Stroke Centers Increase and Refine Use of Thrombectomy

A pooled analysis of the recent positive endovascular thrombectomy trials that was presented at the conference “gives us a starting point to further improve the target metrics for imaging and puncture times,” Dr. Saver said. “We want to shorten door-to-needle times for t-PA and door-to-puncture times for thrombectomy, and the processes that need to be addressed for rapid delivery of both of these are very similar. We need for patients to only make a pit stop in the [emergency department], we need to have the catheterization team ready to go in the thrombectomy suite within 30 minutes, and we need to emphasize speed in access to the target clot rather than time-consuming diagnostic angiography.”

“We now face the issue of how to best integrate t-PA treatment and clot removal,” said Thomas A. Kent, MD, Professor of Neurology and Director of Stroke Research and Education at Baylor College of Medicine in Houston. “People are still trying to work that out. With parallel processing there is some overuse of resources. Some patients recover with t-PA alone and do not need thrombectomy,” he pointed out. “We are getting closer to the cardiology model of [myocardial infarction] treatment. It is now clear that there needs to be a simple, safe, and effective way to do both t-PA treatment and thrombectomy. We need to model ourselves on the cardiology experience.”

“If you can deal with the t-PA decision in the same room without moving patients from room to room, from a scanner to a catheterization suite, you can really shorten the time to treatment,” Dr. Smith explained. “This is identical to the model that cardiologists have developed. We should now consider taking stroke patients directly to the angiography room in addition to administering t-PA. We still need cross-sectional imaging, but the quality of the image from an angiography suite is probably sufficient to make a t-PA decision. So,<hl name="5"/> you can start t-PA while you are getting arterial access. The idea is simultaneous approaches to the patient, instead of serial.”

Efforts to establish the quickest route to endovascular thrombectomy have raised the question of whether t-PA remains necessary. The answer, at least for now, is that all signs indicate that giving t-PA helps and is worth delivering.

“The 2015 thrombectomy trials had big differences among them in the dosage of t-PA administered and in the percentage of patients who received t-PA. When 100% of patients received t-PA, they had the best outcomes,” Dr. Kent said. “There was a clear synergistic relationship between thrombectomy and t-PA. There has been a trend to think about sending patients straight to thrombectomy and skipping t-PA, but my colleagues and I think that we need to hold off on doing that. For now, if a patient is eligible to receive t-PA, they should get it and then quickly move to endovascular therapy. We are not yet ready to know it’s okay to go straight to endovascular treatment. In SWIFT-PRIME, it was pretty clear that the good outcomes were attributable to both [thrombectomy plus t-PA]. Treating patients with t-PA helps soften the clot to make it easier to remove, and improves flow through collateral arteries.”

Simpler Imaging to Save Time?

Although it’s not yet proven, another new wrinkle in working up patients with acute ischemic stroke for t-PA and thrombectomy treatment is the idea that simpler and more widely available CT imaging, especially CT angiography of cerebral arteries, may suffice for confirming and localizing the clot.

This concept received a significant boost at the International Stroke Conference in data reported from the Pragmatic Ischaemic Stroke Thrombectomy Evaluation (PISTE) trial, a study that compared treatment with t-PA alone with t-PA plus endovascular thrombectomy in 65 randomized patients who were treated at any of 11 UK centers. PISTE had a low enrollment level because the trial stopped prematurely in July 2015, after several completed trials had established the superiority of endovascular thrombectomy plus t-PA, thereby making it unethical to continue the randomized study.

This premature stoppage prevented PISTE from observing a statistically significant difference for its primary efficacy end point in favor of the combined treatment. The results did, however, show a nominal advantage to using thrombectomy plus t-PA over t-PA alone that was fully consistent with the other studies, said Keith W. Muir, MD, Professor of Neuroscience at the University of Glasgow.

Keith W. Muir, MD

But what made the PISTE results especially notable was that the trial achieved this consistent outcome with a simpler imaging protocol for patients during their workup that used only CT angiography, thus avoiding the cerebral CT perfusion imaging or MRI used in several of the other trials, noted Dr. Muir.