To determine whether metallic stent implantation within a coronary artery modifies the accuracy of angina or exercise test results in predicting stenosis, we studied 172 patients assigned to stent implantation and 153 patients assigned to balloon angioplasty enrolled in the Benestent trial comparing de novo stenting with conventional balloon angioplasty. Sensitivity and specificity curves were constructed for the prediction of percentage diameter stenosis and minimal lumen diameter. Receiver-operator curves were constructed for comparison of diagnostic accuracy. Identical exercise load and duration were achieved in the two groups, despite a better angiographic result in patients treated with a stent. Similarly, the diagnostic accuracy of clinical symptoms or exercise test results as a function of the angiographic results were similar in patients with and patients without a stent. The intersection points of the sensitivity and specificity curves for recurrent angina or ST-segment depression were 72% to 77%. The corresponding cut-off points for percentage diameter stenosis were, respectively, 52% and 50% for patients with and without a stent (1.35 and 1.50 mm for minimal lumen diameter). We conclude that the presence of an intracoronary stent does not affect the diagnostic accuracy of recurrent angina or exercise-induced ST depression in predicting residual stenosis. We also conclude that exercise tolerance is similar after balloon angioplasty, with or without stenting, despite a better angiographic outcome in the group receiving a stent, suggesting a minimal threshold beyond which the patient is no longer at risk for ischemia during exercise. (Am Heart J 1997;133:240-8.)