Paul A. Grayburn, MD; L David Hillis, MD
Grant Support: Dr. Grayburn is supported by a Mid-Career Investigator in Patient-Oriented Research Award (K24-HL03980) from the National Heart, Lung, and Blood Institute.
Requests for Single Reprints: Paul A. Grayburn, MD, Baylor Heart and Vascular Institute, 3500 Gaston Avenue, Dallas, TX 75246.
Current Author Addresses: Dr. Grayburn: Baylor Heart and Vascular Institute, 3500 Gaston Avenue, Dallas, TX 75246.
Dr. Hillis: Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9030.
Internists and cardiologists are often asked to estimate the risk for perioperative myocardial infarction or cardiac death in patients being considered for noncardiac surgery. Estimating this risk in an individual patient is difficult and complex. Although noninvasive imaging tests are often used for this purpose, a review of the literature reveals that the positive predictive value of noninvasive imaging tests is uniformly low and that they do not provide information beyond that obtained by assessing simple clinical risk variables. Moreover, no evidence exists that noninvasive imaging tests lead to a therapeutic strategy that reduces the risk for perioperative myocardial infarction or cardiac death. Since the publication of guidelines for preoperative risk stratification by the American College of Cardiology/American Heart Association in 1996 and the American College of Physicians in 1997, three clinical trials have shown that -blocker therapy reduces the risk for perioperative cardiac events. This paper focuses on the relationship between risk stratification and subsequent therapy to minimize or eliminate risk. In short, the paradigm is shifting from predicting which patient is at high risk for having a perioperative cardiac event to minimizing the likelihood of such an event with specific perioperative pharmacologic therapy.
Table 1. Critical Elements for Risk Stratification in Patients Undergoing Noncardiac Surgery
Table 2. Major Cardiac Event Rates by the Revised Cardiac Risk Index
Is it accurate? Yes. The receiver-operating characteristic curve area greater than 0.8 indicates that the revised cardiac risk index is accurate in segregating patient risk groups.
Does it add to pretest knowledge? Yes.
Is the harmsbenefit tradeoff favorable? Yes. The revised cardiac risk index is derived inexpensively from the history, physical examination, and serum creatinine level.
Table 3. Studies of Vasodilator Stress Nuclear Perfusion Imaging for Risk Stratification
Is it accurate? No. The positive likelihood ratio is low. The negative likelihood ratio is good in some studies but poor in others. Two large prospective, blinded studies showed that myocardial perfusion imaging did not provide independent prognostic value beyond clinical risk stratification (34, 39).
Does it influence outcome? No published prospective trials have addressed this question.
Is the harmsbenefit tradeoff favorable? No. Patients with positive test results often are subjected to further evaluation, such as coronary angiography. Such a strategy is costly and may delay surgery unnecessarily.
Table 4. Studies of Dobutamine Stress Echocardiography for Risk Stratification
Is it accurate? No. The likelihood ratio of a positive test result is poor. The negative likelihood ratio is good in all but one study. A recent large study (43) showed that
DSE did not add incremental value in low- or medium-risk patients (score of 0 to 2 on the revised cardiac risk index).
Does it influence outcome? No studies have addressed this prospectively.
Is the harmsbenefit tradeoff favorable? No. Dobutamine stress echocardiography has a low positive predictive value. Patients with positive test results are often subjected to further evaluation, which may cause an unnecessary delay in noncardiac surgery.
Proposed clinical algorithm for risk stratification.
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Grayburn PA, Hillis LD. Cardiac Events in Patients Undergoing Noncardiac Surgery: Shifting the Paradigm from Noninvasive Risk Stratification to Therapy. Ann Intern Med. 2003;138:506-511. doi: 10.7326/0003-4819-138-6-200303180-00017
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Published: Ann Intern Med. 2003;138(6):506-511.
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