Preoperative Cardiology Consultation

Director of Vascular Anesthesia, Department of Anesthesia & Critical Care, Beth Israel Deaconess Medical Center, and Associate Professor of Anaesthesia, Harvard Medical School.Received from the Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, Massachusetts.In a 1998 survey of New York metropolitan area anesthesiologists, surgeons, and cardiologists, 1the three specialties were in general agreement that important purposes of a cardiology consultation are to treat an inadequately treated cardiac condition before surgery (e.g. , unstable angina or congestive heart failure [CHF]), to provide data to use in anesthesia management (e.g. , ischemic threshold of tachycardia on stress test or left ventricular ejection fraction), and possibly to diagnose a medical condition before surgery (e.g. , the cause of a new-onset atrial fibrillation). The yield of a cardiology consultation, in terms of new therapy or significant effect on patient management strategy prior to surgery, has, however, been reported to vary widely from 10% to more than 70%. 1–3The reasons why the consultation process often falls short of ideal are probably multifold, but may often originate from vague understanding of the consultation process. The physician initiating the consultation, whether an anesthesiologist or a surgeon, may not make it clear to the cardiologist why the consultation is being sought. In a retrospective review of 202 cardiology consultations at a university hospital, 2it was found that 108 just asked for an “evaluation,” 79 asked for a “clearance,” and 9 did not specifically request anything. Only six posed a specific question. As a result, the consultant often makes broadly inclusive, general remarks about perioperative management of the patient and may recommend preoperative diagnostic work-up that does not influence the patient's outcome but prolongs the hospital stay. 4In this review are presented (1) the indications for cardiology consultations as implied in the American College of Cardiology–American Heart Association (ACC–AHA) guidelines on preoperative cardiac evaluation, 5and (2) suggestions on how the ACC–AHA guidelines may be critically applied to, and improve, the consultation process.The ACC–AHA guidelines on preoperative cardiac evaluation were published initially in 1996 and were also endorsed by the Society of Cardiovascular Anesthesiologists and the Society for Vascular Surgery. 6An updated version of the guidelines was published in 2002. 5The guidelines were based on the then-available literature as well as expert opinions from the disciplines of anesthesiology, cardiology, electrophysiology, vascular medicine, vascular surgery, and noninvasive cardiac testing. The guidelines provided an 8-step algorithm for stratifying the patient's risks and triaging to either surgery or cardiac evaluation.The first three steps of the guidelines consider the urgency of the operation and the recency of cardiac evaluation and intervention. If the operation is not emergent and if there has not been recent cardiac evaluation and/or intervention with no significant interim changes, then the remainder of the guidelines are applied. Steps 4 through 7 deal with an assessment of the patient's clinical predictors of cardiac risk, functional status, and the risk of the surgery proposed. Step 8, or noninvasive cardiac testing to further define the patient's risk, is indicated (1) if the patient has a major clinical predictor, (2) if the patient has an intermediate clinical predictor and either has poor functional status or is undergoing a high-risk surgery, or (3) if the patient has poor functional status and is undergoing a high-risk surgery. As defined by the ACC–AHA, major clinical predictors are unstable coronary syndrome, decompensated congestive heart failure (CHF), significant arrhythmias, and severe valvular disease. Intermediate clinical predictors are mild angina pectoris, history of myocardial infarction (MI) or CHF, diabetes mellitus, and chronic renal failure with serum creatinine greater than 2 mg/dl. A high-risk surgery carries a greater than 5% perioperative risk of cardiac events such as MI, CHF, or death and is exemplified by emergent major operations, especially in the elderly, aortic, and other major vascular procedures, peripheral vascular bypass procedures, and anticipated prolonged surgical procedures associated with large fluid shifts and/or blood loss. An intermediate-risk surgery carries 1–5% perioperative risk of cardiac events and is exemplified by carotid endarterectomy, intraperitoneal and intrathoracic surgery, orthopedic surgery, head and neck surgery, and prostate surgery. Poor functional status is defined as inability to perform activities of greater than 4 metabolic equivalents (METs), where one MET is the rest-ing