Curriculum in CardiologyAtrial fibrillation, anticoagulation, fall risk, and outcomes in elderly patients
Section snippets
Stroke prevention
Multiple clinical trials and subsequent meta-analyses have demonstrated the benefit of aspirin compared with placebo, as well as warfarin compared with placebo, in reducing stroke risk among AF patients (Table I). In a pooled analysis of 3 randomized controlled trials (RCTs), the Atrial Fibrillation Investigators found that the relative risk reduction for aspirin versus placebo was 21% (95% CI 0%-38%, P = .05).12 In addition, another meta-analysis of 6 RCTs of aspirin versus placebo for stroke
Hemorrhagic complications
The relative benefit of warfarin compared with aspirin in preventing embolic stroke is known12, 13; however, warfarin therapy is not without risk. The association of hemorrhagic complications with warfarin use is well established, and elderly patients appear to be at higher risk.9, 16 In one analysis, when compared with patients <50 years of age, the unadjusted relative risk of patients ≥80 years of age having a life-threatening or fatal bleed on warfarin was 4.5 (95% CI 1.3-15.6); after
Warfarin monotherapy
Recommendations for anticoagulation therapy in AF patients should consider the balance of stroke risk, bleeding risk, and other complications of warfarin therapy, all of which appear to be at least in part associated with the intensity of anticoagulation. Prothrombin time ratio is a strong predictor of bleeding risk in all age groups.18 In addition, international normalized ratio (INR) may be associated with worse stroke outcomes. For example, in one study of AF patients taking warfarin who
Anticoagulation and risk of falls
Although increasing age is consistently associated with increased bleeding risk in warfarin therapy, an evaluation that specifically focused on fall-related hemorrhagic events showed that warfarin treatment was not associated with an increased risk of bleeding complications. In this study, the cohort treated with warfarin (379 falls patients) exhibited a hemorrhagic event rate of 6%, compared with 11% among patients (2,256 falls) not treated with warfarin (P = .01).26 However, these results
Future directions
The ACTIVE trials explored the role of clopidogrel (an irreversible inhibitor of the platelet P2Y12 receptor) plus aspirin versus aspirin alone in warfarin-intolerant patients (ACTIVE A) and clopidogrel plus aspirin versus warfarin (ACTIVE W) in AF patients who were able to take warfarin.27 These trials included patients with AF at enrollment or ≥2 episodes of AF in the previous 6 months, in addition to ≥1 of the following risk factors for stroke: age >74 years, hypertension, previous stroke or
Conclusions
The population of elderly patients with AF presents challenges with regard to the decision to provide anticoagulation treatment as well as which therapy, aspirin or warfarin, to choose. A higher likelihood of drug-drug interactions with warfarin, more adverse effects, and more comorbidities are at play in making these decisions. However, the available data suggest that physicians' decisions are guided more by their concerns over bleeding than an evaluation of the patient's risk for stroke; in
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George J. Klein, MD served as guest editor for this article.