RESUMEN
Myocardial diseases are among the important causes of mortality and morbidity in children. This drew the authors attention to the study of myocardial diseases in children to find out the outcome, factors affecting the outcome, and management strategies. The authors retrospectively studied children who had been diagnosed with primary myocardial diseases at six university hospitals in Thailand from January 1996 to December 2000. The total number of cases was 209 which accounted for 1.2 per cent of cardiovascular diseases in children. The patients' ages ranged from 0.1-15 years. These myocardial diseases included dilated cardiomyopathy (DCM) 45 per cent, acute myocarditis 27.3 per cent, hypertrophic cardiomyopathy (HCM) 18.2 per cent, hypertrophic obstructive cardiomyopathy (HOCM) 8.1 per cent and restrictive cardiomyopathy (RCM) 1.4 per cent. Fifty-six per cent of the patients were female. Congestive heart failure was the most common presenting symptom (75%). Median ejection fraction (EF) of acute myocarditis was 42 per cent (15-79%) which was significantly higher than DCM (33.5%, 10-57%). Serum cardiac troponin T (cTnT) was also significantly higher in acute myocarditis than in DCM (0.08 ng/ml, 0.01-0.16 vs 0.01 ng/ml, 0.01-0.10). Within the follow-up period of 1 year (0.1-5.5 years), the mortality rates were 18.8 per cent, 17.0 per cent, 5.4 per cent and 33.3 per cent in DCM, acute myocarditis, HCM and RCM respectively. Factors associated with the mortality rate in acute myocarditis were admission to ICU and low left ventricular EF at presentation while IVIG administration and cTnT level did not. Conclusion: Primary myocardial diseases are uncommon. Most of the patients had compromised cardiovascular reserve. Admission to ICU and low EF were factors that affected the mortality in acute myocarditis while intravenous immunoglobulin administration did not. Mortality rate in the subacute follow-up period was high in all groups.