Preoperative cardiac risk assessment for patients having peripheral vascular surgery

Abstract

Purpose: To review the methods used for preoperative cardiac risk stratification of patients having peripheral vascular surgery.

Data sources: Relevant studies published before August 1991 were identified using a MEDLINE search of the English-language literature, followed by a manual search of the references of all identified articles.

Study selection: All clinical studies evaluating methods used for preoperative cardiac risk stratification of patients having peripheral vascular surgery.

Data extraction: The key data extracted from each article included the inclusion and exclusion criteria of the study patients, the techniques used for testing and the corresponding definitions of positive test results, and the clinical outcomes of the tested patients. Data were analyzed using a Bayesian conceptual framework, and pretest probabilities were converted to post-test probabilities using calculation of likelihood ratios.

Results: Patients with high scores on clinical cardiac risk indexes (Goldman index greater than 12 or Detsky index greater than 15), or more than three of the criteria identified by Eagle (age greater than 70 years, diabetes, angina, Q waves on electrocardiogram, or ventricular arrhythmias) are likely to be at higher risk for cardiac death and myocardial infarction after vascular surgery. Those with both low scores and none of Eagle's criteria may be at lower risk, but this result has not been reproduced by independent studies. Neither group of patients would benefit from further investigation for cardiac risk stratification. Patients with one or two of these criteria may be at intermediate risk and would benefit most from further testing for the purposes of risk stratification. Most of the published evidence shows that the absence of redistribution on dipyridamole-thallium scanning identifies a low risk for postoperative cardiac complications, whereas the presence of redistribution predicts a high risk. Preliminary reports suggest that preoperative monitoring for silent myocardial ischemia may also be useful in identifying a high-risk subset of patients.

Conclusions: Patients identified clinically to be at either very low or high risk for cardiac complications after peripheral vascular surgery are unlikely to benefit from further risk stratification. Dipyridamole-thallium scanning is the test of choice for further evaluation of patients at intermediate clinical risk because studies have shown that it is sensitive enough to rule out a high-risk status for patients who do not have redistribution.