Significance of graft occlusion and coronary atherosclerosis 5 years after coronary artery bypass grafting. A quantitative angiographic study with serial exercise testing.

Abstract

OBJECTIVE: To evaluate the relative importance of graft occlusions and progression of atherosclerosis in coronary arteries as causes of the occurrence of angina pectoris and impairment of physical performance 5 years after coronary artery bypass surgery. DESIGN: A 5-year follow-up study. SETTING: University hospital in south-western Finland. SUBJECTS: Altogether, 174 consecutive electively operated bypass patients. MAIN OUTCOME MEASURES: Serial clinical evaluation and bicycle exercise tests (pre-operatively, at 6 months, and at 1 and 5 years). Quantitative coronary angiography pre-operatively and 5 years after the surgery. RESULTS: Subjects with patent grafts had fewer angina pectoris symptoms at the 5-year follow-up (24 vs. 52%, P = 0.001) and were treated less frequently with long-acting nitrates (3 vs. 15%, P = 0.037) than subjects with graft occlusions. Fewer of them were in classes II-III of the functional classification of the Canadian Cardiovascular Society (39 vs. 74%, P = 0.001). The exercise test was interrupted less often because of chest pain (23 vs. 41%, P = 0.03) and improvement in exercise test variables during the follow-up period was significantly greater in subjects with patent grafts (P<0.002). Amongst patients without graft occlusions, those with new > or =50% diameter stenoses in coronary arteries were more often in functional classes II-III (59 vs. 32%, P = 0.03) than those without new stenoses, but the groups were similar with respect to angina pectoris and exercise tests variables. In patients with graft occlusions, those with and without new > or =50% diameter stenoses were similar with respect to functional class, angina pectoris and exercise test variables. CONCLUSIONS: Angina pectoris and impairment of physical capacity 5 years after coronary artery bypass grafting are mainly due to occlusion of bypass grafts and not to progression of atherosclerosis in coronary arteries.