Prognostic factors in patients with minor troponin-I elevation but without acute myocardial infarction

Abstract

OBJECTIVES: Although cardiac troponin I is widely used as a marker for myocardial infarction, its minor elevations are also observed in other clinical situations, and the prognostic factors in such clinical settings have not been well established. The aim of this study was to identify predictors of mortality in patients with minor troponin elevations without an acute myocardial infarction. METHODS: We consecutively enrolled 134 patients from the emergency department with a peak troponin I level greater than the lower limit of detectability (0.04 ng/ml) but less than the 10% coefficient of variation cutoff value for diagnosis of myocardial infarction (0.26 ng/ml). These patients had chest pain or nonspecific symptoms of a circulatory abnormality but lacked the traditional features of an acute myocardial infarction. End point was defined as death from all causes. Cox regression analysis was used to test relations between clinical and biochemical variables and the outcome. RESULTS: During the follow-up of 7.6+/-7.4 months, 12 patients died. Age, log creatine kinase myocardial isoform, and log C-reactive protein were found to be significantly correlated with death. After adjusting for possible confounders in the multivariate model, age (hazard ratio 1.09, confidence interval 1.02-1.16, P=0.012), log creatine kinase myocardial isoform (hazard ratio 13.11, confidence interval 2.01-85.52, P=0.007), and log C-reactive protein (hazard ratio 1.64, confidence interval 1.02-2.56, P=0.041) were identified as independent predictors of mortality. CONCLUSIONS: Creatine kinase myocardial isoform and C-reactive protein levels and age can be integrated to risk-stratify patients with minor troponin I elevation for reasons other than acute myocardial infarction.