Guidelines on perioperative cardiovascular evaluation: what have we learned over the past 6 years to warrant an update?

I n March 1996, a Committee convened by the American College of Cardiology/American Heart Association published Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery (1). As outlined in the original guideline process, the Committee was queried every year since publication to determine if significant new information had been published which would warrant updating the Guidelines. In 2000, the Committee deemed there was sufficient new information, the culmination of which is published in this issue of Anesthesia & Analgesia (2). Using a MEDLINE search, the committee identified and reviewed over 400 relevant new articles. When the original Guidelines were developed, the number of randomized trials addressing perioperative cardiovascular evaluation and therapy was extremely limited. Most of the literature reported on the relationship between adverse events and known risk factors or interventions. To develop a meaningful document, we incorporated these data with information from the nonsurgical arena to make recommendations. The goal of the final document was to define those situations in which testing and perioperative interventions may benefit patients and situations in which those interventions are not indicated. Using a Delphi approach, the Committee proposed an algorithm to define the need the further diagnostic testing before noncardiac surgery, incorporating patient and surgeryspecific factors and exercise tolerance. Considering the nature of the original guidelines, what should be the basis of any update? Clearly, the proposed algorithm needs validation. In fact, several nonrandomized studies published during the intervening years demonstrated low morbidity and mortality using an approach either identical or similar to the one advocated in the Guidelines (3,4). Importantly, no randomized trials have been published during the intervening period. In reviewing the components of the decision to perform further diagnostic testing (clinical factors, surgical risk, and exercise tolerance), there have been numerous papers to refine or confirm the previous designations. For example, chronic renal insufficiency is now considered an intermediate risk marker, but recent myocardial infarction (more than 7 days but less than or equal to 1 mo before examination) with evidence of important ischemic risk by clinical symptoms or noninvasive study is a major predictor. Finally, a recent report confirmed the value of self-reported exercise tolerance and its association with an increased incidence of perioperative morbidity and mortality (5). This is an important finding in light of statements made in the Guidelines published by the American College of Physicians in 1997, in which the use of self-reported exercise tolerance is questioned because of the lack of evidence (6). The greatest advancements have been made in the area of perioperative interventions. Numerous randomized clinical trials have been published during the intervening years (7). These include trials of betaadrenergic blocking drugs, alpha-2 agonists and other medical therapies. Based on this stronger evidence, the Committee was able to rate the strength of evidence and provide formal recommendations using a classification schema: