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tPA-ultrasound combination increases reopening of blocked arteries after stroke

A pilot study led by University of Cincinnati researchers showed that standard clot-busting medication combined with low-energy ultrasound appears to reopen clogged arteries in stroke patients better than medication alone.

The findings, says the University of Cincinnati's Joseph Broderick, co-principal investigator of the study, are encouraging and support a much broader phase-3 trial planned to begin soon.

Broderick, at the University of Cincinnati ( UC ) and co-principal investigator Thomas Tomsick, at UC and Cincinnati's University Hospital, presented their findings at the International Stroke Conference.

The study, known as Interventional Management of Stoke Study or IMS-II, involved 73 participants between the ages of 18 and 80 treated in 13 participating centers and suffering from severe ischemic stroke. Each was given lower than standard doses of tissue plasminogen activator ( tPA ) during a 30-minute period within three hours of the onset of stroke.

Subjects were then immediately taken for an angiography where a microcatheter was placed into a groin artery and threaded to the site of the blocked artery in their brain.
Twenty-one participants without a visible and treatable clot received no additional therapy.
The remainder of participants ( 52 ) who had visible, treatable clots was treated with up to 22 milligrams of additional tPA delivered through the catheter directly to the blockage.

Whenever possible, they were also given a low-energy ultrasound treatment at the site of the clot. The ultrasound, which attempted to break up the clot, was administered using the EKOS Micro-Infusion Catheter MicroLysus infusion system.
In 18 participants, where the EKOS MicroLysus catheter could not access the clot, a standard catheter was used to deliver tPA to the clot site.

Partial or complete reopening of the blocked brain artery occurred in 69 percent of the 34 patients receiving the ultrasound treatment. This was an improvement when compared with the IMS-I study, in which 55 percent of patients involved achieved partial or complete reopening of the blocked artery.
The IMS-I study used only a microcatheter to deliver tPA directly to the location of the stroke-causing clot.

" After adjustment for differences in baseline stroke severity, age and time-to-treatment, the likelihood of IMS-II subjects attaining functional independence at three months was 65 percent relatively greater compared to IV-only tPA-treated subjects in IMS-I," Broderick says.

The mortality of the IMS-II participants ( 16 percent ) was identical to those in IMS-I.
Participants in the earlier NINDS tPA Stroke Trial, which tested the benefit of tPA administered within three hours after onset of stroke, had a 21 percent mortality.
Broderick noted, however, that the rate of bleeding in the brain that resulted in worsening of the participants' condition during the IMS-II study was 11 percent as compared to 6.3 percent in the IMS-I study.

" A combined analysis of IMS I and II studies to investigate the effect of treatment on patient outcome, reopening of arteries, and safety is being planned," says Broderick.

Quickly reopening clogged brain arteries in stroke patients is important because the longer the blood supply to the brain is blocked, the more likely long-lasting brain damage will occur.

Source: University of Cincinnati, 2006