The purpose of this study was to determine whether systolic function is compromised in segments of the left ventricle that manifest early relaxation and are supplied by a diseased coronary artery. Regional fractional area of shortening (FAS) was evaluated from resting ventriculograms of 24 patients. Nine patients had no cardiac disease or segmental early relaxation (SER) and served as controls. Fifteen patients had single-vessel coronary artery disease (60% to 95% diameter stenosis of the left anterior descending coronary artery). Among these 15 patients, seven had no evidence of SER and eight had SER localized to the anterior wall. In patients with coronary disease and SER, and FAS of the anterolateral segment, 1.30 +/- 0.08, was greater than either controls, 1.07 +/- 0.12 (p less than 0.01) or patients with coronary disease but no SER, 1.03 +/- 0.19 (p less than 0.01). Among patients with coronary disease and SER, the FAS of the anterolateral segment was greater than the corresponding diaphragmatic segment (1.30 +/- 0.08 vs 0.97 +/- 0.12) (p less than 0.001). There was no difference in the FAS between these two segments in either controls or in patients with coronary disease, but without SER. These results indicate that SER of the anterior wall in patients with disease of the left anterior descending coronary artery is associated with enhanced systolic function of the anterolateral region. This observation is incompatible with the concept that ischemia is an underlying mechanism of SER.