metabolic rate or the amount of oxygen consumed while sitting at rest and is 3.5 ml O2· kg−1· min−1. Activities that require less than 4 METS are exemplified by driving, cooking, bowling, walking for exercise at 5 km/h or less, raking leaves, and golfing while riding a cart. 7For the purpose of deciding whether to seek a cardiology consultation, the guidelines may be modified as shown in figure 1. The noncardiologist physician, whether an anesthesiologist or a surgeon, should assess (1) the presence or absence of major or intermediate clinical predictors, (2) the patient's functional status, and (3) the risk of surgery, as well as obtain information about previous cardiac intervention and testing. A satisfactory history and physical examination would usually provide all of these pieces of information. Then an anesthesiologist or a surgeon may apply the algorithm of figure 1to determine whether consultation is indicated. If a cardiologist is vaguely asked to provide an “evaluation,” the consultant is actually being asked to determine whether cardiology consultation is indicated, and if so, to take the necessary diagnostic and therapeutic measures.A pervading theme of the updated ACC–AHA guidelines is that “in general, indications for further cardiac testing and treatments [in the operative setting] are the same as those in the nonoperative setting.”6A patient who did not need an echocardiogram previously does not suddenly need one, because that patient is now facing surgery. In figure 1, there are three primary indications for cardiology consultations. (1) A patient with a major clinical predictor, i.e. , a condition that requires acute cardiac intervention such as unstable coronary syndrome should have preoperative cardiology consultation unless in need of an emergent, life-saving operation. Next, if there has not been corrective cardiac intervention or surgery within 5 yr without significant interim change in symptoms or a favorable cardiac evaluation within 2 yr, a cardiology consultation may be sought to perform any indicated noninvasive testing for stratification of risks; (2) for patients undergoing an intermediate-risk surgery who have both a poor functional capacity and an intermediate clinical predictor; or (3) for patients undergoing a high-risk surgery who have either an intermediate clinical predictor of cardiac risk or a poor functional capacity.It should also be noted that while the ACC–AHA guidelines give examples of surgeries that may be classified as high-risk or intermediate-risk, the definition is according to the actual perioperative risk. Application of the algorithm to different groups of surgeries should be tailored to each institution's risks, whenever possible. For example, the rate of stroke or death is related to the annual surgical volume for carotid surgeries. In a survey of hospitals in Georgia, 8a less than 3% rate of stroke or death after carotid endarterectomy was achieved only in hospitals that performed more than 50 carotid endarterectomies per year. In hospitals where carotid endarterectomy is rarely performed and carries a greater than 5% rate of perioperative cardiac events, it should be considered a high-risk surgery and the algorithm applied accordingly. While institution- and procedure-specific complication rates should ideally be used in application of the algorithm, monitoring such data may rarely be possible to most physicians. 9Use of the ACC–AHA classification of surgical risk would provide an acceptable approach to obtaining cardiac consultations in the absence of such data.Indications for percutaneous coronary intervention or surgery for CAD are ever evolving with new studies of the relative merits of medical and surgical therapies, 10and there is often disagreement even among the experts on what constitutes the optimal therapy. 11Several randomized trials in the 1970s and 1980s demonstrated that surgical therapy may be preferable to medical therapy in patients with stenosis of the left main coronary artery or in patients with three-vessel disease and left ventricular dysfunction, but there appears to be no clear benefit of surgery for other patients with CAD. 12Studies comparing percutaneous transluminal coronary angioplasty (PTCA) and medical therapy have shown that angioplasty improves exercise performance and reduces coronary symptoms to a greater extent than standard medical therapy, but may be associated with a slightly increased rate of major cardiac events such as myocardial infarction (MI) and death. 13–15In the second Randomized Intervention Treatment of Angina (RITA-2) trial, the incidence of death or MI was 6.3% in patients treated with PTCA and 3.3% for patients treated with conservative medical care over a median follow-up period of 2.7 yr (P = 0.02). 