MRI Could Help Guide Acute Stroke Therapy

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acute stroke

According to a retrospective study, patients who suffer from acute strokes and undergo endovascular therapy, may greatly benefit if an MRI is used to navigate the therapy.

According to M. Shazam Hussain, MD, of the Cleveland Clinic, and co-workers, a procedure that added MRI to the traditional CT-based evaluation was linked with a lower percentage of patients who received endovascular therapy (51.7% versus 96.6%, P<0.05), however, a larger percentage who attained a good clinical outcome at 30 days (23.6% versus 9.1%,P=0.01) as opposed to a CT-based approach alone.

The addition of MRI also was linked with a lower rate of 30-day mortality (25% versus 48.5%, P<0.001), they reported online in Stroke: Journal of the American Heart Association.

Albeit only a handful of centers around the U.S. are utilizing MRI in this way, "we think that this will probably become a more widely accepted way of selecting patients. Of course, this is preliminary data. We do need more data along these lines to really prove that this is an effective way to select patients, but it certainly enters us into the discussion on this topic,” said Hussain.

Intravenous thrombolytic therapy has been shown to improve outcomes when administered shortly after the onset of an acute stroke, but few patients receive the treatment. Another option is endovascular therapy, which includes mechanical thrombectomy, angioplasty or stenting, and intra-arterial thrombolytics.

“Clinical experience indicates that these alternate treatments work, but recent trials, including the IMS III and the SYNTHESIS Expansion trials presented last year at the International Stroke Conference, have not shown a significant benefit. The trial failures could be a reflection of suboptimal patient selection,” said Hussain.

After studying at their own data, Hussain and his team determined that CT probably wasn't giving them all of the information they required in order to select patients for endovascular stroke therapy. They applied a protocol that added MRI, which provided more information about the size of the infarct and the amount of salvageable brain tissue.

The current analysis included 88 adult patients with large vessel occlusions considered for endovascular stroke therapy prior to the addition of MRI to the standard CT-based protocol and 179 considered following the protocol change. In both time periods, the endovascular team was activated as soon as CT angiography revealed a large occlusion.

Although there were no differences in stroke severity between the two time frames, the percentage of patients who received IV thrombolytics was numerically, although not significantly, lower in the pre-MRI period (36.4% versus 46.6%, P=0.12).

After MRI was added to the protocol, the number of patients who actually received endovascular therapy decreased, but the percentage of patients who had a good clinical outcome, outlined by a modified Rankin Scale score of 2 or lower, increased and the percentage who died decreased. Outcomes were better among the patients overall and among those who received endovascular treatment.

The data held its own in a multivariate analysis; at 30 days, endovascular therapy performed following the addition of MRI to the protocol was still linked with an increased probability of a good clinical outcome (OR 3.4, 95% CI 1.1-10.6) and reduced mortality (OR 0.16, 95% CI 0.06-0.37).

Resolving concerns that adding MRI could delay treatment, the median time from stroke onset to the first run of endovascular therapy was no different prior or after the addition of MRI to the protocol (407 versus 390 minutes, P=0.81).

The authors acknowledged that their analysis was limited by the retrospective, single-center design. and by the inability to account for factors that might have changed over time and influenced the results.

Hussain also mentioned that another concern with adding MRI is cost and said that he and his team are currently searching for ways to make their approach more cost-effective.

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