYA) functional class status and exercise tolerance, which was determined by the treadmill exercise test, were recorded and an echocardio graphic observation was performed before, and 1 week, 3 months and 1 year a fter the implantation of a permanent DDD pacemaker. The atrioventricular de lay (AVd) was determined by measuring the point of peak rapid filling veloc ity and maximum cardiac output (CO). Two patients were not implanted with a permanent pacemaker because their CO and blood pressure decreased or becau se palpitation occurred during temporary pacing. The ratio between early an d late peaks of how velocity (1.56, 1.21, 0.95, and 0.86 before implantatio n and 1 week, 3 months and 1 year after implantation, respectively); decele ration time (ms: 263.2, 217.6, 204.6, 187.0); peal; filling late (ml/s: 146 .3, 704.0, 233.2, 243.6); NYHA functional class status (2.0, 1.8, 1.6, 1.3) ; and exercise tolerance (s: 203, 264, 403, 480) were significantly improve d after implantation. However, left ventricular dimension, percent fraction al shortening, ejection fraction, acceleration time and the isovolumic rela xation time were not changed significantly. In conclusion, DDD pacing impro ved symptoms and the NYHA functional class status, which is associated with improvement of left ventricular diastolic function, it is proposed that DD D pacing would be useful in patients not only with obstructive but also non -obstructive hypertrophic cardiomyopathy refractory to medical treatment, d epending on the careful selection of subjects.