Troponin in Stable Ischemic Heart Disease and Diabetes
What are the prognostic implications of high-sensitivity cardiac troponin levels among patients with stable ischemic heart disease and diabetes?
The investigators measured the cardiac troponin T concentration at baseline with a high-sensitivity assay in 2,285 patients who had both type 2 diabetes and stable ischemic heart disease and were enrolled in the BARI 2D (Bypass Angioplasty Revascularization Investigation 2 Diabetes) trial. They tested for an association between the troponin T concentration and a composite endpoint of death from cardiovascular causes, myocardial infarction, or stroke; and evaluated whether random assignment to prompt revascularization reduced the rate of the composite endpoint in patients with an abnormal troponin T concentration (≥14 ng/L) as compared with those with a normal troponin T concentration (<14 ng/L). Cox proportional-hazards models were used to estimate the adjusted association between troponin T concentration and the risk of the primary composite endpoint of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke, as well as the risks of the secondary endpoints of death from any cause, heart failure, and the composite of death from any cause, myocardial infarction, stroke, or heart failure.
Of the 2,285 patients, 2,277 (99.6%) had detectable (≥3 ng/L) troponin T concentrations and 897 (39.3%) had abnormal troponin T concentrations at baseline. The 5-year rate of the composite endpoint was 27.1% among the patients who had had abnormal troponin T concentrations at baseline, as compared with 12.9% among those who had had normal baseline troponin T concentrations. In models that were adjusted for cardiovascular risk factors, severity of diabetes, electrocardiographic abnormalities, and coronary anatomy, the hazard ratio for the composite endpoint among patients with abnormal troponin T concentrations was 1.85 (95% confidence interval [CI], 1.48-2.32; p < 0.001). Among patients with abnormal troponin T concentrations, random assignment to prompt revascularization, as compared with medical therapy alone, did not result in a significant reduction in the rate of the composite endpoint (hazard ratio, 0.96; 95% CI, 0.74-1.25).
The authors concluded that cardiac troponin T concentration was an independent predictor of death from cardiovascular causes, myocardial infarction, or stroke in patients who had both type 2 diabetes and stable ischemic heart disease.
This study involving patients with both type 2 diabetes and stable ischemic heart disease reports that baseline cardiac troponin T concentrations above the upper limit of normal were associated with approximately a doubling of the risks of myocardial infarction, stroke, heart failure, death from cardiovascular causes, and death from any cause. However, the addition of prompt coronary revascularization to intensive medical therapy did not improve the outcome in these patients. It appears that elevated cardiac troponin T concentration among those with type 2 diabetes and stable ischemic heart disease may have important prognostic implications, and we need to develop novel therapies to ameliorate these risks.
Keywords: Angioplasty, Diabetes Mellitus, Type 2, Heart Failure, Metabolic Syndrome X, Myocardial Infarction, Myocardial Ischemia, Primary Prevention, Risk Factors, Stroke, Troponin T
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