Stroke and Bleeding in Atrial Fibrillation With Chronic Kidney Disease

Stroke and Bleeding in Atrial Fibrillation With Chronic Kidney Disease

Atrial fibrillation and chronic kidney disease are each linked to increased risk for stroke and systemic thromboembolism. The goal of this large cohort study was to examine these risks and the effects of antithrombotic therapy in patients with both conditions, which has not been fully studied to date. The investigators identified all patients who were discharged with a diagnosis of nonvalvular atrial fibrillation between 1997 and 2008, as listed in Danish national registries.
Time-dependent Cox regression analyses allowed determination of the risk for stroke or systemic thromboembolism and bleeding associated with non-end-stage chronic kidney disease and with end-stage chronic kidney disease (defined as the need for renal replacement therapy). The investigators also compared the effects of treatment with warfarin, aspirin, or both in patients with chronic kidney disease vs those without renal disease.
Non-end-stage chronic kidney disease was present in 3587 (2.7%) of 132,372 patients included in the analysis, and end-stage chronic kidney disease in 901 (0.7%).
Risk for stroke or systemic thromboembolism was increased in patients with non-end-stage chronic kidney disease compared with those without renal disease (hazard ratio [HR], 1.49; 95% confidence interval [CI], 1.38-1.59; P < .001). Severity of renal disease, as determined by the intensity of treatment with loop diuretics, did not affect this risk.
In patients with end-stage chronic kidney disease, the risk for stroke or systemic thromboembolism was even higher (HR, 1.83; 95% CI, 1.57-2.14; P < .001). In both groups of patients, treatment with warfarin alone, but not in combination with aspirin, significantly reduced this risk.
The risk for bleeding was also increased in both groups and was further increased with warfarin alone, aspirin alone, or both in combination. Among patients with non-end-stage chronic kidney disease, the risk for bleeding was associated with the dose of loop diuretics and with the cause of the chronic kidney disease.

Viewpoint

Study limitations include an observational cohort design with possible residual confounding, possible underestimation of frequencies of risk factors, inclusion of only hospitalized patients with atrial fibrillation, bleeding outcome restricted to events resulting in hospitalization or death, and lack of brain imaging data. Nonetheless, the findings of this large cohort study suggest that chronic kidney disease was associated with an increased risk for stroke or systemic thromboembolism and bleeding in patients with atrial fibrillation. Although warfarin therapy was associated with a reduction in risk for stroke or systemic thromboembolism in patients with chronic kidney disease, both warfarin and aspirin were associated with an increased risk for bleeding.
The risks and benefits of warfarin therapy should be carefully weighed in patients with chronic kidney disease and atrial fibrillation. Patients who take warfarin should have close monitoring of the international normalized ratio. Clinical trials could help determine the role of warfarin or of other anticoagulants in this patient population.source medscape