Although idiopathic cardiomyopathies(i-CMP) are very important in all age groups, the epidemiology of i-CMP in children has not been well defined. A retrospective study in Korean children was performed in 1998 to obtain basic data on i-CMP.

The medical records of all patients aged birth to 15 years from the hospitals where pediatric cardiologists worked were reviewed to obtain information on i-CMP. Pediatric cardiologists from a total of 22 hospitals were participated in reviewing the medical records of their patients and filling up the protocol. The data were pooled to the study committee and reviewed.

Of the 278 cases with i-CMP, there were dilated cardiomyopathy (d-CMP) in 182 (65.4%): hypertrophic cardiomyopathy (h-CMP) in 74 (26.6%): restrictive cardiomyopathy (r-CMP) and unclassified in 17 (6.1%) and 5 (1.9%) each. The average annual occurrence of new cases as a whole was 2.65 per 100,000 (95% CI: 1.5-3.7): d-CMP, 1.73/100,000/year (95% CI: 0.73-2.73): h-CMP, 0.71/100,000/year (95% CI: 0.35-1.07): r-CMP, 0.16/100,000/year (95% CI: 0.02-0.3). The median age at the time of diagnosis was 11 months in d-CMP: 3.0 years in h-CMP: 6.9 years in r-CMP. The survival rate in d-CMP was 76% at 1 year, 72.5% at 2 year, 70% at 5 year. There was no difference in survival rate according to age (in d-CMP, between children less than 2 years of age and over 2 years of age (74% vs. 79% at 1 year: 67% vs. 76% at 5 year, p=NS): in h-CMP, between children less than 1 year of age and over 1 year of age (84% vs. 96% at 1 year: 63% vs. 81% at 5 year, p=NS)). R-CMP showed the worst survival rate (72% at 1 year, 30.2% at 5 year).

In spite of the inherent defects of retrospective analysis, this study provides the useful epidemiological data in children with i-CMP. However, more systemic approach is needed to define the nature of the i-CMP in children.