Clinical profile and outcome of idiopathic restrictive cardiomyopathy

Background-Idiopathic restrictive cardiomyopathy is a poorly recognized ent ity of unknown cause characterized by nondilated, nonhypertrophied ventricl es with diastolic dysfunction resulting in dilated atria and variable systo lic function. Methods and Results-Between 1979 and 1996, 94 patients (61% women) 10 to 90 years old (mean, 64 years) met strict morphological echocardiographic crit eria for idiopathic restrictive cardiomyopathy, mainly dilated atria with n onhypertrophied, nondilated ventricles. None had known infiltrative disease , hypertension of >5 years' duration, or cardiac or systemic conditions ass ociated with restrictive filling. Nineteen percent were in NYHA class I, 53 % in class II, and 28% in class III or IV. Atrial fibrillation was noted in 74% of patients and systolic dysfunction in 16%. Follow-up (mean, 68 month s) was complete for 93 patients (99%). At follow-up, 47 patients (50%) had died, 32 (68%) of cardiovascular causes. Four had heart transplantation. Th e death rate compared with actuarial statistics was significantly higher th an expected (P<0.0001), Kaplan-Meier 5-year survival was 64%, compared with expected survival of 85%. Multivariate analysis using proportional hazards showed that the risk of death approximately doubles with male sex (hazard ratio [HR] = 2.1), left atrial dimension >60 mm (HR=2.3), age >70 years (HR =2.0), and each increment of NYHA class (HR=2.0). Conclusions-Idiopathic restrictive cardiomyopathy or nondilated, nonhypertr ophic ventricles with marked biatrial dilatation, as defined morphologicall y by echocardiography, affects predominantly elderly patients but can occur in any age group. Patients present with systemic and pulmonary venous cong estion and atrial fibrillation and have a poor prognosis, particularly men >70 years old with higher NYHA class and left atrial dimension >60 mm.