Stroke Rounds: MRI Works for Stent Retriever Tx Selection

So rather than working on coming up with solutions for every stroke patient we have our medical staff working to improve  results for those who have smaller strokes. Lazy irresponsible bastards. This would require staffed MRIs in all stroke hospitals. Managers should be tackling the hard problems not just tweaking the existing recommendations. But we have NO leaders in stroke so we shouldn't complain when they do worthless things.
http://www.medpagetoday.com/Cardiology/Strokes/54471?

Picks patients more likely to do well -- and more of them, study suggests

MRI "compares favorably" with CT for selection of ischemic stroke patients for endovascular thrombectomy when combined with clinical characteristics, an observational study suggested.
A favorable outcome, with modified Rankin Scale (mRS) score of 2 or less at 90 days, occurred in 52.5% of patients determined likely to benefit by the MRI and clinical criteria, compared with 25.0% of patients determined uncertain to benefit by the same criteria but who were treated anyway (P=0.02).

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The MRI-based determination was the only factor to remain significantly associated with outcome on multivariable logistic regression, Thabele M. Leslie-Mazwi, MD, of Massachusetts General Hospital in Boston, and colleagues found.
Even among those who actually achieved successful reperfusion, the MRI-based determination still selected a group more likely to do well: 74.1% (20 of 27) in the "likely to benefit" group versus 33.3% (eight of 24) "uncertain to benefit" patients had a favorable outcome (P=0.004).
"Patients prospectively classified as likely to benefit based on diffusion MRI and clinical criteria (including age and time from onset) have a likelihood of favorable outcome after successful thrombectomy similar to that found in recent trials," the authors concluded.
The difference was "that MRI use in a clinical setting produced a higher treated to screened ratio," they wrote in the paper online in JAMA Neurology.
The ratio of treated to screened patients was one to three in their single-center prospective cohort of 72 patients with middle cerebral artery or terminal internal carotid artery ischemic stroke who got thrombectomy from 2012 through 2014.

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By comparison, "the most selective recent trials" EXTEND-IA and SWIFT PRIME had ratios of one in 13 and one in 7.5, respectively, Leslie-Mazwi noted in an email to MedPage Today. "These findings may point to a better way of identifying which severe stroke patients will benefit from invasive treatments."
The exact imaging criteria required for entry have varied across the spate of recent positive trials with mechanical clot busters.
EXTEND-IA used perfusion CT imaging to measure salvageable brain as an indication of "likely to benefit." SWIFT PRIME required perfusion imaging by CT or MR angiography, while ESCAPE used noncontrast CT and CT angiography with MRI discouraged as too time consuming.
No clear mandate has emerged for one over the other, and experts have noted that MR CLEAN showed a benefit of thrombectomy over medical treatment alone with little in the way of imaging required to confirm small core infarct.
However, patient selection appears key to the magnitude of benefit, with trials that did require CT selection showing about double the advantage over medical treatment as MR CLEAN and REVASCAT.

Leslie-Mazwi's group labeled those as likely to benefit as age under 80, with a time from stroke onset or last seen well to groin puncture of less than 6 hours, and a premorbid baseline mRS score of 1o or less, as well as more than 12 months of life expectancy, and a diffusion-weighted imaging stroke volume less than 70 mL.
Patients somewhat outside of those criteria -- 80 and older, with a 6 to 8 hour time from onset, premorbid mRS score of 2 to 3, 6 to 12 months' life expectancy, or a lesion volume of 70 to 100 mL -- were considered uncertain to benefit.
"We should rigorously investigate the limits of this therapy," Leslie-Mazwi told MedPage Today. "Imaging selection is part of that rigorous evaluation. We will see attempts being made to understand better who can be treated late, and who can be treated with stroke in the posterior circulation, populations where many questions remain. We think MRI will be essential in defining those parameters."
Meanwhile, centers must commit to speed not just in whatever imaging strategy they choose, but also in priming the interventional team, using bundled kits for material, and every other strategy that can shave precious minutes off the time to reperfusion, SWIFT PRIME primary investigator Jeffrey Saver, MD, of the University of California Los Angeles, told MedPage Today in an earlier interview on best practices.