Preoperative Cardiac Evaluation of Noncardiac Surgical Patients

Transcription

1 GENERAL SURGERY BOARD REVIEW MANUAL STATEMENT OF EDITORIAL PURPOSE The Hospital Physician General Surgery Board Review Manual is a peer-reviewed study guide for residents and practicing physicians preparing for board examinations in general surgery. Each quarterly manual reviews a topic essential to the current practice of general surgery. PUBLISHING STAFF PRESIDENT, GROUP PUBLISHER Bruce M. White EDITORIAL DIRECTOR Debra Dreger SENIOR EDITOR Becky Krumm ASSISTANT EDITOR Rita E. Gould EXECUTIVE VICE PRESIDENT Barbara T. White EXECUTIVE DIRECTOR OF OPERATIONS Jean M. Gaul Preoperative Cardiac Evaluation of Noncardiac Surgical Patients Series Editor: Kamal M.F. Itani, MD, FACS Chief of Surgery, Boston VA Health Care System; Professor of Surgery, Boston University; Associate Chief of Surgery, Boston Medical Center and The Brigham and Women s Hospital; Boston, MA Contributors: Jamal J. Hoballah, MD, MBA, FACS Professor of Surgery, University of Iowa, Roy J. and Lucille A. Carver College of Medicine; Director, Division of Vascular Surgery, The University of Iowa Hospital and Clinics, Iowa City, IA Alan F. Ross, MD Associate Professor of Anesthesia, University of Iowa, Roy J. and Lucille A. Carver College of Medicine, Department of Surgery and Department of Anesthesia, University of Iowa Hospital and Clinics, Iowa City, IA PRODUCTION DIRECTOR Suzanne S. Banish PRODUCTION ASSISTANT Kathryn K. Johnson ADVERTISING/PROJECT MANAGER Patricia Payne Castle SALES & MARKETING MANAGER Deborah D. Chavis NOTE FROM THE PUBLISHER: This peer-reviewed publication has been developed without involvement of or review by the American Board of Surgery. Endorsed by the Association for Hospital Medical Education Table of Contents Introduction Preoperative Clinical Assessment of Cardiac Risk Preoperative Cardiac Diagnostic Testing Role of Coronary Revascularization Prior to Surgery Conclusion References Cover Illustration by Joe Wilder, MD Copyright 2005, Turner White Communications, Inc., Strafford Avenue, Suite 220, Wayne, PA , All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, mechanical, electronic, photocopying, recording, or otherwise, without the prior written permission of Turner White Communications. The preparation and distribution of this publication are supported by sponsorship subject to written agreements that stipulate and ensure the editorial independence of Turner White Communications. Turner White Communications retains full control over the design and production of all published materials, including selection of appropriate topics and preparation of editorial content. The authors are solely responsible for substantive content. Statements expressed reflect the views of the authors and not necessarily the opinions or policies of Turner White Communications. Turner White Communications accepts no responsibility for statements made by authors and will not be liable for any errors of omission or inaccuracies. Information contained within this publication should not be used as a substitute for clinical judgment. General Surgery Volume 8, Part 3 1

2 GENERAL SURGERY BOARD REVIEW MANUAL Preoperative Cardiac Evaluation of Noncardiac Surgical Patients Jamal J. Hoballah, MD, MBA, FACS, and Alan F. Ross, MD INTRODUCTION Cardiovascular complications are a major concern for patients undergoing noncardiac surgery. Many patients with coronary artery disease (CAD) such as stable angina pectoris undergo noncardiac surgery without complications. Yet others, including some with no obvious cardiac disease, have suffered devastating postoperative myocardial infarction (MI). How does one determine the risks for a particular patient? This review will address both clinical assessment of preoperative cardiac risk and the application of invasive and noninvasive technologies. The indications for preoperative cardiac screening testing will be discussed, and a practical approach to the preoperative management of patients undergoing noncardiac surgery will be presented. PREOPERATIVE CLINICAL ASSESSMENT OF CARDIAC RISK CASE PRESENTATION A 71-year-old woman is referred to the vascular surgery service with an asymptomatic 5.8-cm abdominal aortic aneurysm. Her past medical history is significant for hypertension, insulin-dependent diabetes, and chronic renal insufficiency. She denies any previous MI and has a sedentary lifestyle. She has no cardiac murmurs or abnormal cardiac sounds. Her blood urea nitrogen level is 35 mg/dl, and her serum creatinine level is 2.1 mg/dl. She is not a candidate for endovascular treatment and a standard open surgical replacement is recommended. Her electrocardiogram (ECG) is normal. How can the cardiac risks of the proposed procedure be estimated based on clinical assessment in this patient? CLINICAL RISK INDICES Cardiac complications following noncardiac surgical procedures account for a major portion of perioperative mortality and morbidity. Several clinical criteria and algorithms 1 4 have been developed to stratify patients and identify those at increased risk of developing perioperative myocardial events. Many clinicians regard the publication of Goldman s cardiac risk index (CRI) 5 in 1977 as the beginning of clinical cardiac risk assessment for noncardiac surgery. However, major contributions were made prior to this time. Risk factors identified prior to Goldman s study included age over 60 years; emergency surgery; intraperitoneal and intrathoracic surgery; prior coronary disease; recent (< 3 months) MI; cardiac enlargement; congestive heart failure; aortic valve disease; and preoperative ECG abnormality such as atrial fibrillation, atrial flutter, heart block, or bundle branch block. The most important risk factor identified by the early studies was that a MI within 6 months of surgery significantly increased the risk of postoperative reinfarction. Goldman Cardiac Risk Index In 1977, Goldman and colleagues proposed a landmark CRI in a study of 1001 patients older than 40 years undergoing major noncardiac surgery. 5 Nine independent preoperative characteristics were identified that correlated to adverse postoperative outcomes of MI, pulmonary edema, or ventricular tachycardia. Each risk factor was assigned a point value based on its significance (Table 1), and 4 risk classes were established by point totals (Table 2). According to the Goldman criteria, the patient in this case study had 2 risk factors: age older than 70 years and aortic operation. Her cardiac risk score would be 9, placing her in a Goldman CRI class II, which is associated with a 7% cardiac complication rate. The Goldman CRI was widely accepted. It provided a simple, yet statistically valid means of prioritizing cardiac risk assessment. The analysis found that many characteristics, such as smoking, diabetes, hypertension, and angina, were not significant for predicting adverse cardiac outcomes. One criticism of the Goldman study was that detection of 2 Hospital Physician Board Review Manual

