Impact of troponin I-autoantibodies in chronic dilated and ischemic cardiomyopathy

Abstract

The aim of this study was to investigate the prognostic value of circulating troponin I (TNI)-autoantibodies in plasma of patients with chronic heart failure. Sera of 390 heart failure patients were tested for the presence of anti-TNI antibodies by enzyme-linked immunosorbent assay (ELISA), including 249 (63.8% of total) patients with dilated cardiomyopathy (DCM) and 141 (36.2% of total) patients with ischemic cardiomyopathy (ICM). A total of 72 patients (18.5% of total) were female and 318 (81.5% of total) were male. Mean patient age was 54.6±11.3years and mean follow-up time was 3.8±3.2years. TNI-autoantibodies (titer of ≥1:40) were detected in 73 out of 390 patients (18.7% of total). In TNI-autoantibody positive patients mean left ventricular ejection fraction (LVEF) was 27.6±5.8%, compared to 25.8±5.9% in TNI-autoantibody negative patients, P=0.03. The combined end-point of death (n=118, 30.3% of total) or heart transplantation (HTX) (n=44, 11.3% of total) was reached in 162 patients (41.5% of total). Kaplan-Meier analysis demonstrated superior survival (combined end-point of death or HTX) in patients with DCM versus ICM (P=0.0198) and TNI-autoantibody positive patients versus TNI-autoantibody negative patients (P=0.0348). Further subgroup analysis revealed a favorable outcome in TNI-positive patients with heart failure if the patients suffered from DCM (P=0.0334), whereas TNI-autoantibody status in patients with ICM was not associated with survival (P=0.8486). In subsequent multivariate Weibull-analysis, a positive TNI serostatus was associated with a significantly lower all-cause mortality in DCM patients (P=0.0492). The presence of TNI-autoantibodies in plasma is associated with an improved survival in patients with chronic DCM, but not ICM. This might possibly indicate a prophylactic effect of TNI-autoantibodies in this subgroup of patients, encouraging further studies into possible protective effects of antibodies against certain cardiac target structures.