November 15, 2002 Table of Contents
Preoperative Cardiac Risk Assessment
BERNARD M. KARNATH, M.D., University of Texas Medical Branch at Galveston, Galveston, Texas Related Editorial
Heart disease is the leading cause of mortality in the United States. An important subset of heart disease is perioperative myocardial infarction, which affects approximately 50,000 persons each year. The American College of Cardiology (ACC) and American Heart Association (AHA) have coauthored a guideline on preoperative cardiac risk assessment, as has the American College of Physicians (ACP). The ACC/AHA guideline uses major, intermediate, and minor clinical predictors to stratify patients into different cardiac risk categories. Patients with poor functional status or those undergoing high-risk surgery require further risk stratification via cardiac stress testing. The ACP guideline also starts by screening patients for clinical variables that predict perioperative cardiac complications. However, the ACP did not feel there was enough evidence to support poor functional status as a significant predictor of increased risk. High-risk patients would sometimes merit preoperative cardiac catheterization by the ACC/AHA guideline, while the ACP version would reserve catheterization only for those who were candidates for cardiac revascularization independent of their noncardiac surgery. A recent development in prophylaxis of surgery-related cardiac complications is the use of beta blockers perioperatively for patients with cardiac risk factors. (Am Fam Physician 2002;66:1889–96. Copyright© 2002 American Academy of Family Physicians.) Perioperative management of the elderly patient is increasingly important as the elderly population continues to grow. Currently, there are more than 34 million elderly persons in the United States.1 Heart disease is the leading cause of mortality in the United States, accounting for nearly half a million deaths in 1998.2 Each year, approximately 50,000 patients have perioperative myocardial infarctions (MIs) and about 40 percent will die.3 Most perioperative MIs occur without the typical chest pain. Factors that may contribute to the silent nature of perioperative MI include use of analgesics after surgery, residual effects from the anesthesia, and other perioperative painful stimuli.3 Risk factors for perioperative cardiac complications include coronary artery disease (CAD), previous MI, heart failure, aortic stenosis, and age older than 70 years. Other clinical predictors are diabetes, poorly controlled hypertension, and poor functional capacity.4 Two studies5,6 have evaluated the incidence of MI after general anesthesia in patients with previous MI. A reinfarction rate of 27 to 37 percent occurred in patients who underwent surgery within three months of infarction. The reinfarction rate was 11 to 16 percent in patients who underwent surgery between three and six months of MI. The reinfarction rate remained stable (5 percent) for patients who underwent surgery more than six months after MI. Preoperative Cardiac Risk Index
Goldman and colleagues7 were the first to develop a preoperative cardiac risk index with multifactorial predictors. They evaluated 1,001 consecutive patients undergoing non-cardiac surgery and reported nine variables associated with an increased risk for perioperative cardiac complications. Each risk factor was assigned a point score, and patients were stratified into four risk categories based on their total points. In 1986, Detsky and colleagues8 modified the original multifactorial index by adding variables such as angina and pulmonary edema (Table 17,8). With this index, patients are stratified into three risk categories based on their total points. The modified index also adds predictive information for patients undergoing major and minor surgery. Major surgeries include vascular, orthopedic, intra-thoracic, intraperitoneal, and head and neck surgery. Examples of minor surgeries are...