3 Table 1. Goldman Cardiac Risk Index Variables by Point Value Variable some variables, such as third heart sound, jugular venous distension, and aortic stenosis murmur might vary according to the clinical skills of the examining physician. Another issue was that postoperative ECGs and cardiac enzymes were not routinely obtained on every patient but only if symptoms or physician suspicions warranted assessment. Thus, it is likely that the Goldman study underestimated the number of cardiac complications. The Goldman CRI has been tested by several investigators. Some found it predictive of outcome, but others did not. An important issue identified was that the Goldman CRI significantly underestimated cardiac risk when applied to vascular surgery patients. In each risk class, more adverse outcomes occurred than the CRI had predicted. From an epidemiologic standpoint, this is understandable. The Goldman CRI was created from a population of general surgery patients. When applied to a higher-risk population, such as vascular surgery patients, a greater number of adverse events is not unexpected. Nonetheless, for the clinician, it was important to recognize that vascular surgery patients required special attention. Detsky Modified CRI Points S 3 or jugular venous distension 11 Recent MI 10 Non-sinus rhythm or premature atrial 7 contractions on ECG More than 5 premature ventricular 7 contractions Age greater than 70 years 5 Emergency operation 4 Poor general medical condition 3 Intraperitoneal, intrathoracic or aortic 3 operation Important valvular aortic stenosis 3 ECG = electrocardiogram; MI = myocardial infarction. Adapted with permission from Goldman L, Caldera DL, Nussbaum SR, et al. Multifactorial index of cardiac risk in noncardiac surgical procedures. N Engl J Med 1977;297:848. Copyright 1977 Massachusetts Medical Society. All rights reserved. Detsky and colleagues judged that the Goldman CRI needed significant alterations to be useful for preoperative medical consultation. In 1986, they proposed a Table 2. Goldman Cardiac Risk Index Risk Classes Cardiac Class Point Range Complication Rate (%) I II III IV > Adapted with permission from Goldman L, Caldera DL, Nussbaum SR, et al. Multifactorial index of cardiac risk in noncardiac surgical procedures. N Engl J Med 1977;297:848. Copyright 1977 Massachusetts Medical Society. All rights reserved. modified CRI based on consensus opinions of their cardiology consultation team. 6 New variables were added, such as clinical angina, history of pulmonary edema, and any previous MI prior to the evaluation. Some of the Goldman variables were deleted, such as jugular venous distension, third heart sound, and type of surgery (ie, intra-abdominal, intrathoracic, or aortic). Thus, despite superficial resemblance, the Detsky modified CRI contained major differences from the original Goldman CRI. The new modified index depended more on historic information than physical findings. Over time, neither index has been shown to be clearly superior to the other. Furthermore, neither the Goldman nor the Detsky CRI could accurately define the low-risk patient. In other words, some patients classified in the lowest risk category by either of these methods still experienced adverse cardiac outcomes. Eagle Risk Factors In 1985, Boucher and colleagues reported that preoperative dipyridamole thallium imaging could predict postoperative ischemic cardiac events in patients undergoing vascular surgery. 7 This discovery was a breakthrough because such patients often could not perform exercise testing and had a high incidence of asymptomatic CAD. Subsequently, Eagle and colleagues demonstrated that both clinical criteria and dipyridamole thallium scan results could be correlated to outcome in vascular surgery patients. 8,9 A key proposal was that clinical variables alone were sufficient to identify low- and high-risk patients. Clinical variables included advanced age (> 70 years), Q-wave on the ECG, diabetes, history of angina, and history of ventricular dysrhythmia. Patients with 0 risk factors were classified as low-risk; patients with 1 or 2 risk factors were classified as intermediate risk, and patients with 3 or more risk factors were classified as high-risk. In low- and high-risk patients, dipyridamole General Surgery Volume 8, Part 3 3

4 Table 3. Revised Cardiac Risk Index: Predictors of Cardiac Risk High-risk type of operation History of ischemic heart disease History of congestive heart failure History of cerebrovascular disease Preoperative treatment with insulin Preoperative serum creatinine > 2.0 mg/dl Data from Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 1999;100: thallium scanning did not add to risk prediction. Instead, the dipyridamole thallium scan was most effectively applied to patients with intermediate clinical risk. 8,9 Revised CRI In 1999, Lee et al collaborated with Goldman to create the Revised Cardiac Risk Index. 10 This index was based on a study of 4315 patients aged 50 years or older who were undergoing major noncardiac procedures. Patients were assessed for major postoperative cardiac complications including MI, pulmonary edema, ventricular fibrillation or primary cardiac arrest, and complete heart block. Six independent predictors of such complications were identified and determined to be of equal weight (Table 3). 