Pradaxa Study Sees Higher Bleeding, Clot Risk after Atrial Fibrillation Ablation

A study published in February reported that patients who took Pradaxa (dabigatran) following radiofrequency ablation to treat atrial fibrillation experienced more bleeding and blood clots compared to people who were treated with warfarin post-procedure.  The authors of the study, published in the Journal of the American College of Cardiology, noted that the lack of antidote to reverse life-threatening Pradaxa bleeding side effects “makes the risk of excessive bleeding complications all the more important.”

The study looked at 290 patients who had undergone atrial fibrillation ablation procedures performed at eight high-volume hospitals from January 2010 to July 2011.  Roughly half were treated with 150 mg of Pradaxa  twice daily for at least 30 days before AF ablation.  Pradaxa was withheld on the day of surgery and restarted 3 hours after ablation.  The remaining patients were assigned uninterrupted periprocedural warfarin.

Overall, 2.1% of patients assigned Pradaxa experienced thromboembolic complications vs. none in the warfarin group. The Pradaxa group also showed a significantly higher major bleeding rate (6% vs. 1%) total bleeding rate (14% vs. 6%) and composite of bleeding and thromboembolic complications (16% vs. 6%).    According to the analysis performed by the study authors, use of Pradaxa and age over 75 were the only predictors of bleeding.

“Although our study provides initial data on slightly increased bleeding with dabigatran compared with warfarin in patients undergoing AF ablation, large randomized, controlled studies are required to confirm our results and identify an optimal periprocedural anticoagulation protocol,” the researchers concluded.

Pradaxa was approved by the U.S. Food & Drug Administration (FDA) in October 2010 to prevent strokes in patients with an irregular heartbeat called non-vavular atrial fibrillation as a warfarin replacement. The FDA launched a review of Pradaxa this past December over reports of bleeding-related side effects, while regulators in Europe and Japan have directed Boehringer Ingelheim to strengthen warnings for the drug.  According to the Institute for Safe Medicine Practices’ (ISMP) latest QuarterWatch report, the FDA received 3,781 adverse event reports associated with Pradaxa in 2011.  These included 541 deaths, 2,367 reports of hemorrhage, 291 reports of kidney failure and 644 reports of stroke.  Pradaxa was also a suspect in more than 15 cases of liver failure reported to the FDA.

Both Pradaxa and warfarin can cause internal bleeding, but there are readily available antidotes for warfarin bleeding.  Pradaxa lawsuits allege the drug caused serious, uncontrollable bleeding side effects, including gastrointestinal bleeding and cerebral hemorrhaging for which there is no reversal agent.