Various evidence suggest that myocardial ischemia is a major factor in the progression of hypertrophic cardiomyopathy (HCM). In this study, we investigated the effects of nicorandil on left ventricular (LV) systolic and diastolic function in 12 symptomatic patients with HCM using echocardiography and radionuclide angiography. Nicorandil (6 mg), when administered intravenously, produced no significant changes in any parameter, including LV filling dynamics. However, accelerated LV peak early filling velocity (0.51 +/- 0.13 to 0.59 +/- 0.14 m/sec, p < 0.01), and reduced peak velocity in atrial contraction (0.54 +/- 0.17 to 0.50 +/- 0.15 m/sec, p < 0.05) were observed by Doppler echocardiography after 4 weeks of oral administration of 10 mg nicorandil 3 times daily. This oral administration did not affect heart rate, blood pressure, LV outflow gradient, or LV systolic function. The same favorable results were observed in a wall motion analysis with radionuclide angiography: peak filling rate (PFR) in global LV (3.21 +/- 0.76 to 3.52 +/- 0.87 end-diastolic volume (EDV)/sec, p < 0.02), and apical (4.73 +/- 1.18 to 5.42 +/- 1.55 EDV/sec, p < 0.01) and lateral (4.78 +/- 1.60 to 5.52 +/- 1.51 EDV/sec, p < 0.05) segments was increased, and the time to peak filling rate (TPF) in septal (245 +/- 31 to 203 +/- 40 msec, p < 0.01) and lateral (222 +/- 54 to 193 +/- 34 msec, p < 0.05) segments was reduced. These findings indicate that nicorandil has beneficial effects on LV diastolic function in HCM. These favorable effects may be due to the improvement of subendocardial ischemia.