Catheter ablation has gained a prominent role in the management of atrial fibrillation (AF), with recent data providing positive evidence on hard outcomes, including hospitalization and mortality. Ablation, however, exposes the patient to a rather unique situation, combining risks for both major bleeding and thromboembolic events. In this setting, the critical 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 adjusted to achieve and maintain a target activated clotting time of ≥300 seconds. Whereas observational studies and randomized controlled trials support the safety and efficacy of uninterrupted NOAC strategy for AF catheter ablation, recent experiences have questioned this point, showing a greater unfractionated heparin requirement in NOAC-treated patients compared with vitamin K antagonists-treated patients to achieve the target activated clotting time. Important gaps in evidence regarding optimal intraprocedural anticoagulation management need to be acknowledged. A thorough appreciation of the physiology of anticoagulation during AF catheter ablation and the relevant differences between vitamin K antagonists and NOACs is required, while also understanding the limitations of activated clotting time measurement with regard to accurate intraprocedural anticogulation monitoring. This review aims to provide a critical look at this relatively ignored aspect of AF catheter ablation, especially pitfalls in NOAC monitoring, and to identify gaps in knowledge that need to be addressed in the near future.
Keywords: activated clotting time; atrial fibrillation catheter ablation; heparin; monitoring; non-vitamin K antagonist oral anticoagulant.