A Research Success for Endovascular Stroke Treatments

Ischemic stroke is a neurological emergency.  An artery in the brain has been blocked by a blood clot, and brain cells begin to die by the millions every minute.  Time is of the essence, but time to do what?

The best-established therapy is to give a “clot busting” drug such as intravenous tissue plasminogen activator (tPA) within three hours after the first symptoms (four and a half for some patients).

  But more aggressive treatments have also been suggested.  One recent area of debate has involved endovascular procedures, sometimes called intra-arterial or interventional neuroradiological procedures, to either deliver a clot-busting drug directly to the clot, or to pull the clot out of the body.

The way it works is that a wire is threaded from elsewhere in the body, such as the femoral artery, up into the vessels of the brain.  A very thin tube is then threaded over that wire.  Through that catheter tube, the physician can either deliver a clot busting drug such as tPA directly at the clot, or they can use one of a few different devices to grab the clot and then pull it back out the way the wire went in. 

It sounds like a good idea, and it frankly looks very impressive to see that clot being extracted like some big, red, brain-eating worm.  Scans that show blood flow in the brain often show almost immediate restoration of normal blood flow into vessels that had been parched for oxygen just minutes before.

Like many good ideas, though, the trouble was that it didn’t seem to actually work.  Several studies done in 2013 showed that despite restored blood flow and clot removal, people didn’t seem to get better.  People who did the procedure argued that those studies had some significant flaws.  They mentioned that there was often a great deal of time between the onset of stroke and removal of the clot.

  They also mentioned that newer devices with a better track record of success had been developed since those earlier studies were done.  Skeptics countered that such arguments may have been financially motivated.

In early 2015, though, trials were published that began to change the tide of neurological opinion.  In fact, the Multicenter randomized Endovascular treatment for Acute ischemic stroke in the Netherlands (MR-CLEAN), as well as other similar studies, may dramatically alter the way acute stroke care is done.

MR-CLEAN was a large randomized trial involving 500 patients, about half of which were assigned to an endovascular procedure.  This time, only those patients whose symptoms had started less than 6 hours ago could be included.  Furthermore, they had to have strokes due to verified blockages in arteries that could be easily reached by the wire and catheter.  The study made use of retrievable stents, which had been shown to be superior to previous technology.

The investigators then looked at various measures of patient improvement, such as their quality of life, how independent they were in day-to-day activities, and their neurological examination.

  Those who received the endovascular procedure did better on all of those measures. 

On the other hand, about 9 percent of those who received the endovascular treatment showed signs of embolic stroke in other blood vessels.  This suggests that the act of threading the needle may sometimes cause little clots to shower through the brain.  Because the patients still tended to do better with the procedure, any injury caused by those clots may have been minor, but it’s still something to keep in mind.

It would be foolish to change practice based on just one study. But several other studies have also suggested benefits of endovascular treatment of acute stroke: EXTEND-IA (Extending the Time for Thrombolysis in Emergency Neurological Deficits—Intra arterial), SWIFT-PRIME (SolitaireTM FR with the intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke), ESCAPE (Endovascular treatment for Small Core and Anterior circulation Proximal occlusion with Emphasis on minimizing CT to recanalization times), and REVASCAT (RandomizEd Trial of revascularization with SolitaireTM FR device vs. best medical therapy in the treatment of Acute stroke due to anterior circulation large vessel occlusion presenting within eight hours of symptom onset).

It’s important to recognize that these studies selected their patients very carefully.  Not everyone with a stroke would benefit from such a procedure.  However, these techniques may offer better outcomes for those who have a large stroke in an easily accessible artery, especially if they arrive to the hospital as soon as possible. 

Sources: 

Berkhemer, O.A., Fransen, P.S., Beumer, D., et al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med 2015;372; 11-20.

Broderick JP, Palesch YY, Demchuk AM, et al. Endovascular therapy after intravenous t-PA versus t-PA alone for stroke. N Engl J Med 2013;368:893-903

Ciccone A, Valvassori L, Nichelatti M, et al. Endovascular treatment for acute ischemic stroke. N Engl J Med 2013;368:904-913

Kidwell CS, Jahan R, Gornbein J, et al. A trial of imaging selection and endovascular treatment for ischemic stroke. N Engl J Med 2013;368:914-923

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