The aim of this study was to evaluate the relation of coronary flow velocity (CFV) and coronary flow reserve (CFR) to exercise capacity in ten verapamil-treated patients with hypertrophic cardiomyopathy (HC). Using Doppler transesophageal echocardiography, we assessed diastolic CFV in the proximal left anterior descending coronary artery at baseline and after administering 0.56 mg/kg intravenous dipyridamole. The CFR was calculated as the post-dipyridamole/baseline diastolic CFV ratio. A maximal symptom-limited exercise treadmill test was performed according to a modified Bruce protocol and the exercise capacity was expressed as metabolic equivalents. The mean value for baseline diastolic CFV was 59 +/- 27 cm/s; this increased after dipyridamole to 134 +/- 57 cm/s. The CFR was 2.37 +/- 0.67. Baseline diastolic CFV correlated negatively with both exercise duration (r = -0.69; P < 0.05) and value for metabolic equivalents (r = -0.70; P < 0.05). CFR was weakly and non-significantly related to exercise duration (r = 0.40; P > 0.05) and to the value for metabolic equivalents (r = 0.32; P > 0.05). Shortening of exercise time and decreasing metabolic equivalents were correlated with increased baseline diastolic CFV. Dipyridamole-assessed CFR, was weakly related to parameters of exercise capacity.