In one of the largest studies of its kind, a trial of Boston Scientific’s small, permanent cardiac implant showed that it could potentially serve as an alternative to long-term blood thinners among people looking to reduce their lifetime risk of stroke due to an abnormal heart rhythm.
Atrial fibrillation is the most common arrhythmia, and is estimated to affect nearly 5% of the U.S. population. When the upper chambers beat out of sync with the rest of the heart, the chaotic flow of blood may cause clots to form, which can travel downstream and block oxygen from reaching vital organs or the brain. People with afib are five times more likely to experience a stroke—and in many cases, the clots initially form in a pocket in the wall of the cardiac muscle, known as the left atrial appendage.
Boston Scientific’s Watchman implant seals off that pocket and stops blood from pooling there. The minimally invasive platform has obtained multiple regulatory approvals over the past decade, including one from the FDA for people who cannot tolerate long-term anticoagulants due to elevated risks of dangerous bleeding.
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The CHAMPION-AF randomized trial was launched to see if closing the left atrial appendage upfront could work just as well as some of today’s leading blood thinner regimens, with a class of medications known as non-vitamin K antagonist oral anticoagulants, or NOACs.
The study—with late-breaking data presented at the annual meeting of the American College of Cardiology in New Orleans—enrolled 3,000 patients with non-valvular afib, with half receiving the Watchman FLX, regardless of whether they previously underwent an afib ablation procedure.
After three years, the Watchman FLX showed it was non-inferior to NOACs when it came to a combined measure of stroke, embolisms and cardiovascular or unexplained deaths, with statistically similar rates of 5.7% and 4.8%, respectively.
However, the implant outperformed the blood thinners when it came to serious cases of bleeding, especially outside the hospital—posting a 10.9% rate compared to 19%—for what Boston Scientific described as a 45% relative risk reduction. The trial’s results were simultaneously published in The New England Journal of Medicine.
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“These positive data, which have the potential to support updated clinical guidelines globally, will be used in our submission to expand the indication and coverage for the well-established Watchman platform as a first-line stroke risk reduction option, providing physicians with more choices in care for a wider range of patients who have atrial fibrillation,” Boston Scientific’s chief medical officer for its atrial fibrillation division, Brad Sutton, M.D., said in a statement.
“Today, 40% of patients with AF who are prescribed blood thinners for stroke risk reduction are not taking their medications consistently, significantly increasing their risk of stroke,” Sutton added. Boston Scientific estimates that more than 600,000 people worldwide have received a Watchman implant.
CHAMPION-AF will continue tracking patients for a total of five years. When looking at the trial’s endpoint measures individually, researchers found no statistical differences among deaths, systemic embolisms or hemorrhagic strokes, but they did log more ischemic strokes among those undergoing the Watchman procedure.
“There was a slightly higher number of ischemic strokes among people in the left atrial appendage closure group—3.2% versus 2% among those in the medical therapy group, but event rates were low in both groups—and this is something we will look at again at five years,” said the study’s co-principal investigator, Saibal Kar, M.D., program director for cardiovascular disease fellowship at Los Robles Regional Medical Center, and national physician director for interventional cardiology at HCA Healthcare.
“Our data suggest that the left atrial appendage closure device used in this trial is a potential and reasonable alternative to medication—even among patients who are suitable for long-term blood thinners—and may be discussed as part of a shared decision-making process,” Kar said in a statement.
“This is an important finding because we studied people who we thought were good candidates for blood thinners—they are not contraindicated for long-term anticoagulation and they have low bleeding risk—and in spite of that, they had increased bleeding over time,” he said.
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The CHAMPION-AF study’s non-inferiority results diverge from another recent study of left atrial appendage approaches, presented late last year at the annual scientific sessions of the American Heart Association and published in The New England Journal of Medicine earlier this month.
The three-year CLOSURE-AF trial recruited 912 high-risk afib patients in Germany, with half following physician-directed drug regimens, including direct-acting oral anticoagulants, and half receiving a CE-marked implant—mostly from either Boston Scientific’s Watchman or Abbott’s Amplatzer platforms, with some receiving the LAmbre device developed by LifeTech.
The study failed to show the devices worked as well as blood thinners across a composite outcome measure, including stroke, embolism, major bleeding and death. Additionally, the device group saw more serious complications compared to medical therapies.
In an NEJM editorial accompanying CHAMPION-AF, Gregory Marcus, M.D., a professor of medicine at the University of California, San Francisco, said the results should be considered in the context of CLOSURE-AF’s missed endpoint. The non-industry-funded study raises the burden of proof for noninferiority, he added, noting that the jury is still out.
“Given the long track record and robust evidence supporting the efficacy and safety of NOACs, why would an alternative that is only ‘just as good’ even be entertained? One compelling argument is that the harms of anticoagulation may accrue uniquely among patients receiving NOACs over an extended period of time, and indeed, a 5-year follow-up assessment of the patients in the CHAMPION-AF trial is already planned,” Marcus wrote.
“Although the data in the current trial support expanding consideration of left atrial appendage closure for selected patients on a case-by-case basis, they are likely to be insufficient for a definitive declaration that this approach is as efficacious as conventional NOAC therapy in the great majority of patients with atrial fibrillation,” he added.
