Coumadin Aspirin Reinfarction Study - CARS


Low dose aspirin and low-dose warfarin versus aspirin alone after acute MI.


To compare chronic administration of aspirin alone with lower dose aspirin in combination with fixed low-dose regimens of oral anticoagulation in acute MI patients.

Study Design

Study Design:

Patients Screened: Not reported
Patients Enrolled: 8803
NYHA Class: Not reported
Mean Follow Up: maximum 33 months (median 14 months)
Mean Patient Age: 21-85 years (82% <70 years old)
Female: 23%
Mean Ejection Fraction: Not reported

Patient Populations:

Patients 21–85 years of age with a documented MI 3–21 days (mean 9.6 days) prior to enrollment.


CHF (Killip class III or IV), circulatory shock, rest angina refractory to medical therapy, serious ventricular arrhythmias in prior 24 hours, stroke (without full recovery or prior hemorrhage), history of bleeding, liver disease (enzymes >2X upper limit of normal), renal disease (creatinine >2x normal), anemia (hemoglobin <10 gm/dl), thrombocytopenia (platelet count <100,000), abnormal thyroid-hormone profile, hematuria, acute pericardial involvment with index infarction, known hypersensitivity to warfarin derivatives, SBP >180 mm Hg or DBP >100 mm Hg, requirement for long-term anticoagulation, planned CABG surgery, perioperative index infarction.

Primary Endpoints:

MI, stroke, and cardiovascular death.

Secondary Endpoints:

all-cause mortality, unstable angina requiring hospital admission, transient ischemic attack, silent MI (new Q waves), systemic embolization.

Drug/Procedures Used:

Aspirin 160 mg/day, aspirin 80 mg/day and warfarin 1 mg/day, or aspirin 80 mg/day and warfarin 3 mg/day. Average measured INRs at week 4 were 1.02 (aspirin alone), 1.05 (aspirin and warfarin 1 mg/day), and 1.27 (aspirin and warfarin 3 mg/day).

Principal Findings:

There was no significant difference between the groups in the incidence of the compsoite primary end point (1-year rates 8.6% [aspirin], 8.8% [aspirin and warfarin 1 mg/day], 8.4% [aspirin and warfarin 3 mg/day]). Life table estimates for ischemic stroke at 1 year were lowest in the aspirin alone group (0.58% vs 1.1% [aspirin + warfarin 1mg/day; p vs aspirin alone = 0.05] and 0.80% [aspirin + warfarin 3 mg/day; p vs aspirin alone = 0.16). The aspirin + warfarin 3 mg/day group had a higher rate of spontaneous major hemorrhage versus aspirin alone: 0.74%/yr vs. 1.4%/yr (p = 0.014).


Combination therapy with warfarin (1 or 3 mg/day) and low-dose aspirin (80 mg/day) had similar efficacy as aspirin 160mg/day alone in acute MI patients.


Lancet 1997;350:389–396. Related trials: AFTER (BMJ 1996;313:1429–1431), ASPECT (Lancet 1994;343:499–503)

Clinical Topics: Anticoagulation Management

Keywords: Stroke, Warfarin, Coronary Disease, Hemorrhage

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