Thirty-four consecutive patients had coronary flow velocity assessed under basal and hyperemic conditions in the proximal and distal coronary artery, followed by rest-stress technetium 99m sestamibi myocardial tomography within 3 months of successful coronary angioplasty. In spite of significant angiographic improvement, 29% of patients had a persistent reversible myocardial perfusion defect associated with a residual abnormality of the proximal-to-distal coronary average peak velocity ratio (p/d APV = 2.2 +/- 1.5 vs 1.1 +/- 0.6; p = 0.02). Patients with an abnormal p/d APV ratio (>1.7) had more numerous angioplasty-zone perfusion defects (4.2 +/- 3.3 vs 0.8 +/- 2.0; p = 0.005). Multivariable analysis of clinical, angiographic, coronary flow, and scintigraphic data demonstrated that the relative risk of cardiac events (n = 11) was greatest in patients with a reversible angioplasty-zone perfusion defect (relative risk, 5.5), poststenotic coronary flow reserve <2.0 (relative risk, 8.3) and p/d APV ratio >1.7 (relative risk, 6.2). Residual basal coronary flow-velocity abnormalities are significant physiologic correlates of stress-induced myocardial perfusion defects and are a prognostic covariable associated with future ischemic cardiac events.