15Medical therapy, including an aggressive cholesterol-lowering regimen, may be associated with a significantly lower rate of cardiac events compared with PTCA. 16Studies that compared coronary artery bypass graft surgery (CABG) with medical therapy were performed before the introduction of an aggressive cholesterol-lowering therapy and a new comparison such as with the ongoing COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive druG Evaluation) trial may shed a different light on the relative benefits. 17Depending on the results of studies such as the COURAGE trial, a significant percentage of patients one refers to the cardiology consultant for the major clinical predictor of unstable coronary syndrome may be treated medically, rather than interventionally.Anticoagulants such as low-molecular weight heparin and antiplatelet medications such as glycoprotein IIb/IIIa inhibitors play prominent roles in current medical therapy for unstable angina. 18Therefore, patients whom the cardiology consultant opts to treat medically may not be any less enigmatic than patients who receive interventional therapy before a noncardiac surgery. Just as patients presenting for noncardiac surgery shortly after PTCA have an increased risk of restenosis or bleeding (see section 3), 19patients on medical therapy may have the same problem of increased bleeding with continuance of the anticoagulant or of major cardiac event with discontinuance of anticoagulant regimen in the perioperative period. Whether noncardiac surgery should proceed will depend on the relative urgency of the coronary syndrome and the noncardiac surgical indication, with the understanding of the increased risk involved.For patients with stable angina, development of oral glycoprotein IIb/IIIa inhibitors and inclusion of these medications in the treatment of stable angina will necessitate development of guidelines on perioperative management of these medications.The cardiac risk of a patient with known or suspected CAD undergoing major noncardiac surgery can be reduced with perioperative use of a β-adrenergic blocker. Recent studies with perioperative use of β-adrenergic blockade suggest that patients with suspected or known CAD may undergo major noncardiac surgery with relative safety when they are given β-adrenergic blockade perioperatively. 20–22In particular, Poldermans et al. 22studied 112 high-risk patients undergoing elective abdominal aortic or infrainguinal vascular reconstruction who had new reversible wall motion abnormalities during preoperative dobutamine stress echocardiography. The patients received bisoprolol or placebo perioperatively. Bisoprolol reduced 30-day mortality from 17 to 3.4% and nonfatal MI from 17 to 0%. It should be noted that the 3.4% mortality of the bisoprolol group compares favorably to the sum of the mortality of routine CABG (3%*) and of noncardiac surgery in survivors of CABG (1.7%23). The benefit of perioperative bisoprolol was durable to at least 2 yr after surgery. 24Thus for those patients who are able to take a β-adrenergic blocker, “prophylactic” coronary revascularization may not convey a survival advantage in the immediate perioperative period, even when preoperative testing indicates the presence of uncorrected CAD. For these patients, preoperative noninvasive or invasive cardiac testing itself, and therefore, preoperative cardiology consultation to perform such testing, may not be indicated. Indications 2 and 3 of figure 1might be altered to read that if amenable, β-adrenergic blockade should be used perioperatively and cardiac consultation is not indicated for preoperative work-up. Any indicated cardiac workup and follow-up may be done postoperatively in a routine manner.The beneficial effect of perioperative β-adrenergic blockade has been demonstrated not only with bisoprolol, 22,24but also with atenolol, 20,21esmolol, 25labetalol, 26oxprenolol, 26and metoprolol 27and may thus be a class effect, rather than being particular to a specific β-adrenergic blocking agent. More important than which agent is used may be how it is used. Raby et al. 25advocated using a β-adrenergic blocking agent to keep the heart rate 20% below each patient's ischemic threshold or the lowest heart rate at which the patient has been demonstrated to experience myocardial ischemia. Such a regimen was shown to be beneficial in a small cohort (N = 26) of patients undergoing vascular surgery. Tailoring the dose of the β-adrenergic blocker to each patient may be logical, but no rationale for choosing a target rate 20% below the ischemic threshold was presented. In many patients, the ischemic threshold is not known. A reasonable rule of thumb may be that the anesthesiologist should use a β-adrenergic blocker perioperatively to achieve a heart rate that is as low as possible without causing inadequate levels of coronary perfusion pressure, and that