Primary prevention of arterial thromboembolism in non-rheumatic atrial fibrillation in primary care: randomised controlled trial comparing two intensities of coumarin with aspirin.

OBJECTIVE: To investigate the effectiveness of aspirin and coumarin in preventing thromboembolism in patients with non-rheumatic atrial fibrillation in general practice. DESIGN: Randomised controlled trial. PARTICIPANTS: 729 patients aged >/=60 years with atrial fibrillation, recruited in general practice, who had no established indication for coumarin. Mean age was 75 years and mean follow up 2. 7 years. SETTING: Primary care in the Netherlands. INTERVENTIONS: Patients eligible for standard intensity coumarin (international normalised ratio 2.5-3.5) were randomly assigned to standard anticoagulation, very low intensity coumarin (international normalised ratio 1.1-1.6), or aspirin (150 mg/day) (stratum 1). Patients ineligible for standard anticoagulation were randomly assigned to low anticoagulation or aspirin (stratum 2). MAIN OUTCOME MEASURES: Stroke, systemic embolism, major haemorrhage, and vascular death. RESULTS: 108 primary events occurred (annual event rate 5.5%), including 13 major haemorrhages (0.7% a year). The hazard ratio was 0.91 (0.61 to 1.36) for low anticoagulation versus aspirin and 0.78 (0.34 to 1.81) for standard anticoagulation versus aspirin. Non-vascular death was less common in the low anticoagulation group than in the aspirin group (0.41, 0.20 to 0.82). There was no significant difference between the treatment groups in bleeding incidence. High systolic and low diastolic blood pressure and age were independent prognostic factors. CONCLUSION: In a general practice population (without established indications for coumarin) neither low nor standard intensity anticoagulation is better than aspirin in preventing primary outcome events. Aspirin may therefore be the first choice in patients with atrial fibrillation in general practice.

Primary prevention of arterial thromboembolism in nonrheumatic atrial fibrillation: the PATAF trial study design.

Patients with nonrheumatic atrial fibrillation (NRAF) have a higher risk of thromboembolism than patients in sinus rhythm. Several trials have been conducted to establish the best preventive regimen in patients with NRAF, but not in the primary-care setting. The Primary Prevention of Arterial Thromboembolism in Nonrheumatic Atrial Fibrillation (PATAF) study, a primary-care-based trial, was set up to compare the preventive efficacy of low-intensity anticoagulation (AC), target range International Normalized Ratio (INR) 1.1 < INR < 1.6 and regular-intensity AC (2.5 < INR < 3.5) therapies with that of aspirin 150 mg/d for the occurrence of thromboembolism in NRAF patients. Patients eligible for regular-intensity AC were randomly assigned to aspirin at 150 mg/d, low-intensity AC, or regular AC in group I. In cases of noneligibility for regular AC, the trial randomized patients between aspirin and low-intensity AC (assigned to group II). Primary outcome events were stroke (including intracranial hemorrhage), systemic embolism, major hemorrhage, or vascular death. Analysis of the data was based on Cox regression to compute the hazard ratio (HR) with a 95% confidence interval, using the likelihood ratio test. The trial randomized 729 patients. Patient enrollment and follow-up has been stopped, and the final analysis is now complete. We shall publish the main results as soon as possible.