Activated clotting time monitoring during atrial fibrillation catheter ablation: Does the anticoagulant matter?

Introduction Atrial fibrillation (AF) catheter ablation is performed in patients receiving direct oral anticoagulants (DOACs). Guidelines recommend to perform the procedure with uninterrupted anticoagulation and intra-procedural unfractionated heparin (UFH) administration to achieve activated clotting time (ACT) at 300 seconds, as recommended for vitamin K antagonist (VKA). Objective To determine whether ACT monitoring might be transposed from VKA to DOAC-treated patients. Methods From 124 patients receiving either uninterrupted DOAC (dabigatran, rivaroxaban, apixaban) or VKA or being untreated, blood sampling was performed for anticoagulation testing. DOAC concentrations, and INR for VKA were measured. ACT was determined at baseline, and after spiking with UFH doses equivalent to 1000, 2500, 5000 and 10000 IU in vivo. Results At baseline, the extent to which oral anticoagulants prolonged ACT differed: despite similar concentrations, ACT was longer with dabigatran and shorter with apixaban (both P  Conclusion UFH administration to achieve ACT at 300 seconds may be transposed from VKA to uninterrupted dabigatran-treated patients but not to patients receiving FXa inhibitors, especially apixaban: targeting 300 seconds might expose to UFH overdosing, and bleeding complications. These findings question the indiscriminate use of ACT in AF ablation.