Renal Function in Atrial Fibrillation

Articles, see pp 24 and 37Cardiac function and renal function gradually decrease with aging. Therefore, atrial fibrillation, as an expression of myocardial dysfunction, and conditions with reduced renal filtration of endogenous and exogenous substances often coexist. Both cardiac dysfunction and renal dysfunction are associated with increased risk of thromboembolism, which is further amplified by concurrent atrial fibrillation. Oral anticoagulation for stroke prevention is therefore commonly used in patients with atrial fibrillation and poor or worsening renal function. The clinical dilemma of balancing the risk of ischemic stroke and the risk of major bleeding when deciding on treatment with a non–vitamin K antagonist oral anticoagulant (NOAC) or vitamin K antagonist is thus frequently being encountered in elderly patients with atrial fibrillation. These issues are highlighted by 2 articles in this issue of Circulation 1,2 and several other recent articles.3–7 Nearly 1 of 5 of the patients enrolled in the atrial fibrillation trials comparing different NOACs with warfarin had a creatinine clearance <50 mL/min.4,6,7 In these trials, the risk of stroke, death, and bleeding was higher among patients with lower renal function at baseline in both the warfarin and NOAC arms. Substudies on outcomes in relation to renal function for the factor Xa inhibitors apixaban and rivaroxaban and the factor IIA inhibitor dabigatran have demonstrated that the superior efficacy and safety of these NOACs seen in the overall trial population extend to patients with renal dysfunction.4,6,7 Apixaban was even associated with a larger benefit in major bleeding compared with warfarin in patients with atrial fibrillation and renal dysfunction.7 The consistent effects …