The Amulet Device
The Amplatzer Amulet Left Atrial Appendage Occluder is a percutaneous (delivered through the skin), catheter-based cardiac implant designed to permanently close the left atrial appendage (LAA). It is approved by the FDA for patients with non-valvular atrial fibrillation who are at increased risk of stroke seeking an alternative to long-term oral anticoagulants.
Implantation does not require open-heart surgery. The device is delivered through a catheter that moves from a small incision in the groin, through the blood vessels, and into the heart. Once positioned at the opening of the left atrial appendage, the device is deployed to seal it shut.
The Amulet uses what is called a dual-seal design. One portion – the lobe – sits slightly inside the appendage and conforms to its internal shape. The second portion – the disc – covers the entrance (the ostium) of the appendage, creating an additional barrier. Together, these components are intended to ensure complete closure and reduce the chance of residual blood flow. The device comes in eight different sizes to accommodate variation in cardiac anatomy.
Why is the Amulet Used?
The Amulet is used to reduce the risk of stroke in AFib patients.
In AFib, the atria (upper chambers of the heart) do not produce coordinated contractions, and instead quiver rather than squeeze. Because the contractions are ineffective, blood can stagnate, particularly in the LAA, and that stagnated blood can then coagulate to form a thrombus (blood clot). If or when that clot breaks free, it can travel through the bloodstream and into the brain, where it can obstruct the small arteries and cause an ischemic stroke. Up to 90% of stroke-causing clots originate in the left atrial appendage.1
Oral anti-coagulants, such as Warfarin, chemically reduce the blood’s ability to clot, and though they’re effective, they can increase the risk of bleeding. They can also be unsuitable for patients who are a fall risk, on medications that have contraindicated interactions, or have difficulty maintaining a medication schedule.
The Amulet is the mechanical solution for isolating the LAA, where clots usually form. Notably, the Amulet is approved to provide immediate and complete closure without requiring oral anticoagulants at discharge, which distinguishes it from some alternative devices, like the Watchman FLX.
What is the LAA, and Why is it Relevant in AFib Patients?
The left atrial appendage (LAA) is a small outpouching of muscle that extends from the left atrium. As an embryo, it actually develops separately from the rest of the atria, with an internal surface lined by muscular ridges rather than the smooth lining seen elsewhere in the chamber.
In normal cardiac physiology, the LAA helps regulate blood volume. With increased pressure and stretching of the heart wall in response to increased fluid volume, the LAA releases hormones that signal other parts of the body to promote sodium excretion, water loss, and vasodilation (widening of blood vessels).
The LAA is clinically significant in AFib because the irregular heart rhythm increases the likelihood of blood stagnation and clotting. Rather than being of regulatory help, the LAA becomes a liability by causing life-threatening blood clots. AFib patients have approximately a fivefold increased risk of stroke compared to individuals without atrial fibrillation, so minimizing risk is of utmost importance.
Despite the hormonal function of the LAA, its closure does not prevent the heart from performing its primary job of circulating blood.
Who is and is not a Good Candidate for the Amulet Device?
The appropriate candidates for receiving the Amulet device are:
- Non-valvular atrial fibrillation
- Increased stroke risk based on scoring systems such as CHADS₂ or CHA₂DS₂-VASc (risk stratification tools that account for factors like age, heart failure, hypertension, diabetes, and prior stroke)
- Suitability for temporary use of blood-thinning therapy during this healing window after implantation of the device
- A rationale for seeking a non-pharmacologic alternative to long-term oral anticoagulants
The Amulet is contraindicated and should not be implanted in patients who:
- Have an intracardiac thrombus (an existing clot inside the heart), since disturbing it could dislodge the clot
- Have active endocarditis or bacteremia (active bloodstream infection), because introducing a device could worsen infection
- Have cardiac anatomy where device placement would interfere with other intracardiac or intravascular structures
The decision to implant the device ultimately depends on individualized anatomical assessment and overall clinical judgment to balance procedural risk against long-term stroke prevention.
Dr. Andrea Tordini is a board-certified clinical cardiac electrophysiologist (EP) with advanced fellowship training dedicated exclusively to the diagnosis and treatment of heart rhythm disorders.
- Arora, Y., Jozsa, F., & Soos, M. P. (2023, September 4). Anatomy, Thorax, Heart Left Atrial Appendage. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK553218/.