Context Despite years of use in coronary artery disease (CAD) and several studies
of its effectiveness, the role of oral anticoagulants (OAs) remains controversial.
Objective To determine the effects of long-term OA therapy, stratified by the
intensities of anticoagulation and aspirin therapy, on outcomes in patients
Data Sources Studies were identified by MEDLINE, EMBASE, and CURRENT CONTENTS searches
(1960-July 1999) and by reviewing reference lists and inquiring with experts
and pharmaceutical companies.
Study Selection Studies were included if they were published between 1960 and July 1999,
were randomized, had recruited patients with CAD, who had used OA therapy
for at least 3 months. Of 43 articles identified, 30 articles (31 trials)
Data Extraction Information on type, duration, and method of monitoring OA therapy,
as well as rates of death, myocardial infarction (MI), thromboembolic complications,
stroke, and bleeding were abstracted by 2 independent observers.
Data Synthesis With high-intensity (international normalized ratio [INR], 2.8-4.8)
OAs vs control (16 trials, 10,056 patients), clear reductions in mortality
(odds reduction [ORed], 22%; 95% confidence interval [CI], 13%-31%), MIs (ORed,
42%; 95% CI, 34%-48%), and thromboembolic complications including stroke (ORed,
63%; 95% CI, 53-71%) were observed, but were associated with a 6.0-fold (95%
CI, 4.4- to 8.2-fold) increase in major bleeding. For moderate OAs (INR, 2-3)
vs control (4 trials, 1365 patients) the ORed for death was 18% (95% CI, −6%
to 37%); for MI, 52% (95% CI, 37%-64%); and for stroke, 53% (95% CI, 19%-73%),
but it increased bleeding by 7.7-fold (95% CI, 3.3- to 18-fold). For moderate-
to high-intensity OAs (INR, ≥2) vs aspirin (7 trials, 3457 patients), no
reduction in death, MI, or stroke was observed, and it was associated with
a 2.4-fold (95% CI, 1.6- to 3.6-fold) increase in major bleeding. For moderate-
to high-intensity OAs and aspirin vs aspirin alone (3 trials, 480 patients),
the ORed for death, MI, or stroke was 56% (95% CI, 17%-77%) and major bleeding
increased by 1.9-fold (0.6- to 6.0-fold). For low-intensity OAs (INR, <2.0)
and aspirin vs aspirin alone (3 trials, 8435 patients), no significant reduction
in death, MI, or stroke was observed, and major bleeding increased by 1.3-fold
(95% CI, 1.0- to 1.8-fold).
Conclusions Among patients with CAD, high-intensity and moderate-intensity OA are
effective in reducing MI and stroke but increase the risk of bleeding. In
the presence of aspirin, low-intensity OA does not appear to be superior to
aspirin alone, while moderate- to high-intensity OA and aspirin vs aspirin
alone appears promising and the bleeding risk is modest, but this requires
confirmation from ongoing trials.