Background: The National Institute for Health and Care Excellence (NICE) guidelines for atrial fibrillation (AF) diagnosis and management 2021 recommends offering patients with AF and a CHA2DS2VASc >2 anticoagulation with a direct-acting oral anticoagulant (DOAC) first line where appropriate for stroke prevention. For patients on vitamin-K antagonists, their anticoagulation control is assessed according to time in therapeutic range (TTR). Patients with a TTR<65% have been shown to have an increased risk of hospitalization, mortality, and thromboembolic events and as such should have anticoagulation strategy reassessed.
Objective(s): To identify and evaluate patients on warfarin for AF, with a poor TTR, for safe switching to DOAC therapy to reduce potential risk of bleeding and thromboembolism.
Method: A specialist cardiovascular pharmacist contacted anticoagulation clinics in 3 boroughs to identify patients currently being treated with warfarin for AF (target INR 2–3) with a TTR<65%. These patients were reviewed for suitability for a switch to a DOAC using the Royal Pharmaceutical Society (RPS) guide for safe switching of warfarin to DOACs. If patients were deemed suitable, they were contacted by a member of the primary care multidisciplinary team (MDT) to discuss their> R<65%. These patients were reviewed for suitability for a switch to a DOAC using the Royal Pharmaceutical Society (RPS) guide for safe switching of warfarin to DOACs. If patients were deemed suitable, they were contacted by a member of the primary care multidisciplinary team (MDT) to discuss their poor TTR and possibility of switching to a DOAC. If agreeable, patients were switched from warfarin to DOAC. All patients were followed up 1 month after initiation to assess for adherence and tolerability to the new therapy. This study did not require ethics approval.
Results: Between February 2023 and May 2023, 796 patients with AF across 3 boroughs were being treated with warfarin. A total of 9% (74/796) of patients treated had a TTR <65% and 66% (49/74) of these patients were deemed suitable for a switch, whilst the remaining 33% (25/74) were unsuitable. This was due to variety of factors including creatinine clearance <15 ml/min, extreme body weight, medication interactions and patients declining to switch. A total of 45% (22/49) of patients were successfully switched to a DOAC, whilst the remaining 55% (27/49) are in process of being switched over to a DOAC. Patients’ anticoagulation clinics were also informed of the switch.
Conclusions: Active monitoring of TTR on a regular basis, in addition to specialist cardiovascular pharmacist input into the primary care MDT, has facilitated in a safe and effective transition from warfarin to DOAC therapy to improve patient safety. ❑
