Left ventricular (LV) early diastolic performance is determined by LV behavior in the late systole to early diastole and may relate to the physical potential of patients. Isovolumic relaxation flow (IRF) velocity was obtained by continuous Doppler echocardiography in the left ventricle from the apex in 26 patients with atypical chest pain and 63 patients with coronary artery disease (CAD) with or without prior myocardial infarction (MI) who underwent cardiac catheterization. In each patient, a time constant of LV relaxation (tau) was calculated from the LV pressure waves obtained by a catheter-tipped micromanometer. The LV end-systolic volume index was measured using contrast left ventriculography. IRF velocity in patients having CAD with prior MI (24.8 +/- 5.4 cm/s) was significantly less than in those with atypical chest pain (41.2 +/- 9.6 cm/s). It was also significantly less than in patients having CAD without prior MI (37.3 +/- 6.8 cm/s). IRF velocity significantly correlated with the time constant tau (r = -0.42, p < 0.001) and LV end-systolic volume index (r = -0.84, p < 0.001). This study indicates that IRF velocity obtained by continuous Doppler echocardiography in the left ventricle provides important information regarding LV systolic performance and early diastolic performance.