Restrictive cardiomyopathy is a rare type of cardiomyopathy that represents approximately 5% of pediatric cardiomyopathies worldwide. Restrictive cardiomyopathy is characterized by sudden death or signs and/or symptoms of heart failure such as fatigue, shortness of breath, tissue swelling (edema) and abdominal enlargement. The heart is structurally normal, though histological abnormalities are often present, depending on the etiology of the restrictive cardiomyopathy. Systolic ventricular function is usually preserved. Restrictive cardiomyopathy may manifest as a solitary abnormality, though restrictive filling patterns of the left ventricle can be seen in patients with dilated or hypertrophic cardiomyopathy. Because this disease is so rare, its pathogenesis, natural history, and treatment are not well defined. Medical therapy, primarily diuretics, is directed at symptom relief. Cradiac transplantation should be considered early in the course of restrictive cardiomyopathy in the pediatric population because it is the only intervention that improves mortality.

Linkage analysis in a large family with multiple patients affected with cardiomyopathy identified TNNI3 (Troponin I3, Cardiac Type) as a likely disease gene. Mutation analysis in this family revealed a novel missense mutation that cosegregated with the disease in the family (Asp190His). Futhermore, 6 of 9 unrelated restrictive cardiomyopathy patients with restrictive filling patterns, biallelic dilatation, normal systolic function, and normal wall thickness exhibited TNNI3 mutations. All mutations appeared in conserved and functionally important domains of the gene.