if the ischemic threshold is known, is below it.Despite the literature evidence on the benefit of perioperative β-adrenergic blockade, it has been in surgical relative to the use of a β-adrenergic blocker or poor ventricular or heart and to β-adrenergic of perioperative use of β-adrenergic how well the are without the perioperative period a in which to the can be and if a effect is perioperative use of an may a benefit to perioperative β-adrenergic blockade has been of the literature on the of demonstrated that while myocardial be the incidence of myocardial infarction or death did not with the evidence for the benefit of perioperative use of an is not as as that for the benefit of β-adrenergic blockade and the of using an perioperatively should not be considered to the need for cardiology consultation when indicated 2 and 3 of a β-adrenergic blocker or other is in the perioperative period, then the surgical surgeon and the should a follow-up with either a an or a physician, that if indicated, the patient may be on the on a on the benefit of a β-adrenergic blocker or an perioperatively is the ACC–AHA no is given to the presence of a intermediate clinical predictor of cardiac risk the presence of intermediate clinical the literature indicates that the perioperative risk of cardiac events with the of risk a of patients undergoing elective major noncardiac et al. six predictors of high-risk surgery, history of history of CHF, history of preoperative treatment with and preoperative creatinine greater than the same as the intermediate clinical predictors of the ACC–AHA The presence of 1, or more than 3 of these risk was associated with and risks, of cardiac was also a complication rate in patients with poor functional capacity in those with functional It may be noted that even in the by et al. , high-risk surgery is an predictor of risk and poor functional capacity is associated with a poor The of intermediate clinical predictors can be by Step of the algorithm in figure clinical predictor and poor functional to intermediate clinical predictor and poor functional or intermediate clinical the ACC–AHA coronary revascularization may be considered if the of the invasive and/or noninvasive cardiac testing is for significant CAD. Revascularization either by percutaneous transluminal coronary angioplasty (PTCA) with or without or by coronary artery bypass graft surgery (CABG) may survival benefit in patients with CAD (see section to the patient to undergo coronary revascularization before noncardiac surgery to the perioperative cardiac risk of the surgery, three should be are (1) that the risk of coronary and coronary revascularization does not the risk of the noncardiac surgery performed without (2) that coronary revascularization should significantly lower the cardiac risk of the performed noncardiac surgery, with the of risk greater than the risk of coronary and and (3) that the from coronary revascularization should be short that the noncardiac surgery, especially if it is is not these are not any indicated revascularization may be performed after the noncardiac one to the risk of coronary and especially relative to the risk of the noncardiac surgery performed without the risk of coronary and revascularization is to vary from one to the the mortality rate from CABG in the was 3% in 1998 The mortality was if the surgery was by a for CABG and aortic and for CABG and if the surgery was emergent for emergent CABG and for emergent for surgeries for elective for for and for the for those in and for those in It should be also noted that for patients with a major clinical predictor of cardiac risk such as unstable angina or evolving MI, the cardiac surgical intervention is to be performed or thus the mortality and of For PTCA performed the mortality from the in was and had to be to where the mortality may be as as if the from PTCA to CABG is less than however, one to consider not only the mortality associated with the but also immediate the often results in inadequate of the or coronary The mortality and the immediate rate of PTCA depend on the of the coronary and the urgency with which the is PTCA of coronary with class in the of an acute MI, the mortality is over CABG rate is over the rate of nonfatal major is and the immediate rate of PTCA is only A large of these patients may be to a significant risk with no immediate benefit when to PTCA. elective PTCA of coronary with class may a mortality of less than a nonfatal complication rate of and an immediate rate of one should be of the mortality and rates for either CABG or PTCA each specific at or when revascularization medical and to the risk of with the noncardiac surgery without coronary The information may not be and the cardiologist consultant and the surgical will be left to make the The should then be compared with studies