Elevations of Cardiac Troponin I Associated With Myocarditis Experimental and Clinical Correlates

Background Endomyocardial biopsy is currently the standard method used to diagnose myocarditis. However, it is invasive and has a low diagnostic yield. Because the histological diagnosis of myocarditis requires the presence of myocyte injury, we sought to determine whether measurement of cardiac troponin I (cTnI), which is a serum marker with high sensitivity and specificity for cardiac myocyte injury, could aid in the diagnosis of myocarditis. Methods and Results To validate this approach, cTnI values were first measured in mice with autoimmune myocarditis. cTnI values were elevated in 24 of 26 mice with myocarditis but were not elevated in any of the control animals (P<.001). Next, cTnI values were measured in the sera from 88 patients referred to the Myocarditis Treatment Trial and were compared with creatine kinase–MB (CK-MB) values measured in the same patients. cTnI values were elevated in 18 (34%) of 53 patients with myocarditis and in only 4 (11%) of 35 patients without myocarditis (P=.01). In con...