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Anesth Analg 2002;95:512-516 © 2002 International Anesthesia Research Society
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Abstract |
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In this study, we examined the utility of preoperative dobutamine stress echocardiograms (DSE) obtained for 85 patients in accordance with guidelines published by the American College of Cardiology (ACC) and the American Heart Association (AHA). The medical record of each patient was reviewed to identify the clinical criteria that indicated the need for a DSE, the DSE results, therapeutic interventions rendered as a result of the DSE, and any perioperative cardiac morbidity. The DSE was positive for inducible ischemia in 4 patients (4.7%), negative in 74 (87.1%), and nondiagnostic in 7 (8.2%). DSEs that were obtained for 48 patients because of a history of diabetes mellitus, mild angina, or "minor clinical predictors" produced only negative results. Of the four patients with positive DSE results, three underwent coronary angiography, and one of those three underwent bypass grafting before surgery. An additional 29 patients received a preoperative DSE but were excluded from the study because the criteria for ordering the DSE did not meet the ACC/AHA guidelines. No patient had any perioperative morbidity related to myocardial ischemia. The total patient charge for the 85 DSEs obtained at our institution was US$104,635. Use of the ACC/AHA guidelines for preoperative DSEs does not appear to be cost-effective. However, the current algorithm could be significantly improved by altering the criteria for obtaining preoperative DSEs.
IMPLICATIONS: This study was a retrospective review of 85 patient charts that found a low cost-effectiveness of using American College of Cardiology/American Heart Association guidelines for obtaining preoperative dobutamine stress echocardiograms. Suggested modifications of these guidelines should improve their specificity with no loss in sensitivity.
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Introduction |
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Significant advances have been made in reducing the costs associated with preoperative evaluation of patients scheduled for elective surgery. Many tests that were at one time considered routine have now been eliminated or are ordered only when there is a specific indication. Despite these advances in improving the cost-effectiveness of the preoperative assessment, it is important that we continue to evaluate the various algorithms that are used to determine whether to obtain a specific test for a given patient.
In 1996, the American College of Cardiology (ACC) and the American Heart Association (AHA) published suggestions regarding the preoperative management of patients at risk for myocardial ischemia (1). These guidelines included an algorithm to help physicians decide which of these patients should have noninvasive testing as part of their cardiac evaluation. For many patients in a majority of institutions, this noninvasive testing consists of a dobutamine stress echocardiogram (DSE). The algorithm uses the patient’s exercise tolerance, the clinical predictors for cardiovascular disease, and the risk level of the surgical procedure to determine the need for a DSE. Because of a lack of adequately controlled or randomized clinical trials, this algorithm was "based on collected observational data and expert opinion" (1). Despite this lack of clinical trials, the ACC/AHA algorithm is widely endorsed (2–6). The rationale for using these ACC/AHA guidelines is that, by identifying patients with significant coronary artery disease (CAD), appropriate medical or surgical interventions can be instituted to reduce the patient’s risk of a perioperative myocardial infarction or death.
It has been our impression that the use of the ACC/AHA guidelines results in a large percentage of negative DSEs. In the event of a positive DSE, the results often made little difference in the care that the patient received. The cost of this test exceeds US$1200 at our institution and frequently delays scheduled procedures. We therefore performed this retrospective study to quantify the usefulness of preoperative DSEs that were ordered in accordance with the ACC/AHA guidelines.
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Methods |
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Approval from the Institutional Review Board at the University of Texas Medical Branch was obtained for the review of the charts of all patients who had a DSE ordered in the Anesthesiology Preoperative Evaluation Clinic between May 26, 1999, and May 11, 2001. As performed at our institution, the DSEs consisted of echocardiograms and electrocardiograms that were recorded during incremental infusion of dobutamine to a maximum dose of 40 µg · kg-1 · min-1. A maximum dose of 1 mg of atropine sulfate was administered when necessary to increase the heart rate to a diagnostic threshold. The chart review for these patients sought to determine 1) the ACC/AHA criteria that indicated the need for a preoperative DSE and 2) the results of the DSE (see Fig. 1).
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Using these data, the patients were grouped according to their ACC/AHA criteria. The incidence of positive, negative, and nondiagnostic DSEs in each patient group was then calculated. For patients with a positive or nondiagnostic DSE, additional data were collected in two categories: 1) further cardiac interventions performed (after the DSE but before surgery) and 2) intraoperative management and invasive monitoring (see Table 1). Adverse outcomes related to myocardial ischemia that occurred from the day of surgery until the time of patient discharge were also recorded.
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Results |
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Over the 2-yr study period, 14,855 patients scheduled for elective surgery were evaluated in the Anesthesiology Preoperative Clinic. Eighty-five of these patients received a preoperative DSE in accordance with the ACC/AHA guidelines. In none of these patients was there any morbidity associated with obtaining the DSE. In these 85 patients, the DSE was positive for inducible ischemia in 4 patients (4.7%), negative in 74 (87.1%), and nondiagnostic in 7 (8.2%). Thus, the positive predictive value of the ACC/AHA guidelines for selecting patients with a positive DSE was 4.7%.