such as those of Poldermans et al. , that patients with preoperative dobutamine stress who undergo high-risk surgery can have a low 30-day mortality rate of 3.4% and nonfatal MI rate of with perioperative use of a β-adrenergic blocker in the absence of one to that the cardiac risk of the noncardiac surgery will be significantly by prior cardiac whether by CABG or PTCA. the of in the risk of the noncardiac surgery should be to or greater than the risk of cardiac intervention. data are on the cardiac risk of major noncardiac surgery in patients who have major clinical predictors of cardiac risk or noninvasive cardiac of the presence of uncorrected CAD and who then undergo the noncardiac surgery without coronary In one review of patients undergoing or emergent vascular surgeries within of a MI, the cardiac complication rate was no trials have the benefit of coronary either by CABG or in the perioperative cardiac risk of noncardiac surgery. the other retrospective that those who CABG may have a reduced cardiac risk at the of a noncardiac surgery and that this reduced risk may be with that of those with no CAD. the such et al. from a review of patients of the that prior surgical revascularization is associated with a lower MI and death rate in high-risk noncardiac compared with medical therapy for the benefit of PTCA on noncardiac surgery is et al. patients who noncardiac surgeries after PTCA and reported only one cardiac patients Such data that PTCA may be cardiac events during noncardiac of coronary revascularization is that benefit should be in such a that the noncardiac surgery is not et al. that the risk of cardiac after noncardiac surgery be reduced by prior but only if the PTCA and the noncardiac surgery was greater than et al. that if a noncardiac surgery is performed within of PTCA with a then the risk of and death in the perioperative period be from MI and 2 from major bleeding in patients or 20% mortality in A recent also a patient who had a cardiac after after PTCA with and an emergent PTCA to the are used in PTCA and recent in and antiplatelet have reduced the 30-day rate to as low as and are before PTCA with and for on the risk of The risk of after the surgery may be associated with of the and the risk of may be increased by surgical may have been antiplatelet therapy in the period may not during the perioperative period. undergoing a major noncardiac surgery during the period a significant in that of the antiplatelet therapy the risk of and MI while with or without anticoagulant regimen such as the risk of major bleeding In the data suggest that if the noncardiac surgery be for to after then revascularization by PTCA may not be to the cardiac the period, et al. cardiac death rate mortality in patients a CABG and a peripheral vascular surgery, cardiac death rate mortality in patients a CABG and then a peripheral vascular surgery 5 to 3 after CABG within the same and cardiac death rate in patients who had a CABG and then a peripheral vascular surgery during a to yr after In review of patients undergoing aortic or peripheral vascular bypass surgeries within a of CABG (N = 30-day mortality was than a of a over in other patients undergoing (P data suggest that if the patient requires a noncardiac surgery that be or and also has indications for coronary coronary revascularization either by PTCA or CABG may not in The anesthesiologist or the surgeon may a cardiology consultant to determine whether to proceed with noncardiac surgery with β-adrenergic blockade and consider coronary revascularization such a will be based on the rather than literature ACC–AHA guidelines were from studies in which patients were of the Heart data that and many risk the of each was different the a of CAD at any of the major risk than what may a or predictor of perioperative cardiac risk for may be different than for For example, unstable angina is classified as a major clinical predictor and stable angina as an intermediate clinical predictor of cardiac risk in the ACC–AHA it should be that is a less of CAD in of such as and coronary artery are to be more in than in are three as to have a compared to when to for of an CAD in with was less than if they had less than risk for but was if more than 2 risk were the ACC–AHA guidelines in this one may need to require that example, at and 7 of have intermediate clinical predictors before one cardiac testing with cardiology In in history of that has not been demonstrated to be from CAD may not need to be considered an intermediate clinical predictor, unless risk for CAD et al. a retrospective of perioperative cardiac in patients undergoing elective surgery, of whom were In the the cardiac risk and the New York Heart Association functional classification were not predictors of perioperative cardiac were cardiac and therapy. predictors of cardiac