Preoperative cardiac risk assessment for noncardiac surgery

Abstract

Coronary artery disease (CAD) represents an important risk in patients undergoing elective noncardiac surgical procedures, in whom the stress of surgery and postoperative recovery can represent a significant ischemic burden. Population considerations: Preoperative cardiac assessment should be based on the prevalence of CAD (if known) in the population undergoing the procedure and the institutional event rate for the procedure. Procedures considered high-risk are vascular, intra-abdominal or thoracic, major orthopedic, and any emergency procedures. Individual considerations:

Clinical history: A history of angina, congestive heart failure, diabetes mellitus, prior myocardial infarction, ventricular ectopy, and/or elderly (age > 70) are clinical parameters of increased risk. Functional capacity: Good functional capacity is the ability of a 50-70-year-old patient to achieve 6-8 METS of activity without significant symptoms of dyspnea on exertion. Further noninvasive testing: Preoperative testing may include routine treadmill exercise testing, ambulatory ECG monitoring, echocardiographic stress testing with dobutamine or exercise, and/or thallium perfusion imaging. Strategy for high risk patients: Assessing the severity of an abnormality (e.g., with thallium) results in a small percentage of positive test results yielding a high positive predictive value for events. Therefore, more aggressive interventions should be reserved for the most abnormal noninvasive test results, and the severity of the risk assessment should impact the timing of any coronary revascularization procedure, not the decision to proceed to more invasive testing and therapies. In summary, it is important to realize that most of the patients being screened, even vascular surgery patients (with high prevalence of CAD and procedural risk), will be found suitable to go to surgery without additional invasive intervention and cardiac revascularization. Thus good functional capacity and absence of cardiac risk factors should direct 30-40% of this population to elective surgery without further evaluation. The finding of high-risk perfusion scan abnormalities appears to be limited to 15-20% of those patients being recommended for further noninvasive testing.