10 A specific patient s risk could be determined by adding the number of individual risk factors as shown in Table 4. According to the revised CRI, the patient in the case study presented would have 4 risk factors: history of ischemic heart disease, highrisk surgery, insulin treatment, and a creatinine level greater than 2 mg/dl. This places her in a high-risk category, which is associated with a 9% to 11% cardiac complication rate. The Revised CRI differs dramatically from the original Goldman CRI. New variables of diabetes requiring insulin, renal insufficiency, and cerebrovascular disease have replaced the older variables of recent MI, jugular venous distension or presence of a third heart sound, aortic stenosis, and arrhythmia. Thus, broad indicators of medical conditions have replaced specific cardiovascular findings. 10 The authors compared the Revised CRI to 3 other risk stratification tools: the original Goldman CRI, the Detsky Modified CRI, and the American Society of Anesthesiologists (ASA) Physical Status classification. Receiver-operator characteristic curve analysis suggested superiority of the Revised CRI. This analysis also Table 4. Revised Cardiac Risk Index: Risk Categories Derivation Validation Cohort Cohort Number of Complication Complication Risk Factors Rate, % Rate, % Data from Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 1999;100: showed the ASA classification to be superior to both the original Goldman index and the Detsky modified index. 10 Simple observation of the data is also revealing. The original Goldman and Detsky indices stratified a large majority of patients into the lowest risk category. Despite being the lowest risk category, cardiac complications were still noted. The Revised CRI provides a more even distribution of patients into risk classes. However, only the ASA physical status classification method identified a low-risk class in which no cardiac complications occurred. 10 Finally, the variable of aortic stenosis is absent from the Revised CRI. Our opinion is that significant aortic stenosis still warrents concern. PREOPERATIVE CARDIAC DIAGNOSTIC TESTING Is further preoperative cardiac work-up necessary for the case patient, or should the surgical team proceed with the proposed surgery? ROLE OF DIAGNOSTIC TESTING Several cardiac tests are available for the preoperative assessment of cardiac risk. These tests include ventricular function and ejection fraction determination, echocardiography, stress testing (including exercise and pharmacologic stress testing), coronary arteriography, magnetic resonance coronary angiography, and coronary artery calcium score determined by electron beam computed tomography. 11 Several algorithms for cardiac testing have been proposed to assess the perioperative cardiac risks, which attests to the fact that preoperative cardiac evaluation is by no means a simple task that can be easily and uniformly applied to every patient. 2 4 The potential morbidity and expense of diagnostic 4 Hospital Physician Board Review Manual

5 testing requires that these tests be applied selectively, and several organizations have published guidelines regarding their use. The consensus is that preoperative assessment of the patient for noncardiac surgery ought to be based on clinical assessment with specialized testing reserved for selected patients. 2,4 In addition to factors determined by the patient s overall cardiac and medical condition, other considerations play a significant role in screening patients who are about to undergo noncardiac surgical procedures. These factors include the urgency, complexity, duration, and expected fluid shifts and hemodynamic stresses of the procedure. In the presence of an emergency (eg, perforated viscus, ruptured abdominal aneurysm, other types of intra-abdominal bleeding), the preoperative cardiac evaluation will be limited. An experienced anesthesia team is vital to the ultimate outcome of the procedure. Aggressive intraoperative monitoring with the use of pulmonary artery catheters or transesophageal echocardiography may help guide the intraoperative management of the patient. Every attempt is made to limit the blood pressure swings and myocardial stresses that will contribute to the development of intraoperative MI. Overall, cardiac testing appears to play a more important role in the management of patients who are to undergo elective or semi-elective procedures, such as the patient presented in the case study. RESTING LEFT VENTRICULAR FUNCTION The resting left ventricular function as reflected by the left ventricular ejection fraction (LVEF) has been used as a method of predicting perioperative cardiac morbidity. LVEF can be measured noninvasively by radionuclide ventriculography or echocardiography and invasively by contrast ventriculography. Radionuclide ventriculography using a multi-gated acquisition scan is a commonly used technique for LVEF measurement. This technique has minimal radiation exposure and allows for the evaluation of left ventricular systolic and diastolic function at rest and during exercise. It also can allow visualization of myocardial wall motion abnormalities. Early studies suggested that measurement of LVEF can be a good predictive test of the occurrence of MI in patients undergoing vascular procedures. When the LVEF was less than 30%, MIs occurred at an alarmingly high rate (approximately 70%) following lower extremity revascularization and at a rate of approximately 80% following aortic procedures. 