Persistently Increased Serum Concentrations of Cardiac Troponin T in Patients With Idiopathic Dilated Cardiomyopathy Are Predictive of Adverse Outcomes

Abstract

Background —The measurement of serum concentrations of cardiac troponin T (TnT) is a simple, useful method to detect myocyte injury that may be repeated multiple times to follow patients without interobserver variability. Methods and Results —Multiple measurements of TnT with a second-generation assay were performed in 60 patients with dilated cardiomyopathy confirmed by coronary angiography and endomyocardial biopsy between April 1996 and December 1999. Three evolutionary patterns of TnT concentrations were identified. Thirty-three patients had concentrations of TnT <0.02 ng/mL throughout the follow-up period (group 1). The remaining 27 patients had high initial serum concentrations of TnT (≥0.02 ng/mL). In 10 of these 27 patients, TnT decreased to <0.02 ng/mL during follow-up (group 2), whereas 17 had persistently high serum TnT concentrations despite being conventionally treated for chronic congestive heart failure (group 3). Although the initial echocardiographic left ventricular diastolic dimension (LVDd) and left ventricular ejection fraction (LVEF) were not significantly different among the 3 groups, follow-up echocardiography showed significantly decreased LVDd and increased LVEF in group 1 (each P <0.01) and group 2 (each P <0.05) compared with increased LVDd and decreased LVEF in group 3 (each P <0.05). The cardiac event-free rate was significantly lower in group 3 than in groups 1 and 2 (each P <0.001), and the survival rate was lower in group 3 than in group 1 ( P <0.05). Conclusions —Persistently increased TnT concentrations in dilated cardiomyopathy suggest ongoing subclinical myocyte degeneration associated with deterioration of the patients’ clinical status.