Changes in Maximal Exercise Performance in the Evaluation of Saphenous Vein Bypass Surgery

Abstract

To evaluate the improvement in myocardial oxygen delivery following saphenous vein graft surgery (SVG) for angina pectoris (AP), 46 patients underwent a multistage treadmill test of maximal exercise capacity before and 3-22 (average 8) months after SVG. Variables from exercise testing were correlated with symptomatic response, left ventricular hemodynamics, and graft patency. Functional capacity (NYHA) improved in 38 (85%), while 27 (59%) had a significant improvement in exercise performance. Functional aerobic impairment (FAI), or the percentage deviation from expected V _{O O2 max , improved by a mean of 16% ( P < 0.001). Maximal systolic pressure-rate product/100 increased 36 ( P < 0.002). Twenty of 29 (66%) with presurgical S-T segment depression had a normal response after surgery. Thirty-three patients were studied for graft patency and had quantitative angiography. Seventeen had all grafts patent and demonstrated a mean improvement of 21% in FAI ( P < 0.0007). Those with occluded grafts showed no improvement in exercise performance. Sixteen of 22 (73%) with severe exercise impairment showed significant improvement, but only four of 14 (29%) with mild impairment showed a significant improvement. There were no mean changes in left ventricular end-diastolic pressure, cardiac index, contraction plot, or systolic ejection fraction (SEF) in any of the patients. Preoperatively nine had a depressed SEF (<50%), and no improvement in exercise performance could be demonstrated. Maximal treadmill testing has demonstrated objectively that SVG can improve functional capacity and that it is correlated with graft patency. Ideal surgical candidates appear to be those with severe exercise impairment and unimpaired ventricular performance.}