Aspirin and Tranexamic Acid for Coronary Artery Surgery - ATACAS

Contribution To Literature:

The ATACAS trial showed that preoperative aspirin neither reduced thrombotic complications nor increased bleeding complications. Tranexamic acid was associated with a lower risk of bleeding than placebo, without a higher risk of death or thrombotic complications.

Description:

The goal of the trial was to evaluate preoperative treatment with aspirin compared with placebo and tranexamic acid compared with placebo among patients undergoing coronary artery bypass surgery (CABG).

Study Design

  • Randomized
  • Parallel
  • Placebo

Patients undergoing CABG were randomized to preoperative aspirin 100 mg daily (n = 1,059) versus placebo (n = 1,068) 1 to 2 hours before surgery. Aspirin was administered postoperatively according to local practices. Warfarin or clopidogrel was held 7 days before surgery. Patients were also randomized to tranexamic acid (n = 2,311) versus placebo (n = 2,320).

  • Total number of enrollees: 4,631
  • Duration of follow-up: 30 days
  • Mean patient age: 67 years
  • Percentage female: 17%
  • Percentage diabetics: 33%

Other salient features/characteristics:

  • Myocardial infarction within 90 days: 7.2%
  • EuroSCORE: 4.1%
  • Primary CABG: 75%
  • Median number of bypass grafts: 3
  • Duration of surgery: 3.8 hours
  • Postoperative aspirin within 24 hours: 78%
  • Median time to administration of aspirin postoperatively: 18.5 hours

Inclusion criteria:

  • Patients undergoing CABG (on-pump or off-pump), with or without valve surgery or another cardiac procedure
  • Not taking aspirin regularly before the trial or cessation of aspirin at least 4 days before surgery

Principal Findings:

Aspirin versus placebo:

The primary outcome, death or thrombotic complications (myocardial infarction, stroke, pulmonary embolism, renal failure, or bowel infarction) within 30 days, occurred in 19.3% of the aspirin group versus 20.4% of the placebo group (p = 0.55). Findings were the same among all tested subgroups.

Secondary outcomes:

  • Myocardial infarction: 13.8% vs. 15.8% (p = 0.20), respectively for aspirin vs. placebo
  • Reoperation for hemorrhage: 1.8% vs. 2.1% (p = 0.75), respectively for aspirin vs. placebo
  • Cardiac tamponade: 1.1% vs. 0.4% (p = 0.08), respectively for aspirin vs. placebo

Tranexamic acid versus placebo:

The primary outcome, death or thrombotic complications (myocardial infarction, stroke, pulmonary embolism, renal failure, or bowel infarction) within 30 days, occurred in 16.7% of the tranexamic acid group versus 18.1% of the placebo group (p = 0.22).

Secondary outcomes:

  • Total number of transfused blood products: 4,331 vs. 7,993 (p < 0.001), respectively for tranexamic acid vs. placebo
  • Reoperation for hemorrhage: 1.4% vs. 2.8% (p = 0.001), respectively for tranexamic acid vs. placebo
  • Seizure: 0.7% vs. 0.1% (p = 0.002), respectively for tranexamic acid vs. placebo

Interpretation:

Among patients undergoing CABG, preoperative aspirin neither reduced thrombotic complications nor increased bleeding complications. Lack of benefit or harm was likely due to early administration of nonstudy aspirin, as per local practices. An important eligibility criterion was not regularly taking aspirin (or cessation of aspirin at least 4 days before surgery). This is reflected in the low frequency of enrollees with recent myocardial infarction (also the percentage of patients with coronary stents was not provided). Aspirin is an important perioperative medication, which this trial does not diminish. Among relatively low-risk patients (stable ischemic heart disease) undergoing CABG, options include preoperative administration of aspirin or early administration postoperatively.

Tranexamic acid was not associated with a reduction in the risk of primary outcome. Tranexamic acid was associated with a reduction in the total number of transfused blood products and the need for reoperation for hemorrhage; however, it was associated with a small absolute increase in seizures.

References:

Myles PS, Smith JA, Forbes A, et al., on behalf of the ATACAS Investigators of the ANZCA Clinical Trials Network. Tranexamic acid in patients undergoing coronary-artery surgery. N Engl J Med 2016;Oct 23:[Epub ahead of print].

Presented at the ANESTHESIOLOGY Annual Meeting, October 23, 2016, Chicago, IL.

Myles PS, Smith JA, Forbes A, et al., on behalf of the ATACAS Investigators of the ANZCA Clinical Trials Network. Stopping vs. Continuing Aspirin before Coronary Artery Surgery. N Engl J Med 2016;374:728-37.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Pericardial Disease, Vascular Medicine, Interventions and Coronary Artery Disease, Interventions and Vascular Medicine

Keywords: Aspirin, Cardiac Surgical Procedures, Cardiac Tamponade, Coronary Artery Bypass, Coronary Artery Bypass, Off-Pump, Coronary Artery Disease, Hemorrhage, Myocardial Infarction, Pulmonary Embolism, Renal Insufficiency, Stroke, Thrombosis


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