Problem Atrial fibrillation
Format Multi-center RCT
Treatment Warfarin or Aspirin
Control Placebo
Population 1300
Inclusion criteria Constant or intermittent atrial fibrillation
-ECG documentation in the preceeding 12 months
Inpatients or outpatients from public, private and veteran healthcare
Exclusion criteria Prosthetic heart valves
MI or angioplasty within previous 3 months
CABG in last year
Echocardiographic evidence of mitral stensosis
Mitral regurgitation w/ CCF and LV diam > 5.5xm
Dilated cardiomyopathy w/ CCF
Other requirements or contraindications for/to aspirin/warfarin
Life expectency less than 2 years
Chronic renal failure

N.B. Patients were judged ineligable for group 1 (warf/aspirin/placebo) and hence put in group 2 (aspirin/placebo) if:
-Age > 75
-Lone AF complex (abandoned)
-Repeated galls/unstable gait predisposing to head trauma
-Positive stool for FOB
-Chronic alcohol
-GI/GU bleeding in last 6 months
-Uncontrolled hypertension
-Occupational hazards
-Severe haemorrhage an anticoagulants despite previous therapeutic PT
-Recurrent syncope or uncontrolled seizure disorder
-Intrinsic PT prolongation > 2s beyond on 2+ occasions
-Previous intracranial haemorrhage
Alcohol abuse
No stroke within previous 2 years
-7% had prior clinical brain ischaemia
Follow-up Mean 1.3 years
Primary endpoint Rate of ischaemic stroke and systemic embolism
Secondary endpoint(s) Composite of TIA, myocardial infarction and unstable angina
Details Wanted to assess whether aspirin > placebo in ALL patients, and if warfarin > placebo in the less risky subgroup. Didn't intend to go out to compare warfarin vs. aspirin - aim for SPAF-II

INR 2.0 - 4.5 target
Brief summary: Aspirin or warfarin (on own) superior to placebo
PAPER: Stroke Prevention in Atrial Fibrillation Study. Final results.
Date 1 Aug 1991
Journal Circulation. 1991 Aug;84(2):527-39.
Information Aimed to compare:
1) Aspirin vs. placebo in all patients
-Primary events (ischaemic stroke or systemic embolism) reduced by 42%
-Primary events or death reduced by 32%

2) Warfarin vs. placebo in eligible subgroup
-Primary events (ischaemic stroke or systemic embolism) reduced by 67%
-Primary events or death reduced by 58%

N.B. So few events in warfarin/aspirin subgroup that trial did not aim to investigate relative efficacy