EXPERT ANALYSIS FROM THE ANNUAL INTERNAL MEDICINE PROGRAM
ESTES PARK, COLO. (FRONTLINE MEDICAL NEWS) – The latest American College of Cardiology/American Heart Association guidelines on perioperative cardiovascular evaluation in patients undergoing noncardiac surgery create several major new responsibilities for physicians doing the evaluations.
Some primary care physicians will be uncomfortable with several of the new recommendations. Perhaps that shouldn’t come as a surprise, since not a single primary care physician was included among the 17 members of the writing committee or the 38-member review committee. Cardiologists of all subspecialties, surgeons, anesthesiologists, hospitalists, a patient representative – all had a voice. But not primary care, Dr. Robert E. Burke noted at a conference on internal medicine sponsored by the University of Colorado.
He was quick to add, however, that the document ( Circulation. 2014 Dec 9;130:e278-333 ) is an impressive, thoughtful piece of work built upon 490 reference citations, and it deserves to be incorporated into daily clinical practice, albeit with a few caveats.
“I think the writing panel did a really good job, but the recommendations are only as good as the evidence – and there are a couple of areas where the evidence is not very strong … It’s up to you and your patient to decide what to do in the controversial areas,” said Dr. Burke, assistant chief of hospital medicine at the Denver VA Medical Center and an internist at the university.
A big change from the previous 2007 ACC/AHA guidelines that Dr. Burke fully supports is that it’s no longer sufficient for the evaluating physician to formally consider only the level of risk posed by the patient’s planned noncardiac surgery, which can vary from a low-risk operation such as cataract surgery to a far-higher-risk procedure addressing, for example, an expanding abdominal aortic aneurysm.
Under the 2014 guidelines, it’s also important to incorporate the surgical risk with an estimate of the individual’s personalized risk of perioperative major adverse cardiovascular events. If the estimated risk is less than 1%, it’s appropriate to proceed straightaway with surgery. In contrast, a 1% or greater perioperative risk is considered high, and it’s then recommended to continue along a lengthy management algorithm. This involves sending the patient for cardiac stress testing provided two conditions are met: the surgeon has to be unwilling to operate without the stress test results and the patient must be willing to undergo CABG before the noncardiac surgery, should the stress test and follow-up cardiac catheterization prove positive.
The guidelines recommend using either of two validated risk-prediction tools for calculating patient risk: the Revised Cardiac Risk Index ( Circulation 1999 Sep 7;100:1043-9 ) or the American College of Surgeons’ National Surgical Quality Improvement Project (NSQIP) predictor . Dr. Burke prefers the NSQIP tool. It predicts multiple cardiac and noncardiac outcomes, including all-cause mortality, within 30 days of surgery, and it has been validated in 525 U.S. hospitals with more than 1 million operations. It’s also quite user-friendly, according to Dr. Burke.
In his view, the guidelines contain two major areas of controvery. One involves the much more aggressive approach to revascularization prior to noncardiac surgery in high-cardiovascular-risk patients compared with the 2007 guidelines. The current guidelines give a class I recommendation to revascularization before noncardiac surgery in patients with left main or triple-vessel disease, as well as two-vessel disease that includes the left anterior descending coronary artery. He said this is a leap that’s not supported by the best available evidence, which comes from the older CARP (Coronary-Artery Revascularization before Elective Major Vascular Surgery) trial.
In CARP, 510 military veterans with documented coronary artery disease and planned vascular surgery were randomized to preoperative revascularization or not. The only exclusions were left main disease, severe aortic stenosis, or a left ventricular ejection fraction below 20%. After 2.8 years of follow-up post surgery, preoperative revascularization wasn’t associated with any mortality benefit in any patient subgroup ( N Engl J Med. 2004 Dec 30;351:2795-804 ).
“I want to restate that in this well-done randomized controlled trial, they could not find any benefit in any outcome in any group within this very-high-risk group of patients. This is really the main trial that exists in perioperative care, and I’m very impressed with the results. The guidelines extrapolate from studies in other areas. This is one area where I think the cardiologists are more interventional than I would like. If I had a patient in my office I could not tell him with a straight face that revascularization before their planned surgery is going to offer them any benefit during up to nearly 3 years of follow-up unless they have left main disease, which was an exclusion in CARP,” Dr. Burke said.
The other main controversy in his view is the ACC/AHA stance on postoperative troponin measurement. It gets a class III rating – meaning no benefit, don’t do it – for routine screening in unselected patients without signs or symptoms suggestive of myocardial ischemia. This recommendation is based upon the absence to date of a prospective trial showing that acting on an elevated postoperative troponin in such patients improves outcomes. True enough, Dr. Burke conceded, but he finds persuasive the results of VISION (Vascular Events in Noncardiac Surgery Patients Cohort Evaluation), a prospective international study in which more than 15,000 patients undergoing noncardiac surgery underwent screening troponin measurements on the first 3 days after surgery.
Thirty-day mortality in the VISION study was 1% in those with a peak fourth-generation troponin of 0.01 ng/mL or less. Mortality was significantly increased in the nearly 12% of patients with a troponin of at least 0.02 ng/mL, climbing to a peak mortality rate of 16.9% in those with a postoperative troponin of 0.30 ng/mL or more ( JAMA. 2012 Jun 6;307:2295-304 ).
“I don’t know of any other test in the perioperative setting that’s as good as this in terms of risk-stratifying patients. We can’t just sit by and let this sort of 30-day mortality rate happen. We should do something. I think that if you treat these asymptomatic patients with an elevated postop troponin as if they had an MI – get them on optimal medical therapy and really push smoking cessation – it’s likely to have a benefit on outcomes,” said Dr. Burke.
He reported having no financial conflicts regarding his presentation.