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CMS Covers Percutaneous Left Atrial Appendage Closure Device
Device for stroke-risk reduction in patients with nonvalvular AF
S
troke is the fifth leading cause of death in
the United States. While there has been a
decline in the incidence and mortality of
stroke over the past decades, the number of stroke
sufferers remains immense: close to 800,000
people annually. Its cost to society is also significant. The annual direct and indirect cost of stroke
in the United States is $33 billion dollars.1
Atrial fibrillation (AF) is a strong risk factor for
stroke; nonvalvular AF increases the risk of stroke
five-fold. As people age, AF increasingly becomes
the etiology of stroke. In men and women ages
80–89, 23.5% of stroke is attributable to AF. When
subclinical AF is considered, the rates of stroke
due to AF may be much higher.1 Two commonly
used risk stratification scoring systems for estimating an individual’s risk of stroke in the setting of
AF are the CHADS2 and CHA2DS2-VASc scores,
both of which incorporate patient specific factors.
Antithrombotic agents, including warfarin and
the novel oral anticoagulants, have been the mainstay
of therapy for reducing stroke risk in patients with
AF. Warfarin offers a 64% relative risk reduction for
stroke, and the newer oral anticoagulants are all noninferior or superior in efficacy for stroke prevention
with lower rates of intracranial hemorrhage.2 All these
agents, however, carry with them the risk of bleeding.
The Watchman™ left atrial appendage closure
technology (Boston Scientific) is a novel device designed to permanently implant in the left atrial appendage of the heart, thereby occluding and isolating the appendage and preventing blood clots from
traveling into the systemic circulation. The FDA
approved it for use in March 2015 for patients with
nonvalvular AF for whom anticoagulation is recommended and who can be treated with warfarin, but
have an appropriate reason for a non-drug alternative to anticoagulation. By FDA approval guidelines,
the Watchman™ is not for use in patients who cannot tolerate blood thinning medications.3
The two randomized clinical trials that demonstrated the Watchmen™ device’s safety and effectiveness for
stroke prevention are the PROTECT AF and PREVAIL
trials. The PREVAIL trial was conducted in answer to
concerns that the PROTECT AF trial enrolled a lower
risk patient population; the PREVAIL trial enrolled
patients with a CHADS2 score of at least 2, or 1 with
a second high-risk feature for stroke. Both of these
trials enrolled warfarin eligible patients, and protocol
required the use of warfarin for at least 45 days after
implant, with prolonged anticoagulation therapy in the
absence of left atrial appendage seal at 45 days.4,5
Four-year follow up data from the PROTECT
AF trial have shown noninferiority and superiority
16
CardioSource WorldNews: Interventions
of the Watchman™ device compared to warfarin
for preventing the combined outcome of stroke,
systemic embolism and cardiovascular death.4
In Feb. 2016, CMS announced that it would
cover percutaneous left atrial appendage closure
devices for non-valvular AF for patients with
a CHADS 2 score of at least 2 as a second line
therapy to oral anticoagulants. Echoing the FDA
approval, the CMS guidelines state patients must be
eligible for warfarin therapy in the short term, but
are not suitable for long-term oral anticoagulation.6
The safety profile of the
Watchman™ device has
improved with maturation
of the technology.
Data presented at the American College of Cardiology Scientific Sessions 2016 showed a positive
post-FDA approval experience. Seventy-four institutions in the United States were implanting the
Watchman™. The initial 1,000 patients implanted
following FDA approval were studied, and findings
showed a 96% procedural success rate and with no
measurable residual jet in 97% of cases.7
The safety profile of the Watchman™ device has
improved with maturation of the technology and
operator use. All studies have shown a higher rate
of initial adverse events at time of device implant
compared with medical therapy, but as experience
with the device improves, so does the periprocedural
complications. While the initial PROTECT AF trial
showed an 8.7% 7-day periprocedural complication
rate, the multicenter EWOLUTION registry, a nonrandomized pooled cohort of 1,021 patients recruited between 2013 and 2015, the 7-day complication
rate was only 2.8% with the primary complications
of major bleeding and pericardial effusion.8
Currently FDA approval and CMS coverage for the
Watchman™ still require patients to be eligible for
warfarin use for at least 6 weeks after implantation to
allow for endothelialization of the device. This limits
its use in those people with AF and true contraindications to anticoagulation and leaves these patients without an effective means to reduce the risk of stroke. The
ASAP trial studied this exact population, and its data
were first published in 2013.9 It was a nonrandomized
multicenter trial of 150 patients with nonvalvular AF
and a CHADS2 score of at least 1 who were ineligible
for warfarin therapy. This trial involved implantation
of the Watchman™ device with at least 6 months of
dual antiplatelet therapy. The overall observed ischemic stroke rate was 1.7% per year, a 77% reduction
in expected event rates for a hypothetical population
with the same thromboembolic risk profile treated
only with aspirin. Five-year follow-up data published
May 2016 in JACC showed a 1.8% ischemic stroke or
systemic embolism event rate, 75% lower than that
expected for a similar hypothetical cohort on aspirin
alone.10 These are promising data for patients who
have absolute contraindications to oral anticoagulation
and will hopefully lead to future randomized controlled trials for this patient population.
Other left atrial appendage occlusion devices
are under development, including the Amulet, the
second generation Amplatzer cardiac plug (St Jude
Medical), the Lariat (SentreHEART Inc.), and the
WaveCrest (Coherex), but the Watchman™ is currently the only device FDA approved for left atrial
appendage closure. ■
REFERENCES
1. Mozaffarian D, et al. Circulation. 2016;133:e38-e360.
2. January CT, Wann LS, Alpert JS, et al. Circulation.
2014;doi:10.1161/CIR.0000000000000040
3. U.S. Food and Drug Administration. WATCHMAN LAA
closure technology - P130013. URL: fda.gov/Medical
Devices/ProductsandMedicalProcedures/DeviceApprovals
andClearances/Recently-ApprovedDevices/ucm440621.
htm. Last updated 4/2/15, accessed 6/6/16.
4. Reddy VY, et al. JAMA. 2014;312(19):1988-98.
5. Holmes DR, et al. J Am Coll Cardiol. 2014;64(1):1-12.
6. Centers for Medicare and Medicaid Services: Decision
memo for percutaneous left atrial appendage (LAA) closure therapy. URL: cms.gov/medicare-coverage-database/
details/nca-decision-memo.aspx?NCAId=281. Dated
2/8/16, accessed 6/9/16.
7. Holmes DR, et al. J Am Coll Cardiol. 2016;67(13S):665.
8. Boersma LVA, et al. European Heart Journal.
2016;doi:10.1093/eurheartj/ehv730
9. Reddy VY, et al. J Am Coll Cardiol. 2016;67(18):2190-2.
10. Sharma D, et al. J Am Coll Cardiol. 2016;67(18):2190-2.
Stacy Westerman, MD, MPH, is a
Clinical Cardiac Electrophysiology
fellow at Emory University in
Atlanta, GA.
July/August 2016