Magnitude of Troponin Elevation and Long-Term Clinical Outcomes in Acute Coronary Syndrome Patients Treated With and Without Revascularization

BACKGROUND: In patients with non-ST-segment-elevation acute coronary syndrome (NSTE ACS), elevated troponin levels identify patients at high risk for adverse outcomes; however, it is unknown whether the magnitude of troponin elevation during hospitalization remains predictive of subsequent events in patients undergoing coronary revascularization. METHODS AND RESULTS: We studied 12 635 patients with NSTE ACS in the Thrombin Receptor Antagonist for Clinical Event Reduction in Acute Coronary Syndrome (TRACER) study with at least 1 troponin measurement during index hospitalization. Cox proportional hazards regression was used to examine the relationship between peak troponin level (standardized as the ratio of peak troponin value measured during hospitalization and local laboratory upper reference limit URL) and revascularization on all-cause mortality at 2 years. Revascularization (percutaneous coronary intervention or coronary artery bypass graft) was performed during index hospitalization in 8586 patients (68.0%); revascularized patients had higher peak troponin ratios (median, 23 versus 9.5× URL). Among patients that did not undergo revascularization, the mortality rate at 2 years increased in a curvilinear fashion with increasing levels of peak troponin. In contrast, the mortality rate at 2 years remained constant irrespective of peak troponin levels among revascularized patients (P for interaction=0.004). This relationship was unchanged after multivariable adjustment. CONCLUSIONS: There is a differential relationship between the magnitude of troponin elevation and long-term mortality in ACS patients treated with and without revascularization. Although prognostically important in patients treated without revascularization, the prognostic implications of peak troponin level seem to be minimal in revascularized patients. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00527943.