Cardiomyopathies (CMs) can be classified as idiopathic dilated, hypertrophic, restrictive/obliterative, and so-called "ischemic cardiomyopathy." We have observed a subgroup of patients with congestive heart failure, dilated hearts, and severe coronary artery disease in the absence of myocardial infarction and therefore not fulfilling the criteria for ischemic CM. To better elucidate this group, which we called "coronary" CM, 54 consecutive necropsy patients who had congestive heart failure were retrospectively studied. Nineteen patients had idiopathic dilated CM, 26 had ischemic CM, and nine had coronary CM. The mean age of the patients with coronary CM and ischemic CM was significantly greater than that of the patients with idiopathic dilated CM (62 +/- 10 and 64 +/- 10 years versus 47 +/- 19 years, respectively). The duration of congestive heart failure was longest in the coronary CM group (4.1 +/- 3.4 years); half of these patients died suddenly or from arrhythmias. Hearts from patients with coronary CM had marked biventricular dilatation and severe coronary artery disease (mean number of coronary arteries with more than 75% narrowing, 2.2). No acute or healed infarcts were grossly visible, but interstitial and focal perivascular fibrosis were present in the myocardium of all coronary CM hearts. Although coronary CM may comprise a subset of so-called "ischemic cardiomyopathy," these cases may also represent idiopathic dilated CM with coincidental coronary artery disease.