Troponin, BNP Tests Key to Reducing Perioperative Cardiac Complications After Noncardiac Surgery
Both the average age of patients and the risk of cardiac complications are on the rise among the more than 200 million adults undergoing major noncardiac surgery each year, a new review claims. New methods for estimating and tracking risk, however, may help curb the use of costlier or more intensive tests and consultations.
Writing in the New England Journal of Medicine, P.J. Devereaux, MD, PhD, of McMaster University (Hamilton, Canada), and Daniel I. Sessler, MD, of the Cleveland Clinic (Cleveland, OH), say that an estimated 10 million adults worldwide experience a major cardiac complication in the first 30 days after surgery.
And while efforts to decrease anesthesia-related deaths have been successful (now occurring in fewer than 1 in 100,000 noncardiac surgeries), the authors note postoperative mortality still carries an estimated death rate of 1.5% within 30 days.
A key issue, Devereaux and Sessler say, is developing adequate prediction methods to pinpoint at-risk patients. This includes ongoing efforts to improve cardiac risk indexes and noninvasive testing. Of all of the tests currently in use, measurement of B-type natriuretic peptide (BNP) levels may be the most advantageous. One recent meta-analysis, they note, found that compared with a preoperative clinical risk model alone, the addition of baseline BNP measurement improved the ability to estimate 30-day and ≥ 180-day risk of death and nonfatal MI (net reclassification index: 20%, P < .001; and net reclassification index: 11%, P = .003, respectively).
Additionally, “the cost of measuring natriuretic peptide levels is much lower than the cost of a stress test,” the authors point out, noting that “results can be obtained within minutes with testing at the point of care. [This approach] is thus preferable to stress testing because it is more accurate and convenient, faster, and less expensive. In fact, measurement of natriuretic peptide levels costs less than an internal medicine or cardiology consultation, so the test might be used to decide which patients should be referred for consultation with a specialist.”
No RCTs have identified an effective and safe intervention to prevent perioperative cardiac complications, Devereaux and Sessler say, but a few trials have suggested ways to improve safety. For example, the POISE-2 trial, which failed to show that giving aspirin prior to surgery reduces the risk of death or nonfatal MI, suggested that aspirin should not be administered during the perioperative period but importantly should be reinitiated at 8 to 10 days post-surgery in patients with an indication for long-term aspirin use.
Another promising method for improving outcomes is enhanced monitoring on surgical wards and rapid management of cardiac complications when they occur. The authors cite a recent study from the Cleveland Clinic suggesting that closer monitoring could prevent many cases of hypoxemia in the first 48 hours after surgery. Hypoxemia lasting more than 5 minutes is associated with an increased risk of myocardial ischemia.
One of the greatest challenges in terms of monitoring is how to avoid missing a perioperative MI, give that most patients who develop one have no symptoms, Devereaux and Sessler observe. Since analgesics can mask symptoms of ischemia, they advocate troponin monitoring.
“Without monitoring of perioperative troponin levels during the first few days after surgery in patients with known vascular disease or risk factors, the majority of myocardial infarctions and injuries will go undetected,” they write. “There may also be value in obtaining a measurement of troponin levels before surgery, because it may provide independent prognostic information. In addition, and in centers where a highly sensitive troponin assay is used, physicians may find it helpful to evaluate the preoperative-to-postoperative changes in these levels.”
Devereaux PJ, Sessler DI. Cardiac complications in patients undergoing major noncardiac surgery. N Engl J Med. 2015;373:2258-2269.
- Devereaux reports grant support from Abbott Diagnostics, Boehringer Ingelheim, Covidien, Octopharma, Roche Diagnostics, and Stryker.
- Sessler reports grant support from Covidien and VectraCor.