The new thinking on perioperative medicine
From the May ACP Observer, copyright © 2006 by the American College of Physicians.
By Deborah Gesensway
An elderly patient wanted hip replacement surgery so she could walk comfortably again. But she was in her early 90s, lived in a nursing home, suffered from heart disease—and had a family who was very nervous about the prospect of surgery.
To advise her and to alleviate her family's concerns, Philadelphia general internist Roger B. Daniels, ACP Member, could draw upon the whole armamentarium of perioperative medicine advances over the last decade: a simple, validated prediction tool in the Revised Cardiac Risk Index; perioperative beta-blockade; non-invasive pharmacological stress testing; and even the possibility of revascularization before the non-cardiac surgery. He reassured the family and the patient that she could safely undergo surgery, and the procedure was a success. The patient has since opted to replace her other hip as well.
Experts say internists should rethink the use of stress tests, even for patients at intermediate risk of cardiac complications from non-cardiac surgery.
"It's very exciting because it means that age has become much less a limiting factor for the availability of these surgical methods," Dr. Daniels said, reflecting on the dramatic advances in perioperative medicine he has witnessed over the course of his 38-year medical career.
But all these advances in perioperative medicine still can't guarantee a complication-free surgery. Ischemia, which many consider a harbinger of true cardiac events, occurs in about 30% of patients undergoing non-cardiac surgery. And true cardiac events—meaning post-operative myocardial infarction (MI)—happen to between 1% and 5% of unselected patients undergoing non-cardiac surgery, according to Amir K. Jaffer, ACP Member, a hospitalist and medical director of the Internal Medicine Preoperative Assessment Consultation and Treatment (IMPACT) Center at the Cleveland Clinic in Cleveland.
Moreover, perioperative medicine experts point out that new trials are calling into question some of the core assumptions that have guided internists over the past 10 years in perioperative evaluations. Beta-blockers are being used both too much and too little, they say, while standard practices like stress testing and revascularization may be significantly overused.
Plus, new developments in cardiac care are complicating preoperative management strategies—and the only practice guideline on preoperative cardiac evaluation, from the American College of Cardiology/American Heart Association, is in the process of being updated and not due out until later this year. In the meantime, internists are being urged to rethink some basic perioperative principles. (Also see "New perioperative guideline from ACP.")
Rethinking stress testing
One of the most common mistakes general internists make today is regularly ordering stress tests, even for patients at low risk of developing cardiac complications from surgery, according to perioperative medicine experts.
'If a patient is at relatively low risk for cardiac complications, a stress test is not going to be very useful.'
—H. Quinny Cheng, ACP Member
"If a patient is at relatively low risk for cardiac complications, a stress test is not going to be very useful," said H. Quinny Cheng, ACP Member, a hospitalist and associate clinical professor of medicine at the University of California, San Francisco (UCSF). "It will either be normal, which confirms what you already know, or it will be positive." However, if the baseline risk is relatively low, even a positive stress test does not predict a very high complication rate because the test has poor positive predictive value, he explained.
New research has also led experts to rethink knee-jerk stress testing for patients at intermediate risk of cardiac complications following non-cardiac surgery.
For these patients, the decision to order a preoperative stress test is often the first step toward coronary artery revascularization, a veritable "tune-up" before elective major surgery. That strategy doesn't pay off, according to the results of a study published in the Dec. 30, 2004, issue of New England Journal of Medicine.
In the study, 510 patients with coronary artery disease scheduled for vascular operations at 18 Veterans Affairs hospitals were randomly assigned to receive either coronary artery revascularization before their surgery or medical management alone. When the researchers found no difference between the two groups in terms of their 30-day or long-term outcomes following surgery, they concluded that "revascularization before elective vascular surgery among patients with stable cardiac symptoms cannot be recommended."
"A common mistake is going down the revascularization pathway without having a clear sense of what the potential downsides of revascularization may be in terms of delaying surgery or harming the patient," Dr. Cheng said.
Doing stress testing and revascularization is fine, he added, "if you were going to stent the patient or do a CABG [coronary artery bypass graft] anyway." But those interventions shouldn't be used just because a patient is about to get a new hip, abdominal aortic aneurysm repair or a gastrointestinal procedure.
"Don't revascularize [a patient] thinking that that is going to make his outcomes better," Dr. Cheng said. Not only is there an upfront risk of injury from the prophylactic procedure, but long-term improvement is questionable.
