Clinical Evaluation

The Big Heart Disease Lie

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Historically, the preoperative assessment of patients before elective surgery was based almost entirely on the clinical evaluation and examination. The American Society of Anesthesiology has used the ASA physical status classification system (1963) to grade perioperative risk. This classification could identify those at extremely high risk of complications from surgery, but did not offer much sensitivity in assessing patients' risk. The patients in level IV or V were at extremely elevated risk, but patients categorised in level III constituted a very wide spectrum of risk and comorbid disease. Furthermore, the ASA classification system does not focus on cardiac risk per se. It offers no consideration for the presence or absence of serious coronary disease in otherwise asymptomatic or undiagnosed patients.

Lee Goldman, then a resident at Massachusetts General Hospital, conducted a study that identified clinical factors conferring elevated risk of surgical complications.2 By performing a multivariate logistic regression analysis of a wide range of clinical parameters on 1000 consecutive patients undergoing elective surgery at the Massachusetts General Hospital, Goldman and his colleagues identified clinical markers of increased risk, and appropriately weighted them based on the epidemiological risk they conferred. The Goldman grading system allowed an estimate of the weighted risk of perioperative cardiac complications based on the presence or absence of clinical factors including the history of recent myocardial infarction, presence of congestive heart failure, critical aortic stenosis, significant non-cardiac organ failure or disease, urgency of surgery, and advanced age. The presence of these factors, particularly when added together, correlated with elevated risk. However, the majority of patients studied did not have markers of high risk and the index proved to be insensitive for discriminating risk in patients who would be considered intermediate in risk. The Goldman index did not include evaluation by objective stress testing, nor does it allow one to infer a plan for appropriate further steps in the evaluation process.

Several other studies have confirmed the utility of clinical evaluation in identifying patients at increased risk of significant coronary disease. L'Italien and others reviewed the clinical risk factors of patients undergoing elective vascular surgery at Massachusetts General Hospital, University of Massachusetts Medical Center, and the University of Vermont Medical Center, and analysed these clinical risk assessments with the results of thallium functional testing, also done before surgery.3 This group initially identified a small list of clinical factors that conferred risk based on multivariate logistic regression analysis. These clinical factors are advanced age, a history of diabetes, myocardial infarction, angina, or congestive heart failure. This group's findings, corroborated by other groups, revealed that the absence of any of these clinical markers of risk conferred a very low risk of complications of surgery (3% in this study). Likewise, the presence of one or two of these factors conferred a moderately increased risk (8%) and the presence of three or more a high risk of death or myocardial infarction during vascular surgery (18% in this study).

Paul and colleagues reviewed an extensive database of cardiac catheterisation results on 878 consecutive patients undergoing elective vascular surgery at the Cleveland Clinic.4 They reviewed these same five clinical markers of risk, and observed that the presence of three or more of these clinical markers was coincident with a high likelihood of three vessel or left main coronary artery disease. Similarly, the absence of any of these markers of risk was coincident with a very low likelihood of having severe coronary artery disease on catheterisation. Taken together, these studies of clinical markers of cardiac risk suggest that patients who are properly evaluated, and have none of these clinical markers of risk, have a very low likelihood of suffering cardiac complications of surgery. This finding has recently been corroborated in clinical trials of the effect of perioperative P blockade on cardiac complications.

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