Background: Patients with chronic renal failure (CRF) and atrial fibrillation (AF) are at increased risk of ischemic stroke and of bleeding. There is insufficient data regarding optimal treatment of patients with AF and severe CRF. We examined the impact of renal function on treatment and outcomes in a historical cohort of AF patients.
Methods: A prospective historical cohort study, conducted using the Clalit Health Services Research Institute (CHRI) database, between 2004 and 2011. Patients with nonvalvular AF (NVAF) were stratified into five categories according to eGFR (>90, 89-60, 59-30, 29-15 and <15). Primary endpoints were cerebro-vascular stroke, death, major bleeding and the composite endpoint of death and stroke.
Results: During the study period, 98,811 patients with new onset of non-valvular AF were identified. Mean follow-up time was 48.8 months. The average age was highest in the moderate CRF group (79 years). Patients with severe CRF had higher incidence of heart failure, hypertension, diabetes and dyslipidemia. Patients with severe CRF had a lower chance of being treated with Warfarin (15.2% of the patients). The severity of the kidney disease was correlated with mortality rates. Stroke incidence was highest among patients with moderate CRF, and the lowest among patients with normal kidney function. On multivariate analyses eGFR was not an independent predictor of stroke. Among patients with severe renal impairement incidence of composite stroke or death was similar between patients with or without Warfarin (190 per 1000PY), but the use of Warfarin was associated with a significantly longer time before reaching the endpoint (22.7 months vs. 37.6).
Conclusion: In this large contemporary study of patients with AF, stroke incidence was highest among patients with moderate CKD, and mortality rate increased with decreased eGFR throughout the entire range of renal function. The use of Warfarin among patients with severe renal impairment was associated with longer survival time.
