Warfarin not always required following ablation
MURRAY, UTAH. Current guidelines for stroke prevention after catheter ablation for atrial fibrillation (AF) call for anticoagulation with warfarin (Coumadin) for at least 2 months following the procedure. Electrophysiologists at the Intermountain Medical Center now report that warfarin therapy may not be necessary among afibbers with no or only one stroke risk factor [hypertension, diabetes, heart failure, age over 75 years, and a history of prior stroke or transient ischemic attack (TIA)].

Their study involved 690 AF patients who underwent a total of 934 ablation procedures (repeat rate of 35%) at the Center during the period 2005 to 2008. The average age of the study participants was 65 years and 52% had paroxysmal, 30% persistent, and 18% permanent AF. The procedure protocol was quite extensive and involved not only a standard PVI, but also the placing of left atrial ablation lines in 69% of the patients and mapping and ablation of complex fractionated electrograms and sites of frequent atrial ectopy. Ablation was carried out with an open-tip irrigated catheter using ICE (intracardiac echocardiography) guidance. Patients were followed for one year through clinic visits and telephone contact. At the end of the follow-up period 71.6% of ablatees were in normal sinus rhythm without the use of antiarrhythmic drugs.

Of the 630 patients, 20% were discharged on 325 mg/day of aspirin, while the remaining 80% were discharged on warfarin (INR to be controlled between 2.0 and 3.0). The aspirin group consisted of younger afibbers (average age of 60 years) with, at the most, one risk factor for ischemic stroke (41% had 0 risk factors, and 59% had 1 risk factor). Only 14% had structural heart disease so the aspirin group consisted mainly of lone afibbers, although 55% did have hypertension. In contrast, the patients in the warfarin group were older (average age of 66 years) and generally unhealthier. Only 14% of the group had no risk factors for stroke, 32% had 1 risk factor, and the remaining 52% had 2 or more risk factors. Warfarin group patients were also more likely to have persistent or permanent afib than were those in the aspirin group (55% vs. 22%).

During the year following the ablation procedure there were no deaths, strokes, TIAs or other cerebrovascular events in the aspirin group. There were 5 deaths and 4 strokes in the warfarin group. The stroke victims had 2, 3 or 4 risk factors for stroke. Two of the deaths in this group were due to major gastrointestinal and intracranial bleeding (hemorrhagic stroke). It is of interest to note that substantially more patients in the aspirin group, which consisted mainly of lone afibbers, were free of afib at the end of the follow-up than was the case for the warfarin group. In the aspirin group, 92% of paroxysmal afibbers were free of afib as compared to only 66% in the warfarin group. Corresponding percentages for persistent/permanent afibbers were 90% and 70%.

The Intermountain EPs conclude that AF patients with none or, at the most, one risk factor for ischemic stroke do not need to be anticoagulated with warfarin following a catheter ablation for AF provided the protocol used involves the use of ICE guidance and an open-tip, irrigated catheter which is less likely to result in clot formation during the procedure.

Bunch, TJ, et al. Warfarin is not needed in low-risk patients following atrial fibrillation ablation procedures. Journal of Cardiovascular Electrophysiology, September 2009, pp. 988-93

Editor's comment: As all who have experienced it, being on warfarin is a real nuisance and dangerous as well if inadequately monitored. It is therefore of considerable interest that lone afibbers with none or, at most, one risk factor for ischemic stroke do not need to be on warfarin after their ablation procedure.