Abstract
Background: Activated Clotting Time (ACT) guided heparinization is the gold standard for titrating unfractionated heparin (UFH) administration during atrial fibrillation (AF) ablation procedures. The current ACT target (300 s) is based on studies in patients receiving a vitamin K antagonist (VKA). Several studies have shown that in patients receiving Direct Oral Anticoagulants (DOACs), the correlation between ACT values and UFH delivered dose is weak. Objective: To assess the relationship between ACT and real heparin anticoagulant effect measured by anti-Xa activity in patients receiving different anticoagulant treatments. Methods: Patients referred for AF catheter ablation in our centre were prospectively included depending on their anticoagulant type. Results: 113 patients were included, receiving rivaroxaban (n = 30), apixaban (n = 30), dabigatran (n = 30), and VKA (n = 23). To meet target ACT, a higher UFH dose was required in DOAC than VKA patients (14,077.8 IU vs. 9565.2 IU, p < 0.001), leading to a longer time to achieve target ACT (46.5 min vs. 27.3 min, p = 0.001). The correlation of ACT and anti-Xa activity was tighter in the VKA group (Spearman correlation ρ = 0.53), compared to the DOAC group (ρ = 0.19). Despite lower ACT values in the DOAC group, this group demonstrated a higher mean anti-Xa activity compared to the VKA group (1.56 ± 0.39 vs. 1.14 ± 0.36; p = 0.002). Conclusion: Use of a conventional ACT threshold at 300 s during AF ablation procedures leads to a significant increase in UFH administration in patients treated with DOACs. This increase corresponds more likely to an overdosing than a real increase in UFH requirement.
Highlights
Catheter ablation has become a widely used technique in the treatment of atrial fibrillation (AF) [1]
Our results show that the correlation between Activated Clotting Time (ACT) and heparin activity represented by anti-Xa values seem to be correct in vitamin K antagonist (VKA) patients, but appear to be very unreliable in Direct Oral Anticoagulants (DOACs) patients
The difficulty to reach the ACT target in patients receiving DOACs is associated with a significantly higher procedural anti-XA activity compared to patients receiving VKA. These contradictory results corroborate the hypothesis of a potential heparin overdosing during AF ablation procedures in patients treated with DOACs, already discussed by other authors [19]
Summary
Catheter ablation has become a widely used technique in the treatment of atrial fibrillation (AF) [1]. Thromboembolic events are among the most serious complications of the procedure [2] These are mainly due to blood clot formation secondary to the presence of intracardiac catheters. Additional anticoagulation with unfractionated heparin (UFH) is necessary during the procedure to fully control this transient embolic risk This combination of anticoagulants can expose patients to hemorrhagic complications, from femoral access bleeding to tamponade [4]. Since UFH dose required is highly variable between patients, Activated Clotting Time (ACT) guided heparinization has become the reference strategy for titrating anticoagulation during the procedure. Activated Clotting Time (ACT) guided heparinization is the gold standard for titrating unfractionated heparin (UFH) administration during atrial fibrillation (AF) ablation procedures. Several studies have shown that in patients receiving Direct Oral Anticoagulants (DOACs), the correlation between ACT values and UFH delivered dose is weak. This increase corresponds more likely to an overdosing than a real increase in UFH requirement
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