Clinical Benefit of American College of Chest Physicians versus European Society of Cardiology Guidelines for Stroke Prophylaxis in Atrial Fibrillation.

BACKGROUND: Guidelines for anticoagulant therapy in patients with atrial fibrillation (AF) conflict with each other. The American College of Chest Physicians (ACCP) guidelines suggest no anticoagulant therapy for patients with a CHADS2 score of 0. The European Society of Cardiology (ESC) prefer anticoagulant therapy for patients with a CHA2DS2-VASc of 1, which includes 65-74-year-olds with a CHADS2 score of 0. Resolving this conflicting advice is important, because these guidelines have potential to change anticoagulant therapy in 10 % of the AF population.

METHODS: Using the National Registry of Atrial Fibrillation (NRAF) II data set, we compared these guidelines using stroke equivalents. Based on structured review of 23,657 patient records, we identified 65-74-year-old patients with a CHADS2 stroke score of 0 and no contraindication to warfarin. We used Medicare claims data to ascertain rates of ischemic stroke, intracranial hemorrhage, and other hemorrhage. We calculated net stroke equivalents for these (N = 478) patients using a weight of 1.5 for intracranial hemorrhages (ICH) and 1.0 for ischemic stroke. In a multivariate analysis, we used 14,466 records with documented atrial fibrillation and adjusted for CHADS2 and HEMORR2 HAGES score.

RESULTS: In 65-74-year-old patients with a CHADS2 stroke score of 0, the stroke equivalents per 100 patient-years was 2.6 with warfarin and 2.9 without warfarin; the difference between these two strategies was not significant (0.3 stroke equivalents, 95 % CI -3.2 to 3.7). However, rates of hemorrhage per 100 patient-years were nearly tripled (hazard ratio 2.9; 95 % CI 1.5-5.4; p = 0.0011) with warfarin (21.1) versus without it (7.4). The most common site for major hemorrhage was gastrointestinal (ICD-9 code 578.9).

CONCLUSIONS: By expanding warfarin use to 65--74-year-olds with a CHADS2 score of 0, rates of hemorrhages would rise without a significant reduction in stroke equivalents.