2017 Update in perioperative medicine: 6 questions answered
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.
WHAT IS THE APPROPRIATE TIMING FOR SURGERY AFTER PCI?
A 2014 American College of Cardiology/American Heart Association guideline recommended delaying noncardiac surgery for 1 month after percutaneous coronary intervention (PCI) with bare-metal stents and 1 year after PCI with drug-eluting stents.15 The guideline suggested that surgery may be performed 6 months after drug-eluting stent placement if the risks of delaying surgery outweigh the risk of thrombosis.15
The primary rationale behind these timeframes was to provide dual antiplatelet therapy for a minimally acceptable duration before temporary interruption for a procedure. These recommendations were influenced largely by observational studies of first-generation devices, which are no longer used. Studies of newer-generation stents have suggested that the risk of stent thrombosis reaches a plateau considerably earlier than 6 to 12 months after PCI.
2016 Revised guideline on dual antiplatelet therapy
Although not separately delineated in the recommendations, risk factors for stent thrombosis that should influence the decision include smoking, multivessel coronary artery disease, and suboptimally controlled diabetes mellitus or hyperlipidemia.17 The presence of such stent thrombosis risk factors should be factored into the decision about proceeding with surgery within 3 to 6 months after drug-eluting stent placement.
Holcomb et al: Higher postoperative risk after PCI for myocardial infarction
Another important consideration is the indication for which PCI was performed. In a recent study, Holcomb et al16 found an association between postoperative major adverse cardiac events and PCI for myocardial infarction (MI) that was independent of stent type.
Compared with patients who underwent PCI not associated with acute coronary syndrome, the odds ratios and 95% confidence intervals (CIs) for major adverse cardiac events in those who underwent PCI for MI were:
- 5.25 (4.08–6.75) in the first 3 months
- 2.45 (1.80–3.35) in months 3 to 6
- 2.50 (1.90–3.28) in months 6 to 12.
In absolute terms, patients with stenting performed for an MI had an incidence of major adverse cardiac events of:
- 22.2% in the first 3 months
- 9.4% in months 3 to 6
- 5.8% in months 6 to 12
- 4.4% in months 12 to 24.
The perioperative risks were reduced after 12 months but still remained greater in patients whose PCI was performed for MI rather than another indication.16
The authors of this study suggested delaying noncardiac surgery for up to 6 months after PCI for MI, regardless of stent type.16
A careful, individualized approach
Optimal timing of noncardiac surgery PCI requires a careful, individualized approach and should always be coordinated with the patient’s cardiologist, surgeon, and anesthesiologist.3,15 For most patients, surgery should be delayed for 30 days after bare-metal stent placement and 6 months after drug-eluting stent placement.3 However, for those with greater surgical need and less thrombotic risk, noncardiac surgery can be considered 3 to 6 months after drug-eluting stent placement.3
Additional discussion of the prolonged increased risk of postoperative major adverse cardiac events is warranted in patients whose PCI was performed for MI, in whom delaying noncardiac surgery for up to 6 months (irrespective of stent type) should be considered.16
CAN WE USE STATINS TO REDUCE PERIOPERATIVE RISK?
Current recommendations from the American College of Cardiology/American Heart Association support continuing statins in the perioperative period, but the evidence supporting starting statins in this period has yet to be fully determined. In 2013, a Cochrane review18 found insufficient evidence to conclude that statins reduced perioperative adverse cardiac events, though several large studies were excluded due to controversial methods and data.
In contrast, the Vascular Events in Noncardiac Surgery Patients Cohort Evaluation (VISION) study,4 a multicenter, prospective, cohort-matched study of approximately 7,200 patients, found a lower risk of a composite primary outcome of all-cause mortality, myocardial injury after noncardiac surgery, or stroke at 30 days for patients exposed to statin therapy (relative risk [RR] 0.83, 95% CI 0.73–0.95, P = .007).4
London et al retrospective study: 30-day mortality rate is lower with statins
In 2017, London et al5 published the results of a very large retrospective, observational cohort study of approximately 96,000 elective or emergency surgery patients in Department of Veterans Affairs hospitals. The patients were propensity-matched and evaluated for exposure to statins on the day of or the day after surgery, for a total of approximately 48,000 pairs.
The primary outcome was death at 30 days, and statin exposure was associated with a significant reduction (RR 0.82; 95% CI 0.75–0.89; P < .001). Significant risk reductions were demonstrated in nearly all secondary end points as well, except for stroke or coma and thrombosis (pulmonary embolism, deep vein thrombosis, or graft failure). Overall, the number needed to treat to prevent any complication was 67. Statin therapy did not show significant harm, though on subgroup analysis, those who received high-intensity statin therapy had a slightly higher risk of renal injury (odds ratio 1.18, 95% CI 1.02–1.37, P = .03). Also on subgroup analysis, after propensity matching, patients on long-term moderate- or high-intensity statin therapy for 6 to 12 months before surgery had a small risk reduction for many of the outcomes, including death.
The authors also noted that only 62% of the patients who were prescribed statins as outpatients received them in the hospital, which suggests that improvement is necessary in educating perioperative physicians about the benefits and widespread support for continuing statins perioperatively.5
