Abstract Background: Viruses are the most prevalent ausative agents of myocarditis in young children. Studies have shown acute myocarditis in post mortem examinations during viral disease outbreaks. The aims of this study are to assess the prevalence of and risk factors for subclinical acute myocarditis in young children hospitalized with an acute viral disease. Objectives: Evaluation of the prevalence of asymptomatic myocarditis or decrease in heart functions during viral infection. Methods: A prospective study was conducted between 1st January and 30th September, 2009. The study included 45 children 3-60 months old hospitalized with febrile illness with no clinical or microbiological evidence of acute bacterial infection. Serum levels of troponin were obtained, and ECG and echocardiography were performed in all the children. Parameters that determined myocarditis included: (1) ECG ST-T changes suggestive of myocarditis; (2) Increased serum troponin level; (3) Echocardiography findings including: shortening fraction less than 28%, left ventricle end diastolic diameter > than 2 standard deviations for age, abnormal mitral valve incompetence, or abnormal diastolic function. Clinical and epidemiological data were analyzed in order to determine parameters related to findings suggestive of silent acute myocarditis. Results: In 16 (35%) children at least one parameter, and in 7 (16%) at least 2 parameters of acute myocarditis were found. Impaired diastolic function was found in 11 cases (69%), ECG changes in 5 children (35%, left ventricle dilatation in 4 (25%), and decreased shortening fraction in 3 cases (18%]. Other symptoms and signs of myocarditis were not found in any of the 16 children, and no clinical or epidemiological parameter was significantly associated with silent myocarditis. Conclusions: In a third of the patients, some evidence of myocardial dysfunction was documented. In seven of them (16% of all cases), there were two different categories of myocardial dysfunction. Those cases are suspected to be silent acute myocarditis. No clinical and epidemiological parameters associated with the disease were found. The clinical importance of this phenomenon should be determined by a long-term follow-up study. Summary: In this preliminary study, we found a high prevalence of cardiac involvement in hospitalised children with viral infections. It seems that this cardiac involvement is due to acute sub-clinical myocarditis. The importance of these findings should be evaluated.
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