Chronic kidney disease (CKD) has been related to poor quality of anticoagulation and an increased risk of bleeding. This study aims to evaluate the association between impaired renal function (eGFR <60mL/min/1.73 m²) and anticoagulation control in patients with non-valvular atrial fibrillation (AF) on vitamin K antagonists (VKA) therapy.

This is an ancillary analysis of the prospective NATURE AF registry (NAtionalTUnisianREgistry of Atrial Fibrillation). Between March and June 2017, we prospectively registered information of 912 patients with a recently diagnosed AF and they were followed for one year. Patients with CKD were in turn categorized according to their eGFR level (Stage 3A: 59–45mL/min, Stage 3B: 44–30mL/min, Stage 4:29-15mL/min and Stage 5: <15mL/min). The calculations for the time in therapeutic range (TTR) were made for the 12 months in each group and compared with the TTR of patients without CKD.

A total of 103 patients (11.4%) had eGFR <60mL/min/1.73 m². Anticoagulation control levels progressively worsened across each stage of CKD till the stage 3B then it progressively improved in stages 4 and 5. In the subgroup of patients with preserved renal function (75.5%), the concomitant use of anti-platelet agents was associated with better TTR (Table 1).

Early stages of CKD seem to be associated with poorer anticoagulation control in patients with non-valvular AF taking VKA but without statistically significant difference. Larger studies with longer follow-up are necessary.