Disappointing Results with Dabigatran for Mechanical Valves 1

Despite being more durable than bioprosthetic valves, mechanical heart valves are often not chosen because of the requirement for lifelong anticoagulant therapy. It has been hoped that the newer generation of oral anticoagulants might eventually replace warfarin, making anticoagulation more tolerable and better accepted, since these agents don’t require continuous monitoring and have much fewer serious interactions with other drugs and food. So far, however, there has been no convincing demonstration that the the newer agents are as safe and effective as warfarin for this indication.

RE-ALIGN was a phase 2 dose-validation study of dabigatran in patients with mechanical heart valves. Results of the trial were presented at the European Society of Cardiology meeting in Amsterdam and published simultaneously in the New England Journal of Medicine.  Patients in the trial were randomized to dabigatran or warfarin.

After 252 patients had been randomized, the trial was stopped early due to an increase in thromboembolic and bleeding events in the dabigatran group:

Click here to read the full post on Forbes.

Pradaxa To Be Contraindicated In Patients With Mechanical Heart Valves 1

Boehringer Ingelheim is starting to inform physicians about a new contraindication for its oral anticoagulant drug Pradaxa (dabigatran). The company has told investigators in trials utilizing dabigatran that it will shortly be sending a “Dear Doctor Letter,” also known as a Direct Healthcare Professional Communication (DHPC), to healthcare professionals. The letter will inform physicians that Pradaxa is now contraindicated in patients with mechanical heart valves. The change was based on a recent decision of the FDA, BI told its investigators.

The FDA action follows a similar decision by the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency, which announced last week that it had recommended that Pradaxa be contraindicated in patients with prosthetic heart valves.

Both the FDA and the CHMP actions appear to be based on findings from the RE-ALIGN trial in patients with mechanical heart valves, which Boehringer Ingelheim announced last week had been stopped prematurely. (Click here for the CardioBrief story.As reported here in October, the company had previously terminated one arm of the study after an interim review of the data by the trial’s Data Safety Monitoring Board

One cardiologist who is a dabigatran investigator told CardioBrief that the label change

is consistent with the findings in Re-Align, although I wish it were presented and published in a peer reviewed journal. I do understand the urgency on behalf of the FDA to ensure that the use does not stray beyond its labeling for A-fib given both the prospective, randomized data from Re-Align and case reports of strokes on Pradaxa with mechanical valves. I don’t think this is the final word on Pradaxa (or other new generation anticoagulants), but if we are to use them, the doses will undoubtedly be different, and presumably higher, than the doses used for A-fib. The question is whether one can find a dose that prevents thromboembolic strokes with the new generation anticoagulants at an acceptable level of bleeding. It’s also worth noting that they did not recommend Pradaxa in patients with bioprosthetic valves, but didn’t absolutely contraindicate it. Yet.