Pediatric cardiomyopathy: The Australian experience

Population-based studies have provided insight into the natural history of adult cardiomyopathy (CM), but comparable information for affected children is lacking. All Australian children diagnosed with primary CM at age 0-10 years between 1.1.1987 and 12.31.1996 were enrolled in a longitudinal cohort study. A single cardiologist and pathologist reviewed all cardiac investigations and histopathological material, respectively. During the study period, the overall incidence of CM was 1.24/10⁵ person-years at risk. Indigenous children had a higher incidence of DCM (relative risk 2.8) and a higher rate of presenting death (16.7% vs. 2.6%). The 5-year freedom from death or transplantation was 63% for children with DCM (n = 184), 83% for those with HCM (n = 80), 53% for those with left ventricular non-compaction (LVNC) (n = 29) and 38% for those with RCM (n = 8). In subjects with DCM, positive viral identification and/or lymphocytic myocarditis were found in 30/44 (68.2%) cases with available early histology and 8/9 cases presenting with sudden death. Risk factors for death/transplantation comprised presenting age > 5 years, familial DCM, lower initial fractional shortening Z score and failure to increase fractional shortening Z score during follow-up. In subjects with HCM, an underlying syndromal, genetic or metabolic condition was identified in 46 (57.5%) of subjects. Risk factors for death/transplantation included concentric LV hypertrophy, presenting age < 1 year, lower initial fractional shortening Z score and increasing LV posterior wall Z score. Lymphocytic myocarditis and LVNC are important causes of childhood CM. This population-based study identifies pediatric subjects at risk of adverse events.