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Effects of coronary-artery bypass on global and regional left ventricular function during exercise.

To determine the effect of coronary revascularization on exercise-induced abnormalities of left ventricular-ejection fraction and regional contraction, we obtained electrocardiograph-gated 99mTc radionuclide cineangiograms before and after operation in 23 consecutive patients. At rest, their average ejection fraction remained unchanged: 51 +/- 3 versus 54 +/- 4 per cent (+/- S.E.M.). However, 17 of the patients showed improvement of ejection fraction during postoperative exercise (increase of 51 per cent). The remaining six patients had no change or a decreased ejection fraction during exercise. All patients with improved ejection fractions during exercise were symptomatically improved. No improvement of regional function occurred at rest, but improvement did occur in regions of exercise-induced dysfunction. Although coronary revascularization has little effect on left ventricular function at rest, the ejection fraction during exercise and exercise-induced wall-motion abnormalities improve in most patients who experience symptomatic improvement.