[Analysis of factors associated with anticoagulant treatment indication in chronic atrial fibrillation. Prospective study of 170 patients admitted at an internal medicine service].

Background: Anticoagulant therapy reduces the risk of stroke among patients with chronic atrial fibrillation. The objective of this study was to evaluate the use of anticoagulant therapy and to analyze the factors associated with the indication of anticoagulants in patients with chronic atrial fibrillation.

Patients And Methods: Prospective study of all patients with chronic atrial fibrillation admitted to our Department of Internal Medicine from February 1997 to September 1998. From each patient data related to the cause of atrial fibrillation, other associated vascular risk factors, use of anticoagulant and/or antiplatelet agents and contraindication to anticoagulants were recorded.

Results: A total of 170 patients with chronic atrial fibrillation were studied. The mean age of patients was 77 years (range: 49-94). One hundred and four patients (61%) were older than 75 years. Atrial fibrillation was the main cause for admission only in 11 patients (6.5%). One hundred and sixty-seven patients (98%) had indication for receiving anticoagulant therapy; however, it was indicated in only 67 patients (39%). In other 68 patients (40%), antiplatelet agents were used. Patients over 75 years received anticoagulants less frequently (p < 0.0001). Factors associated with the prescription of anticoagulants in the bivariate analysis included: diabetes mellitus (p = 0.046), high cholesterol level (p = 0.023), age < or = 75 years old (p < 0.0001), history of previous embolic events (p = 0.001) and valvular atrial fibrillation (p < 0.0001). The multivariate analysis showed that only two factors were indeed associated with the prescription of anticoagulants: age < or = 75 years (OR: 6.15) and valvular atrial fibrillation (OR: 4.24).

Conclusions: Anticoagulant therapy is underused in patients with chronic atrial fibrillation, particularly in elderly patients.