Aims: To compare the long-term prognostic value of troponins (Tn) vs. conventional cardiac biomarker creatine kinase (CK) and CK-MB across the spectrum of acute coronary syndromes (ACS).
Methods and results: In the prospective, observational Canadian ACS Registry, 4627 patients with ACS were enrolled from 51 centres. The CK, CK-MB, Tn samples were analysed in each hospital clinical laboratory and the results related to the reference levels of the individual laboratories. The study cohort comprised 3138 (67.8%) patients who had both CK (or CK-MB) and Tn measurements during the first 24 h of hospitalisation. Vital status at one-year was determined by standardized telephone interview. 61.2% and 59.0% of patients had abnormal Tn and CK (or CK-MB) levels, respectively. Vital status at one-year was ascertained for 2950 patients (6% lost to follow-up). Among patients with normal CK (or CK-MB) levels, elevated Tn was associated with increased one-year mortality (odds ratio [OR] 2.06; 95% CI 1.37-3.11; P=0.001). Similarly, among patients with abnormal CK (or CK-MB) levels, abnormal Tn predicted higher one-year mortality (OR 1.83; 95% CI 1.14-2.93; P=0.01). In contrast, abnormal CK (or CK-MB) was not predictive of mortality after stratification by Tn status. In multivariable analysis controlling for other known prognosticators including creatinine, abnormal Tn (adjusted OR 1.78; 95% CI 1.30-2.44; P<0.001) but not CK/CK-MB was independently associated with increased one-year mortality.
Conclusions: Elevated Tn was independently associated with worse outcome at one-year, while CK or CK-MB status did not provide incremental prognostic information. Our findings support the use of Tn in the risk stratification of unselected ACS patients.