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10-06-2010 | Stroke | Article

Warfarin helps prevent stroke during catheter ablation of AF


Free abstract

MedWire News: Continuing warfarin during catheter ablation for atrial fibrillation (AF) may help to reduce patients’ risk for periprocedural stroke, researchers have found.

The reported risk for stroke during catheter ablation varies from 0.9% to 5.0%. Even with an open irrigated catheter, stroke incidence ranges from 0.8% to 1.4%.

The current study assessed the outcomes of 6454 patients undergoing catheter ablation in nine centers. The researchers divided these patients into three groups according to ablation protocol. All patients received heparin during ablation and aspirin immediately after.

All patients were on warfarin before ablation, but in two groups the drug was stopped 3 days before the procedure and enoxaparin 1 mg/kg given from 3 days to 12 hours before ablation.

Patients in one of these two groups (n=2488) underwent ablation with an 8-mm catheter, and their periprocedural stroke or transient ischemic attack (TIA) rate was 1.1%.

Patients in the other group (n=1348) underwent ablation with an open irrigated catheter. Their stroke/TIA rate was 0.9%.

The third group (n=2618) continued on warfarin and underwent ablation with an open irrigated catheter. Patients in this group were required to have a therapeutic international normalized ratio (INR) of at least 2.0.

These patients underwent more aggressive ablation than patients in the other two groups, were more likely to have permanent AF, and more likely to have a CHADS2 score higher than 2 (ie, more likely to have congestive heart failure, hypertension, age over 75 years, diabetes, and previous stroke or TIA).

Yet no patient in this group suffered periprocedural stroke or TIA, reports the team in the journal Circulation.

“Therefore… the absence of thromboembolic events in this group is of remarkable importance,” say Andrea Natale (St David’s Medical Center, Austin, Texas, USA) and colleagues.

They believe it is “most likely related to the anticoagulation protocol in which warfarin was not discontinued, because cerebrovascular accidents have been reported even with open irrigated catheters.”

Bleeding complications occurred in 0.4–0.8% of patients and did not vary between the groups. Rates of pericardial effusion also did not vary with ablation protocol, but patients given warfarin required more protamine for postprocedural anticoagulation reversal, more blood transfusion, and were more likely to need fresh frozen plasma.

The researchers say their findings highlight the pitfalls of a bridging anticoagulation strategy. They say it exposes patients to increased embolism risk both during the procedure and for several days after, as it can take this long to re-establish a therapeutic INR.

“Our results suggest that periprocedural therapeutic anticoagulation with warfarin can reduce the risk for procedural stroke without increasing the risk for bleeding complications,” they conclude.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Eleanor McDermid