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

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 greater than or equal to 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 greater than or equal to 50% diameter stenses 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.