Expanded use of clot-busting therapy is strongly endorsed for patients with acute ischemic stroke, while mechanical thrombectomy devices garner only lukewarm support in updated acute ischemic stroke guidelines from the American Heart Association and American Stroke Association. The guidelines appeared in the January 31 online Stroke.
The “door-to-needle time” for IV administration of clot-busting recombinant tissue plasminogen activator (t-PA) should be within 60 minutes from hospital arrival, according to a new class I, evidence level A recommendation.
Clinicians are advised to consider a noncontrast brain CT or MRI and a series of blood tests in all patients with suspected ischemic stroke before administering t-PA, but ultimately, the guidelines state that “the only laboratory result required in all patients before fibrinolytics therapy is initiated is a glucose determination; use of finger-stick measurement devices is acceptable.”
The treatment window for t-PA therapy is also extended from 3 hours to 4.5 hours after stroke onset—as recommended in the AHA/ASA 2009 update on the extended time window for administration of fibrinolytic agents.
“It’s clear that time is brain,” said lead guideline author Edward Jauch, MD, Director of Emergency Medicine at the Medical University of South Carolina in Charleston, in an interview. “We are making a much greater emphasis that patients should be evaluated as quickly as possible and get treated as quickly as possible to give them the maximum opportunity for benefit.”
The FDA and the Treatment Window
Dr. Jauch noted that the recommendations could reignite the long-standing controversy over the use of t-PA in stroke patients, particularly in light of the FDA’s recent decision not to expand approval of t-PA to include treatment up to 4.5 hours, as the European Medicines Agency has done.
“The FDA makes decisions largely based on American data, and we make guidelines based on all available data,” he said, noting that safety data were also obtained from Genentech, maker of the t-PA activase (Alteplase).
Two European trials reported last year that t-PA therapy within six hours of symptom onset increased the proportion of people who were alive and independent on follow-up.
Patrick Lyden, MD, Chair of Neurology and Director of the Stroke Program at Cedars-Sinai Medical Center in Los Angeles, said reducing the battery of blood tests prior to t-PA administration is particularly important and pointed out that when the FDA first approved t-PA to treat stroke on the basis of an NIH study, it “took the research protocol and turned it into a package insert.
“It’s taken the intervening 16 years for people to do studies and realize that you don’t need to do all the things in the package insert,” he said. “So the AHA, for the first time, is endorsing a much more practical, a much more optimal use of t-PA for stroke.”
The arrival of new classes of anticoagulants has prompted the AHA/ASA to add a new recommendation that the use of IV or intra-arterial t-PA in patients taking direct thrombin inhibitors like dabigatran (Pradaxa) or direct factor Xa inhibitors such as rivaroxaban (Xarelto) “may be harmful” and is not recommended unless specialized testing is normal, or the patient has been off the drug for more than two days.
“I think that’s overreaching; I don’t think the data support that,” said Dr. Lyden, who was not a member of the guidelines writing committee. He added that his team has had “no safety issues whatsoever” when administering the anticoagulant argatroban in patients on t-PA.
Dr. Jauch counters that data are lacking to support the safety of t-PA in patients on the new anticoagulants. Common blood tests—such as the international normalized ratio used for warfarin—do not register the anticoagulant effects of these drugs, and reversal strategies are not yet known. “As a community, we have a ways to go to figure out the optimal way to manage stroke in patients who come in on these drugs,” he said.
When mechanical thrombectomy is pursued, stent retrievers are generally preferred to coil retrievers. The guidelines note that the Merci embolus retrieval system, Penumbra System, Solitaire FR, and TREVO thrombectomy devices “can be useful” in achieving recanalization alone or in combination with fibrinolytics in carefully selected patients, but that “their ability to improve patient outcomes has not been established” and continued study in randomized trials is warranted.
Although these devices can restore blood flow very quickly, part of the problem in evaluating them is that the time from when patients develop their stroke to when they get to the catheterization lab continues to increase, Dr. Jauch said.
“One of the challenges we have is, yes, we have a great device and if you happen to have your stroke on the catheterization table, you’re in great luck,” he said. “But if you transfer multiple times or there’s a delay in getting the patient evaluated sufficiently, then it diminishes the chance of getting a good outcome.”