This study has examined the prognostic significance of troponin-I (Tn-I) levels after catheter-based coronary interventions in coronary arteries and saphenous vein grafts lesions. Tn-I and creatine kinase-MB (CK-MB) fraction levels were measured at 6 and 18 to 24 hours after catheter-based coronary intervention in 1,129 consecutive patients with normal preintervention plasma levels of Tn-I, and CK-MB levels below the cutoff for myocardial infarction. Patients were stratified according to maximal postangioplasty Tn-I levels. Group I (n = 784) had no elevated Tn-I (<0.15 ng/ml), group II (n = 170) had Tn-I at 0.15 to 0.45 ng/ml, and group III (n = 175) had Tn-I elevation >0.45 ng/ml. Major in-hospital complications (death, 0-wave infarction, and emergent coronary bypass grafting) and out-of-hospital intermediate-term (8 months) outcomes were compared between the 3 groups. Tn-I elevation >0.45 ng/ml was associated with increased risk of mortality (group III, 1.6%; group II, 0.6%; and group I, 0.1%; p = 0.019) and major in-hospital complications (3.2%, 1.7%, and 0.5%; p = 0.004). There was no difference in death (1.8%, 3.2%, and 2.4%; p = 0.74), Q-wave infarction (0.6%, 0%, and 0.3%; p = 0.66), or target lesion revascularization (10.1%, 9.0%, and 9.3%; p = 0.86) between the 3 groups at follow-up. Cardiac event-free survival was similar between groups (p = 0.3). By multivariate analysis, Tn-I >0.45 ng/ml was an independent predictor for major in-hospital complications (odds ratio 2.1, 95% confidence interval 1.2 to 3.9, p = 0.01). The degree of risk was also associated with the conjoint elevation of Tn-I and CK-MB levels (odds ratio 1.1, 95% confidence interval 1.02 to 1.2, p = 0.01). We conclude that Tn-I levels >3 times the normal limit and conjoint elevation of Tn-I and CK-MB levels after coronary angioplasty are associated with increased risk of major in-hospital complications, but have no incremental risk of adverse intermediate-term (8 months) clinical outcomes.