Dabigatran and catheter ablation
KANSAS CITY, KANSAS. Catheter ablation for atrial fibrillation (AF) is associated with an approximately 1% risk of procedure-related ischemic stroke. The risk arises from the formation of blood clots (thrombi) on catheters and sheaths as well as from the stagnation of blood in the left atrial appendage. It is also possible that char formed on catheters due to overheating may be dislodged and carried to the small arteries in the brain where they, like the above-mentioned thrombi, may cause a stroke.

In order to prevent a procedure-related stroke, prospective ablation patients are placed on warfarin (INR 2.0-3.0) for two months prior to the procedure. Warfarin is usually discontinued a day or two before the ablation and replaced with heparin, which is also infused during the procedure. After a couple of days "bridging" with heparin, warfarin therapy is reintroduced and the patients are maintained on this for 3 to 6 months post-procedure.

A group of American and Italian electrophysiologists (EPs) have found that not discontinuing warfarin prior to and during the ablation procedure essentially eliminates the risk of procedure-related ischemic stroke. The researchers also found that patients, in the proper INR range and not experiencing AF on the day of the procedure, do not need a pre-procedure transesophageal echocardiogram (TEE).

Now a group of American and Italian EPs specializing in catheter ablation report on their investigation aimed at determining if it would be possible to replace warfarin with dabigatran (Pradaxa) in the period prior to, during and following radiofrequency catheter ablation for atrial fibrillation (AF). Their study included 290 patients with AF with an average age of 60 years with 79% being male. Most (57%) were paroxysmal and 52% had hypertension, while 20% had been diagnosed with sleep apnea and 17% had coronary artery disease.

The study participants were randomly assigned to a group (145 patients) which received uninterrupted warfarin therapy for 30 days prior to and during the procedure, and for 3 to 6 months following (warfarin group), or to a group (145 patients) which received dabigatran (150 mg twice daily) for 30 days prior to and after the procedure, but did not receive their morning dose on the day of the procedure (dabigatran group). Patients in both groups underwent a standard pulmonary vein antrum isolation procedure with additional lesions as required. They all received unfractionated heparin before transseptal puncture and as required to maintain an activated clotting time (ACT) of between 300 and 400 seconds while the catheters remained in the left atrium.

Complication rates for the two groups are given below.
*Transient ischemic attack (TIA) or ischemic stroke. These complications all occurred in persistent afibbers treated with dabigatran. No hemorrhagic strokes or deaths were observed in either group. The researchers conclude that the use of dabigatran (odds ratio: 2.76) and age over 75 years (odds ratio: 3.82) were independent predictors of bleeding and thromboembolic complications. The authors of the report conclude that continuation of dabigatran during the periprocedural period (immediately before, during and immediately after) is associated with an increased risk of complications compared with uninterrupted warfarin therapy.
Lakkireddy, D, Natale, A, et al. Feasibility and safety of dabigatran versus warfarin for periprocedural anticoagulation in patients undergoing radiofrequency ablation for atrial fibrillation. Journal of the American College of Cardiology, Vol. 59, No. 13, March 27, 2012