BACKGROUND: Most cardiomyopathies recognizable in utero are the dilated 
type-with dilated, poorly contractile left ventricle. We propose a diagnostic 
criterion for the rare spongiform (noncompacted) cardiomyopathy.
CASES: Three perinatal cases with echocardiography and autopsy are presented. 
The apical ventricular myocardium was thickened and markedly trabeculated. The 
ventricles were not dilated in two, and the atria were enlarged in all. Hydrops 
and bradycardia were present in all three despite normal or only mildly 
diminished contractility. Although the cardiomyopathy was familial in two 
siblings, two of three cases were female, ruling out Barth syndrome (with 
sex-linked recessive inheritance). Although all three of our cases with hydrops 
died, rare survivors have been reported in the eighth decade.
CONCLUSION: Although spongiform cardiomyopathy may eventually develop into a 
dilated cardiomyopathy, its early characteristic is relatively diagnostic: a 
restrictive cardiomyopathy with no enlargement of the ventricles and prominent 
atria.