Thromboembolism Prophylaxis in Chronic Atrial Fibrillation

BACKGROUND AND PURPOSE: By 1992, several prospective trials established the efficacy of anticoagulation (AC) and to some extent antiplatelet (AP) agents in the prevention of stroke in the setting of atrial fibrillation (AF). The objective of this study was to determine whether practice patterns in AF stroke prophylaxis reflect the findings of clinical trials and whether stroke prophylaxis in AF differs between community hospitals and tertiary teaching hospitals. METHODS: Retrospectively, 1250 hospital charts were reviewed. After patients who had undergone recent surgery, received treatment for malignancy, or were not in chronic AF on discharge were eliminated, 651 remaining records were analyzed for the presence of 26 clinical factors influencing the selection of thromboembolism prophylaxis. Descriptive statistics and logistic regression were used to analyze the association between clinical and demographic factors and the decision to treat with AC, AP, or no specific antiembolic therapy. RESULTS: Of the 651 patients in AF, 273 (42%) received noemboli prophylaxis while 219 (34%) were treated with AC (warfarin), 146 (22%) were treated with AP, and 13 (2%) received both agents. Patients discharged in AF from community hospitals were significantly less likely to be treated with either AC or AP agents than patients discharged from tertiary centers. A strong bias against thromboembolism prophylaxis with either AC or AP agents in AF existed with age over 45 years. Multivariate logistic regression indicated that the decision to treat was associated only with the presence of prosthetic valve, history of prior stroke, mitral disease, and absence of a recent gastrointestinal bleed or occult blood in stool. Even after adjustment for these factors, a significant bias against treatment with either AC or AP agents with advancing age and discharge from community hospitals remained. CONCLUSIONS: Thromboembolism prophylaxis with either AC or AP agents is underutilized in the setting of AF. Furthermore, factors known to increase the risk of embolization in AF such as age, hypertension, diabetes, and heart disease were not associated with decisions to treat with either AP or AC agents. This study suggests that the use of clinical guidelines suggested by trials of thromboembolism prophylaxis in AF could reduce the incidence of stroke.