Evaluation of right ventricular function in patients with idiopathic dilated and ischemic cardiomyopathy by equilibrium radionuclide ventriculography.

We performed equilibrium radionuclide ventriculography in 12 patients with idiopathic dilated cardiomyopathy, 11 patients with ischemic cardiomyopathy and 11 normal subjects to determine whether measurements of right ventricular function could be used to distinguish dilated cardiomyopathy from ischemic cardiomyopathy. The left ventricular ejection fraction in patients with dilated cardiomyopathy (26 +/- 8%, mean +/- SD) or ischemic cardiomyopathy (32 +/- 5%) was significantly lower than in normals (69 +/- 6%, p less than 0.001). The right ventricular ejection fraction (RVEF) in normals was 57 +/- 7%. RVEF was decreased in 11 of 12 patients with dilated cardiomyopathy and the mean value (32 +/- 10%) was significantly lower than that in patients with ischemic cardiomyopathy (56 +/- 7%, p less than 0.001), none of whom had decreased RVEF. Our data show that right ventricular dysfunction commonly exists in patients with dilated cardiomyopathy but not in patients with ischemic cardiomyopathy. This finding may be useful in the differentiation between dilated and ischemic cardiomyopathy.