Cardiac risk assessment calculators: utility and limitations

Cardiovascular events have been recognized as a major cause of perioperative morbidity and mortality after noncardiac surgery. One of the first indices that facilitated perioperative cardiac risk stratification was published in 1977 by Goldman et al, who prospectively studied 1001 patients aged 40 years and older undergoing major orthopedic, urologic, or general surgery procedures. Nine factors that had a statistically significant correlation with cardiac outcomes were identified [S3 gallop or jugular vein distension preoperatively, myocardial infarction (MI) in the preceding 6 months, rhythm other than sinus or premature atrial contractions on preoperative electrocardiogram, > 5 premature ventricular contractions documented at any time before the procedure, intraperitoneal, intrathoracic or aortic procedure, age above 70 years, important valvular aortic stenosis, emergency procedure, and poor general medical condition]. Cardiac outcome was defined as the occurrence of postoperative pulmonary edema, MI, ventricular tachycardia, or cardiac death. The authors recommended that only truly life-saving procedures be performed on high-risk patients, and preoperative consultation with cardiology be pursued in high-risk patients. In 1986, Detsky and colleagues proposed a modified cardiac risk index that incorporated additional clinically important variables. They applied the concept of pretest probability based on the patient’s clinical risk factors to create a nomogram to predict the posttest probability of a cardiac outcome for each type of surgery. In this study, 455 consecutive patients referred to the general medicine consultation service for preoperative cardiac risk assessment before a major or minor noncardiac procedure were included. Cardiac outcome was defined as the occurrence of nonfatal pulmonary edema, nonfatal MI, or cardiac death. The authors cautioned on variations in the pretest probability if applied outside the intended use for a different population or in a different setting. In the past 43 years, since the publication of Goldman’s index, there has been an increasing awareness about the perioperative cardiac risk and cardiac risk factors, greater attention to preoperative optimization, and advancements in surgical and anesthetic monitoring and techniques. Despite these efforts, 1 in 33 hospitalizations for noncardiac surgery may still have a major cardiovascular or cerebrovascular event perioperatively. Multiple cardiac risk calculators have been reported in the literature since Goldman’s multifactorial cardiac risk index (Fig. 1). The 2014 American College of Cardiology/American Heart Association (ACC/AHA) guidelines state that a validated riskprediction tool can be useful in predicting the risk of a perioperative major adverse cardiovascular event (MACE) in patients undergoing noncardiac surgery (class IIa recommendation, level of evidence: B). Their algorithm uses these tools to separate lowrisk patients (<1% chance of MACE in whom no further cardiac testing is required) from those at elevated risk. Three cardiac risk indices were discussed in these guidelines: (a) Lee’s Revised Cardiac Risk Index (RCRI), (b) American College of Surgeon’s (ACS) Surgical Risk Calculator (ACS-SRC), or (c) Gupta’s ACS MI and cardiac arrest (MICA) calculator. The 2014 European Society of Cardiology/European Society of Anesthesiology guidelines also recommend the use of 1 of these 3 cardiac risk indices for perioperative risk stratification (class I recommendation). We will discuss these 3 risk indices for noncardiac surgery first, followed by a few others that have been reported in the recent literature (Table 1).