The real world
Scientific evidence may make the case against routine preoperative stress testing. But in the real world, as everyone knows, evidence and practice do not always mesh. In St. Louis, general internist Roger Guillemette, MD, who is with the four-physician Bellevue Internal Medicine, said he is frustrated trying to put this evidence into practice. In his experience, many anesthesiologists cancel elective surgeries if such cardiac workups are not done.
"This is my biggest struggle," he said. "They want us to do cardiac workups, meaning stress test and sending for revascularization, if the patient has some strain on their ECG and longstanding hypertension and controlled cholesterol and blood pressure."
That can be a challenge, Dr. Cheng agreed. "I don't think it's a major concession to acquiesce to a noninvasive stress test to reassure the anesthesiologist," he said. "However, I would not pursue invasive work-up or intervention unless you feel it is indicated."
"There is no such thing as a preoperative tune-up unless you want to tune [patients] up anyway," said Andrew D. Auerbach, ACP Member, a hospitalist, UCSF assistant professor of medicine and editorial consultant for the College's PIER module on cardiac preoperative risk assessment. (Dr. Auerbach also co-authored a paper on routine preassessment strategies published in the March 14, 2006, issue of Circulation.)
If you would not recommend that a patient undergo angioplasty or bypass generally, he said, don't advise it just because that patient is about to have an operation. And "if there is no role for preoperative revascularization, that gets us to ask if there is a role for doing any noninvasive stress testing ever."
Of course, Dr. Auerbach added, there are some exceptions to that rule, such as when a patient is at extraordinarily high risk but for some reason is not having symptoms, or if you cannot rule out that the patient has unstable coronary disease. But some of the exceptions people consider—such as age or functional status, neither of which is included in the Revised Cardiac Risk Index—do not hold up to scrutiny. (See "Revised Cardiac Risk index: calculating patient risk.")
"Age by itself is not a major predictor of perioperative cardiac complications" in the absence of either a history of heart disease or symptoms, Dr. Cheng said. He recommended that doctors look at a patient's "physiological age" rather than her "chronologic age." If a 95-year-old can walk a few blocks without symptoms, for example, then he recommends a physician treat her the same as he would a younger patient.
In terms of prophylactic revascularization, another wrinkle is that one of the most popular ways of revascularizing patients—with a drug-eluting stent—has some preoperative complications of its own.
"This change in coronary stenting is having a major impact on internists and their patients," said Howard H. Weitz, FACP, a cardiologist at Thomas Jefferson University in Philadelphia and an expert on preoperative medicine for surgical patients.
Dr. Weitz startled an internal medicine audience at ACP's Annual Session last year when he presented a case of a patient who had received a drug-eluting stent nearly three months before needing vascular surgery. The patient's clopidogrel was discontinued prior to surgery and he then developed acute stent thrombosis.
"I'm getting calls everyday about what to do about patients who had drug-coated stents put in and then they need surgery," Dr. Weitz said. "My concern is that the internist, whom they will go to for preoperative assessment, may not be aware of how important a longer duration of uninterrupted antiplatelet therapy is."
The FDA has approved the Cypher stent, which is coated with sirolimus, in conjunction with three months of aspirin and the antithrombotic drug clopidogrel. The Taxus drug-eluting stent requires six months of the dual antiplatelet therapy.
If antiplatelet therapy is stopped prematurely, the risk of thrombosis goes up significantly, said Dr. Weitz. On the other hand, if clopidogrel is not stopped at least five days before surgery, the risk of perioperative bleeding increases.
His advice? Avoid using drug-eluting stents, despite their obvious benefits in terms of lower restenosis risk, if a patient is going into another surgery in the near future. In that case, a bare metal stent that requires a shorter course of dual antiplatelet therapy may be the best option.
"If the stent is in and you have to do surgery fairly soon, you are between a rock and a hard place," Dr. Cheng added. In such cases, he recommended that internists discuss the relative bleeding risk vs. the thrombosis risk with the surgeon.
The right way to use beta-blockers
State-of-the-art medical management has also recently gotten more complicated. After a decade in which the message was pounded home that prescribing perioperative beta-blockers significantly lowers the risk of MI and cardiac death associated with surgery, two studies published last year questioned that strategy.
That leaves most experts in perioperative medicine anxiously awaiting the results of the international,10,000-patient Perioperative Ischemic Evaluation Study (POISE) trial. Until then, they caution that beta-blockers are not for everyone—and that they are being used both too much and too little.
The "too much" charge comes mainly from a study published in the July 28, 2005, issue of New England Journal of Medicine that looked back—using an administrative database—at nearly 800,000 patients who underwent non-cardiac surgery. The researchers found that when patients had Revised Cardiac Risk Index scores of 2 or more (intermediate or high risk), they benefited from beta-blockade. But if their score was 0 or 1, meaning they were at low risk of developing cardiac complications from surgery, they not only failed to be helped by the beta-blocker, but may have been harmed by it.
