A surgeon’s view of risk in coronary artery surgery
Risk related to coronary artery surgery has declined significantly in 13 years of active practice. Reasons for this improvement involve multiple factors, and different conclusions have been reached by numerous investigators. Statements on risk are influenced by rapid technological advances that have occurred during the past 5 years. Whereas results have doubtless improved, an important question is whether technologic changes are responsible or whether lower risk surgical candidates are selected. In a survey of the Cleveland Clinic experience in myocardial revascularization, comparing 1967–1970 to 1978, we found a rising median age (50 to 56), more extensive coronary atherosclerosis (44% multiple-vessel disease compared to 89%) and greater prevalence of preoperative left ventricular dysfunction (41% vs 54%). The incidence of perioperative myocardial infarction and other forms of morbidity, with the exception of neurologic deficit, has fallen significantly when the early years are compared with later experiences. Other positive signs include less blood usage (from 11 units to 2 units per hospitalization), more grafts per patient (1.5 to 3.0), and higher incidence of complete revascularization (50% to 80%). So it would appear that higher-, not lower-risk patients are being accepted; yet the operative mortality has declined to 1%, morbidity has been clearly reduced, and operations are more complete.1
Certain aspects of risk can be calculated statistically. By multivariate analysis, Hammermeister and Kennedy2 determined the main risk factors for 1870 surgically treated patients and found that preoperative ventricular arrhythmia, left ventricular status, congestive heart failure, and left main stenosis were highly predictive of survival.