12 Other investigators, however, found no correlation between the degree of left ventricular dysfunction and the development of perioperative MIs. The reasons behind these inconsistent reports can be explained by the fact that LVEF reflects the function of the myocardium as a whole rather than that of the myocardium at risk for perioperative MI. It is the myocardium at risk that typically results in major morbidity if it progresses into infarction. Low LVEF is usually the result of prior infarction and scarring of the myocardium. Although a low LVEF can predict the development of postoperative congestive heart failure, it is not necessarily predictive of the development of MI. More importantly, the presence of a normal LVEF does not preclude the presence of significant CAD as evidenced by the large number of individuals with normal ejection fractions who undergo coronary artery bypass graft (CABG) for severe, correctable CAD. A low LVEF may be associated with a poor outcome; however, a normal LVEF by no means guarantees a good outcome. STRESS TESTING Perioperative MI typically results from the inability of the coronary circulation and the myocardium to handle the stress imposed by the surgical procedure. The myocardium s response to provocative tests that mimic the perioperative and intraoperative conditions can be helpful in identifying patients at risk for developing postoperative MI. Such tests can stratify the risks for developing perioperative cardiac events and can help identify a high risk group. The stress is induced either by exercise or by using pharmacologic agents. The most commonly used pharmacologic agents are vasodilator drugs (eg, dipyridamole, adenosine) or inotropic agents (eg, dobutamine). Myocardial response can be measured using ECG monitoring, echocardiography, or radionuclide imaging. Exercise Treadmill Testing With exercise testing, the ECG, heart rate, and blood pressure are monitored continuously while the patient exercises. The treadmill is the most commonly used form of exercise. For individuals who cannot use the treadmill, stationary bicycling or isometric hand gripping is used. Throughout the exercise, the patient is closely monitored. The test is halted if the patient develops any cardiac ischemic symptoms. The goal for each patient is to achieve the age- and sex-predicted exercise level without developing cardiac symptoms or electrocardiographic evidence of ischemia. For the exercise stress test to be useful, the patient needs to reach at least 85% of the targeted maximal heart rate. The limitations of the exercise stress test relate to the fact that a large number of patients may not be able to achieve the desired heart rate goal, resulting in an indeterminate test result. 12 This result typically occurs in General Surgery Volume 8, Part 3 5

6 A A B Figure 1. (A) Decreased thallium uptake in the inferolateral aspect of the myocardium after adenosine injection. (B)Thallium uptake in the inferolateral aspect of the myocardium at rest, indicating a reperfusion defect. B Figure 2. Persistent decreased uptake of thallium in the anterolateral aspect of the myocardium (A) after adenosine injection and (B) at rest, indicating a fixed defect or attenuation because of breast tissue or the diaphragm. patients with peripheral vascular disease (PVD), who may be limited by their claudication and unable to achieve the desired goal. Similarly, elderly patients with sedentary lifestyle may not be able to complete the test or reach the desired exercise level. Another major limitation is that, even in patients who reach the desired exercise target, the absence of ECG findings of ischemia or the absence of development of cardiac symptoms does not necessarily rule out the presence of silent CAD. Exercise treadmill testing has a specificity for significant CAD that ranges from 50% to 80% and sensitivity that ranges from 74% to 88%, with a false-positive rate of 40% and, more importantly, a false-negative rate of 15%. 13 Stress Echocardiography Both dipyridamole and dobutamine have been used to stress the heart before evaluating it with echocardiography. 14 Dobutamine stress echocardiography is frequently used. Dobutamine stresses the heart by stimulating β 1 -, β 2 -, and α 1 -adrenergic receptors. It increases myocardial oxygen demand by its positive inotropic and chronotropic effects. The test is performed by infusing dobutamine at 2.5 µg/kg body weight per min. The infusion rate is increased by increments of 5 µg/kg per min to reach 30 to 50 µg/kg per min. Cardiac wall motion is then evaluated using transthoracic echocardiography. The infusion is stopped and the test is terminated if any of the following develops: symptoms of angina, decline in systolic blood pressure of more than 15 mm Hg, ST depressions greater than 2 mm, significant arrhythmias, new regional wall motion abnormality or thickening in 2 or more wall segments, or side effects such as nausea or headache. Dobutamine stress echo (DSE) has been found to be effective in identifying patients at risk of developing myocardial events following aortic surgery. In one study, 29% of patients with abnormal DSE results had cardiac events. In the presence of normal DSE testing, only 4.6% of the patients developed cardiac events. 15 The reported sensitivity of DSE is 92%, with a specificity of 44%. Its positive predictive value for cardiac complications after aortic surgery was reported to be 29% with a negative predictive value of 95%. 16 The specificity of DSE has been reported to improve with use of transesophageal echocardiography. 17 This test should not be used in patients with severe aortic stenosis, severe hypertension, unstable angina, recent MI, tachyarrhythmias, or poor left ventricular function. Radionuclide Cardiac Imaging Radionuclide cardiac imaging is typically conducted by inducing maximal coronary artery blood flow pharmacologically or through exercise. At the peak of coronary artery blood flow, a radionuclide is injected and myocardial images are immediately taken. When the myocardium is stressed, the ischemic areas will have decreased blood flow and thus decreased uptake. Scarred myocardium will not take up the radionuclide. Cardiac imaging is then repeated once the coronary flow is back to its baseline level and compared to the images taken during peak coronary artery blood flow. Areas that show new uptake of thallium are reversible defects and represent myocardium at risk for infarction (Figure 1). Areas that continue to show no uptake are fixed defects and represent scarred myocardium at the site of previous infarction (Figure 2). False-positive results are noted in patients with significant left ventricular hypertrophy. They also can be attributed to soft 6 Hospital Physician Board Review Manual

