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Should we stop aspirin before noncardiac surgery?

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In patients with cardiac stents, do not stop aspirin. If the risk of bleeding outweighs the benefit (eg, with intracranial procedures), an informed discussion involving the surgeon, cardiologist, and patient is critical to ascertain risks vs benefits.

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In patients using aspirin for secondary prevention, the decision depends on the patient’s cardiac status and an assessment of risk vs benefit. Aspirin has no role in patients undergoing noncardiac surgery who are at low risk of a major adverse cardiac event.1,2

Aspirin used for secondary prevention reduces rates of death from vascular causes,3 but data on the magnitude of benefit in the perioperative setting are still evolving. In patients with coronary stents, continuing aspirin is beneficial,4,5 whereas stopping it is associated with an increased risk of acute stent thrombosis, which causes significant morbidity and mortality.6

SURGERY AND THROMBOTIC RISK: WHY CONSIDER ASPIRIN?

The Vascular Events in Noncardiac Surgery Patients Cohort Evaluation (VISION) study7 prospectively screened 15,133 patients for myocardial injury with troponin T levels daily for the first 3 consecutive postoperative days; 1,263 (8%) of the patients had a troponin elevation of 0.03 ng/mL or higher. The 30-day mortality rate in this group was 9.8%, compared with 1.1% in patients with a troponin T level of less than 0.03 ng/mL (odds ratio 10.07; 95% confidence interval [CI] 7.84–12.94; P < .001).8 The higher the peak troponin T concentration, the higher the risk of death within 30 days:

  • ng/mL or less, risk 1.0%
  • ng/mL, risk 4.0%
  • to 0.29 ng/mL, risk 9.3%
  • 0.30 ng/mL or greater, risk 16.9%.7

Myocardial injury is a common postoperative vascular complication.7 Myocardial infarction (MI) or injury perioperatively increases the risk of death: 1 in 10 patients dies within 30 days after surgery.8

Surgery creates substantial physiologic stress through factors such as fasting, anesthesia, intubation, surgical trauma, extubation, and pain. It promotes coagulation9 and inflammation with activation of platelets,10 potentially leading to thrombosis.11 Coronary thrombosis secondary to plaque rupture11,12 can result in perioperative MI. Perioperative hemodynamic variability, anemia, and hypoxia can lead to demand-supply mismatch and also cause cardiac ischemia.

Aspirin is an antiplatelet agent that irreversibly inhibits platelet aggregation by blocking the formation of cyclooxygenase. It has been used for several decades as an antithrombotic agent in primary and secondary prevention. However, its benefit in primary prevention is uncertain, and the magnitude of antithrombotic benefit must be balanced against the risk of bleeding.

The Antithrombotic Trialists’ Collaboration13 performed a systematic review of 6 primary prevention trials involving 95,000 patients and found that aspirin therapy was associated with a 12% reduction in serious vascular events, which occurred in 0.51% of patients taking aspirin per year vs 0.57% of controls (P = .0001). However, aspirin also increased the risk of major bleeding, at a rate of 0.10% vs 0.07% per year (P < .0001), with 2 bleeding events for every avoided vascular event.13

WILL ASPIRIN PROTECT PATIENTS AT CARDIAC RISK?

The second Perioperative Ischemic Evaluation trial (POISE 2),1 in patients with atherosclerotic disease or at risk for it, found that giving aspirin in the perioperative period did not reduce the rate of death or nonfatal MI, but increased the risk of a major bleeding event.

The trial included 10,010 patients undergoing noncardiac surgery who were randomly assigned to receive aspirin or placebo. The aspirin arm included 2 groups: patients who were not on aspirin (initiation arm), and patients on aspirin at the time of randomization (continuation arm).

Death or nonfatal MI (the primary outcome) occurred in 7.0% of patients on aspirin vs 7.1% of patients receiving placebo (hazard ratio [HR] 0.99, 95% CI 0.86–1.15, P = .92). The risk of major bleeding was 4.6% in the aspirin group vs 3.8% in the placebo group (HR 1.23, 95% CI 1.01–1.49, P = .04).1

George et al,14 in a prospective observational study in a single tertiary care center, found that fewer patients with myocardial injury in noncardiac surgery died if they took aspirin or clopidogrel postoperatively. Conversely, lack of antithrombotic therapy was an independent predictor of death (P < .001). The mortality rate in patients with myocardial injury who were on antithrombotic therapy postoperatively was 6.7%, compared with 12.1% in those without postoperative antithrombotic therapy (estimated number needed to treat, 19).14

Next Article:

Aspirin: 4,000 years and still learning

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