The effects of postextrasystolic potentiation (PESP) on regional left ventricular (LV) wall motion were evaluated in 40 coronary artery disease (CAD) patients. Of the 40 CAD patients, 20 had a prior myocardial infarction and 20 had a history of angina pectoris. PESP was obtained by applying programmed atrial stimulation during LV angiography, in a way that basal cycle length, premature beat, and postextrasystolic pause were almost identical in all patients. Segmental wall motion was evaluated by calculating regional ejection fraction (EF) of 5 different areas with a computerized method before and after the premature beat. The results were compared to those obtained in a group of 8 normal subjects. LV areas were classified as normokinetic, mildly hypokinetic, severely hypokinetic, and hyperkinetic, on the basis of their regional EF in respect to normals, and classified as "responder" (R) and "nonresponder" on the basis of the magnitude of the increase of regional EF with PESP. Of a total of 200 areas 129 were normokinetic (68% R), 45 were mildly hypokinetic (78% R), 17 severely hypokinetic (76% R), and 9 were hyperkinetic (78% R). Infarcted patients had a higher percentage of hypokinetic areas in basal conditions (p less than 0.001), however, the percentage of hypokinetic areas that responded to PESP was not significantly different from noninfarcted patients. In CAD patients, as a whole, a significant direct correlation was found between basal regional EF and regional EF after PESP (r = 0.88, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)