CARDIAC TROPONIN-T IN PATIENTS WITH CLINICALLY SUSPECTED MYOCARDITIS

Objectives. The present study investigated whether myocyte injury can be assessed sensitively by measurement of serum levels of cardiac trop onin T (cTnT) in patients with clinically suspected myocarditis and wh ether cTnT levels may predict the results of histologic and immunohist ologic analysis of endomyocardial biopsy specimens. Background. Conven tionally used laboratory variables often fail to show myocyte injury i n patients with clinically suspected myocarditis, possibly because of a low extent of myocardial injury in these patients, Sensitive variabl es for myocyte injury have not yet been investigated, Methods. Eighty patients with clinically suspected myocarditis were screened for creat ine kinase (CK) activity, MB isoform of CK (GK-MB) activity and cTnT, Endomyocardial biopsy specimens were examined histologically and immun ohistologically. Results. cTnT was elevated in 28 of 80 patients with clinically suspected myocarditis, CK in 4 and CK-MB in 1. Histologic a nalysis alone of the endomyocardial biopsy specimen revealed evidence of myacarditis in only live patients, all with elevated cTnT levels, T wenty-three of 28 patients dth elevated cTnT levels had histologically negative findings for myocarditis. Additional immunohistologic analys is revealed evidence of myocarditis in 26 (93%) of 23 patients with el evated cTnT levels and in 23 (44%) of 52 patients with normal cTnT lev els, Mean cTnT levels mere higher in patients with myocarditis preyed histologically or immunohistologically, or both, than in patients with out myocarditis (0.59 +/- 1.68 vs. 0.04 +/- 0.05, p < 0.001). Conclusi ons. Measurement of serum levels of cTnT provides evidence of myocyte injury in patients with clinically suspected myacarditis more sensitiv ely than does conventional determination of cardiac enzyme levels. Myo cardial cell damage map be present even in the absence of histologic s igns of myocarditis. Additional immunohistologic analysis often shoes lymphocytic infiltrates in these patients, Elevated levels of cTnT are highly predictive for myocarditis in this group. (C) 1997 by the Amer ican College of Cardiology.