OBJECTIVE: To establish rates of and risk factors for cardiac complications after noncardiac surgery in veterans.
DESIGN: Prospective cohort study.
SETTING: A large urban veterans affairs hospital.
PARTICIPANTS: One thousand patients with known or suspected cardiac problems undergoing 1,121 noncardiac procedures.
MEASUREMENTS: Patients were assessed preoperatively for important clinical variables. Postoperative evaluation was done by an assessor
blinded to preoperative status with a daily physical examination, electrocardiogram, and creatine kinase with MB fraction
until postoperative day 6, day of discharge, death, or reoperation (whichever occurred earliest). Serial electrocardiograms,
enzymes, and chest radiographs were obtained as indicated. Severe cardiac complications included cardiac death, cardiac arrest,
myocardial infarction, ventricular tachycardia, and fibrillation and pulmonary edema. Serious cardiac complications included
the above, heart failure, and unstable angina.
MAIN RESULTS: Severe and serious complications were seen in 24% and 32% of aortic, 8.3% and 10% of carotid, 11.8% and 14.7% of peripheral
vascular, 9.0% and 13.1% of intraabdominal/intrathoracic, 2.9% and 3.3% of intermediate-risk (head and neck and major orthopedic
procedures), and 0.27% and 1.1% of low-risk procedures respectively. The five associated patient-specific risk factors identified
by logistic regression are: myocardial infarction <6 months (odds ratio [OR], 4.5; 95% confidence interval [CI], 1.9 to 12.9),
emergency surgery (OR, 2.6; 95% CI, 1.2 to 5.6), myocardial infarction >6 months (OR, 2.2; 95% CI, 1.4 to 3.5), heart failure
ever (OR, 1.9; 95% CI, 1.2 to 3.0), and rhythm other than sinus (OR, 1.7; 95% CI, 0.9 to 3.2). Inclusion of the planned operative
procedure significantly improves the predictive ability of our risk model.
CONCLUSIONS: Five patient-specific risk factors are associated with high risk for cardiac complications in the perioperative period of
noncardiac surgery in veterans. Inclusion of the operative procedure significantly improves the predictive ability of the
risk model. Overall cardiac complication rates (pretest probabilities) are established for these patients. A simple nomogram
is presented for calculation of post-test probabilities by incorporating the operative procedure.
Key words cardiac risk - noncardiac surgery - risk index - risk factors - heart disease
Investigator Initiated Merit Review Proposal #91-017 was funded by Health Services Research and Development Service, Department
of Veterans Affairs.