Aortic stenosis (AS) with otherwise normal coronary arteries may be associated with angina pectoris and microvascular abnormalities. In this study, using the thrombolysis in myocardial infarction (TIMI) frame count (TFC) method, we tested whether the coronary blood flow velocity is decreased in patients with AS. Twenty-eight patients with severe AS and an otherwise normal coronary arteriogram (group I) and 25 subjects with atypical chest pain and a normal coronary arteriogram (group II) were included in this study. After transthoracic echocardiographic evaluation, all participants underwent coronary arteriography either to evaluate their coronary artery status before surgery or to exclude coronary artery disease. Later, TFC was calculated and compared for each artery, including the left anterior descending (LAD), circumflex (Cx), and right coronary arteries (RCA) in both groups. Baseline characteristics of the study groups were similar. In both groups, TIMI-3 flow was present in each artery at the time of arteriography and the coronary arteries were entirely normal. All subjects with AS had echocardiographic septal and posterior wall thickness more than 12 mm. The mean aortic valve area was 0.78 +/- 0.26 cm2. Peak and mean transvalvular gradients were 92 +/- 16 and 48 +/- 7, respectively. In group I, corrected TFC, Cx, and RCA frame counts were significantly higher than those of group II (24.6 +/- 2.1 vs 21.8 +/- 2.2 frames/s, P < 0.05; 24.4 +/- 1.7 vs 22.8 +/- 2.4 frames/s. P < 0.05; 23.2 +/- 2.0 vs 21.4 +/- 1.8 frames/s, P < 0.05, respectively). Coronary blood flow velocity is decreased in patients with aortic stenosis compared with patients having normal coronary arteries, probably due to microvascular dysfunction.