A clinical trial shows devices inserted into an artery after a stroke to remove a blood clot, used with clot-dissolving drugs, do not improve chances of living independently after 90 days compared to the use of drugs alone. The results of the study, funded by National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health, are reported online today in the New England Journal of Medicine.
The study assessed the risks and benefits of drug delivery to treat blood clots in the brain, called tissue plasminogen activator or t-PA drugs, with a catheter to the blocked artery in the brain. In the trial the catheter method was tested in combination with intravenous delivery of t-PA drugs — the current standard of care — compared to intravenous delivery alone. After the treatments, researchers measured the patient’s progress on a standard scale of disability symptoms related to stroke, as well as evidence of further hemorrhaging in the brain and mortality.
Earlier studies suggest that adding the intra-arterial delivery to the standard intravenous administration of t-PA would reduce stroke-related disability by eliminating large clots that would otherwise persist even though intravenous drugs were used. However, intra-arterial treatment is associated with risks to the patient. In this trial, about one in six patients (16%) had complications from the minimally-invasive surgical procedure.
The trial planned to enroll some 900 adult stroke patients at 71 locations in the U.S., Canada, Europe, and Australia. All patients received the intravenous t-PA treatments within three hours of their stroke symptoms. Within 40 minutes of that therapy, patients with a treatable blockage were randomized into intra-arterial therapy with one of five types of devices, or continued receiving the drugs through intravenous delivery.
By April 2012, after 656 participants were enrolled, the results showed patients receiving only the intravenous t-PA treatments (39%) were about as likely to recover from a stroke after 90 days, as those that received the drugs through both the intravenous and device delivery methods (41%). At that point, the trial’s monitoring board advised that the study be stopped early because of the lack of clear outcomes.
Joseph Broderick of University of Cincinnati who led the trial notes the study, “highlights that improved reopening of arteries and delivery of blood flow to the brain is not a guarantee of improved clinical efficacy.” The researchers report that intra-arterial therapy was 40 percent more effective at removing clots and re-establishing blood flow in the brain, but they did not improve signs of disability in the patients from the stroke.
Broderick points to the somewhat longer time to start intra-arterial treatments as a potential cause for the lack of benefit with the device. In earlier pilot studies, physicians were able to start intra-arterial treatments 32 minutes sooner on average. “We probably did not open the arteries quickly enough,” says Broderick.
He also notes that many patients do not have immediate access to intra-arterial procedures needed for successful clinical benefits. Instead, stroke patients are often treated with intravenous t-PA drugs at a local hospital, then transferred to another hospital, which further delays the time to treatment.
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