eComment: Anticoagulants after atrial fibrillation ablation: the potential use of dabigatran

We read with great interest the review of Gray et al. [1] concerning the safety of warfarin discontinuation after successful surgery for atrial fibrillation (AF). According to the HRS/EHRA/ECAS Expert Consensus Statement [2], the discontinuation of warfarin therapy post ablation is not generally recommended in patients who have a CHADS2 score of =2 because of limited data regarding the safety of treatment cessation. A large body of evidence monitoring patients after curative procedures for AF, mostly after catheter ablation, highlights the fact that recurrent asymptomatic AF can occur commonly, depending on the subset of patients studied as well as the duration and frequency of monitoring. The literature suggests that although the number of undetected AF episodes may increase after catheter ablation, the duration of individual episodes decreases, usually to ≫24 h – a duration not associated with thromboembolic events. If warfarin is discontinued after successful ablation, it should be reinstated once AF recurrence is confirmed in high-risk patients for thromboembolic events, regardless of the type of AF. The presence of hypercoagulability in the LA of patients with paroxysmal AF and thromboembolic risk has been demonstrated, even in the non-paroxysmal period, suggesting that patients with paroxysmal AF are at high risk for developing cerebral thromboembolism even during sinus rhythm [3]. At the same time, stroke rates as well as stroke risk factors in patients with paroxysmal AF have been proven to be similar to those in patients with persistent AF [3]. Notably, advanced age and structural heart disease were independent predictors for thrombus formation in the LA. Therefore, the resumption of warfarin treatment should not be based on the type of AF, but on the thromboembolic risk in patients with AF recurrence. AF may occur late after catheter ablation, which is not predictable by any cardiac rhythm monitoring. Late AF recurrence is more likely to occur in patients with hypertension, persistent AF, and in older patients [3]. Thus, the discontinuation of warfarin after successful ablation should be based on risk factors. However, anticoagulation therapy using warfarin involves some issues, such as bleeding, intolerability or unstable INR control, all of which may be attributable to thromboembolism in patients who are taking warfarin. The Canadian Cardiovascular Society guidelines recommend that warfarin or dabigitran be used for oral anticoagulation in patients with a CHADS2 score of =1, and concluded that dabigatran is preferred over warfarin in most patients [4]. This recommendation was based on the results of the RE-LY trial, which reported that dabigatran 150 mg po bid is superior to warfarin for the prevention of stroke with an equivalent risk of bleeding while dabigatran 110 mg po bid is equivalent to warfarin in terms of stroke prevention with a significantly reduced risk of hemorrhage [4]. Interestingly, a recent study concerning the use of dabigatran immediately after atrial fibrillation ablation revealed that there were no pre-procedural or intra-procedural thromboembolic episodes or bleeding in patients that received dabigatran. Moreover, there were no post ablation strokes, transient ischemic attacks, or systemic thromboemboli in any of the patients, rendering dabigatran a safe and well-tolerated alternative to warfarin after AF ablation [5].