High-sensitivity cardiac troponin I measurement for risk stratification in a stable high-risk population.

BACKGROUND: Past investigations regarding the utility of high-sensitivity cardiac troponin I (cTnI) assays have been focused primarily on the acute coronary syndrome setting. We assessed whether such assays can predict future ischemic cardiovascular events in a stable high-risk population.
METHODS: We quantified serum cTnI using an investigational high-sensitivity assay (hs-cTnI IUO, Beckman Coulter) in 2572 participants from the Heart Outcomes Prevention Evaluation (HOPE) study. The derived ROC curve cutoff and the 99th percentile for the hs-cTnI assay were assessed by Kaplan-Meier and Cox analyses for the primary outcome [composite of myocardial infarction (MI), stroke, and cardiovascular death] at 4.5 years of follow-up. We also assessed individual outcomes (MI, stroke, cardiovascular death) and the combined outcome (MI/cardiovascular death) by regression analyses to determine hazard ratios (HRs) and c statistics in models that included established risk factors, C-reactive protein, and N-terminal pro-B-type natriuretic peptide (NT-proBNP).
RESULTS: Participants with hs-cTnI >6 ng/L (ROC cutoff) were at higher risk for the primary outcome (HR 1.38, 95% CI 1.09-1.76; P = 0.008, adjusted models). For the individual outcomes, participants with hs-cTnI above the 99th percentile (≥10 ng/L) had higher risk for cardiovascular death (HR 2.15, 95% CI 1.32-3.52; P = 0.002) and MI (HR 1.49, 95% CI 1.05-2.10; P = 0.025) but not stroke (HR 1.38, 95% CI 0.76-2.47; P = 0.288, adjusted models). Addition of hs-cTnI to an established risk model with NT-proBNP also yielded a higher c statistic for the combined outcome of MI/cardiovascular death.
CONCLUSIONS: The investigational Beckman Coulter hs-cTnI assay provides prognostic information for future MI and cardiovascular death in a stable high-risk population.