A sensitive cardiac troponin T assay in stable coronary artery disease

Abstract

Background: In most patients with stable coronary artery disease, plasma cardiac troponin T levels are below the limit of detection for the conventional assay. The distribution and determinants of very low circulating troponin T levels, as well as their association with cardiovascular events, in such patients are unknown.

Methods: We used a new, high-sensitivity assay to determine the concentration of cardiac troponin T in plasma samples from 3679 patients with stable coronary artery disease and preserved left ventricular function. Results of the assay were analyzed in relation to the incidence of cardiovascular events during a median follow-up period of 5.2 years.

Results: With the highly sensitive assay, concentrations of cardiac troponin T were at or above the limit of detection (0.001 microg per liter) in 3593 patients (97.7%) and at or above the 99th percentile for apparently healthy subjects (0.0133 microg per liter) in 407 patients (11.1%). After adjustment for other independent prognostic indicators, there was a strong and graded increase in the cumulative incidence of cardiovascular death (adjusted hazard ratio per unit increase in the natural logarithm of the troponin T level, 2.09; 95% confidence interval [CI], 1.60 to 2.74; P<0.001) and of heart failure (adjusted hazard ratio, 2.20; 95% CI, 1.66 to 2.90; P<0.001) in this study group. Increased risk associated with higher levels of troponin T was evident well below the limit of detection of conventional cardiac troponin T assays and below the 99th percentile of values in a healthy population. There was no association between troponin T levels as measured with the highly sensitive assay and the incidence of myocardial infarction (adjusted hazard ratio, 1.16; 95% CI, 0.97 to 1.40; P=0.11).

Conclusions: After adjustment for other independent prognostic indicators, cardiac troponin T concentrations as measured with a highly sensitive assay were significantly associated with the incidence of cardiovascular death and heart failure but not with myocardial infarction in patients with stable coronary artery disease.

2009 Massachusetts Medical Society

Figures

Figure 1

Distribution of High-Sensitivity Cardiac Troponin T in Patients with Stable Coronary Artery Disease (CAD) and in Apparently Healthy Blood Donors.

Figure 2

Incidence of Cardiovascular Death According to Quartile of High-Sensitivity Cardiac Troponin T Level.

Figure 3. Covariate-Adjusted Receiver-Operating-Characteristic Plots for the Use of High-Sensitivity Cardiac Troponin T to Predict the Risk of Cardiovascular Death

Panel A shows the curves for the model adjusted for treatment assignment, age, sex, smoking status, and high-sensitivity C-reactive protein level. Panel B shows the curves for the model that included these with the addition of the N-terminal pro–brain natriuretic peptide level.