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

Objective. To evaluate the relative importance of graft occlusions and prog ression of atherosclerosis in coronary arteries as causes of the occurrence of angina pectoris and impairment of physical performance 5 years after co ronary 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 test s (pre-operatively, at 6 months, and at 1 and 5 years). Quantitative corona ry 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 frequent ly with long-acting nitrates (3 vs. 15%, P = 0.037) than subjects with graf t occlusions. Fewer of them were in classes II-III of the functional classi fication of the Canadian Cardiovascular Society (39 vs. 74%, P = 0.001). Th e 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-u p period was significantly greater in subjects with patent grafts (P < 0.00 2). Amongst patients without graft occlusions, those with new greater than or equal to 50% diameter stenoses in coronary arteries were more often in f unctional classes II-III(59 vs. 32%, P = 0.03) than those without new steno ses, but the groups were similar with respect to angina pectoris and exerci se tests variables. In patients with graft occlusions, those with and witho ut new greater than or equal to 50% diameter stenses were similar with resp ect to functional class, angina pectoris and exercise test variables. Conclusions. Angina pectoris and impairment of physical capacity 5 years af ter coronary artery bypass grafting are mainly due to occlusion of bypass g rafts and not to progression of atherosclerosis in coronary arteries.