Atrial fibrillation no longer has to mean a lifetime of blood thinners for patients at high risk of stroke. Left atrial appendage closure (LAAC) can provide a permanent and effective alternative to anticoagulation for non-valvular atrial fibrillation, and Mount Sinai Heart is a leader in the study and practice of this treatment option.

In August 2020, a team led by Vivek Reddy, MD, Director of Cardiac Electrophysiology for the Mount Sinai Health System, became the first on the East Coast to implant the new generation WATCHMAN-FLX device in a patient to close off the left atrial appendage. And in June 2020, Mount Sinai published a study in Journal of the American College of Cardiology that found mechanical LAAC to be comparable to non-vitamin K antagonist oral anticoagulants (NOACs) in high-risk patients with AFib in providing protection against stroke, systemic embolism, and bleeding.

That study, Prague-17, which was funded by the Czech Ministry of Health, has set the stage for two global, multicenter clinical trials of LACC devices that are now enrolling participants: CATALYST (Clinical Trial of Atrial Fibrillation Patients Comparing Left Atrial Appendage Occlusion Therapy to Non-vitamin K Antagonist Oral Anticoagulants), will evaluate the safety and efficacy of the Amulet LAAC device, made by Abbott. And CHAMPION-AF (Comparison of Anticoagulation With Left Atrial Appendage Closure After AF Ablation) will evaluate the WATCHMAN-FLX LAAC device, made by Boston Scientific.

“Atrial fibrillation affects nearly six million Americans, and many are not good candidates for taking blood thinners over the long term,” says Dr. Reddy, who is principal investigator of the CATALYST trial and serves on the steering committee of the CHAMPION-AF trial. “LAAC is a nonsurgical catheter procedure that our research has strongly indicated for the first time to be as effective as NOACs, which in recent years have replaced vitamin K antagonists as first-line therapy for AFib stroke prevention.”

The CHAMPION-AF trial, which intends to enroll about 3,000 subjects, will compare WATCHMAN-FLX to treatment with NOACs, considered the leading contemporary drugs for stroke risk reduction in patients with non-valvular atrial fibrillation. It will also evaluate the technology as first-line therapy for patients who cannot tolerate anticoagulation.

The CATALYST trial will evaluate the Amulet LACC device against NOAC therapy, enrolling about 2,650 participants. Subjects in this prospective trial will be randomized in a 1:1 ratio between the Amulet device and a commercially available NOAC medication. For both trials, the primary endpoints are major bleeding and a composite of ischemic stroke, systemic embolism, or cardiovascular mortality.

Dr. Reddy, the Leona and Harry B. Helmsley Charitable Trust Professor of Medicine in Cardiac Electrophysiology, led a team of physicians at Mount Sinai to successfully implant the WATCHMAN-FLX device in an 81-year-old AFib patient who in July 2020 had a stroke while off anticoagulants due to a large leg hematoma. The device—the size of a quarter—was inserted through a vein in the leg and guided into the left atrial appendage of the heart. The one-time, catheter-based procedure is performed in the electrophysiology laboratory under sedation only (without general anesthesia), and typically takes about 30 minutes.

Approximately 90 percent of stroke-causing clots emanating from the heart are formed in the left atrial appendage, says Dr. Reddy, making closure of this pouch an especially effective procedure.

To date, around 30 hospitals across the country have implanted the WATCHMAN FLX, which received approval from the U.S. Food and Drug Administration in July 2020. Globally, more than 100,000 procedures have been performed, most of them with the first-generation WATCHMAN device. “While that device was quite good, the improved safety profile and closure rates of the next-generation LAAC devices make them an even better option for appropriate patients,” Dr. Reddy says.

For more information on the CATALYST Trial, contact the study team at catalyststudy@abbott.com.

Vivek Reddy, MD, has received research grants from and serves as an unpaid consultant to both Abbott and Boston Scientific, makers of LAAC devices.