THE RETURN OF CLINICALLY EVIDENT ISCHEMIA AFTER CORONARY-ARTERY BYPASS-GRAFTING

Although survival after coronary artery bypass grafting (CABG) is the most serious outcome information, the quality of life in living patients is largely determined by the freedom from ischemic events. The return of angina, acute myocardial infarct and sudden death were studied in a large (n = 5880) population of patients undergoing CABG between 1971 and 1987. The freedom from angina pectoris was 95%, 83% and 63% at 1, 5 and 10 years, respectively, after surgery. Early return of angina was related to both procedure incremental risk factors (incomplete revascularization and non-use of the internal mammary (thoracic) artery (IMA) as a conduit) and patient incremental risk factors (aggressiveness of the atherosclerotic process and severity of preCABG symptoms). Late angina return was related to patient risk factors including coexisting factors (hyperlipidemia and hypertension), preCABG symptom severity and gender (female). The freedom from an acute fatal or non-fatal postCABG myocardial infarct was 99%, 96% and 85% at 1, 5 and 10 years after surgery. The incremental risk factors for early infarction were related to incomplete revascularization, but late infarction was related to lipid levels, coexisting diseases (diabetes, positive family history) and non-use of IMA to LAD. The freedom from sudden death was 99.8%, 99% and 97% at 1, 5 and 10 years, respectively, after surgery. The incremental risk factors were dominated by the severity of the left ventricular dysfunction. The freedom from any ischemic event (any of the previous three) was 93%, 79% and 54% at 1, 5 and 10 years, respectively, after surgery. The incremental risk factors included all those cited above for the specific components. Patient-specific predictions validate the influences of these risk factors. They demonstrate that unlike the profound influence of the use of the IMA on survival, there is little benefit of the use of the IMA on return of ischemic events over and above the effect of revascularization per se. The study demonstrates that most patients will experience return of ischemic symptoms within a period of 15-20 years after surgery, but that this is most likely to be return of angina and rarely sudden death.