The results of ABRIDGE-J, a Japanese multicentre randomised study on minimally interrupted dabigatran vs. uninterrupted warfarin for catheter ablation, were presented during a late-breaking trials session at the American Heart Association (AHA) Scientific Sessions (11–15 November 2017, Anaheim, USA). The data, presented by first author of the study Akihiko Nogami (University of Tsukuba, Tsukuba, Japan), show fewer bleeding complications were associated with minimally interrupted dabigatran compared to continual warfarin therapy during ablation.
The RE-CIRCUIT study has shown that dabigatran with no interruption is effective for reducing the risk of stroke at the time of catheter ablation for non-valvular atrial fibrillation (AF), and has a lower bleeding risk than uninterrupted warfarin. “However,” Nogami said at the AHA Scientific Sessions, “the major bleeding events occurred in RE-CIRCUIT in the patients who received the final dose of dabigatran less than eight hours before ablation. On the other hand, while minimally interrupted direct oral anticoagulants are currently used, there are not enough controlled data.” The objective of the ABRIDGE-J trial was thereby to compare the efficacy and safety of minimally interrupted novel oral anticoagulant (NOAC) therapy dabigatran (Pradaxa, Boehringer Ingelheim), a non-vitamin K antagonist, with that of uninterrupted warfarin in non-valvular AF patient candidates for catheter ablation.
The ABRIDGE-J trial was open-label with blinded adjudicated endpoint assessments. Out of 504 enrolled patients, 442 catheter ablation patients with non-valvular AF were randomised into two groups—220 receiving dabigatran and 222 receiving warfarin. In the warfarin arm, the anticoagulant was taken without interruption while in the dabigatran arm, therapy was discontinued around 24 hours before the ablation procedure, with the timing of the last dose taken depending on the scheduled time of ablation. For patients whose interval time between the last dabigatran dose and the ablation procedure exceeded 24 hours, heparin bridging was recommended. Dabigatran was resumed 18 hours after ablation.
The study showed no significant differences in clinical characteristics, baseline demographic, or procedural characteristics. Of the patients in the dabigatran arm, 132 (60%) interrupted their dose with an interval time of less than 24 hours between final dose of dabigatran and ablation. Eighty-three patients (38%) interrupted their dose over 24 hours before ablation, 70% of which received a heparin bridge.
There were no ischaemic events reported in the dabigatran arm, while one event was reported for warfarin. Three major bleeding events occurred with dabigatran and 11 with warfarin, resulting in a significantly lower probability of major bleeding events at three months with the NOAC than with warfarin (1.4±0.8% vs. 5.0±1.5%, p=0.032). “The dabigatran group showed significantly lower instance of major bleeding compared to the warfarin group at the time of three months after the ablation”, Nogami stated at the meeting.
A significant reduction in major bleeding risk in the dabigatran group compared with the warfarin group was also observed consistently across the subgroups (age 65–75 years, male gender, CHA2DS2-VASc score=1, and radiofrequency energy ablation patients), following an analysis of the incidence of adjudicated major bleeding events.
While differences between dabigatran and warfarin arms were significant, there were not enough primary endpoints or events in the ABRIDGE-J trial with which to compare variations within the dabigatran arm. “Because there was no thromboembolic event with dabigatran and a very low instance of the major bleeding events, we cannot analyse the safety and effectiveness of the point of view of the interval of interruption of the value of the heparin bridge”, Nogami explained.