OBJECTIVES: The aims of this study were to assess the prognostic value of cardiac troponin I levels, measured with a new high-sensitivity assay, in low-risk patients with stable coronary artery disease (CAD) and to contrast its determinants and prognostic merit with that of high-sensitivity cardiac troponin T (hs-TnT). BACKGROUND: New, highly sensitive cardiac troponin assays permit evaluation of the association between troponin levels and outcomes in patients with stable CAD. METHODS: High-sensitivity cardiac troponin I (hs-TnI) levels at baseline were assessed in 3,623 patients with stable CAD and preserved systolic function enrolled in the PEACE (Prevention of Events With Angiotensin-Converting Enzyme Inhibitor Therapy) trial. RESULTS: In total, 98.5% of patients had hs-TnI concentrations higher than the detection level (1.2 pg/ml). hs-TnI correlated moderately with hs-TnT (r = 0.44) and N-terminal pro-B-type natriuretic peptide (r = 0.39) but only weakly with age (r = 0.17) and estimated glomerular filtration rate (r = -0.11). During a median follow-up period of 5.2 years, 203 patients died of cardiovascular causes or were hospitalized for heart failure, and 209 patients had nonfatal myocardial infarctions. In analyses adjusting for conventional risk markers, N-terminal pro-B-type natriuretic peptide, and hs-TnT, hs-TnI levels in the fourth compared with the 3 lower quartiles were associated with the incidence of cardiovascular death or heart failure (hazard ratio: 1.88; 95% confidence interval: 1.33 to 2.66; p < 0.001). There was a significant, albeit weaker association with nonfatal myocardial infarction (hazard ratio: 1.44; 95% confidence interval: 1.03 to 2.01; p = 0.031). In the same models, hs-TnT concentrations were associated with the incidence of cardiovascular death or heart failure but not of myocardial infarction. CONCLUSIONS: In patients with stable CAD, hs-TnI concentrations are associated with cardiovascular risk independently of conventional risk markers and hs-TnT. (Prevention of Events With Angiotensin-Converting Enzyme Inhibitor Therapy [PEACE]; NCT00000558).