7 tissue attenuation by breast tissue or the diaphragm. False-negative results are seen in patients with severe occlusive CAD causing persistent poor uptake of radionuclide even at rest. Several radionuclide agents have been used, including thallium 201 (thallous chloride Tl 201), technetium Tc 99m sestamibi, and technetium Tc 99m teboroxime. Thallium 201 is the most commonly used radionuclide in myocardial perfusion studies. Its uptake by the myocardium is linearly related to blood flow, and its myocardial wash-out half-life is 4 to 6 hours. Consequently, the second set of cardiac images is obtained 4 hours after the initial thallium injection. Another source of variation in radionuclide testing is the method of inducing maximal coronary blood flow. Exercise has been replaced mainly with pharmacologic agents, including dipyridamole and adenosine. Dipyridamole thallium scan. Dipyridamole exerts its effect through adenosine. The vasodilatation caused by dipyridamole is greater than that produced by exercise but without the associated increase in myocardial consumption. Dipyridamole thus exaggerates regional differences in coronary blood flow because the vasodilation will be more pronounced in disease-free vessels as compared to stenotic vessels. Several side effects have been reported with the use of intravenous dipyridamole, including lightheadedness, headache, chest pain, shortness of breath, flushing, blurred vision, hypotension, nausea, and vomiting. These side effects are reversed by intravenous aminophylline. Dipyridamole thallium scanning has been extensively used in stratifying the patients undergoing noncardiac vascular surgery procedures. 7,8,14,16 Reversible defects have been identified to be strong predictors of perioperative cardiac events. Fixed defects typically are indicative of previous myocardial events and infarctions. Several studies have warned against the perception of fixed defects as benign, demonstrating them to be associated with increased incidence of perioperative myocardial events In other studies, fixed defects have been identified as strong predictors of late cardiac events. 22 The controversy regarding fixed defects is likely to be related to false-negative results, whereby severely ischemic myocardium may persistently show reduced flow even at rest and after the disappearance of the effect of dipyridamole. In a meta-analysis of dipyridamole thallium imaging from 1985 to 1994, the incidence of postoperative myocardial events was 11.4% in patients with fixed defects and 18.1% in patients with reversible defects. 23 Death or MI occurred in 6.8% of patients with fixed defects and 9.0% of those with reversible defects. This test has been criticized for being oversensitive, with a positive predictive value as low as 4% to 20%. However, the negative predictive value of a normal scan has been uniformly high, approximating 99% for MI or cardiac death. 14,16 The accuracy and efficacy of dipyridamole thallium scanning in predicting perioperative myocardial events can be improved by using clinical parameters of cardiac disease to determine who should undergo scanning. 9 In patients determined to be at very low risk, the scan is most likely to be negative. In patients at high risk, the test can be skipped and replaced directly by coronary angiography. If scans are obtained only in the intermediate-risk groups, the sensitivity and specificity of dipyridamole thallium scanning are likely to increase. Adenosine thallium scan. Adenosine thallium scan follows the same principles as those of dipyridamole thallium scanning. Adenosine has a half-life of less than 10 s, whereas the half-life of dipyridamole is 30 min. The side effects of adenosine are similar to those of dipyridamole and are reversed by aminophylline given intravenously. Side effects occur in up to 80% of patients; however, treatment with aminophylline is only necessary in 0.8% of cases. 24 Contraindications to using adenosine and dipyridamole are severe bronchospasm and asthma; history of allergy to adenosine, dipyridamole, or aminophylline; hypotension; or atrioventricular type 2 heart block. All of the above noninvasive stress tests appear to be comparable. The American Heart Association (AHA) and American College of Cardiology (ACC) recommend that exercise testing be used in patients likely to reach exercise goals. 4 The remaining tests (ie, DSE, dipyridamole thallium scans) are to be selectively chosen based on the presence of contraindications and the institutional experience ACC/AHA GUIDELINES FOR PREOPERATIVE EVALUATION The increasing utilization of specialized testing for preoperative cardiac assessment represented a major expenditure. In 1996, the ACC and the AHA responded to concerns regarding the high costs of such testing by providing an organized approach to preoperative assessment that recognized issues of cost containment. 1 These guidelines were recently updated using an evidence-based approach. 4 Instead of using a CRI based on points, the guidelines utilize an algorithm based on clinical predictors of increased risk (Table 5), risk level of intended surgery (Table 6), and the patient s functional capacity. A patient with a major clinical predictor (Table 5) is not considered a candidate for an elective operation. General Surgery Volume 8, Part 3 7

8 Table 5. Clinical Predictors of Increased Perioperative Cardiac Risk Major Unstable coronary syndromes Recent MI* with evidence of important ischemic risk by clinical symptoms or noninvasive study Unstable or severe angina (Canadian class III or IV) Decompensated congestive heart failure Significant arrhythmias High-grade atrioventricular block Symptomatic ventricular arrhythmias in the presence of underlying heart disease Supraventricular arrhythmias with uncontrolled ventricular rate Severe valvular disease Intermediate Mild angina pectoris (Canadian class I or II) Prior MI by history or pathologic Q waves Compensated or prior congestive heart failure Diabetes mellitus (particularly insulin-dependent) Renal insufficiency Minor Advanced age Abnormal ECG (left ventricular hypertrophy, left bundlebranch block, ST-T abnormalities) Rhythm other than sinus (eg, atrial fibrillation) Low functional capacity (eg, inability to climb 1 flight of stairs with a bag of groceries) History of stroke Uncontrolled systemic hypertension ECG = electrocardiogram; MI = myocardial infarction. *The American College of Cardiology National Database Library defines recent MI as greater than 7 days but less than or equal to 1 month (30 days). May include stable angina in patients who are unusually sedentary. Campeau