Sensitive cardiac troponin in the diagnosis and risk stratification of acute heart failure

BACKGROUND: The aim of our study was to investigate the diagnostic and prognostic value of a sensitive cardiac troponin I (s-cTnI) assay in patients with acute heart failure (AHF). METHODS: Sensitive cardiac troponin I was measured in 667 consecutive patients at presentation to the emergency department with acute dyspnoea. Three s-cTnI strata were predefined: below the limit of detection (<0.01 μg L(-1) , undetectable), detectable but still within the normal range (0.01-0.027 μg L(-1) ) and increased (≥0.028 μg L(-1) , ≥99th percentile). The final diagnosis was adjudicated by two independent cardiologists blinded to the s-cTnI levels. Median follow-up in patients with AHF was 371 days. RESULTS: Levels of s-cTnI were higher in patients with AHF (n = 377, 57%) compared to patients with noncardiac causes of acute dyspnoea (median 0.02 vs. <0.01 μg L(-1) , P < 0.001). In patients with AHF, in-hospital mortality increased with increasing s-cTnI in the three strata (2%, 5% and 14%, P < 0.001). One-year mortality also increased with increasing s-cTnI (21%, 33% and 47%, P < 0.001). s-cTnI remained an independent predictor of 1-year mortality adjusted odds ratio 1.03 for each increase of 0.1 μg L(-1) , 95% confidence interval (CI) 1.02-1.05, P < 0.001 after adjustment for other risk factors including B-type natriuretic peptide. The net reclassification improvement was 68% (P < 0.001), and absolute integrated discrimination improvement was 0.18 (P < 0.001). The diagnostic accuracy of s-cTnI for the diagnosis of AHF as quantified by the area under the receiver operating characteristic curve was 0.78 (95% CI, 0.75-0.82). CONCLUSIONS: Sensitive cardiac troponin I is a strong predictor of short- and long-term prognosis in AHF that helps to reclassify patients in terms of mortality risk. Detectable levels of s-cTnI, even within the normal range, are independently associated with mortality.