Background. To better characterize cardiomyopathy (CM) in children, the NHLBI-sponsored PCMR conducted a study of children with newly diagnosed CM since 1/90.

Methods. From 8/96 to 12/97, 1315 eligible children were enrolled at 44 centers, representing 866 retrospective cases and 449 prospectively identified cases.

Results. The overall group had a mean age at diagnosis of 5.7±6.0 yrs with a mean of 3.3±2.1 yrs of follow-up. 57% were male, possibly reflecting x-linked CM. LV systolic performance was depressed(FS>2-sd)in 61% of pts. LV dilation (EDD>2sd) was noted in 53% of pts. Thickened LV walls (posterior wall thickness>2sd) was noted in 28% of pts. Only 21% had a known etiology for their CM, a figure that is lower than the 43% reported in a 1993 survey of pediatric cardiologists. Among PCMR children with a known etiology, we have observed a broad spectrum of genetic causes: neuromuscular disorders associated with CM (34%), isolated CM(18%), inborn errors of metabolism (21%), malformation syndromes associated with CM (10%) and not specified (17%). Among 639 pts with supplemental PCMR data, many had first degree relatives with CM (28%), sudden death (16%), congenital heart defects (7%), arrhythmias (3%), or recognizable genetic syndromes (5%). The incidence of familial disease of potential relevance was higher than expected, occurring in 39% of CM pts. 48% of PCMR pts had an ICU admission for CM and 66% of all pts are on anticongestive therapy. Other therapies reported included 18% antiarrhythmic, 41% ACE inhibitor, 7% calcium antagonist, 11% beta adrenergic antagonist, 15% carnitine, 3% pacemaker, and 13% dietary modification.

Conclusion Even at centers with an interest in pediatric CM, the incidence of CM without a known etiology is surprisingly high. Our data suggests that genetic contributions to pediatric CM are likely to be underestimated.