New data from a study of Boston Scientific (NYSE:BSX)’s Watchman left atrial appendage closure device reports positive results in a study comparing it to warfarin, an anticoagulant drug treatment, in patients with nonvalvular atrial fibrillation.
The 2,406-patient study, published in the Journal of the American College of Cardiology, reported a lower rate of hemorrhagic strokes, unexplained and cardiovascular death and non-procedural bleeding when compared to warfarin.
“I think the fact that we now actually have some good scientific data in the field is terribly important, it has been lacking. But I think we now have randomized trial data as well as this now very well controlled register data that gives us really good information on this specific device and its role in the field,” lead author Dr. David Holmes, of Rochester, Minn.’s Mayo Graduate School of Medicine, told MassDevice.com in an interview.
The difference in the rate of hemorrhagic stroke was significant, the study reports, with 0.15 events per 100 patient years in patients treated with the Watchman, and 0.96 events per 100 patient years in patients treated with warfarin.
“This was one of the most important parts of the trial. When we looked at the incidence of all-cause stroke or systemic embolism in the patients treated with warfarin vs those treated with the watchman device, the hazard ratio was 1 – meaning there was absolutely no difference. However, there was a difference in the specific sub-group in the type of stroke. In patients who received the Watchman device, there was a dramatic reduction in hemorrhagic stroke. Hemorrhagic stroke is the worst stroke to have because it has the highest morbidity, highest mortality and the highest occurrence rate. It was dramatically less,” Dr. Holmes said.
The study also reported a reduction in unexplained or cardiovascular death, with 1.1 events per 100 patient years versus 2.3 events per 100 patient years when compared to warfarin. Non-procedural bleeding was also reduced, with a 6% rate in Watchman patients and an 11.3% rate in warfarin patients.
“As you can imagine, incidences of major bleeding that are not related to the procedure are dramatically less with the Watchman. That makes sense – if you were to put a patient today with NVAF on warfarin and have them take that for the rest of their life, they’re going to be at continued increased risk of bleeding. There’s no question about that, whether it’s warfarin or one of the new agents. If you’re on an anticoagulant, there’s more chance of bleeding,” Dr. Holmes said.
Patients treated with the device had a higher rate of ischemic stroke, with 1.6 events per 100 patient years versus 0.9 events with warfarin.
Dr. Holmes said the device was most useful for patients with the highest risk of stroke and bleeding, but could be beneficial for a wide range of patients. He also mentioned that when considering treatment, it would be important for physicians to take into account the risk of an invasive procedure.
“Suppose you were a patient, and you’ve been on warfarin for 6 years and you’ve been doing just fine. You come to see your physician, and your physician says ‘I know you’ve been on this for 5 years and are doing just fine, but there’s a device that’s now been approved that allows you to be off warfarin, and still have the same benefit in terms of stroke reduction.’ You might then say even though it’s been working pretty well, if I think of the rest of my life – taking this drug, over the next 15-20 years of my life, maybe I’m going to reassess things,” Dr. Holmes said. “It’s a matter of what the patient expectations are like, and those are really different.”
Last month, Boston Scientific touted the cost-effectiveness of its Watchman anti-stroke device compared with warfarin or aspirin at the Heart Rhythm Society’s annual meeting in Boston.
The FDA approved Watchman in March only after an unprecedented 3 advisory panel meetings to evaluate the device.
