Millions of people around the world are living with atrial fibrillation (AF),
which starts as an irregular or rapid heart rhythm that gradually becomes
stronger and more constant. Many people do not even know they are living with
the condition as the symptoms can be easily overlooked. However, some people
dealing with AF experience symptoms such as extreme fatigue, feeling faint,
chest pain, shortness of breath, and heart palpitations. The life-threatening
condition results from thrombus
formation, whose prevalence increases with age. Anatomically,
the left atrial
appendage (LAA) is the major source of blood clots in
patients with non-valvular AF. Although oral blood-thinning medications are the
standard treatments for AF, several challenges limit its use such as
non-compliance, bleeding issues, fall risk, frequent prothrombin time
monitoring, etc. The LAA closure device introduced by Boston Scientific, WATCHMAN FLX is a
permanent implantable device that provides prevention against strokes in
high-risk patients with non-valvular atrial fibrillation. The WATCHMAN Implant
is a one-time
procedure that allows the patients to stop their
anticoagulation medicines after 45 days. Watchman FLX is the newest generation of LAA closure device with
more advanced features compared to the previous generation WATCHMAN, which has
been commercially available for use since 2009.
Available in five
sizes for Ostia measuring from 15 mm to 32 mm in width,
the device can be implanted in small as well as large LAA. The device consists
of a self-expanding
nitinol frame structure with 12 “J” shaped fixation
anchors and permeable polyester fabric. Compared to the 10-strut frame in the
previous version, the Watchman FLX device provides 80% more contact points at
the LAA ostium with an 18-strut
frame. The nitinol frame radially expands to maintain a proper
position in the LAA. The device is pre-loaded in the delivery system and comes
in two curve configurations—single, double, for different LAA orientations and
anchors in two rows create a proximal and distal line to help the device
stabilization. The fluoroscopic market at the atraumatic closed distal end
enhances the procedural visibility.
Allowing the flexibility of intra-LAA placement, the device prevents
contact with the left atrial wall and reduces risks of device erosion along
with minimizing interference with the left upper pulmonary vein and mitral
valve. Although the device facilitates a greater compression ranging from 10-27%, it
works best when not over-compressed since the frame has stability at low
compression due to its closed distal end. Just like the previous generation
device, the new WATCHMAN FLX can be partially recaptured or repositioned either
proximally or advanced distally several times before using the “ball technique”, which
enables the right device placement. The device even allows full recapture at
every stage of the procedure before the final device release.
How is
WATCHMAN FLX implanted?
The implantable WATCHMAN device looks like a tiny parachute made
from flexible mesh and spring wires. The doctor inserts the device through a
catheter (flexible tube) into the patient’s vein in the groin area and advances
it to the upper right chamber of the heart. Making a small hole between the two
upper chambers, the catheter reaches into a patient’s LAA. The doctor then
releases the WATCHMAN FLX device into the left atrial appendage (LAA) where it
opens up like an umbrella to prevent harmful blood clots from entering the
bloodstream and prevent possible stroke. The round design of the device allows
optimal placement of the device and assures long-term stability. Once the
device is positioned appropriately, a thin layer of tissue grows within 45
days, which further prevents blood clots from entering the bloodstream. The
broader size range of the newest version of the implant helps to treat more
patients safely and effectively.
Advantages of using Boston Scientific
Watchman FLX
- Traditional open-chest procedure requires sternotomy (large
incision in the chest) and heart-lung bypass machine to take over the
functions of the heart and lungs during the procedures whereas minimally
invasive, catheter-based intervention with Watchman FLX can be
performed while the patient’s heart is beating. Therefore, the Watchman
FLX device reduces the risk of complications, recovery time, medical
costs, and offers long-term stability.
- The insertion of the special catheter which carries the Watchman
device into the large blood vessel is supported with advanced imaging
technology, which reduces the risk of errors and aid in optimal
positioning of the device.
- The one-time intervention takes about an hour,
right from choosing the appropriate sized device to releasing it into the
heart.
- The Watchman FLX device is FDA-approved for its use in the LAA
procedure.
- The implantation of the device can be performed using monitored
anesthesia care.
- The person can be discharged within 24 hours of the procedure with
a catheter-based procedure.
- The device frees people with AFib from the daily challenges of
taking blood-thinning medications, which becomes of utmost significance
for people who are not eligible for long-term blood thinner intake.
Who
should not use the WATCHMAN FLX device?
The WATCHMAN FLX device should not be
implanted in patients who
- Currently have blood clots in the heart
- Undergone surgical repair of the atrial
septum
- Have a too large or small LAA to fit the
device
- Cannot take blood-thinning medications
- Have sensitivity to nitinol or any other
material used in the device
Limitations
Just like all procedures, the
implantation of WATCHMAN FLX carries some degree of risk. For instance, the
blood clot or air can get in the catheter, which is to be further injected into
the heart. If a blood clot or air reaches the brain, stroke is inevitable.
