Myocardial Enzyme Levels and Mortality After Coronary Artery Bypass Graft Surgery

To the Editor: In their study, Dr Domanski and colleagues demonstrated that myocardial necrosis, as measured by CK-MB or troponin elevation in the first 24 hours following CABG surgery, was associated with increased mortality.¹ Among other covariates in their multivariable model, CK-MB ratio was the strongest predictor of 30-day mortality following CABG surgery.

Traditionally, emergency or reoperative CABG surgery and preoperative severe left ventricular dysfunction have been the strongest predictors of mortality following isolated CABG surgery.^2- 4 The high risk of mortality among these 3 groups is likely secondary to increased incidence of perioperative myocardial infarction. Myocardial necrosis as reflected by marked CK-MB or troponin elevation in the first 24 hours postoperatively is likely the root cause of mortality in most patients following isolated CABG surgery, including low-risk patients. In a multicenter prospective study of 384 deaths in 8641 consecutive patients undergoing isolated CABG surgery between 1990 and 1995, heart failure was judged to be the primary mode of death for 65% of the patients.⁵