Prognostic value of elevated high-sensitivity cardiac troponin T levels in a low risk outpatient population with cardiovascular disease.

Abstract

To investigate the prognostic implications of elevated high-sensitivity cardiac troponin T (hs-cTnT) values in presumably stable ambulatory coronary artery disease patients. We conducted a retrospective, single-centre pilot observational study in a low-risk population. All patients received routine measurement of hs-cTnT at index and follow-up visits. Endpoints were all-cause mortality and a composite of all-cause mortality, acute myocardial infarction, stroke and rehospitalization for acute coronary syndrome and heart failure. Nine hundred and sixty-five consecutive patients presenting to our outpatient clinic between June 2009 and June 2010 were screened; 693 patients with a stable clinical course, at least one hs-cTnT value and at least one follow-up visit qualified for analysis. Follow-up was 796 days. Five hundred and forty-seven patients (78.9%) had hs-cTnT values below and 146 patients (21.1%) had values above 14 ng/l, which was defined to categorize high and low levels as it was reported to be the 99th percentile of a reference population. We observed 13 deaths (all-cause mortality) including four cardiovascular deaths. Age, N terminal pro-brain natriuretic peptide levels and impaired renal function were independently associated with an elevated hs-cTnT in a multivariate analysis. Hs-cTnT values >14 ng/l were strongly associated with all-cause mortality (hazard ratio 12.9, 95% confidence interval (CI): 3.5-46.9, p=0.0001), the composite clinical endpoint (hazard ratio 2.35, 95% CI: 1.48-3.72, p=0.0003) and rehospitalization for heart failure (hazard ratio 3.36, 95% CI: 1.73-6.53, p=0.0004). Compared with the multivariable Framingham score hs-cTnT revealed a significantly better performance (area under the receiver operating characteristics curve (AUC) hs-cTnT: 0.882 vs. AUC Framingham score 0.639, p=0.0005). Elevated hs-cTnT levels provide excellent prognostic information regarding all-cause mortality and a combined clinical endpoint in presumably stable ambulatory coronary artery disease outpatients presenting for routine evaluation.