[en] The clinical significance of the mode of left ventricular (LV) diastolic filling in hypertrophic cardiomyopathy was studied by the LV inflow velocity patterns (LVIF) of pulsed Doppler echocardiography and LV early diastolic filling rates (V₂) of radionuclide (RI) angiography. The relationship between the deceleration time (DT) obtained from LVIF and the V₂ was evaluated in 34 patients with nonobstructive hypertrophic cardiomyopathy (HCM) and in nine with obstructive hypertrophic cardiomyopathy (HOCM), and the results were compared with those of 10 patients with dilated cardiomyopathy (DCM), of two with restrictive cardiomyopathy (RCM), and of 19 normal subjects. HCM was subdivided into the following groups according to V₁-DT relationships: Group 1 with prolonged DT and decreased V₁, Group 2 with normal or short DT and normal V₁, and Group 3 with normal or short DT and decreased V₁. There were significant negative correlations between V₂ and DT in Groups 1 and 2 of HCM, normal and HOCM. However, there were significant positive correlations in Group 3 of HCM, DCM and RCM. Nearly all patients in Group 3 had decreased LV ejection fraction and % fractional shortening, distinct B-B' step formation of the mitral valve echogram, and huge A wave of the apexcardiogram. These findings suggested that the LV rapid filling interval gradually became shorter because the LV contraction is decreased as myocardial fibrosis develops in HCM, and that we must pay attention to the diagnosis of such abnormalities, similar to those of DCM or RCM. (author)