And a meta-analysis of 22 different randomized controlled trials of beta-blockers published in the Aug. 6, 2005, issue of British Medical Journal also questioned the medicine's efficacy (but not safety) when used perioperatively in non-cardiac surgery. The analysis concluded that, to date, the evidence is "encouraging but too unreliable to allow definitive conclusions to be drawn."
"Be judicious. Be cautious." That's what Dr. Auerbach said he took away from those articles. "What we are trying to teach our residents and staff here at UCSF is by all means use beta-blockers, but use them in the appropriate patients—and make sure they don't have any other bad things going on before you ramp up their beta-blocker dose."
It may not be that beta-blockers per se are harmful or don't work, he explained; the problem may be more with physicians using them inappropriately, such as giving them to low-risk patients or increasing dosages whenever they see a postoperative patient who is tachicardic or hypertensive. Instead, Dr. Auerbach urged, physicians should evaluate patients thoroughly first to make sure "we are not masking hypoxia, sepsis, pain or pulmonary embolism" with beta-blockers.
Another mistake physicians sometimes make, said the Cleveland Clinic's Dr. Jaffer, is in not giving the beta-blockers in the manner they have been tested: preferably started a couple of weeks before surgery, continued for at least 30 days post-op and then tapered off rather than discontinued abruptly.
According to Dr. Weitz, who is a cardiologist, the need to re-evaluate the use of beta-blockers is long overdue. He has seen patients suffer from the classic beta-blocker side effects of profound bradycardia or hypotension from having been prescribed too much of the drug.
"It took a while for the word to get out there about the benefit of beta-blockers," he said. "And it's taking a while for the word to get out that beta-blockers may not be all they are cracked up to be."
Experts caution, however, that internists should not read more into these two articles than there really is. Beta-blockers still offer tremendous benefit for patients at moderate and high risk of developing cardiac complications of surgery. For every 30-60 patients with multiple risk factors that you treat with a beta-blocker, you will save one life, Dr. Cheng explained. (This contrasts with the data on the medicine's harm: For every 200-500 low-risk patients given the drug, one patient will die.)
A major mistake, therefore, continues to be "too little" beta-blocker use. Studies consistently show that between 40% and 50% of high-risk patients—the ones who clearly benefit from beta-blockers—do not receive the drug at all.
"There is a lot of room for improvement," said Gerald W. Smetana, FACP, a general internist at Beth Israel Deaconess Medical Center and associate professor of medicine at Harvard Medical School. "We know from national literature that only approximately one-third of eligible patients actually receive perioperative beta-blockers."
He is currently helping develop an order set at Beth Israel Deaconess that will prompt physicians during a preoperative evaluation to estimate each person's cardiac risk. That document will have to demonstrate that physicians considered candidacy for perioperative beta-blockers before patients are allowed to proceed to the operating room.
"We don't know what our own prescribing rates are, but our surgical colleagues are the ones who came to us and asked us to help develop this resource," Dr. Smetana said. Despite some recent debate, he added, the consensus is that beta-blockers are still the most effective strategy to reduce cardiac risk for non-cardiac surgery among intermediate and high-risk patients.
"We also eagerly await the results," he said, "of pending large-scale randomized trials to clarify their optimal use."
Deborah Gesensway is a freelance health care writer in Toronto.
The information included herein should never be used as a substitute for clinical judgment and does not represent an official position of ACP.
In last month's April 18 issue, Annals of Internal Medicine published the latest in ACP's series of Clinical Efficacy Assessment Project guidelines. The new guideline—on risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing non-cardiothoracic surgery—is online.
Each risk factor is assigned one point. The presence of two factors identifies a patient at moderate (7%) risk; more than two indicates a high (11%) complication risk rate:
- Suprainguinal vascular
History of ischemic heart disease
- History of myocardial infarction
- History of positive exercise test
- Current complaint of chest pain considered secondary to myocardial ischemia
- Use of nitrate therapy
- ECG with pathological Q waves
History of congestive heart failure
- History of congestive heart failure
- Pulmonary edema
- Paroxysmal nocturnal dyspnea
- Bilateral rales or S3 gallop
- Chest radiograph showing pulmonary vascular redistribution
History of cerebrovascular disease
- History of transient ischemic attack or stroke
Preoperative treatment with insulin
Preoperative serum creatinine of more than 2.0 mg/dL
Source: Circulation, Sept. 7, 1999
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