Abstract 16351: Aspirin or No Antithrombotic Therapy in Patients with Atrial Fibrillation and CHADS2 score=0 in a Real World Community Based Cohort Study
Based on the recent ACCP9 guidelines, thromboprophylaxis for patients with atrial fibrillation (AF) without any consistent risk factor (CHADS2 score=0) may be aspirin or no antithrombotic therapy, whilst oral anticoagulation is the preferred therapy in all other patients with ≥1 risk factors. Some physicians and patients may be reluctant to choose no antithrombotic therapy. The aim of our study was to compare prognosis in AF patients with a CHADS2 score=0 in a ‘real world’ community cohort study, treated with aspirin or no antithrombotic therapy.
Methods: Patients with AF seen between 2000 and 2010 were identified in a database and followed up for mortality, stroke and bleeding events. The CHADS2 score was calculated for each patient as initially described, based on 2 points for a history of stroke or TIA, and 1 point each for age ≥75, hypertension, diabetes, and cardiac failure.
Results: Among 8962 patients with AF seen between 2000-2010, 1526 (17%) had a CHADS2 score=0 and 794 did not receive OAC during follow-up. In these patients (age 50±17 years), aspirin was prescribed on an individual basis for 381 patients (48%) and no antithrombotic treatment for 413 (52%). During a follow-up of 884±1054 days, 19 strokes/thromboembolic events and 29 deaths were recorded in 41/794 patients. The adjusted stroke rate was 0.98%/year. Prescription of aspirin was not associated with a different prognosis in terms of stroke or mortality: relative risk=0.83, 95% CI 0.44-1.5, p=0.55 for the combined risk of death or stroke. This result was similar when one considered separately the 440 patients with an additional moderate risk factor (age 65-74 years, vascular disease or female gender) : relative risk=0.70, 95% CI 0.33-1.49, p=0.36 for the combined risk of death or stroke.
Conclusions: For patients with AF and a CHADS2 score of 0, treatment with aspirin may result in a small and non significant reduction in the risk of stroke or death (2 per 1,000 patients treated for 2 year, number needed to treat of 500 to prevent 1 event).
- © 2012 by American Heart Association, Inc.