L. Grading of angina pectoris. Circulation 1976;54: Reprinted with permission from Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Circulation 2002; ;105:1261. Copyright The American College of Cardiology Foundation and American Heart Association, Inc. Table 6. Cardiac Risk* of Various Surgical Procedures High (reported cardiac risk often > 5%) Emergent major operations, particularly in the elderly Aortic and other major vascular surgery Peripheral vascular surgery Anticipated prolonged surgical procedures associated with large fluid shifts and/or blood loss Intermediate (reported cardiac risk generally < 5%) Carotid endarterectomy Head and neck surgery Intraperitoneal and intrathoracic surgery Orthopaedic surgery Prostate surgery Low (reported cardiac risk generally < 1%) Endoscopic procedures Superficial procedures Cataract surgery Breast surgery *Combined incidence of cardiac death and nonfatal myocardial infarction. Do not generally require further preoperative cardiac testing. Adapted with permission from Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Circulation 2002;105:1262. Copyright The American College of Cardiology Foundation and American Heart Association, Inc. These major clinical predictors are severe conditions that may themselves demand hospitalization. In contrast, patients with only minor clinical predictors are eligible for most operations. The exception is patients with minor predictors who have poor functional capacity and are scheduled for a high-cardiac-risk operation. This exception is important because aortic and peripheral vascular surgery (except carotid endarterectomy) are classified as high-cardiac-risk operations. Vascular disease may limit these patients ability to exercise, and thus specialized noninvasive testing may be necessary prior to scheduling surgery. Patients with intermediate predictors of risk (Table 5) are eligible for intermediate- or low-risk surgery if they have good functional capacity. Noninvasive testing such as dipyridamole thallium scanning is indicated for intermediate-risk patients if functional capacity is poor or a high-risk surgery is planned. Inability to climb a flight of stairs or walk uphill represents poor functional capacity. 8 Hospital Physician Board Review Manual

9 A summary based on the recent ACC/AHA recommendations is provided on Table 7. FURTHER PREOPERATIVE WORK-UP OF CASE PATIENT The patient in this case study has intermediate predictors of risk (ie, prior MI, diabetes, renal insufficiency) and is to undergo a high cardiac risk operation. Based on the ACC/AHA guidelines, further stress testing is indicated. In view of her sedentary lifestyle, she is unlikely to achieve her target stress level using an exercise stress test. She has none of the previously described contraindications for a DSE. Either an adenosine thallium scan, dipyridamole thallium scan or a DSE can provide further assessment of her cardiac status. The choice will be based on institutional preference and resources. The case patient undergoes an adenosine thallium scan that reveals multiple reperfusion defects. LVEF is 60%. Evidence of a fixed defect is attributed to breast tissue attenuation. What should be done when a patient shows evidence of cardiac ischemia on preoperative cardiac stress testing? Each case should be individualized. In general, further cardiac testing is needed in patients with evidence of significant myocardium at risk for ischemia when stressed. Such testing is usually invasive and is conducted to further delineate the cardiac anatomy with a focus toward coronary revascularization. CARDIAC CATHETERIZATION Left-sided cardiac catheterization represents the gold standard for the preoperative evaluation of patients suspected of having CAD. Right heart catheterization is rarely used in the preoperative cardiac evaluation. Rather, it is typically used intraoperatively to guide management in the intraoperative and postoperative period. Catheterization of the left ventricle is typically accomplished under fluoroscopic guidance using a catheter advanced from the femoral or brachial artery. The information obtained from this testing includes pressure measurements, angiography of the coronary arteries, and contrast injection of the left ventricle. This test also provides a measurement of gradient between the left ventricular systolic and aortic systolic pressure in the presence of aortic valve stenosis. The coronary angiography provides a visualization of the coronary anatomy, which is defined by injecting contrast from the left heart catheter after engaging the right and left coronary ostia. Table 7. Summary of ACC/AHA Recommendations for Preoperative Cardiac Evaluation Directly to surgery no cardiac screening tests Emergency surgery Coronary revascularization (CABG) within 5 years without recurrent symptoms or signs Recent favorable coronary evaluation within 2 years without new symptoms or signs Low-risk procedures* Patients without major clinical predictors Intermediate-risk procedures Patients with intermediate clinical predictors and moderate/ excellent functional capacity Patients with minor or no clinical predictors and moderate/excellent functional capacity High-risk procedures Patients with minor or no clinical predictors, with moderate or excellent functional capacity Cardiac screening tests prior to surgery High-risk procedures Intermediate clinical predictors irrespective of functional capacity Minor or no clinical predictors with poor functional capacity Intermediate-risk procedures Intermediate clinical predictors with poor functional capacity Cardiac catheterization prior to surgery Major cardiac predictor irrespective of procedure Adapted from Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Circulation 2002;105:1260. ACC = American College of Cardiology; American Heart Association; CABG = coronary artery bypass graft. *See Table 6. See Table 5. Although this test represents the gold standard with respect to defining the coronary anatomy, its invasiveness and costs precludes its use as a screening test in the preoperative evaluation of patients undergoing noncardiac surgery. Furthermore, the relationship between the degree of CAD and its physiologic significance is not yet determined. An area of stenosis may be supplying an General Surgery Volume 8, Part 3 9