As an incidental finding, there were an additional 29 patients who received a preoperative DSE but were excluded from further analysis because they did not meet the ACC/AHA criteria. Seven of these patients presented with "unstable coronary syndromes" that by ACC/AHA criteria indicated a need for coronary angiography. Instead, each was initially referred for DSE testing, resulting in two positive and five negative tests. The remaining 22 patients did not exhibit a sufficient number of coronary risk factors to qualify for DSE testing by the ACC/AHA algorithm, but a DSE was ordered nonetheless, with 20 negative and 2 nondiagnostic tests. There was a significant cost (approximately US$30,000) associated with the failure in these 22 cases to adhere to the ACC/AHA guidelines.
There are three paths in the ACC/AHA algorithm that result in a recommendation for a preoperative DSE (Fig. 1). The numbers of patients who were referred for DSE testing through Paths 1, 2, and 3 were 56, 9, and 20, respectively. Path 1 produced 3 positive, 49 negative, and 4 nondiagnostic DSEs. Path 2 resulted in one positive, six negative, and two nondiagnostic DSEs. Path 3 produced 19 negative DSEs and 1 nondiagnostic DSE. Three of the four positive DSEs were obtained in patients exhibiting a single intermediate clinical predictor (Table 1). The fourth positive DSE was obtained in a patient who exhibited compensated congestive heart failure, mild angina, and diabetes mellitus. Because of the frequent incidence of negative DSEs (n = 74), the clinical predictors used in the ACC/AHA algorithm were analyzed individually and in comorbid combinations to determine their ability to predict a positive DSE (Table 2). Among patients who exhibited diabetes mellitus, mild angina, or "minor clinical predictors" as their only risk factor for CAD (n = 48), seven patients (14.6%) were taking ß-blockers, and no positive DSEs were obtained.
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Three of the four patients with a positive DSE went on to have coronary angiography. One of those three patients had elective peripheral vascular surgery postponed to undergo a coronary artery bypass graft (CABG). None of the other patients needed further invasive interventions, such as percutaneous transluminal coronary angioplasty (PTCA), stent placement, or CABG, before surgery (Table 1). During surgery, two of these four patients were monitored with an arterial and a central venous catheter. Of the seven patients with a nondiagnostic DSE, none received further cardiac evaluation before surgery. Four of these patients were monitored with an arterial catheter during surgery (Table 1). None of the study patients had any adverse perioperative outcomes related to myocardial ischemia.
The total patient cost for the 85 DSEs obtained at our institution was US$104,635. This figure represents only direct patient fees for the test, excluding all indirect institutional costs. Therefore, the average cost per positive DSE under the current ACC/AHA guidelines is US$26,159. This represents a crude, but objective, attempt at a cost analysis. Other investigators may wish to pursue a more elaborate and subjective approach. Questions to be considered may include cost to the patient and the institution of rescheduling a procedure, the mental and emotional costs associated with not having a definitive procedure performed at the anticipated time, and the costs of failing to obtain an indicated test, proceeding with scheduled surgery, and then experiencing a cardiac morbidity that may or may not have been prevented had the DSE been ordered.
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Discussion |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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DSE was first reported as a diagnostic procedure by Berthe et al. in 1986 (7). Since then, it has shown promise as a clinically useful technique for detecting CAD, with a reported sensitivity of 57% to 89% and a specificity of 65% to 100% (8–12). It is noninvasive, is highly efficient for obtaining good-quality images, and is less expensive than many other techniques (e.g., thallium-201 scintography). For a diagnostic test to be clinically useful, physicians must be able to identify patients who will benefit from the procedure, and the test results must affect patient treatment and outcomes sufficiently to justify its cost (1,13).
Not all patients at risk for CAD require a DSE as part of their preoperative evaluation. It is essential to identify the patients within this population who are most likely to benefit from this noninvasive testing. Recently, Boersma et al. (14) reported that the predictive value of a DSE may be diminished in a subset of low-risk patients who receive perioperative ß-blocker therapy. In our study, no significant difference in cardiac outcomes was detected between patients who were taking ß-blockers and those who were not. The current ACC/AHA guidelines for preoperative evaluation advocate the use of DSE for patients who meet the low- to moderate-risk criteria summarized in Figure 1. However, at our institution, over the two-year study period, 85 patients who met these ACC/AHA criteria produced four positive DSEs, resulting in an average expenditure of US$26,159 per positive test. Stated another way, only 4.7% of patients selected by the ACC/AHA guidelines produced a positive DSE. Thus, it would be desirable to modify the ACC/AHA guidelines to improve their specificity without sacrificing their sensitivity.
Analysis of the study group revealed that no positive DSEs were obtained among patients with one or more minor clinical predictors (n = 20) or among those with diabetes mellitus (n = 15) or mild angina (n = 13) as their only intermediate clinical predictor (Table 2). On the basis of these findings, we suggest that patients in these three groups be cleared for surgery without receiving a preoperative DSE (see Fig. 2). Application of these modifications to the ACC/AHA algorithm would eliminate 45 negative and 3 nondiagnostic DSEs from the study group. Use of this modified algorithm would reduce the total number of DSEs by 48 (56.5%) without eliminating any of the patients with a positive DSE. This represents a total savings of US$59,088 and a reduction of the average cost per positive DSE from US$26,159 to US$11,387.
