Atrial Fibrillation Associated with Accelerated Renal Disease; Ablation May Help

A common arrhythmia in older adults is more common in those with chronic kidney disease (CKD) and may speed progression to the need for kidney dialysis or transplant, according to Nisha Bansal, MD. The Assistant Professor at the University of Washington School of Medicine gave an overview of atrial fibrillation (AF) in CKD and presented new findings on November 14, 2014 during Kidney Week in Philadelphia.

AF has a two to three fold greater incidence in CKD than in the general population, with a recent study finding an overall AF prevalence of 18% for those with CKD. Cardiovascular disease (CVD), including myocardial infarction and heart failure, is associated with CKD. When AF is induced in preclinical studies, it reduces renal blood flow and induces renal vasoconstriction. Studies of renal blood flow in an animal model have also shown that AF can also promote structural changes in the kidney, including disruption of Bowman’s capsule and increased fibrosis.

Clinical studies to delineate the relationship between AF and CKD have been primarily observational, but have shown increased risk for subsequent kidney disease in those with AF; a large Japanese study saw an overall hazard ratio (HR) of 1.80 for kidney disease for individuals with pre-existing AF.

Bansal also presented her own examination of over 200,000 individuals with CKD (estimated glomerular filtration rate [eGFR]<60 ml/min/1.73 m²) but no history of AF or end-stage renal disease (ESRD). This patient group was drawn from a large health plan database, so Bansal and coinvestigators were able to ascertain both incident AF and development of ESRD among the CKD cohort during the study period of 2002-2010. Analysis showed that the adjusted HR for risk of ESRD in patients with known CKD who develop AF is 1.67, and the association held true in subgroup analysis regardless of gender, age, race, or severity of kidney disease. Bansal acknowledged study limitations, including possibility of a selection bias, since only those patients whose serum creatinine was followed by a provider could be included.

Presenting new data examining incident AF and the risk of ESRD, Bansal drew from the multi-center CRIC (Chronic Renal Insufficiency Cohort) study. Excluding individuals with known AF at the beginning of the study, the analysis included 3,091 patients from 13 clinical centers. The cohort, enrolled in CRIC between 2003 and 2008, was followed through 2012 for incident AF and development of ESRD. The mean follow-up time of 5.9 years yielded a total of 624 new cases of ESRD. For those who developed AF, the rate of ESRD was 4.23/100 person-years, vs. 3.54/100 person-years for those without AF. In this group, the adjusted HR for progression to ESRD when incident AF occurs in those with CKD was 3.18.

Treatment of AF in CKD may help prevent disease progression; ablation has been shown produce marked improvement in kidney function as measured by eGFR. A prospective study of individuals undergoing catheter ablation for AF showed that most patients remained AF-free, and that eGFR improved significantly for those with persistent or longstanding persistent AF. The improvements were greatest in those with more pronounced kidney dysfunction.

Bansal noted that she and other investigators working in this field plan to explore the CKD-specific links between kidney function and AF, and to investigate the role that both surgical and medical interventions for AF may have in preserving kidney function in CKD.