10 already infarcted myocardium. Alternatively, an area of myocardium supplied by a stenotic coronary artery also may be receiving significant blood supply from collateral vessels. Finally, coronary angiography is an invasive procedure with morbidity and mortality rates that are not inconsequential. Thus, it is logical to reserve coronary angiography for patients who could benefit from coronary revascularization even if no vascular procedure was needed or who are candidates for coronary revascularization because the findings on coronary angiography can result in a change in the proposed surgical procedure or its cancellation. Case Patient Clinical Course and Outcome Cardiac catheterization was performed, and revealed 3-vessel CAD. She underwent CABG. Two months later, she presented for her abdominal aortic procedure. She tolerated the procedure well and her postoperative course was uneventful. Would this patient have had a similar outcome had she not undergone coronary revascularization prior to her aortic surgery? ROLE OF CORONARY REVASCULARIZATION PRIOR TO SURGERY Coronary revascularization prior to a proposed noncardiac surgical procedure can be achieved by percutaneous transluminal coronary angioplasty (PTCA) or CABG surgery. When performed prior to a noncardiac procedure, PTCA has been reported to have a cardiac morbidity ranging from 5.6% to 11%, with a mortality rate of 1.9%. 25,26 In the United States, inhospital mortality rates between 1987 and 1990 following PTCA ranged from 2.5% to 3.9%. 27 Furthermore, CABG surgery was required following PTCA in 2.8% to 5.3% The role of CABG prior to noncardiac surgery has been mostly studied in patients with vascular disease undergoing vascular reconstructions To date, there are no prospective randomized trials that support the use of prophylactic CABG prior to a noncardiac surgical procedure. Studies conducted with respect to carotid surgery have yielded controversial results. Although it seems intuitive that patients with significant CAD who are about to undergo major vascular procedures would be better served by correcting their underlying coronary occlusive disease, the data to support such an approach are mixed. This is especially true when the morbidity of the coronary angiography and coronary revascularization is included in the overall mortality and morbidity. Furthermore, the presence of PVD is by itself a marker for increased mortality following any coronary revascularization. The mortality rate for coronary revascularizations in patients with PVD was 5.2% compared with a mortality rate of 1.2% in patients without PVD. 33 Similarly, in patients older than 80 years, the mortality rate of CABG is 4 times greater in those with PVD than in those without vascular disease. 34 In a meta-analysis by Mason et al, 32 vascular surgery without preliminary cardiac catheterization and coronary revascularization was found to produce better clinical results. Furthermore, in several studies in which patients were identified as having non-correctable CAD, aortic surgery was still possible and was performed without an excessive increase in mortality. 21 In a recent large randomized study (N = 510), coronary artery vascularization prior to elective vascular surgery in patients with stable CAD did not significantly alter long-term (2.7 y) mortality. 35 The benefits of coronary revascularization can be localized to 2 time periods. The first relates to the shortterm and immediate perioperative period. The second one relates to long-term survival and well being 5 years from the time of the surgery. In data from the Coronary Artery Surgery Study, the perioperative mortality after noncardiac operations when only medical therapy was given for CAD was 2.4% compared to 0.5% in patients without CAD. 36 In those with CAD who underwent preliminary CABG surgery, the mortality rate was 0.9%. 36 These results included mortality from the CABG procedure, which usually ranges from 0% to 5.2%. 33 CABG mortality rates increase with age, being approximately 5.2% in patients younger than 75 years and rising to 9.5% in those older than 75 years. 36 With respect to long-term benefits, it is important to remember that 20% of patients leaving the hospital following noncardiac vascular operations will develop a cardiac event within 2 years. In the classic Cleveland Clinic study, the 5-year survival of patients with PVD who underwent a CABG was 72% compared to 43% in those who refused CABG and 22% in those with severe, noncorrectable CAD. 33 The mortality rate of CABG is doubled when the procedure is performed within 6 hours of PTCA. Thus, the recommendation to perform a CABG prior to noncardiac surgery should be based on its own merits rather than as a means to get a patient through a proposed noncardiac surgical procedure. 4 CONCLUSION Preoperative cardiac evaluation in patients undergoing noncardiac surgery should be individualized. The 10 Hospital Physician Board Review Manual

11 approach will depend on the urgency of the procedure, the complexity of the operation, and the patient s overall medical condition. In all patients, optimization of the cardiac condition is valuable. Patients with emergent conditions should undergo emergent surgery without delay. Similarly, patients undergoing minor procedures should proceed through surgery unless there is evidence of major cardiac risk factors. Patients undergoing intermediate- and high-risk surgery represent the group that most requires screening. Patients with no risk factors and an active lifestyle or who have recently undergone coronary revascularization and are without new symptoms may undergo the proposed surgical procedure without any additional cardiac testing. Patients with sedentary lifestyles or intermediate risk factors should undergo additional testing, including either an exercise treadmill test, stress echocardiography, or radionuclide cardiac imaging. A patient with a high risk of a cardiac event may benefit from direct coronary angiography unless he or she is not a candidate for coronary revascularization. REFERENCES 1. Guidelines for perioperative cardiovascular evaluation for noncardiac surgery. Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). J Am Coll Cardiol 1996;27: Guidelines for assessing and managing the perioperative risk from coronary artery disease associated with major noncardiac surgery. American College of Physicians. Ann Intern Med 1997;127: Palda VA, Detsky AS. Perioperative assessment and management of risk from coronary artery disease. Ann Intern Med 1997;127: Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Circulation 2002;105: Goldman L, Caldera DL, Nussbaum SR, et al. Multifactorial index of cardiac risk in noncardiac surgical procedures. N Engl J Med 1977;297: Detsky AS, Abrams HB, McLaughlin JR, et al. Predicting cardiac complications in patients undergoing non-cardiac surgery. J Gen Intern Med 1986;1: Boucher CA, Brewster DC, Darling RC, et al. Determination of cardiac risk by dipyridamole-thallium imaging before peripheral vascular surgery. N Engl J Med 1985; 312: Eagle KA, Singer DE, Brewster DC, et al. Dipyridamolethallium scanning in patients undergoing vascular surgery. Optimizing preoperative evaluation of cardiac risk. JAMA 1987;257: Eagle KA, Coley CM, Newell JB, et al. Combining clinical and thallium data optimizes preoperative assessment of cardiac risk before major vascular surgery. Ann Intern Med 1989;110: Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 1999;100: Greenland P, LaBree L, Azen SP, et al. Coronary artery calcium score combined with Framingham score for risk prediction in asymptomatic individuals [published erratum appears in JAMA 2004;291:563]. JAMA 2004;291: Pasternack PF, Imparato AM, Bear G, et al. The value of radionuclide angiography as a predictor of perioperative myocardial infarction in patients undergoing abdominal aortic aneurysm resection. J Vasc Surg 1984;1: Cutler BS, Wheeler HB, Paraskos JA, Cardullo PA. Applicability and interpretation of electrocardiographic stress testing in patients with peripheral vascular disease. Am J Surg 1981;141: Beleslin BD, Ostojic M, Stepanovic J, et al. Stress echocardiography in the detection of myocardial ischemia. Headto-head comparison of exercise, dobutamine, and dipyridamole tests. Circulation 1994;90: Lalka SG, Sawada SG, Dalsing MC, et al. Dobutamine stress echocardiography as a predictor of cardiac events associated with aortic surgery. J Vasc Surg 1992;15: McPhail NV, Ruddy TD, Calvin JE, et al. A comparison of dipyridamole-thallium imaging and exercise testing in the prediction of postoperative cardiac complications in patients requiring arterial reconstruction. J Vasc Surg 1989;10: Prince CR, Stoddard MF, Morris GT, et al. Dobutamine two-dimensional transesophageal echocardiographic stress testing for detection of coronary artery disease. Am Heart J 1994;128: Cutler BS. Interpretation and results of intravenous dipyridamole thallium scintigraphy. Semin Vasc Surg 1991;4: Kiat H, Berman DS, Maddahi J, et al. Late reversibility of tomographic myocardial thallium-201 defects: an accurate marker of myocardial viability. J Am Coll Cardiol 1988;12: O Donnell TF. Dipyridamole-thallium scanning for elective aortic aneurysms: its influence on patient management in relationship to contemporary clinical noninvasive General Surgery Volume 8, Part 3 11

12 cardiac screening. Semin Vasc Surg 1991;4s: Kresowik TF, Bower TR, Garner SA, et al. Dipyridamole thallium imaging in patients being considered for vascular procedures. Arch Surg 1993;128: Cutler BS, Hendel RC, Leppo JA. Dipyridamole-thallium scintigraphy predicts perioperative and long-term survival after major vascular surgery. J Vasc Surg 1992;15: Shaw LJ, Eagle KA, Gersh BJ, Miller DD. Meta-analysis of intravenous dipyridamole-thallium-201 imaging (1985 to 1994) and dobutamine echocardiography (1991 to 1994) for risk stratification before vascular surgery. J Am Coll Cardiol 1996;27: Cerqueira MD, Verani MS, Schwaiger M, et al. Safety profile of adenosine stress perfusion imaging: results from the Adenosine Multicenter Trial Registry. J Am Coll Cardiol 1994;23: Allen JR, Helling TS, Hartzler GO. Operative procedures not involving the heart after percutaneous transluminal coronary angioplasty. Surg Gynecol Obstet 1991;173: Huber KC, Evans MA, Bresnahan JF, et al. Outcome of noncardiac operations in patients with severe coronary artery disease successfully treated preoperatively with coronary angioplasty. Mayo Clin Proc 1992;67: Jollis JG, Peterson ED, DeLong ER, et al. The relation between the volume of coronary angioplasty procedures at hospitals treating Medicare beneficiaries and shortterm mortality. N Engl J Med 1994;331: Gersh BJ, Kronmal RA, Frye RL, et al. Coronary arteriography and coronary artery bypass surgery: morbidity and mortality in patients ages 65 years or older. A report from the Coronary Artery Surgery Study. Circulation 1983;67: Huber KC, Evans MA, Bresnaham JF, et al. Outcome of noncardiac operations in patients with severe coronary artery disease successfully treated preoperatively with coronary angioplasty. Mayo Clin Proc 1992;67: Mangano DT, Goldman L. Preoperative assessment of patients with known or suspected coronary disease. N Engl J Med 1995;333: McCollum CH, Garcia-Rinaldi R, Graham JM, DeBakey ME. Myocardial revascularization prior to subsequent major surgery in patients with coronary artery disease. Surgery 1977;81: Mason JJ, Owens DK, Harris RA, et al. The role of coronary angiography and coronary revascularization before noncardiac vascular surgery. JAMA 1995;273: Hertzer NR, Beven EG, Young JR, et al. Coronary artery disease in peripheral vascular patients. A classification of 1000 coronary angiograms and results in surgical management. Ann Surg 1984;199: Mullany CJ, Darling GE, Pluth JR, et al. Early and late results after isolated coronary artery bypass surgery in 159 patients aged 80 years and older. Circulation 1990;82 (5 Suppl):IV McFalls EO, Ward HB, Moritz TE, et al. Coronary-artery revascularization before elective major vascular surgery. N Engl J Med 2004;351: Foster ED, Davis KB, Carpenter JA, et al. Risk of noncardiac operation in patients with defined coronary disease: The Coronary Artery Surgery Study (CASS) registry experience. Ann Thorac Surg 1986;41: Copyright 2005 by Turner White Communications Inc., Wayne, PA. All rights reserved. 12 Hospital Physician Board Review Manual