The present study clarified the effect of
disopyramide on left-ventricular function in patients with
hypertrophic cardiomyopathy (5 obstructive type: HOCM, 21 non-obstructive type: HNCM). The systolic and early diastolic time intervals were assessed 3 hours after a single
oral administration of 100-mg
disopyramide. The following parameters were evaluated at rest and after administration of
disopyramide: 1) left-ventricular ejection time index (LVETI), 2) pre-ejection period index (PEPI), 3) the interval from aortic component of the second heart sound to mitral valve opening (IIA-MVO), and 4) the interval from MVO to O point of apexcardiogram (MVO-O). LVETI in HNCM did not change after
disopyramide but that in HOCM was significantly shortened (P less than .05). PEPI in both HOCM and HNCM was significantly prolonged after administration of
disopyramide. IIA-MVO time in both HOCM and HNCM was not influenced by
disopyramide. MVO-O time in both HOCM and HNCM was significantly shortened after
disopyramide. These results suggest that 1) shortening of LVETI in HOCM after
disopyramide seemed to be due to the decrease in pressure gradient, 2) PEPI prolongation after
disopyramide reflected the decrease in myocardial contractility, and 3) shortening of MVO-O time after
disopyramide indicated the improvement of left-ventricular filling. The authors conclude that
disopyramide may be an important new therapeutic agent in the treatment of patients with
hypertrophic cardiomyopathy.