Features of mildly dilated congestive cardiomyopathy compared with idiopathic restrictive cardiomyopathy and typical dilated cardiomyopathy

Abstract

Congestive cardiomyopathy was recognized in eight patients with only mildly dilated ventricles (an echocardiographic ventricular diastolic dimension index of less than 10% to 15% above the normal range) but with other features typical of end-stage congestive cardiomyopathy. Such patients with mildly dilated cardiomyopathy (MDCM) represented 5% of heart transplant recipients with cardiomyopathy, who were analyzed by us. The clinical, echocardiographic, and hemodynamic data, as well as the gross and microscopic pathologic findings of the hearts in this group were compared with similar data in five patients with idiopathic restrictive cardiomyopathy (IRCM) and 10 patients with typical dilated cardiomyopathy (DCM). Compared with IRCM and DCM, patients with MDCM had a higher incidence of familial cardiomyopathy (p less than 0.009). The echocardiographic features of patients with MDCM and DCM were virtually identical, showing globular hearts with predominant left ventricular dilation and diffuse poor left ventricular contraction. Patients with IRCM had marked atrial dilation but less abnormality of left ventricular size and contraction parameters. On the basis of echocardiographic data, patients with IRCM and MDCM could be well segregated. Cardiac index and light microscopic examinations were similar in the three groups. However, electron microscopy showed a lack of myofibrillar loss in patients with IRCM, little or no myofibrillar loss in those with MDCM, and almost total myofibrillar loss in those with DCM. Patients with MDCM have a high prevalence of familial cardiomyopathy. Absolute heart size and electron microscopic features of the MDCM group were intermediate between IRCM and DCM, but other clinical, echocardiographic and hemodynamic findings were similar to typical DCM.