ASA and Carotid Endarterectomy Trial - ACE (Carotid Endarterectomy)


The acetylsalicylic acid (ASA or aspirin) and carotid endarterectomy ACE trial was a multicenter randomized, blinded trial designed to test whether the rates of perioperative complications in patients undergoing carotid endarterectomy would be affected by the dose of aspirin when administered perioperatively.


Treatment with higher doses of aspirin (650 mg or 1300 mg) would be associated with a reduced incidence of the combined endpoint of stroke, myocardial infarction (MI), and death compared to lower doses of aspirin (81 mg or 325 mg).

Study Design

Study Design:

Patients Enrolled: 2,849
Mean Follow Up: 30 days
Mean Patient Age: Median age 69
Female: 30

Patient Populations:

Patients scheduled for endarterectomy for arteriosclerotic disease that could tolerate 1300 mg aspirin daily


Patients who: participated in another trial, took aspirin or any other antiplatelet medication that could not be stopped, had recent disabling stroke, had cardiac surgery in the previous 30 days or scheduled for cardiac surgery in the next 30 days, or who did not provide informed consent

Primary Endpoints:

Composite of all strokes, MIs, and deaths at 30 days and three months

Secondary Endpoints:

All strokes and deaths, as well as ipsilateral strokes and deaths

Drug/Procedures Used:

Enteric-coated aspirin 81 mg, 325 mg, 650 mg, or 1300 mg per day, started before surgery and continued for three months

Concomitant Medications:

Standard care

Principal Findings:

A total of 2,849 patients scheduled to undergo carotid endarterectomy were enrolled. Forty-six percent of patients had had ischemic symptoms in the past six months. Reported compliance with the study regimen was >85%. There were no differences between the 81 mg and 325 mg groups, or between the 650 mg and 1300 mg groups in any analyses.

The combined rate of stroke/MI/death was lower in the low-dose groups than in the high-dose groups at 30 days (5.4% vs. 7.0%, p=0.07) and at three months (6.2% vs. 8.5%, p=0.03). These effects were consistent, although not statistically significant, across the individual components of the primary endpoint.

In an efficacy analysis, which excluded patients previously taking more than aspirin 650 mg/day or patients randomized within one day of surgery, these rates were 3.7% versus 8.2% at 30 days (p=0.002) and 4.2% versus 10.0% at three months (p=0.0002). Although hemorrhagic stroke was less frequent among patients on low-dose aspirin, this difference was not statistically significant.


In this large randomized trial of patients undergoing carotid endarterectomy, treatment with high-dose aspirin was not associated with an improvement in outcomes; in fact, treatment with high-dose aspirin was associated with a greater incidence of stroke, MI, and death. These results are the opposite of post-hoc observations from NASCET, which found in retrospective analyses that patients on higher doses of aspirin had fewer perioperative strokes.


Taylor DW, Barnett HJ, Haynes RB, et al. Low-dose and high-dose acetylsalicylic acid for patients undergoing carotid endarterectomy: a randomised controlled trial. ASA and Carotid Endarterectomy (ACE) Trial Collaborators. Lancet 1999;353:2179-84.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, Interventions and Vascular Medicine

Keywords: Myocardial Infarction, Stroke, Platelet Aggregation Inhibitors, Cerebrovascular Disorders, Endarterectomy, Carotid, Carotid Stenosis

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