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2017 Update in perioperative medicine: 6 questions answered

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Release date: November 1, 2017
Expiration date: October 31, 2018
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ABSTRACT

The authors performed a MEDLINE search to identify articles published between January 2016 and April 2017 that had significant impact on perioperative care. They identified 6 topics for discussion.

KEY POINTS

  • Noncardiac surgery after drug-eluting stent placement can be considered after 3 to 6 months for those with greater surgical need and lower risk of stent thrombosis.
  • Perioperative statin use continues to show benefits with minimal risk in large cohort studies, but significant randomized controlled trial data are lacking.
  • Patients should be screened for obstructive sleep apnea before surgery, and further cardiopulmonary testing should be performed if the patient has evidence of significant sequelae from obstructive sleep apnea.
  • For patients with atrial fibrillation on vitamin K antagonists, bridging can be considered for those with a CHA2DS2-VASc score of 5 or 6 and a history of stroke, transient ischemic attack, or systemic thromboembolism. Direct oral anticoagulation should not be bridged.
  • Frailty carries significant perioperative mortality risk; systems-based changes to minimize these patients’ risks can be beneficial and warrant further study.


 

References

Perioperative care is increasingly complex, and the rapid evolution of literature in this field makes it a challenge for clinicians to stay up-to-date. To help meet this challenge, we used a systematic approach to identify appropriate articles in the medical literature and then, by consensus, to develop a list of 6 clinical questions based on their novelty and potential to change perioperative medical practice:

  • How should we screen for cardiac risk in patients undergoing noncardiac surgery?
  • What is the appropriate timing for surgery after coronary intervention?
  • Can we use statin therapy to reduce perioperative cardiac risk?
  • How should we manage sleep apnea risk perioperatively?
  • Which patients with atrial fibrillation should receive perioperative bridging anticoagulation?
  • Is frailty screening beneficial for elderly patients before noncardiac surgery?

The summaries in this article are a composite of perioperative medicine updates presented at the Perioperative Medicine Summit and the annual meetings of the Society for General Internal Medicine and the Society of Hospital Medicine. “Perioperative care is complex and changing”1–10 (page 864) offers a brief overview.

HOW TO SCREEN FOR CARDIAC RISK BEFORE NONCARDIAC SURGERY

Perioperative cardiac risk can be estimated by clinical risk indexes (based on history, physical examination, common blood tests, and electrocardiography), cardiac biomarkers (natriuretic peptide or troponin levels), and noninvasive cardiac tests.

American and European guidelines

In 2014, the American College of Cardiology/American Heart Association2 and the European Society of Cardiology11 published guidelines on perioperative cardiovascular evaluation and management. They recommended several tools to calculate the risk of postoperative cardiac complications but did not specify a preference. These tools include:

2017 Canadian guidelines differ

In 2017, the Canadian Cardiovascular Society published its own guidelines on perioperative risk assessment and management.1 These differ from the American and European guidelines on several points.

RCRI recommended. The Canadian guidelines suggested using the RCRI over the other risk predictors, which despite superior discrimination lacked external validation (conditional recommendation; low-quality evidence). Additionally, the Canadians believed that the NSQIP risk indexes underestimated cardiac risk because patients did not undergo routine biomarker screening.

Canadian guidelines on preoperative risk assessment and postoperative monitoring.
Figure 1. Canadian guidelines on preoperative risk assessment and postoperative monitoring.

Biomarker measurement. The Canadian guidelines went a step further in their algorithm (Figure 1) and recommended measuring N-terminal-pro B-type natriuretic peptide (NT-proBNP) or BNP preoperatively to improve risk prediction in 3 groups (strong recommendation; moderate-quality evidence):

  • Patients ages 65 and older
  • Patients ages 45 to 64 with significant cardiovascular disease
  • Patients with an RCRI score of 1 or more.

This differs from the American guidelines, which did not recommend measuring preoperative biomarkers but did acknowledge that they may provide incremental value. The American College of Cardiology/American Heart Association authors felt that there were no data to suggest that targeting these biomarkers for treatment and intervention would reduce postoperative risk. The European guidelines did not recommend routinely using biomarkers, but stated that they may be considered in high-risk patients (who have a functional capacity ≤ 4 metabolic equivalents or an RCRI score > 1 undergoing vascular surgery, or > 2 undergoing nonvascular surgery).

Stress testing deemphasized. The Canadian guidelines recommended biomarker testing rather than noninvasive tests to enhance risk assessment based on cost, potential delays in surgery, and absence of evidence of an overall absolute net improvement in risk reclassification. This contrasts with the American and European guidelines and algorithms, which recommended pharmacologic stress testing in patients at elevated risk with poor functional capacity undergoing intermediate- to high-risk surgery if the results would change how they are managed.

Postoperative monitoring. The Canadian guidelines recommended that if patients have an NT-proBNP level higher than 300 mg/L or a BNP level higher than 92 mg/L, they should receive postoperative monitoring with electrocardiography in the postanesthesia care unit and daily troponin measurements for 48 to 72 hours. The American guidelines recommended postoperative electrocardiography and troponin measurement only for patients suspected of having myocardial ischemia, and the European guidelines said postoperative biomarkers may be considered in patients at high risk.

Physician judgment needed

While guidelines and risk calculators are potentially helpful in risk assessment, the lack of consensus and the conflicting recommendations force the physician to weigh the evidence and make individual decisions based on his or her interpretation of the data.

Until there are studies directly comparing the various risk calculators, physicians will most likely use the RCRI, which is simple and has been externally validated, in conjunction with the American guidelines.

At this time, it is unclear how biomarkers should be used—preoperatively, postoperatively, or both—because there are no studies demonstrating that management strategies based on the results lead to better outcomes. We do not believe that biomarker testing will be accepted in lieu of stress testing by our surgery, anesthesiology, or cardiology colleagues, but going forward, it will probably be used more frequently postoperatively, particularly in patients at moderate to high risk.

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