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 "door-to-needle time" for intravenous administration of clot-busting recombinant tissue plasminogen activator (rtPA) 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 rtPA, but ultimately, the guidelines (Stroke 2013 Jan. 31 [doi:10.1161/STR.0b013e318284056a]) 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."
Dr. Edward Jauch
The treatment window for rtPA 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 (Stroke 2009;40:2945-8).
"It’s clear that time is brain," lead guideline author Dr. Edward Jauch, director of emergency medicine at the Medical University of South Carolina in Charleston, said 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."
Dr. Jauch acknowledges that the recommendations could reignite the long-standing controversy over the use of rtPA in stroke patients, particularly in light of the Food and Drug Administration’s recent decision not to expand approval of rtPA 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 rtPA activase (Alteplase).
Two European trials – the third International Stroke Trial (Lancet 2012;379:2352-63) and a British meta-analysis (Lancet 2012;379:2364-72) – reported last year that rtPA therapy within 6 hours of symptom onset increased the proportion of people who were alive and independent on follow-up.
Dr. Patrick D. Lyden
Dr. Patrick Lyden, 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 rtPA administration is particularly important and pointed out that when the FDA first approved rtPA to treat stroke on the basis of a National Institutes of Health 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 American Heart Association, for the first time, is endorsing a much more practical, a much more optimal use of tPA for stroke."
The arrival of new classes of anticoagulants has prompted the AHA/ASA to add a new recommendation that the use of intravenous or intra-arterial rtPA in patients taking direct thrombin inhibitors like dabigatran (Pradaxa) or direct factor Xa inhibitors like 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 2 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 rtPA.
Dr. Jauch counters that data are lacking to support the safety of rtPA 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 acknowledge 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.
While these devices can restore blood flow very quickly, part of the problem in evaluating them is that the time from when the patient develops their stroke to when they get to the catheterization lab continues to increase, Dr. Jauch said.