To investigate left ventricular function and the prognosis of patients with dilated cardiomyopathy (DCM), regional wall motion of the left ventricle of 38 patients with DCM was observed before and during dobutamine infusion (8 micrograms/kg X min) by two-dimensional echocardiography (2DE). The left ventricle was divided into 11 segments and the severity of wall motion abnormality (WMA) was classified into 4 grades, i.e. akinesis or dyskinesis (A), severe hypokinesis (SH), hypokinesis (H) and normokinesis (N), and numerical scores were assigned to each grade of WMA as follow; A: 3, SH: 2, H: 1, and N: 0. In the 38 patients with DCM, the number of segments with WMA was 8.3 +/- 2.9 (mean +/- SD). Among 418 segments in the 38 patients, we observed A in 71 segments, SH in 104 segments, H in 140 segments, and N in 103 segments. The WMA was not uniform in the left ventricle, and severe WMA was observed in the apex (WMA score: 2.0 +/- 1.0), while the grades of WMA in the lateral and posterior walls were mild (WMA score: 0.8 +/- 1.1) compared with those of other segments. The total sums of the WMA scores in 11 segments for each patient (TWMAS) were significantly greater in patients with severe heart failure (New York Heart Association [NYHA] functional class III or IV) than in patients with mild heart failure (NYHA class I or II) (22.0 +/- 5.2 and 9.9 +/- 4.9, p less than 0.001). TWMAS correlated with the cardiac index (CI) (r = -0.58, p less than 0.005) and pulmonary capillary pressure (PCP) (r = 0.68, p less than 0.001). In 242 segments of 22 patients, whose regional wall motion was observed before and during dobutamine administration, wall motion was improved by one grade in 82 of 170 segments with WMA before dobutamine infusion; i.e. regional wall motion changed from A to SH in six segments, from SH to H in 31 segments, and from H to N in 45 segments with dobutamine administration. According to the change in grade of TWMAS induced by dobutamine administration, 22 patients with DCM were classified into two groups: a good response group (% change of TWMAS greater than or equal to 40%), and a poor response group (% change of TWMAS less than 40%). The poor response group had ventricular tachycardia more frequently, more severe heart failure, lower CI and higher PCP than the good response group.(ABSTRACT TRUNCATED AT 400 WORDS)