Clinical and ECG prognostic markers, ischemic threshold (IT) and extent of coronary disease were analyzed in 383 patients with unstable angina (UA) and correlated with long-term events. Patients >74 years or those with severe heart failure or previous revascularization procedures were excluded. There were 369 events in 245 patients: 87 deaths, 96 myocardial infarction (MI), 111 coronary artery bypass grafting (CABG), and 75 angioplasty procedures (PTCA). Follow-up was obtained in 367 hospital survivors (99%, 114 (44) months) and ST depression on admission ECG, a modest enzyme rise, refractory angina (>2 episodes), two to three vessel coronary disease and a reduced IT (<==130 beats/min) were each associated with cardiac events. A multivariate analysis, however, showed refractory angina (p<0.001) and multivessel disease (p<0.001) as most significant predictors. After their exclusion, IT was most relevant predictor (p<0.001). However, the predictive value of these markers was essentially centered on first-year events (249, 67%). Moreover, refractory angina, minor enzyme rise and admission ST depression were each highly correlated with a reduced IT (p<0.006) and with multivessel disease (p<0.0001). Therefore, these findings underscore that the prognostic value of conventional clinical markers in patients with UA is limited to first-year events and that their remarkable correlation with extensive coronary disease and reduced coronary reserve reveal the anatomical substrate of this prognostic significance.