in this were and a history of by previously MI, a history of angina more than to therapy, or more than on coronary that in the ACC–AHA is as a clinical predictor of risk. the results of et al. are and in other the of in perioperative cardiac risk may be greater in than in mortality rate MI is in than in mortality at rate at is also in than in the of an acute MI as a major clinical predictor of perioperative cardiac risk may be even greater in than in for a exercise stress test were for A exercise stress test in is more to be than in a test in who are able to exercise is less to be a than in because of the lower of CAD among with exercise stress testing that have been noted in a of to or change and a of to levels to or general exercise stress test as a preoperative test probably does not have a in the evaluation of but should be by such as stress or the ACC–AHA a severe valvular disease is considered a major clinical predictor of cardiac risk and should to of or of the noncardiac surgery and of cardiac and/or possible surgery. review studies have that in the of patients with severe aortic stenosis they may undergo a noncardiac surgery with relative as as the perioperative care is provided with management of the associated with et al. reported on experience with patients with severe area who were not or aortic and who a noncardiac surgery. was only one cardiac event with no for a complication rate of about would favorably with the mortality rate for aortic reported by the Society of In a of patients with severe area however, the same group reported perioperative and compared patients with significant area with with preoperative risk other than undergoing surgeries. complication rates were not significantly different the patients with severe may undergo indicated noncardiac surgery provided that the presence of severe is and the patients receive and perioperative care with of the of For the algorithm of figure severe may be from the of major clinical a preoperative cardiac consultation may not be indicated for of there should be an follow-up of are patients with severe stenosis or severe valvular who undergo noncardiac surgery without prior surgery. In of patients with severe et al. reported that in review of such patients, there was a incidence of but not of any cardiac and for preoperative cardiac evaluation of patients should a in the for of surgery. The ACC–AHA guidelines provide for possible of surgery in patients with a major clinical predictor of cardiac risk, but the guidelines are not specific when the operative risk is that the surgery should no be an even after work-up and/or Such a risk may be based on surgical and/or the patient's cardiac and this may be an area where the cardiology consultant may with of that to an perioperative risk will be important in management of medical and in the patients and with and of this is for cardiology consultation based on the ACC–AHA guidelines on preoperative cardiac evaluation have been with a review of of the Application of the algorithm requires that the physician initiating the consultation, whether an anesthesiologist or a surgeon, determine whether cardiology consultation is indicated, from of presence or absence of clinical predictors, the patient's functional status, and the risk of the surgery. In general, patients who require an emergent surgery should proceed to surgery with or without a preoperative cardiology consultation and may receive the in the period as For noncardiac surgery, cardiology consultation may be indicated (1) for patients with a major clinical predictor of cardiac risk such as unstable coronary syndrome or evolving MI, (2) for patients who are undergoing a high-risk surgery, who have either poor functional status or an intermediate clinical predictor of cardiac risk such as stable angina, history of MI or CHF, diabetes mellitus, or chronic renal and (3) for patients who are undergoing an intermediate-risk surgery, who have both poor functional status and an intermediate clinical predictor, or even in the absence of poor functional status, or more intermediate clinical For patients with indications 2 or revascularization within 5 yr or favorable cardiac evaluation within 2 yr with no significant interim in symptoms the need for cardiology for these patients, β-adrenergic blockade in the perioperative period may lower cardiac risk who have been on a β-adrenergic blockade perioperatively should have an follow-up with a an or a physician, that β-adrenergic blockade may be on a if indicated. a cardiology consultation is the relative risks and of interventional medical treatments require obtaining cardiology consultation, the physician initiating the consultation should the for consultation and the consultant to the relative risks and of any further diagnostic or therapeutic steps and follow-up