BACKGROUND AND OBJECTIVES: The measurement of the coronary flow velocity reserve (CFR) using transthoracic Doppler echocardiography (TTDE) has been reported to be useful for assessing the physiological significance of left anterior descending coronary artery (LAD) stenosis. This study was performed to evaluate the usefulness of CFR by TTDE for diagnosis of restenosis following revascularization procedures. SUBJECTS AND METHODS:Patients who were scheduled for follow-up coronary angiography following percutaneous intervention, or coronary bypass, surgery for a LAD lesion were enrolled. Prior to the follow-up coronary angiography, flow velocities in the distal LAD were measured by TTDE, both at rest and during the intravenous infusion of adenosine. CFR was defined as the ratio of the hyperemic to the basal peak diastolic velocities. Angiographic restenosis was defined as a diameter stenosis of more than 50% of the normal value by a quantitative coronary angiography. Of 142 consecutive patients, measurement of the CFR was possible in 95% (n=135), with 39 patients having a myocardial infarction in the LAD territory. The remaining 96 patients were used as the subjects ofin this study. RESULTS: The diameter stenosis was 41+/-26%, with angiographic restenosis found in 33 patients (34%). The mean CFR by TTDE was 2.5+/-1.1. CFR <2.0 was used to diagnose restenosis, with a sensitivity and specificity of 79% (26/33) and 89% (56/63), respectively. CONCLUSION: The noninvasive measurement of the CFR with TTDE is highly feasible, and can be a useful diagnostic modality for restenosis of a LAD following a revascularization procedure.