Influence of oral anticoagulants on activated clotting time (ACT) during catheter ablation of atrial fibrillation

Background Catheter ablation has gained a prominent role in the management of atrial fibrillation (AF), with recent data providing positive evidence on hard outcomes. Ablation, however, exposes the patient to risks for both major bleeding and thromboembolic events. Importance of rigorous anticoagulation during the procedure has been underlined, and the latest international guidelines now recommend performing AF catheter ablation with uninterrupted non-vitamin K antagonist oral anticoagulants (NOACs) and concomitant administration of unfractionated heparin (UFH) adjusted to achieve and maintain a target ACT of ≥ 300 seconds. Purpose Observational studies and randomized controlled trials support the safety and efficacy of uninterrupted NOAC strategy for AF catheter ablation, however heparin doses are not the same for all uninterrupted strategies. The aim of this study is to establish a correlation between ACT and UFH concentration for each oral anticoagulants. Methods We proved with a retrospective study that heparin doses are almost twice superior for patients under direct oral anticoagulants than vitamin K antagonist (VKA) to achieve the target ACT ≥ 300 seconds during AF ablation. A prospective study includes uninterrupted patients requiring AF ablation. Preprocedural NOACs concentration, intraprocedural UFH administration, ACT values and UFH concentration are recorded for each group of direct oral anticoagulant including rivaroxaban, apixaban, dabigatran and for VKA group. Results One hundred and twenty patients (thirty in each anticoagulant group) underwent AF are included for atrial catheter ablation. We study correlation between ACT and UFH concentration for each group. Conclusion This study explores the physiology of anticoagulation during AF catheter ablation and the relevant differences between VKA and NOACs. ACT is not specific to UFH, multiple interferences between DOAC, UFH, and ACT question the reliability of this monitoring.