Left ventricular ejection performance, wall stress, and contractile state were evaluated in 35 patients with chronic aortic regurgitation. Cineangiography and pressure measurements were obtained before and a mean of 26 months after aortic valve replacement, and data were compared with those from 30 normal control subjects. The relation between quantitative changes in wall stress and changes in ejection fraction after surgery was determined. Preoperatively, end-systolic stress was elevated in patients with aortic regurgitation (218 +/- 45 vs. 160 +/- 23 kdynes/cm2 [mean +/- SD] for control subjects, p less than 0.01), and ejection fraction was depressed (0.46 +/- 0.11 vs. 0.65 +/- 0.05, p less than 0.01). End-systolic stress decreased postoperatively (151 +/- 41 kdynes/cm2, p less than 0.01) and ejection fraction increased (0.58 +/- 0.11, p less than 0.01). The magnitude of increase in ejection fraction correlated significantly and negatively (r = -0.65) with the quantitative change in end-systolic stress after surgery. Contractile function, as assessed by the ejection phase index-end-systolic stress relation, did not significantly change: 23 of 35 patients preoperatively and 18 of 35 patients postoperatively had values that clearly fell below the 95% confidence limit of the ejection fraction-end-systolic stress relation for controls. After surgery, individual ejection fraction-end-systolic stress relationships demonstrated a shift parallel to the regression curve for the control subjects. Moreover, persistent postoperative left ventricular hypertrophy was significantly associated with persistent contractile dysfunction. Thus, late improvement in left ventricular ejection performance after aortic valve replacement can be attributed to the reduction in end-systolic stress. Contractile function itself was not improved by surgery. Persistent postoperative hypertrophy may be a marker for myocardial contractile dysfunction.