Assessing and reducing cardiac risks of noncardiac surgery

Lee Goldman, MD The increased risks of noncardiac surgery in patients with heart disease have been known for many decades. Beginning with the simple recognition that patients with a recent myocardial infarction were at increased risk and progressing through a series of more sophisticated multivariate risk indices (1– 4), the prediction of cardiac risk with noncardiac surgery has improved. During the past several decades, observational data indicate that patients whose risk is now recognized based on characteristics such as a recent myocardial infarction, poorly controlled angina pectoris, uncontrolled congestive heart failure, or severe aortic stenosis are less likely to undergo noncardiac surgery until these cardiac conditions are stabilized to reduce risk (1,4). In many circumstances, the approach to surgery may be modified, or the surgery may even be postponed or cancelled, if these cardiac conditions cannot be addressed adequately. Current guidelines have incorporated preoperative assessment based on clinical characteristics as the first step in the approach to the cardiac patient who must undergo noncardiac surgery (5–7). Recent data (4,8) suggest that older approaches, including the American Society of Anesthesiologists classification (9), the Canadian Cardiovascular Society classification (10), two multivariate indices that were derived 15 or more years ago (1,2), and a clinical approach derived from vascular surgery patients who were selected for noninvasive testing (3) may not perform as well as reported in the past. Our most recent index, on the other hand, used six simple factors (highrisk surgery, presence of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, insulin therapy for diabetes, and preoperative serum creatinine greater than 2 mg/dL) to place patients into four risk groups (4). The probability of major cardiac complications ranged from 0.4% to 11% with excellent statistical performance that was significantly better than prior multivariable approaches (1–3) or the American Society of Anesthesiologists classification (9). In some patients, noninvasive testing using exercise electrocardiography (11,12), dipyridamole thallium scintigraphy (13), stress echocardiography (14), or ambulatory ischemia monitoring (15) can improve upon risk estimates. Substantial data suggest that these noninvasive tests are most appropriately utilized in patients whose risk is intermediate based on clinical characteristics. By comparison, a positive noninvasive test does not appear to increase risk appreciably in low-risk patients, and the physician cannot be reassured by a negative noninvasive test in a patient who is high-risk based on clinical characteristics (5). As a result, selective noninvasive testing is preferred over routine testing (5,16). More recently, two randomized trials have demonstrated benefit from perioperative beta-blockers in reducing the risk of either in-hospital major cardiac complications in high-risk patients identified by stress echocardiography (17) or of adverse outcomes at 1 year in patients with or at risk for coronary artery disease (18). Although the total number of patients in these two reports is less than 400, they are the only two randomized trials in the entire literature to demonstrate a significant improvement in a prespecified primary outcome for cardiac patients undergoing noncardiac surgery. A third randomized trial, the European Mivazerol Trial (19), demonstrated a significant reduction in cardiac death (but not the primary endpoint of myocardial infarction and all-cause death) in 1,897 randomized patients with coronary heart disease who underwent noncardiac surgery. In that study, a preplanned subgroup analysis demonstrated a significant reduction in the primary endpoint of myocardial infarction and all-cause death as well as in cardiac death in 904 patients undergoing vascular surgery. Mivazerol is an alpha-2 agonist, which reduces postganglionic norepinephrine output and modulates sympathetic efferent stimuli from the spinal cord. Although the results of the mivazerol study were less definitive than those of the beta-blocker trials, the single mivazerol study actually included about five times as many patients as the two beta-blocker trials combined. These studies with alpha and beta mediators are consistent with prior data showing that each general approach is associated with a reduction in perioperative myocardial ischemia (20 –22). The availability of at least one, if not two, medical interventions to improve outcome in coronary patients undergoing noncardiac surgery raises new questions about the appropriate use of noninvasive testing and of mechanical coronary revascularization (23). Whereas existing consensus guidelines (5,6) tend to recommend noninvasive testing for all intermediate-risk patients, in the hope of separating them into low-risk versus high-risk patients, my current preference is to limit noninvasive Am J Med. 2001;110:320 –323. From the Department of Medicine, University of California, San Francisco, School of Medicine, San Francisco, California. Requests for reprints should be addressed to Lee Goldman, MD, Department of Medicine, University of California, San Francisco, 505 Parnassus Avenue, San Francisco, California 94143-0120.