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One of the most convincing rationales for obtaining a DSE for patients at low to moderate risk of CAD is that a positive DSE may provide an opportunity to offer PTCA, stent placement, or CABG before surgery. These procedures could help to reduce the risk of life-threatening complications arising from the physiologic stress of the operation. Of the four study patients who had a positive DSE, three received coronary angiography. One of these patients had elective surgery postponed to undergo a CABG. None of the other three patients received PTCA, stent placement, or CABG before surgery. The only significant effect of their positive DSEs was that one patient was "medically optimized" before surgery by altering the doses and types of the medication administered. Two of these patients received some form of invasive monitoring during their procedure (Table 1). However, it is impossible to determine whether this invasive monitoring was instituted as a result of the positive DSE or would have been used in any event because of the nature of the surgical procedure. Neither pulmonary artery catheters nor intravenous nitroglycerine was used in any patient with a positive or nondiagnostic DSE, and there was no morbidity related to myocardial ischemia in any of the patients during the perioperative period. Thus, among these patients selected by the current ACC/AHA guidelines, even positive DSE results often had a minimal effect on the care they received.
In conclusion, our data indicate that the use of the current ACC/AHA guidelines for preoperative DSE testing results in a small frequency of positive tests. Given the high cost of obtaining the test and the failure of even a positive test to significantly alter the management of many of these patients, it appears that the cost-effectiveness of the ACC/AHA guidelines could be significantly improved by minor alterations in the current recommended DSE algorithm (Fig. 2). Our data suggest that such an adjustment would not appreciably increase the risk of perioperative morbidity for these patients. A prospective, multicenter study would produce additional valuable information on how to best optimize the use of preoperative DSEs in the evaluation of patients at risk for myocardial ischemia in the perioperative period.
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Acknowledgments |
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This study was internally funded by the Department of Anesthesiology, The University of Texas Medical Branch, Galveston, TX.
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References |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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- Eagle KA, Brundage BH, Chaitman BR, et al. ACC/AHA guidelines for perioperative cardiovascular evaluation for noncardiac surgery. Circulation 1996; 93: 1278–317.
- King MS. Preoperative evaluation. Am Fam Physician 2000; 62: 387–96.[Web of Science][Medline]
- Mangano DT. Assessment of the patient with cardiac disease: an anesthesiologist’s paradigm. Anesthesiology 1999; 91: 1521–6.[Web of Science][Medline]
- Samain E, Farah E, Leseche G, Marty J. Guidelines for perioperative cardiac evaluation from the American College of Cardiology/American Heart Association task force are effective for stratifying cardiac risk before aortic surgery. J Vasc Surg 2000; 31: 971–9.[Web of Science][Medline]
- Park KW. Critical review of the ACC/AHA algorithm for stratifying cardiac patients for noncardiac surgery. Int Anesthesiol Clin 2001; 39: 81–92.[Medline]
- Bartels C, Bechtel JFM, Hossman V, Horsch S. Cardiac risk stratification for high-risk vascular surgery. Circulation 1997; 95: 2473–5.
[Abstract/Free Full Text] - Berthe C, Pierard LA, Hiernaux M, et al. Predicting the extent and location of coronary artery disease in acute myocardial infarction by echocardiography during dobutamine infusion. Am J Cardiol 1986; 58: 1167–72.[Web of Science][Medline]
- Cohen JL, Green TO, Ottenweller J, et al. Dobutamine digital echocardiography for detecting coronary artery disease. Am J Cardiol 1991; 67: 1311–8.[Web of Science][Medline]
- Sawada SG, Segar DS, Ryan T, et al. Echocardiographic detection of coronary artery disease during dobutamine infusion. Circulation 1991; 83: 1605–14.
[Abstract/Free Full Text] - Sahin M, Karakelleoglu S, Alp N, et al. Diagnostic value of dobutamine stress echocardiography in coronary artery disease. Thorac Cardiovasc Surg 1994; 42: 285–9.[Web of Science][Medline]
- Mazeika PK, Nadazdin A, Oakley CM. Diagnostic accuracy of dobutamine stress echocardiography in coronary disease. Circulation 1990; 82 (Suppl 3): 193.
- McNeill AJ, Fioretti PM, El-Said EM, et al. Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography. Am J Cardiol 1992; 70: 41–6.[Web of Science][Medline]
- Dawson-Saunders B, Trapp RG. Evaluating diagnostic procedures. In: Dolan J, Langan C, eds. Basic and clinical biostatistics. Norwalk, CT: Appleton and Lange, 1994: 232–48.
- Boersma E, Poldermans D, Bax J, et al. Predictors of cardiac events after major vascular surgery: role of clinical characteristics, dobutamine echocardiography, and beta-blocker therapy. JAMA 2001; 285: 1865–73.
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