Cardiac troponin T: its role in the diagnosis of clinically suspected acute myocarditis and chronic dilated cardiomyopathy in children.

This study was conducted to assess the use of the serum cardiac troponin T (cTnT) level as a noninvasive indicator to differentiate acute myocarditis and chronic dilated cardiomyopathy in pediatric patients. Myocarditis and dilated cardiomyopathy are clinically difficult to differentiate. Endomyocardial biopsy proved to be quite useful. However, the nature of the procedure--invasiveness, time-consuming, and limited sensitivity--caused some concerns, especially in pediatric patients. Hence, we attempted to find an alternative method that could give a prompt diagnosis of acute myocarditis. Twenty cases with clinically suspected myocarditis or dilated cardiomyopathy and a control group of 21 cases with moderate left-to-right shunt and congestive heart failure were recruited. History, physical examination, electrocardiogram, chest roentgenogram, echocardiogram, cTnT, creatine kinase MB isoenzyme (CK-MB mass), and/or endomyocardial biopsy were compared. The gold standard used to diagnose myocarditis is endomyocardial biopsy (Dallas criteria) and/or recovery from cardiovascular problems within 6 months of follow-up. Ten patients were diagnosed as having myocarditis (group 1) and 10 with chronic dilated cardiomyopathy (group 2). The control group of 21 cases was designated as group 3. The median serum cTnT levels were 0.088 (0.04-3.11), 0.010 (0.010-0.990), and 0.010 (0.010-0.550) ng/ml in groups 1, 2, and 3, respectively. The mean CK-MB mass level for groups, 1, 2, and 3 were 18.35 (7.14-70.00), 4.80 (0.54-108.00), and 2.26 (0.95-7.06) ng/ml. The study showed that both the cTnT and CK-MB mass levels were significantly higher in group 1 than either group 2 or group 3. Histopathology was studied in 9 cases. In 2 of 5 cases and in all 4 cases in group 1 and group 2 histopathology was pathologically proved. Levels of cTnT and CK-MB were significantly higher for myocarditis than for dilated cardiomyopathy and left-to-right shunt with CHF. Further study is needed to assess the optimum cTnT level for differentiating both conditions.