Stroke/TIA Risk Lower in AF Patients Treated With Ablation

April 14, 2011

April 12, 2011 (New Orleans, Louisiana) — The risk of stroke and transient ischemic attack (TIA) is significantly lower at three years among atrial-fibrillation patients treated with radiofrequency catheter ablation when compared with patients receiving antiarrhythmic drug therapy, according to the results from a new retrospective analysis. Investigators also observed a trend toward lower rates of hospitalization for heart failure among the ablation-treated patients, but this finding did not reach statistical significance.

Dr Matthew Reynolds

Lead investigator Dr Matthew Reynolds (Beth Israel Deaconess Medical Center, Boston, MA), who presented the results last week at the American College of Cardiology 2011 Scientific Sessions, told heartwire that the analysis is "an attempt to get an idea of what we're going to find in [the Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation Trial] CABANA without having to wait around for CABANA to be done."

CABANA is an eagerly anticipated 3000-patient, National Heart, Lung, and Blood Institute–sponsored investigation designed to test whether ablation is superior to medical therapy for reducing the risk of total mortality in patients with untreated or incompletely treated atrial fibrillation. In addition to total mortality, stroke is an important secondary end point. CABANA investigators, however, are still recruiting patients, and full results are not expected until September 2015.

In the interim, Reynolds and colleagues performed a retrospective cohort analysis of stroke/TIA and heart-failure events among atrial-fibrillation patients undergoing catheter ablation and patients treated with at least two different rhythm-control medications. The analysis, from the Thomson Reuters MarketScan Research Database, which contains claims information from employers, health plans, hospitals, Medicare, and Medicaid, included 801 propensity-matched atrial-fibrillation patients, of whom 75% were using rhythm-control medications.

"It's also an attempt to leverage claims databases in order to give us an idea of what's happening clinically," added Reynolds. "One of the advantages is that they're real-world data, so you don't have the same problem with generalizability as you do with trials, such as highly selective patients treated at academic centers. The disadvantage is that they aren't randomized data, so you can't always be sure that the inferences you're making are completely free of confounding."

Overall, treatment with ablation was associated with a 40% reduction in the risk of stroke and a nonsignificant 37% reduction in heart-failure–related events. Baseline warfarin use was 70% among patients undergoing ablation and those treated with medical therapy and declined to 50% in both treatment arms at three years. Reynolds said this finding is surprising, but based on the data set, they are unable to determine whether the patients were appropriately treated with warfarin. At three years, 40% of ablation patients were taking some type of antiarrhythmic medication compared with 60% in the no-ablation arm.

Although the extent of the reduction in stroke/TIA risk was a little surprising, Reynolds said the findings should be interpreted cautiously. However, the results provide support for the ongoing randomized clinical trials and their continuing enrollment addressing this important clinical question.

Reynolds reports receiving research grants from Biosense Webster and Sanofi-Aventis and consulting fees/honoraria from Biosense Webster, Sanofi-Aventis, and St Jude Medical.


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