Dilated cardiomyopathy (DCM) is characterized by progressive left ventricular (LV) systolic dysfunction of nonspecific etiology. Fifty-nine DCM patients were serially observed by echocardiography for 4.5 +/- 2.6 years, and 7.3 +/- 3.4 times M-mode and two-dimensional echocardiography was performed during the observation period using SSH-11A (Toshiba). To assess LV systolic function, ejection fraction was calculated by Pombo's method. Myocardial gray level distribution shown by echocardiography was calculated to assess the myocardial tissue character. Two-dimensional echocardiographic images were obtained in the parasternal short-axis view, recorded on U-matic videotape, and transferred to an image processing computer system (MIPRON, Kontron). The images were digitized and stored on the computer. The regions of interest (ROI) were placed in the LV septum, posterior papillary muscle, posterior wall, anterior papillary muscle and entire LV wall. The gray level distributions in each ROI and its quantitative parameters (mean, SD, skewness, excess) were calculated. The corrected myocardial gray level of every ROI (CMD) was also calculated and expressed as the ratio to the mean gray level of the LV cavity. Seven patients exhibited significant decreases in ejection fraction (more than 10%) during the observation period (group A); the remainders showed less change (group B).(ABSTRACT TRUNCATED AT 250 WORDS)