However, physicians can minimize these risks by taking the precautionary step
of flushing out the catheter. Another possible complication during the LAA procedure
can be left atrial appendage rupture, caused by some pressure while the device
is implanted. This complication might require an emergency heart surgery
otherwise the patient could lose his life. Due to a higher-than-anticipated
embolization rate of 3.8%, Boston Scientific had to withdraw WATCHMAN FLX. So,
the manufacturer is planning for more design enhancements in the device
maintaining key benefits of the latest generation WATCHMAN FLX such as enhanced
ostial sea, distal redeployment, enhanced stability, more forgiving placement
at the ostium, etc.
Other Devices for
LAA Occlusion
St. Jude Medical’s
Amplatzer Amulet LAA
Another potential device designed for
the left atrial appendage aims to reduce the risk of stroke arising from Atrial
Fibrillation. The device works by sealing off the opening of LAA to prevent the
entry of clots into the heart, which could further mix into the bloodstream,
reach the brain, and cause a stroke. The Amplatzer Amulet LAA Occluder is the
second-generation device, designed with a longer lobe, wider waist than,
recessed screws, and more stabilizing wires than Amplatzer Cardiac Plug, the
previous version of St. Jude Medical LAA device. The new-gen device facilitates
easier and more stable placements, which leads to shorter procedure time along
with reducing the thrombus formation on the atrial side of the device. Unlike
ACP that required manual loading, the Amulet comes with a preloaded delivery
cable for easy setup.
Available in eight sizes (16, 18, 20,
22, 25, 28, 31, and 34 mm) to accommodate a wider range of varying patient
anatomies (up to 32 mm), the Amplatzer Amulet LAA Occluder stands as a strong
competitor for Watchmen FXL that provides only five different sizes. Also, the
St. Jude LAA occluder is CE mark approved and hit in Europe while Watchman did
not receive much success in the region.
Appriva Medical’s
Percutaneous Left Atrial Appendage Transcatheter Occlusion (PLAATO)
PLAATO device was the first LAA device
that was implanted in humans in 2001. Consisting of a self-expanding nitinol
cage ranging in diameter 15 to 32 mm, three anchors on each strut, the device
was covered with non-thrombogenic polytetrafluoroethylene membrane to exclude
blood flow into the remaining LAA. Despite providing promising results, the
device was withdrawn from the market for commercial reasons after few years.
SentreHEART Inc.
Lariat
The FDA-approved catheter-based
Lariat LAA closure is a complex hybrid procedure requires both epicardial as
well as endocardial approach. The device is not specifically approved for
stroke prevention with AF but for knot tying during surgical applications.
During the LARIAT procedures, two catheters are guided into the heart to seal
the LAA with a pre-tied suture loop via LARIAT Suture Delivery Device.
Gradually, the appendage turns into scar tissue and thus permanently prevents
the blood clots to enter the heart.
Conclusion
The next generation WATCHMAN FLX is the first closure device
that can be redeployed after partial or full re-capture. The WATCHMAN implant
has remained one of the leading devices for percutaneous left atrial globally
and now the new one is taking in-charge due to its higher effectiveness. The
LAA closure procedure is in its infacy, and several issues are yet to be
addressed.
According to TechSci research report on “Global Interventional Cardiology Devices Market By Product Type (Angioplasty
Balloons, Angioplasty Stents, Structural Heart Devices, Catheters, Plaque
Modification Devices, Hemodynamic Flow Alteration Devices, Others) By End User
(Hospitals & Clinics, Ambulatory Surgery Centers, Others) By Region,
Competition Forecast & Opportunities, 2026”, global interventional cardiology devices market is expected to grow
at a formidable CAGR owing to factors like increasing incidences of
cardiovascular problems and technological advancements in medical devices
introduced in this domain.
According to another TechSci research
report on “United
States Cardiology Surgical and Interventional Devices Market By Product
Type (Cardiovascular Surgical Devices, Interventional Devices), By Surgical
Approach (Open-Heart Surgery, Off-Pump Heart Surgery, Minimally Invasive Heart
Surgery), By Type of Cardiac Surgery (Coronary Artery Bypass Grafting (CABG),
Transmyocardial Laser Revascularization (TMR), Heart Valve Repair or
Replacement, Heart Transplant, Arrhythmia Treatment, Others), By End User
(Hospitals & Clinics, Ambulatory Surgical Centers, Others), By Region,
Forecast & Opportunities, 2025”, United States cardiology surgical and
interventional devices market is expected to grow at a significant rate due to
growing geriatric population and rising incidences of coronary artery diseases.