Thromboembolic prophylaxis in 3575 hospitalized patients with atrial fibrillation. The Clinical Quality Improvement Network (CQIN) Investigators.

OBJECTIVE: To define contemporary utilization patterns of anticoagulant and antiplatelet therapy for thromboembolic prophylaxis in atrial fibrillation (AF).

DESIGN: Retrospective medical records audit of patients admitted in 1993 and 1994.

SETTING: Twelve Canadian hospitals.

PATIENTS: Three thousand, three hundred and seventy-five consecutive patients with AF; 1570 females and 2005 males. The mean age was 72 years; 1353 patients were younger than 70 years and 2222 were aged 70 years and older.

MEASUREMENTS AND RESULTS: Overall, 1188 (33%) of the 3575 patients received no prophylaxis, 852 (24%) were treated with warfarin alone, 1247 (35%) received acetylsalicylic acid (ASA) alone and 288 (8%) received both drugs. The pattern of medication use did not change appreciably when possible contraindications to warfarin or ASA therapy were considered. Among the 331 AF patients with valvular heart disease and no contraindications to thromboembolic prophylaxis, 65 (20%) received neither treatment, 181 (55%) received warfarin therapy alone, 46 (14%) received ASA alone and 39 (12%) received both. Among the 2199 AF patients with nonvalvular heart disease and no contraindications, 823 (37%) did not receive either therapy, 677 (31%) received ASA alone, 504 (23%) received warfarin alone and 195 (9%) received both. Elderly and female patients were less likely to receive thromboembolic prophylaxis.

CONCLUSIONS: Anticoagulation and antiplatelet prophylaxis in AF appears to be less than optimal. Although concerns about bleeding may be one reason thromboembolic prophylaxis is so unevenly and incompletely applied, it will be important to determine the reasons for this practice and to develop effective strategies in order to enhance the process of care and patient outcomes.