Stroke. 2006;37:274-275
Published online before print December 8, 2005,
doi: 10.1161/01.STR.0000196914.02476.2c
(Stroke. 2006;37:274.)
© 2006 American Heart Association, Inc.
Antiplatelet Therapy for Preventing Stroke in Patients With Nonvalvular Atrial Fibrillation and No Previous History of Stroke or Transient Ischemic Attacks
Maria I. Aguilar, MD
Robert G. Hart, MD
From the University of Texas Health Science Center at San Antonio.
Correspondence to Maria I. Aguilar, SPS3 Coordinating Center, 4647 Medical Dr, San Antonio, TX. E-mail aguilarm2{at}uthscsa.edu
Key Words: aspirin • antiplatelet therapy • atrial fibrillation • stroke
 |
Introduction
|
|---|
Antiplatelet agents such as aspirin are modestly efficacious
for preventing serious vascular events in patients with atrial
fibrillation (AF) who are not treated with more efficacious
oral anticoagulants.
|
Background
|
|---|
Nonvalvular AF carries an increased risk of stroke. Antiplatelet
therapy (APT) is proven effective for stroke prevention in most
patients at high-risk for vascular events, but its value for
primary stroke prevention in patients with nonvalvular AF merits
separate consideration because of the suspected cardioembolic
mechanism of most strokes in AF patients.
|
Objectives
|
|---|
The goal of this review is to assess the efficacy and safety
of long-term APT for primary prevention of stroke in patients
with chronic nonvalvular AF.
|
Search Strategy
|
|---|
We searched the Cochrane Stroke Group Trials Register (August
2004). In addition, we searched the Cochrane Central Register
of Controlled Trials (The Cochrane Library Issue 1, 2005), MEDLINE
(1966 to June 2004), and the reference lists of recent review
articles. We also contacted experts working in the field to
identify unpublished and ongoing trials.
|
Data Collection and Analysis
|
|---|
Randomized trials comparing long-term APT with placebo or control
in patients with nonvalvular AF and no history of transient
ischemic attack (TIA) or stroke were independently selected
and analyzed by 2 authors, extracting the data for each outcome.
A sensitivity analysis included 1 additional randomized trial
1 involving primary prevention with aspirin plus very low-dose
warfarin versus control. An additional randomized trial, the
Japanese Atrial Fibrillation Stroke Trial, has been completed,
but results have not been published.
|
Main Results
|
|---|
Three trials tested aspirin in dosages ranging from 75 mg to
325 mg per day and 125 mg every other day to placebo (in 2 trials
LASAF
2 and AFASAK
3) or control (in 1 trial SPAF I
4) in 1965
AF patients without previous stroke or TIA. The mean duration
of follow-up averaged 1.3 years per participant. Aspirin was
associated with nonsignificant lower risks of all stroke (odds
ratio [OR], 0.70; 95% CI, 0.47 to 1.07), ischemic stroke (OR,
0.70; 95% CI, 0.46 to 1.07), all disabling or fatal stroke (OR,
0.86; 95% CI, 0.50 to 1.49) and all-cause death (OR, 0.75; 95%
CI, 0.54 to 1.04). The combination of stroke, myocardial infarction,
or vascular death was significantly reduced (OR, 0.71; 95% CI,
0.51 to 0.97;
Figure). No significant increase in intracranial
hemorrhage or major extra cranial hemorrhage was observed, but
numbers were small and CIs wide.
View larger version (15K):
[in this window]
[in a new window]
|
Effect of antiplatelet therapy on all stroke, ischemic stroke and CNS bleed in patients with nonvalvular atrial fibrillation and no history of stroke or transient ischemic attacks.
|
|
|
Reviewers’ Conclusions
|
|---|
Aspirin reduces stroke and major vascular events in patients
with nonvalvular AF similar to its effect in other high-risk
patients (ie, by
25%). For primary prevention among AF patients
with an average stroke rate of 4% per year,
10 strokes would
likely be prevented yearly for every 1000 AF patients given
aspirin.
|
Implications for Practice
|
|---|
The benefits of APT are modest compared with adjusted-dose warfarin,
but APT is relatively safe, easy to take, and therefore an important
treatment option for many AF patients. Anticoagulation with
warfarin and related drugs offers more protection against stroke
(nearly two-thirds reduction), but anticoagulant drugs can cause
severe bleeding and require careful regulation with regular
blood tests. The choice of APT versus anticoagulants should
be individualized based on the patient’s inherent risk
of stroke,
5 ability to tolerate anticoagulation without bleeding,
access to adequate anticoagulation monitoring, and patient preferences.
|
Implications for Research
|
|---|
More randomized data about the efficacy of nonaspirin APT regimens
(including dipyridamole, clopidogrel, and indobufen, alone and
combined with aspirin) might expand the use of APT in AF patients.
|
Footnotes
|
|---|
Section Editor: Graeme J. Hankey, MD, FRCP
Received September 6, 2005;
accepted October 11, 2005.
|
References
|
|---|
- Edvardsson N, Juul-Moller S, Omblus R, Pehrsson K. Effects of low-dose warfarin and aspirin versus no treatment on stroke in a medium-risk patient population with atrial fibrillation. J Intern Med. 2003; 254: 95–101.[CrossRef][Medline]
[Order article via Infotrieve]
- Posada IS, Barriales V. Alternate-day dosing of aspirin in atrial fibrillation. LASAF Pilot Study Group. Am Heart J. 1999; 138: 137–143.[CrossRef][Medline]
[Order article via Infotrieve]
- Petersen P, Boysen G, Godtfredsen J, Andersen ED, Andersen B. Placebo- controlled, randomised trial of warfarin and aspirin for prevention of thromboembolic complications in chronic atrial fibrillation. The Copenhagen AFASAK study. Lancet. 1989; 1: 175–179.[Medline]
[Order article via Infotrieve]
- Stroke Prevention in Atrial Fibrillation Study. Final results. Circulation. 1991; 84: 527–539.[Abstract/Free Full Text]
- Gage BF, van Walraven C, Pearce L, Hart RG, Koudstaal PJ, Boode BS, Petersen P. Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin. Circulation. 2004; 110: 2287–2292.[Abstract/Free Full Text]
Top
Introduction
Background