To assess left ventricular diastolic filling in patients with single-vessel coronary artery disease, Doppler-derived transmitral velocity was studied in 22 normal subjects and in 15 patients with isolated proximal stenosis of the left anterior descending coronary artery (LAD) and normal systolic function of the left ventricle. Transmitral velocity was recorded before and after balloon inflation during coronary angioplasty. At baseline the transmitral velocity pattern in patients with LAD stenosis differed from that of normal subjects with a significant (p at least less than 0.05) decrease in the early diastolic filling phase (E area 0.094 +/- 0.022 m in normal subjects vs 0.078 +/- 0.008 m in patients) and an increase in the late diastolic filling phase (A area 0.034 +/- 0.007 m vs 0.042 +/- 0.008 m). Correspondingly the ratio E area/A area decreased (2.7 +/- 0.51 vs 1.9 +/- 0.4) and the ratio A area/total area increased (0.28 +/- 0.04 vs 0.35 +/- 0.05). During coronary occlusion the E area and the ratio E area/A area decreased further, whereas the A area and the ratio A area/total area increased. The results suggest that patients with single-vessel disease and normal systolic function often exhibit an altered pattern of transmitral velocity even in the absence of overt ischemia, and that during acute regional ischemia early diastolic filling is further compromised with compensatory enhancement of the late diastolic filling phase.