Problem Atrial fibrillation
Format Multi-center RCT
Treatment Warfarin (INR 1.2-1.5) + Aspirin 325mg
Control Warfarin (INR 2-3)
Population 1044 patients
Inclusion criteria Aged > 18
AF documented in the 6 month preceding the study
One or more high risk features
-Impared left ventricular function manifest by recent(100 days) congestive heart failure or left ventricular fractional shortening < 25%
-Previous thromboembolism(systemic stroke ,TIA,systemic embolism) more than 30 days prior to entry
-Systolic blood pressure of more than 160 mmHg at study enrolment
-Women >75 y.
Exclusion criteria Prosthetic heart valves
Mitral stenosis
Prior requirement for anticoagulation
Contra-indications to aspirin or warfarin
Regular use of NSAIDs
Patients who had taken part in previous SPAF studies or similar clinical trials.
Follow-up Mean 1.1 years
Primary endpoint Ischemic stroke and systemic embolism as measured during monthly telephone interview, clinic follow-up every 3 months, and yearly standard symptom questionnaire
Secondary endpoint(s) Transient ischemic attack, intracranial hemorrhage, disabling or fatal stroke.
Details -
Brief summary: INR monitoring necessary for warfarin
PAPER: Adjusted-dose warfarin versus low-intensity, fixed-dose warfarin plus aspirin for high-risk patients with atrial fibrillation: Stroke Prevention in Atrial Fibrillation III randomised clinical trial.
Date 7 Sep 1996
Journal Lancet. 1996 Sep 7;348(9028):633-8.
Information Low-intensity fixed-dose warfarin + aspirin vs. INR 2-3
-7.9%/yr primary event (stroke and systemic embolism) vs. 1.9%
-Increased risk of disabling stroke
-Increased risk of primary event or vascular death
-Similar rates of major bleeding
PAPER: Selecting patients with atrial fibrillation for anticoagulation: stroke risk stratification in patients taking aspirin.
Date 19 Oct 2004
Journal Circulation. 2004 Oct 19;110(16):2287-92.
Information 2580 patients - pooled data from SPAF-III, AFASAK-1, AFASAK-2, and others

CHADS2 scheme identified primary prevention patients at high risk (>5.3/100pt yrs)
-Low-risk patients had 0.5 - 1.4 strokes/100 pr yrs
Other schemes predicted high risk patients as 3.0-4.2/100pt yrs