Objectives Ticlopidine reduces stent thrombosis and other adverse events among patients receiving coronary stents. Whether ticlopidine is beneficial after balloon angioplasty is unknown. Our purpose was to compare the clinical outcome of patients undergoing balloon angioplasty treated with both aspirin and ticlopidine versus aspirin alone. Methods and Results We performed a databank analysis of the Total Occlusion Study of Canada (TOSCA), a randomized trial with angiographic follow-up comparing the frequency of reocclusion after angioplasty of a subtotal or total coronary occlusion in patients receiving ≥1 heparin-coated Palmaz-Schatz stent versus balloon angioplasty alone. In TOSCA, 102 patients undergoing balloon angioplasty were treated with both aspirin and ticlopidine (generally for 15-30 days) and 94 were treated with aspirin alone, by physician preference. After 6 months, failure to sustain patency (less than Thrombolysis in Myocardial Infarction [TIMI] grade 3 flow on follow-up angiography) occurred in 23% of patients on ticlopidine and aspirin versus 16% of patients on aspirin alone (P = .21); the frequency of target vessel revascularization was also similar in the 2 groups (32% vs 25%, P = .27). Myocardial infarction was infrequent in both groups (2.0% vs 1.1%, respectively, P not significant). Patients treated with aspirin and ticlopidine had more adverse angiographic and procedural characteristics, including longer lesions and treatment lengths. Multivariate analysis to adjust for these and other differences failed to reveal a benefit of ticlopidine in maintaining patency and reducing adverse clinical events. Conclusions After balloon angioplasty of a subtotal or total coronary occlusion, no reduction in adverse events was observed among patients in whom ticlopidine was added to aspirin, even after adjustment for clinical and lesion characteristics. (Am Heart J 2001;142:776-81.)