Results of Coronary Bypass: A Long-Term Perspective

Abstract

The coronary bypass procedure has gained widespread acceptance as a highly effective form of treatment for angina pectoris. There is also evidence that it prolongs life in patients with three vessel or left main coronary stenosis. We have been particularly interested in the late results of coronary bypass in regard to relief of symptoms and ~rolongation of life and have therefore determined the fate of 1578 consecutive patients after coronary bypass with followup beyond 5 years in all cases. An initial study was made of clinical, treadmill and angiographic results in 434 patients operated upon between 1968 and 1971. (Lawrie et al. 1977). All patients were followed up for more than 60 months after operation (mean 70.7 months). Of the initial 434 patients, 98 died 0 to 74 (mean 31.1 months) post-operatively. Of the 336 survivors, 152 reentered the hosnital and underwent standardized clinical assessment. Angina was lessened in 93.4 percent (255 of 273) and absent in 51.3 percent (140 of 273) of these patients. Of patients under 65 years of age, 79.2 percent (152 of 192) were still working. Treadmill exercise tests performed in 107 patients showed an ischemic response in 44.9 percent (48 of 107) and an indeterminate response in 9.3 percent (10 of 107). The duration of the exercise, maximal pulse rate and double product all correlated well with the completeness of revasculariza-tion. The patency rate in 131 patients with 193 grafts studied 60 to 88 (mean 69.n months post-operatively was 90.7 percent. In the overall group of 176 pat·-ients with 256 grafts studied 12 to 88 (mean 26.2) months post-'operatively, the patency rate was 86.3 percent. Overall, 137 patients (78.1 percent) had all grafts patent, and 166 (94.3 percent) had one or more patent grafts. In the group of 131 patients studied after 5 years, 126 (96.2) percent had at least one patent graft. Vein graft morphology was excellent. The completeness of revascularization could be assessed in detail in 116 patients. In 37 (31.9 percent), no residual lesion was present; in 56 (48.3 percent) one significant lesion was not byoassed and in 21 (18.1 percent) two significant lesions remained untreated. Only two patients (1.7 percent) had three significant lesions without functioning bypasses. Histologic examinations of 122 graft specimens obtained up to 7 years after operation indicated that intimal proliferation occurred in all grafts but rarely caused occlu-sion. Atherosclerosis was observed in only 17 grafts and, in our experi·-ence, the annual incidence of atherosclerosis up to 7 years after operation has been only 0.5-1%. Furthermore, atherosclerosis occurred mainly in patients with severe hyperlipidemia. Thus, in our ex~erience, graft function has remained excellent beyond 5 years. (Lawrie et al. 1976, Lie et al. 1977) • In our patients, left ventricular function, as assessed by end·-diastolic pressure and left ventriculograohy, has been stable over a 5-year interval. Furthermore, because our patients have continued to have good treadmill performance beyond 5 years, we believe that the operation is effective in the long-term relief of myocardial ischemia. 40 A. M. Gotto Jr. et al. (eds.), Atherosclerosis V