Boston Scientific Corporation announces results
from the ASA Plavix (ASAP) Study, which studied the WATCHMAN® Left Atrial
Appendage Closure (LAAC) device. The data showed a reduction in the risk of
ischemic stroke by 75 percent in patients with atrial fibrillation who have a
contraindication to oral anticoagulants such as warfarin. Vivek Reddy, M.D.,
Director of Cardiac Arrhythmia Service at Mount Sinai
Medical Center
in New York and Coordinating Investigator of
the study presented results today during a late-breaking session at the Heart
Rhythm Society’s 33rd Annual Scientific Sessions in Boston.
The prospective multi-center ASAP Study evaluated 150
patients with contraindications to warfarin, who were implanted with the
WATCHMAN Device and treated with dual antiplatelet therapy for six months
post-procedure. Subjects were followed for a mean average of 14.4 months. The
study employed the widely recognized CHADS2 risk stratification score, which
provides a clinical prediction tool for estimating the risk of stroke in
patients with atrial fibrillation. The CHADS2 score has been validated by
numerous studies and is regularly used to determine whether treatment is
required with anticoagulation or antiplatelet therapy.
“WATCHMAN is the most studied LAA closure device with more
than 2,000 patients enrolled in prospective studies and nearly 4,000
patient-years of follow up,” said Keith D. Dawkins, M.D., global chief medical
officer for Boston Scientific. “This novel device has been well received in
more than 30 countries where it offers a safe and effective alternative to
long-term treatment with oral anticoagulants.”
Atrial fibrillation affects approximately 15 million
patients worldwide and is a disorder that disrupts the ability of the heart to
beat regularly and pump blood efficiently. Patients in atrial fibrillation are
at greater risk for stroke due to the migration of clots formed in the left
atrial appendage (LAA). Anticoagulants such as warfarin have traditionally been
the only therapy for reducing stroke risk in these patients. The Boston
Scientific percutaneously delivered WATCHMAN Device is an alternative to
long-term anticoagulation in patients eligible for anticoagulant therapy. It is
designed to close the LAA, thereby preventing clots forming within the
appendage and being dislodged into the bloodstream where they can potentially
cause a stroke.
“Findings from the ASAP Study are promising in that closure
of the LAA with the WATCHMAN Device produced a
significant reduction in the expected ischemic stroke rate for this patient
population,” said Dr. Reddy. “These results are very impressive and show
potential for an effective device-based solution for higher-risk patients with
limited pharmacologic options to reduce their risk of stroke.”
For patients in the ASAP Study, the average baseline CHADS2
score of 2.8 equated to a predicted ischemic stroke rate of approximately 7.1
percent per year. The observed rate of ischemic stroke for patients implanted
with the WATCHMAN Device was 1.7 percent per year, a 75 percent reduction in
stroke risk from the predicted stroke rate based on the CHADS2 score
(p<0.01). The corresponding upper confidence bound yielded a stroke rate of
4.4 percent per year, lower than the predicted stroke rate of 7.1 percent.
Stroke rates in the ASAP study were similar to those
observed in the PROTECT AF study, which assessed similar subjects not
contraindicated to warfarin. In the multi-center, randomized PROTECT AF trial,
the WATCHMAN Device proved to be non-inferior to warfarin and demonstrated a 38
percent relative risk reduction for stroke, cardiovascular death and systemic
embolism compared to long-term warfarin therapy in 707 patients.
The WATCHMAN Device was approved for marketing in Europe and other CE Mark countries in 2009. Boston
Scientific is currently enrolling U.S. patients in the PREVAIL study,
a confirmatory study designed to gain U.S. Food and Drug Administration
approval. Enrollment is expected to be completed in the second quarter of 2012.
The WATCHMAN Device is contraindicated in patients who are not eligible for
anticoagulation therapy. In the U.S.,
the WATCHMAN Device is an investigational device, limited by applicable law to
investigational use and not available for sale. The device was developed by
Atritech, which Boston Scientific acquired in March 2011. For more information,
visit www.Atritech.net.
For more news about Boston Scientific at the Heart Rhythm
Society 33rd Annual Scientific Sessions, please follow us on Twitter @bostonsci.
About Boston
Scientific
Boston Scientific is a worldwide developer, manufacturer and marketer of
medical devices that are used in a broad range of interventional medical
specialties. For more information, please visit: www.bostonscientific.com.
