The ability to predict reversibility of ventricular dysfunction should be important in determining operability. This study examined the usefulness of postextrasystolic potentiation as such a predictor. Left ventricular wall motion was studied using cineventriculography in 31 patients before and after revascularization surgery. Preoperative ejection fraction and wall motion were analyzed during a sinus beat and after a random ventricular extrasystole, whereas postoperative ejection fraction and wall motion were examined only during a sinus beat. Changes in ventricular motion were correlated with changes in vascular supply achieved by operation. Of the 7 patients whose ejection fraction was improved postoperatively, 6 had shown postextrasystolic potentiation compared with only 10 of the 24 patients without such improvement (P less than 0.05). Regional wall motion analysis also showed a significant association between postextrasystolic potentiation and postoperative improvement in wall motion. Of 26 zones judged to have an increased vascular supply after operation, 11 showed increased motion postoperatively. All 11 had shown postextrasystolic potentiation, compared with only 5 of 15 zones with increased vascular supply but without increased postoperative motion (P less than 0.001). Thus, postextrasystolic potentiation seems to be a useful predictor of the ability of asynergic myocardium to respond to successful revascularization surgery.