Clinical characteristics of cardiomyopathy with mild dilatation

The clinical features of 20 patients with mildly dilated cardiomyopathy (MDCM) were investigated by electrocardiography and echocardiography. MDCM was defined as conditions with: 1) left ventricular end-diastolic dimension between 55 and 65 mm and 2) left ventricular fractional shortening between 10 and 25%. Nine patients (45%) had no histories of congestive heart failure. Eight patients had atrial fibrillation, and the other 12 patients were in regular sinus rhythm. Two patients had supraventricular premature contractions and five patients had ventricular premature contractions. One patient had paroxysmal atrial tachycardia. During the 40-months' span of this echocardiographic study, left ventricular end-diastolic dimension (60.8 +/- 3.8 mm to 57.3 +/- 4.6 mm) and left ventricular fractional shortening (17.2 +/- 4.6% to 22.7 +/- 7.1%) did not change significantly. One patient died suddenly. These results suggest that 1) some patients with MDCM have neither definite histories nor symptoms to suggest heart failure; 2) the hemodynamic conditions of patients with MDCM do not always deteriorate, but rather stabilize, and even improve during follow-up periods; 3) several types of arrhythmias can be observed, even in standard resting electrocardiograms; and 4) patients with MDCM may die suddenly.