VIDEO: Ischemic-stroke thrombectomy use widens and refines

LOS ANGELES – The use of endovascular thrombectomy in the United States to treat appropriate patients with acute ischemic stroke mushroomed during the past year, following several early-2015 reports that collectively documented the dramatic clinical benefit of the treatment.

As endovascular thrombectomy use grows, stroke centers are also refining and reshaping delivery of the treatment in concert with administration of intravenous tissue plasminogen activator (TPA; alteplase; Activase), which remains a key partner in producing best outcomes for acute ischemic-stroke patients with a proximal occlusion of a large cerebral artery. Collapsing delivery of the two treatments into a more seamless and streamlined process shaves critical minutes to treatment delivery, an approach called parallel processing. Recent findings have also emboldened stroke specialists to seriously consider simplifying the brain imaging that stroke patients receive prior to these treatments, a step that could further cut time to intervention while also making thrombectomy even more widely available.

Use of thrombectomy surges

Dr. Thomas A. Kent

The biggest endovascular thrombectomy news of the past year is how it has taken off for treating selected patients with acute ischemic stroke. “The rollout over the past year has been explosive. Everything pretty much shut down after the negative trial results in 2013, but now more hospitals are offering thrombectomy,” said Dr. Thomas A. Kent, professor of neurology and director of stroke research and education at Baylor College of Medicine in Houston, in an interview at the International Stroke Conference sponsored by the American Heart Association.

The best documentation of this surge came in a poster presented at the conference by researchers at the University of California, San Francisco. They analyzed data on treatment of 357,973 patients with acute ischemic stroke who were hospitalized at any one of 161 U.S. academic medical centers during October 2009-July 2015 and included in the University Healthsystem Consortium database. They tracked the percentage of patients treated endovascularly during each calendar quarter of the study period.

During 2009-2013, use of endovascular treatment rose steadily but gradually, from 1.5% of stroke patients in 2009 to 3.1% during the fourth quarter of 2012. Then, following three reports of no benefit from endovascular treatment presented at the International Stroke Conference in February 2013 – the IMS III, MR RESCUE, and SYNTHESIS trials – the endovascular rate dropped immediately and quickly bottomed out at a level of 2.6% that remained steady through the third quarter of 2014. But when the positive endovascular results from the MR CLEAN study became public in the final week of 2014, endovascular use began to quickly rise again, and then began to skyrocket during the first quarter of 2015 with three additional positive trial results reported during the Stroke Conference in February 2015. By the end of the second quarter of 2015, usage stood at 4.7%, representing a projected year-over-year increase of about 150% for all of 2015, compared with 2014, reported Dr. Anthony S. Kim, a vascular neurologist and medical director of the Stroke Center at the University of California, San Francisco, and his associates.

To put these percentages in perspective, experts estimate that roughly 10%-15% of all stroke patients qualify for thrombectomy intervention.

Their data also showed that the percentage of hospitals included in the database that performed endovascular therapies for stroke rose steadily from about 40% of centers in 2009 to nearly 60% by mid-2015.

Dr. Wade S. Smith

“Endovascular therapy with newer-generation devices is increasingly part of standard treatment for acute ischemic stroke,” they said in their poster. In addition, they cited a “new urgency to evaluate regional access to embolectomy [another name for thrombectomy] nationally and to identify system-based solutions to improve access in underserved areas.”

Several stroke experts interviewed at the conference added their own anecdotal view of thrombectomy’s rapidly expanding use for appropriate acute ischemic stroke patients during 2015, and the need for continued effort to broaden its U.S. availability.

“The number of thrombectomies fell off after the negative 2013 trials and stayed flat until a year ago, but then jumped up. It has been very dramatic,” said Dr. Wade S. Smith, professor of neurology and director of the neurovascular service at the University of California, San Francisco.

“Thrombectomy use tremendously increased since February 2015,” said Dr. Mark J. Alberts, professor of neurology and medical director of the neurology service at the University of Texas Southwestern Medical Center in Dallas, in a video interview during the conference. But despite this growth, “the major challenge [today] is geography;” that is, reaching patients in suburban and rural areas who are not as close to the primarily urban medical centers that currently offer the procedure.