Stent Retrievers, Left Atrial Appendage Occlusion Devices Could Revolutionize Stroke Care

By Jof Enriquez,
Follow me on Twitter @jofenriq

In light of new evidence from recent clinical trials, the American Heart Association (AHA) and the American Stroke Association (ASA) are, for the first time, recommending stent retriever devices as endovascular treatment for acute ischemic stroke in select patients.

Meanwhile, The American College of Cardiology, Heart Rhythm Society, and Society for Cardiovascular Angiography have released a joint overview suggesting that the use of left atrial appendage occlusion devices could significantly prevent stroke in certain arrhythmia patients. These medical societies have considered, or are reviewing, the results of numerous clinical trials supporting the safe and effective use of anti-stroke devices with advanced technologies, progress that could herald a new era in stroke care.

According to a news release, the AHA/ASA, through a focused update of its 2013 guidelines, now recommends a stent retrieval device to remove clots obstructing the large arteries supplying blood to the brain, used in conjunction with the gold standard treatment involving tissue plasminogen activator (tPA) infusion. The update emphasizes that tPA administration remains the optimal treatment, but also states that using stent retrievers, in addition to tPA, could bring added benefit. Moreover, the update states that stent retrievers are preferred over other mechanical thrombectomy devices, although the final decision of which specific device to use is left to the judgement of the physician.

Per the release, the focused update published in the journal Stroke states that stent retrievers are recommended for a selection of stroke patients who:

• Have no significant disability prior to the current stroke
• Received tPA within 4.5 hours of symptom onset
• Have a clot blocking a large artery supplying blood to the brain
• Are at least 18 years old
• Have had an acute, severe stroke
• Have imaging showing that more than half of the brain on the side of the stroke is not permanently damaged
• Can have the procedure start within six hours after symptom onset

“What we’ve learned in the last eight months, from six new clinical trials, is that some people will benefit from additional treatment with a stent retrieval device if a clot continues to obstruct one of the big vessels after tPA is given,” said William J. Powers, M.D., lead author of the focused update and chair of the department of neurology at the University of North Carolina at Chapel Hill, in the release.

In a statement, Medtronic claims that five of the clinical trials, results of which were published in The New England Journal of Medicine (NEJM), involved the use of the company's Solitaire stent retriever device. A micro-catheter inserted at the groin delivers the Solitaire device at the site of the clot (thrombus), wherein a mesh is expanded to mechanically remove the clot and restore blood flow to the artery and to the brain.

According to Medtronic, its device was used exclusively in three trials: “SOLITAIRE FR With the Intention For Thrombectomy as PRIMary Endovascular Treatment for Acute Ischemic Stroke” (SWIFT PRIME); “Endovascular Revascularization With Solitaire Device Versus Best Medical Therapy in Anterior Circulation Stroke Within 8 Hours” (REVASCAT); and “EXtending the Time for Thrombolysis in Emergency Neurological Deficits – Intra-Arterial” (EXTEND-IA). Medtronic presented the results of the SWIFT PRIME and REVASCAT studies at the European Stroke Organisation Conference in April.

"Since Medtronic's invention of the first stent retriever in 2007, our commitment to fighting stroke has not wavered," said Brett Wall, president of the Neurovascular business, part of the Restorative Therapies Group at Medtronic, in the statement. "We helped to bring the five global trials to bear that have proven this device can be a gamechanger in the treatment of stroke, reducing functional disability in patients. The AHA/ASA guidelines have validated our commitment to and belief in this technology, and we will work hard to make it accessible to as many stroke patients as possible."

According to Medtronic, 240,000 out of 695,000 acute ischemic stroke victims in the United States are eligible to receive stent retrievers. However, these devices only are available at about 500 hospitals. The AHA/ASA said the use of stent retrievers in clot removal currently is limited to specialized facilities, such as Comprehensive Stroke Centers, or facilities with specially trained people, including some Primary Stroke Centers.

"The new national guidelines recognize stent retrievers as a major advance in stroke care, and indicate that we should strive to deliver catheter-based reperfusion to patients widely and rapidly," said Jeffrey L. Saver, MD, director of the University of California, Los Angeles (UCLA) Comprehensive Stroke Center, in the Medtronic press release.

In a separate development, The American College of Cardiology, Heart Rhythm Society, and the Society for Cardiovascular Angiography and Interventions recently released a joint overview on left atrial appendage occlusion devices and their ability to prevent stroke in patients suffering from atrial fibrillation, which affects some 2.7 million Americans, per AHA.

“The implantation of left atrial appendage occlusion devices may lower the risk of stroke in patients with atrial fibrillation. As new devices are developed, it is anticipated that the use of left atrial appendage occlusion technologies in clinical practice will expand,” states the overview.

The three societies acknowledge that some patients who are poor candidates to undergo standard coagulant therapy for stroke prevention may benefit from the implantation of said devices in the left atrial appendage, a small sac in the muscle wall of the left atrium thought to be a source of clots in patients with atrial fibrillation.

The overview cites the need for more clinical data to support the efficacy and safety of left atrial appendage occlusion implants before uniform guidelines can be drawn for their use. These guidelines would include expert consensus statements, requirements for training, operator credentialing, and institutional policies intended to keep up with anti-stroke medical device technology.

“The use of left atrial appendage occlusion devices is likely to increase with the recent approval by the FDA of the WATCHMAN device for patients who are at an increased risk of stroke based upon their clinical profile, are deemed suitable for anticoagulation therapy with warfarin, and have an appropriate rationale to seek a non-pharmacological alternative to warfarin therapy after taking into account the safety and effectiveness of the device,” the overview states.