An Assessment of the Concentration-Related Prognostic Value of Cardiac Troponin I Following Acute Coronary Syndrome

In 2004 the British Cardiac Society redefined myocardial infarction by cardiac troponin I (cTnI) concentration: ≤0.06 μg/L (unstable angina), >0.06 to <0.5 μg/L (myocardial necrosis), and ≥0.5 μg/L (myocardial infarction). We investigated the effects of this classification on all-cause mortality in 1,285 patients from the Evaluation of the Methods and Management of Acute Coronary Events (EMMACE)-2 registry. There were 528 deaths (6.6-year all-cause mortality 41.1%). Survival was greatest in the cTnI ≤0.06-μg/L subgroup at 30 days (p = 0.005), 6 months (p = 0.015), 1 year (p = 0.002), and 6.6 years (p = 0.045). After adjustment there was no significant difference in survival between the cTnI >0.06- to <0.5-μg/L and ≥0.5-μg/L subgroups. Increased mortality (hazard ratio, 95% confidence interval) was associated with ages 70 to 80 years (2.58, 1.17 to 3.91) and >80 years (3.30, 3.50 to 5.06), peripheral vascular disease (1.50, 1.16 to 1.94), heart failure (1.36, 1.05 to 1.83), diabetes mellitus (1.68, 1.36 to 2.07), severe left ventricular systolic dysfunction (1.50, 1.00 to 2.21), and creatinine per 10 μmol/L (1.65, 1.02 to 1.08), whereas ages 50 to 60 years (0.55, 0.32 to 0.96), β blockers (0.53, 0.44 to 0.64), aspirin (0.80 0.65 to 0.99), angiotensin-converting enzyme inhibitors (0.67, 0.56 to 0.80), statins (0.73, 0.59 to 0.90), and revascularization (0.33, 0.12 to 0.92) were associated with a lower risk of death. In conclusion, although quantitative evaluation of cTnI concentration in patients with acute coronary syndrome with cTnI >0.06 μg/L was associated with no added prognostic information, the dichotomization of patients by cTnI status (“positive” and “negative”) facilitates acute coronary syndrome risk stratification.