The influence of diabetes and hypertension on the results of coronary revascularization

HbA1c predicts length of stay in patients admitted for coronary artery bypass surgery

Diabetes mellitus is associated with coronary artery disease, and diabetic patients are frequently referred for coronary bypass graft surgery. It is well known that HbA1c, which reflects long-term glycemic control, is related to diabetic morbidity and mortality. It is not known whether HbA1c is related to postoperative length of stay among patients who undergo coronary artery bypass surgery. The authors evaluated 135 patients who underwent bypass surgery at the Westchester Medical Center (Valhalla, NY). HbA1c was measured in all patients preoperatively; a value of 7% or greater was used as a threshold for uncontrolled hyperglycemia. A postoperative length of stay of 6 days or more was used as the cutoff for an extended length of stay. Linear regression was used to assess the relationship between HbA1c, adjusted for age, and length of stay in days. Logistic regression, with length of stay a binary variable <6, > or =6 days, was used to assess the accuracy of HbA1c <7%, > or =7%, adjusted for age, in predicting length of stay. An HbA1c of 7% or greater was found to be a strong predictor of a length of stay of 6 days or longer. These data suggest that HbA1c can be used as a surrogate marker for cardiac and noncardiac morbidity that prolongs hospitalization after coronary artery bypass surgery.

Perioperative morbidity in diabetics requiring coronary artery bypass surgery

We retrospectively evaluated the operative results in 384 patients with diabetes mellitus operated on for ischemic coronary artery disease over a six-year period compared with a random group of 396 patients selected from 2,069 nondiabetic patients who underwent operation during the same study period. In our analysis of 13 preoperative and 5 intraoperative variables, diabetics revealed a significantly increased incidence of hypertension (p less than 0.05) and a smaller proportion of men (p less than 0.05). All other variables were not significantly different. The incidence of perioperative myocardial infarction, renal failure, neurological sequelae, leg infections, or thromboembolic events was similar in diabetic and nondiabetic patients. Hospital stay, however, was significantly increased in the diabetic group (p less than 0.05). The diabetic patients requiring intraaortic balloon counterpulsation had a significantly higher incidence of all postoperative complications analyzed compared with diabetics without balloon support (p less than 0.01), whereas the nondiabetic subset requiring intraaortic balloon counterpulsation exhibited only a significantly higher incidence of renal failure (p less than 0.01) and neurological complications (p less than 0.05). These results indicate that diabetes per se does not significantly increase morbidity in coronary bypass surgery.

Clinical and angiographic predictors of operative mortality from the collaborative study in coronary artery surgery (CASS)

Fifteen institutions participating in the Collaborative Study in Coronary Artery Surgery (CASS) have performed isolated coronary artery bypass surgery upon 6630 patients (1061 women and 5569 men) for coronary artery disease. The overall operative mortality (OM) was 2.3% (range 0.3-6.4%). Mortality increased with age, from 0 in the group 20-29 years old to 7.9% in the group 70 years and older. OM was higher for women in each group, ranging from 2.8% for ages 30-39 years to 12.3% for age 70 years and older (0.8% and 5.8% for men). Clinical manifestations of congestive heart failure were associated with increased OM. Mortality was 1.4% in one-vessel, 2.1% in two-vessel and 2.8% in three-vessel disease (diameter narrowing greater than or equal to 70%). Among 1019 patients with left main coronary artery (LMCA) stenosis, OM ranged from 1.6% in patients with mild stenosis and a right-dominant system to 25% in patients with severe (greater than or equal to 90%) stenosis and left dominance. OM varied with ejection fraction (EF) (1.9% for EF greater than or equal to 50% to 6.7% for EF less than 19%) and left ventricular wall motion score (1.7% for least abnormal to 9.1% for most abnormal). For elective surgery, OM was 1.7%, for urgent surgery 3.5%, and for emergency surgery 10.8%. Mortality was 40.0% among 30 patients with severe LMCA stenosis who underwent emergency revascularization. Advanced age, female sex, symptoms of heart failure, LMCA stenosis, impaired left ventricular function and nonelective surgery are associated with a higher OM. These factors should be considered in the selection of patients for coronary artery surgery.