Coronary bypass surgery. Value of maximal exercise testing in assessment of results

To evaluate the relationship of results of maximal treadmill testing and results of saphenous vein bypass surgery (SVG), 30 patients underwent a maximal treadmill test before and after SVG; an additional 39 had results of postoperative exercise testing available. These patients were part of a group of 91 patients (95% of 96 survivors) who had complete right- and left-heart catheterizations and coronary angiography before and after operation. Twenty-one per cent had improved ejection fractions postoperatively; in 32% ejection fractions were worse. Duration of maximal treadmill exercise correlated poorly with ejection fraction changes or graft patency. Rate-pressure product (RPP) was usually lower postoperatively in patients with worse ejection fractions, primarily because of a low systolic blood pressure at maximum exercise. RPP postoperatively of less than 25,000 almost always meant poor surgical results, either graft occlusion or poor left ventricular function, while RPP of more than 30,000 meant that left ventricular function was preserved and all grafts or the graft to the anterior descending were patent. Thus, success or failure of SVG in these groups may be predicted without postoperative catheterization. An open graft to the anterior descending coronary generally insured a high RPP with exercise, even if other grafts were closed, as long as ventricular function remained good.