Ablation-associated stroke risk eliminated
AUSTIN, TEXAS. 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 usually 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 researchers now report that not discontinuing warfarin prior to and during the ablation materially reduces the risk of ischemic stroke. Their clinical trial involved 3,966 patients who underwent a pulmonary vein antrum isolation (PVAI) procedure using a 3.5 mm open irrigated radiofrequency-powered catheter. The patients were divided into two groups where group 1 used the conventional warfarin discontinuation approach and group 2 continued warfarin during the procedure. Complication rates for the two groups are presented below.
The researchers conclude that continuous warfarin therapy, from 2 months before catheter ablation to 6 months following, is associated with a very low to non-existent procedure-related risk of ischemic stroke. They also point out 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). Although the standard practice is to keep all ablatees on warfarin for 6 months post-procedure, an exception is made for those with symptomatic AF and a CHADS2 score of 0 who are allowed to go off warfarin after 3 months.

Gopinath, D, et al. Pulmonary vein antrum isolation for atrial fibrillation on therapeutic coumadin: special considerations. Journal of Cardiovascular Electrophysiology, Vol. 22, February 2011, pp. 236-39