Relationship between low Ankle-Brachial Index and rapid renal function decline in patients with atrial fibrillation: a prospective multicentre cohort study.

Objective To investigate the relationship between Ankle-Brachial Index (ABI) and renal function progression in patients with atrial fibrillation (AF). Design Observational prospective multicentre cohort study. Setting Atherothrombosis Center of I Clinica Medica of ‘Sapienza’ University of Rome; Department of Medical and Surgical Sciences of University Magna Græcia of Catanzaro; Atrial Fibrillation Registry for Ankle-Brachial Index Prevalence Assessment-Collaborative Italian Study. Participants 897 AF patients on treatment with vitamin K antagonists. Main outcome measures The relationship between basal ABI and renal function progression, assessed by the estimated Glomerular Filtration Rate (eGFR) calculated with the CKD-EPI formula at baseline and after 2 years of follow-up. The rapid decline in eGFR, defined as a decline in eGFR >5 mL/min/1.73 m2/year, and incident eGFR<60 mL/min/1.73 m2 were primary and secondary end points, respectively. Results Mean age was 71.8±9.0 years and 41.8% were women. Low ABI (ie, ≤0.90) was present in 194 (21.6%) patients. Baseline median eGFR was 72.7 mL/min/1.73 m2, and 28.7% patients had an eGFR60 mL/min/1.73 m2, 153 (23.9%) had a reduction of the eGFR <60 mL/min/1.73 m2. ABI ≤0.90 was also an independent predictor for incident eGFR<60 mL/min/1.73 m2 (HR 1.851, 95% CI 1.205 to 2.845, p=0.005). Conclusions In patients with AF, an ABI ≤0.90 is independently associated with a rapid decline in renal function and incident eGFR