ELEVATED SERUM CONCENTRATIONS OF CARDIAC TROPONIN-T IN ACUTE ALLOGRAFT-REJECTION AFTER HUMAN HEART-TRANSPLANTATION

Objectives. This study evaluates the concept and diagnostic efficacy o f using serum troponin T for the detection of cardiac graft rejection. Background. Cardiac troponin T is a cardiospecific myofibrillar prote in, which is only detectable in the circulation after cardiac myocyte damage. It might be expected to be released during acute heart allogra ft rejection, allowing noninvasive rejection diagnosis. Methods. In 35 control subjects and in 422 samples from 95 clinically unremarkable h eart allograft recipients more than 3 months postoperatively, troponin T serum concentrations were compared to the histological grade of acu te graft rejection in concurrent endomyocardial biopsies. Results. Mea n troponin T serum concentrations were identical in control subjects ( 23.2 +/-: 1.4 ng/liter) and in heart transplant recipients without gra ft rejection International Society for Heart and Lung Transplantation [ISHLT] grade 0; 22.4 +/- 1.7 ng/liter). Mean troponin T concentration s increased in parallel with the severity of graft rejection (ISHLT gr ade 1: 27.8 +/- 1.8 ng/liter; grade 2: 33.2 +/- 2.7 ng/liter; grade 3A : 54.6 +/- 6.5 ng/liter; grade 3B and 4: 105.4 +/- 53.7 ng/liter; p < 0.001 for grades 3 and 4 vs. grades 0 and 1). The proportion of positi ve samples also increased in parallel with rejection severity, reachin g 100% in rejections of grade 3B and 4. Sensitivity and specificity fo r the detection of significant graft rejection (ISHLT grade 3/4 were 8 0.4% and 61.8%, respectively. The negative predictive value was most r emarkable with 96.2%. Intraindividual longitudinal analysis of troponi n T levels and biopsy results in 15 patients during Longterm follow-up confirmed these findings. Conclusions. The present data demonstrate t hat acute allograft rejection after human heart transplantation is oft en associated with increased serum concentrations of troponin T. All c ases of serious forms of graft rejection would have been detected befo re the development of clinical symptoms. Measurement of troponin T lev els may become a useful ancillary parameter for noninvasive rejection diagnosis, being most valuable in the exclusion of severe cardiac graf t rejection. (C) 1998 by the American College of Cardiology.