In order to study left ventricular performance and motion under ischemic stress, incremental atrial pacing was performed in 10 patients with angiographically proven coronary artery disease until angina pectoris or segmental S-T depression appeared. Single-plane left ventricular cineangiograms were obtained in both the resting and the transiently ischemic state induced by pacing.Abnormal motion appeared with pacing in two of three patients with normal contraction at rest; in one of them, gross dyskinesis of the cardiac apex was noted. Seven patients had abnormal contraction at rest; six showed an increase in either the severity or the topographic distribution of abnormality, while one showed no change.Left ventricular end-diastolic pressure and cardiac index were not altered significantly despite changes in the pattern of contraction. Left ventricular end-diastolic volume decreased irrespective of the development of asynergy, but ejection fraction decreased markedly in those patients in whom asynergy was induced de novo or increased.Thus left ventriculography during pacing-induced ischemia may reveal segmental or generalized abnormalities of contraction not necessarily reflected in the usual hemodynamic parameters of function. Moreover, asynergy induced by pacing is associated with a decreased ejection fraction.