Improvement in global and segmental left ventricular function after coronary bypass surgery.

Ventricular function was assessed at rest and during exercise by multiple gated cardiac blood pool scintigraphy before and after coronary artery bypass surgery in 21 patients. Resting left and right ventricular ejection fraction and segmental wall motion were unchanged by surgery. However, the postoperative exercise response of left ventricular ejection fraction (-1 +/- 12% vs 6 +/- 9%) and segmental wall motion score (medium -2.7 [range -8 to 2] vs -0.4 [range -6 to 2]) were significantly improved (p less than 0.05). The normal right ventricular ejection fraction exercise response was maintained after surgery. Previous myocardial infarction in 15 patients did not attenuate the observed improvement in ventricular function. In addition, normal postoperative left ventricular ejection fraction response to exercise was associated with symptomatic improvement. In three of six patients a normal preoperative left ventricular ejection fraction response to exercise was not maintained. Therefore, global and regional left ventricular reserve is improved by coronary bypass surgery and this improvement is not affected by previous myocardial infarction.