MR CLEAN Study: Stroke Interventions Work

A Dutch trial that compared the effectiveness of treating acute ischemic stroke patients with tPA with that of using tPA plus mechanical clot removal and/or other clot-busting agents showed the more aggressive therapies got better results.

The study also found that taking such measures gave treating physicians more time—up to 6 hours after a stroke vs. the 4.5 hours that is the accepted treatment window for tPA.

Known as MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) the 16-center study’s positive findings were in sharp contrast to those of 3 large studies IMS-3, SYNTHESIS and MR RESCUE.

Though that fact has caused some skepticism, the authors, writing in the New England Journal of Medicine, say their results show that patients with a proximal intracranial arterial occlusion of the anterior circulation “have a benefit with respect to functional recovery when intra-arterial treatment is administered within 6 hours after stroke onset”. They cite a “clinically significant increase in functional independence in daily life by 3 months.”

In an accompanying editorial Werner Hacke, MD, PhD, called the study “the first step in the right direction” and noted that more trials are underway.

“We need and will get results from other well-designed trials, not only to confirm or refute the results of MR CLEAN but also to look at effects in subgroups (according to stroke severity, occlusion site, or time to treatment initiation), for which most single trials are underpowered,” Hacke wrote.

Using the Rankin score to assess how patients fared, lead author Olvert Berkhemer, MD and colleagues found that significantly more patients in the intervention group achieved a modified Rankin Scale score of 2 or lowere when assessed 90 days after their stroke.

There were 500 patients in the study, ages 23 to 96, and 58% were men.

In explaining why their patients’ results seem better than those of subjects in the earlier studies, Berkhemer cited the development of retrievable stents was an advance and such devices were not available in the earlier studies. He also credited the fact that patients in the MR CLEAN study all had CT angiography to establish an accurate diagnosis.

The intervention group had some adverse events. Of 233 such patients (193 of whom actually got the interventions), catheterization to treat the clot resulted in downstream embolization in 20 patients, vessel dissections in 4 patients and vessel perforations in 2 patients.

The study was hailed by Penumbra, Inc. a California-based manufacturer of clot-extraction technology.

“Of patients who received intra-arterial treatment, 32.6% achieved a clinically defined positive stroke outcome compared with 19.1% of those who received medical management,” the company said, calling the research results ones that could “improve functional independence for the 15 million stroke patients worldwide who currently have few treatment options.”