The prevalence of atrial fibrillation (AF) is related to age and is projected to rise exponentially as the population ages and the prevalence of cardiovascular risk factors increases. The risk of ischemic stroke is significantly increased in AF patients, and there is evidence of a graded increased risk of stroke associated with advancing age. Oral anticoagulation (OAC) is far more effective than antiplatelet agents at reducing stroke risk in patients with AF. Therefore, increasing numbers of elderly patients are candidates for, and could benefit from, the use of anticoagulants. However, elderly people with AF are less likely to receive OAC therapy. This is mainly due to concerns about a higher risk of OAC-associated hemorrhage in the elderly population. Until recently, older patients were under-represented in randomized controlled trials of OAC versus placebo or antiplatelet therapy, and therefore the evidence base for the value of OAC in the elderly population was not known. However, analyses of the available trial data indicate that the expected net clinical benefit of warfarin therapy is highest among patients with the highest untreated risk for stroke, which includes the oldest age category. An important caveat with warfarin treatment is maintenance of a therapeutic international normalized ratio, regardless of the age of the patient, where time in therapeutic range should be > or =65%. Therefore, age alone should not prevent prescription of OAC in elderly patients, given an appropriate stroke and bleeding risk stratification.

The prevalence of atrial fibrillation (AF) in end-stage renal failure is high, with an increased risk of stroke among these patients with AF compared with the AF population without severe renal impairment. Many trials have shown the net clinical benefit of oral anticoagulation therapy for primary and secondary prevention of stroke in patient populations with AF. However, current stroke risk stratification schemes are based on studies that have deliberately excluded patients with severe renal impairment. Indeed, there are no large randomized controlled trials that assess the real risk/benefit of full intensity anticoagulation in patients with severe renal impairment. Also, rates of major bleeding episodes in anticoagulated hemodialysis patients with AF are high. These data are influenced by the lack of appropriate monitoring, the difficulties in maintaining the international normalized ratio target (variable between the studies), and an inaccurate bleeding classification. Thus, the limited available data may be difficult to apply to such a heterogeneous patient population, characterized by both an increased risk of bleeding and a hypercoagulability state, as seen in the patient population with severe renal impairment.