BACKGROUND: There are limited contemporary data comparing long-term outcomes after cardiac catheterization for ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI). METHODS AND RESULTS: We studied patients undergoing cardiac catheterization for STEMI (n=2413) and NSTEMI (n=1974) between 1999 and 2005 with at least 1 significant coronary lesion > or =75%. We compared adjusted mortality rates over restricted time intervals and the differential impact of early revascularization on mortality stratified by ST-elevation status. Between 1999 and 2007, 1274 patients died, with a median follow-up of 4 years. A piece-wise analysis showed a higher adjusted mortality risk for STEMI during the first 2 months (adjusted hazard ratio, 1.85; 95% confidence interval, 1.45 to 2.38) and a lower adjusted mortality risk for STEMI after 2 months (adjusted hazard ratio, 0.68; 95% confidence interval, 0.59 to 0.83). Compared with late or no revascularization, early revascularization was associated with a lower adjusted risk of mortality for both STEMI (adjusted hazard ratio, 0.73; 95% confidence interval, 0.58 to 0.90) and NSTEMI (adjusted hazard ratio, 0.76; 95% confidence interval, 0.65 to 0.89) (P for interaction=0.22). CONCLUSIONS: Among a contemporary cohort of acute MI patients with significant coronary disease during cardiac catheterization, STEMI was associated with a higher risk of short-term mortality, but NSTEMI was associated with a higher risk of long-term mortality. Early revascularization was associated with a similar improvement in long-term outcomes for both STEMI and NSTEMI. These data suggest that in clinical investigations of early revascularization among patients with NSTEMI, extended follow-up may be necessary to demonstrate treatment benefit.