Use of antithrombotic measures for stroke prevention in atrial fibrillation.

Objective: To evaluate appropriateness of antithrombotic use to prevent stroke in atrial fibrillation.

Design, Patients: 344 patients with atrial fibrillation, stratified by age, were assessed clinically for contraindications to anticoagulation and stroke risk. The use of warfarin and aspirin was compared with recommendations for anticoagulation derived from pooled clinical trial data.

Results: Low risk of stroke was seen in 47 (14%) patients, moderate risk in 213 (62%), and high risk in 84 (24%) patients included in the sample (mean (SD) age 68.4 (17.2) years, 42% men). The proportion of patients requiring anticoagulation varied from 258/344 (75%) to 72/344 (21%) depending upon criteria used, of whom 86/258 (33%) and 36/72 (50%) were receiving warfarin, respectively. Warfarin or aspirin were not being used in 124/297 (42%) patients with moderate to high risk, whereas anticoagulation was being undertaken in 13/47 (27%) patients at low risk of stroke. Antithrombotic use (warfarin or aspirin) was significantly less common in patients over 75 years of age, regardless of absence of contraindications and eligibility according to various criteria (p < 0.001).

Conclusions: A clear need for anticoagulation using clinical criteria existed in about 25% of patients in atrial fibrillation presenting to medical clinics who were at high risk of stroke. Of these, only 50% of eligible patients were being anticoagulated. Appropriate anticoagulation needs to be based on risk assessment rather than age. Consensus is therefore needed on appropriate antithrombotic use in clinical practice.