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WSC 2022 | MR CLEAN-LATE shows benefit of EVT in the late time window for patients with collaterals

Wim H. van Zwam, MD, Maastricht University Medical Center, Maastricht, The Netherlands, shares the findings of MR CLEAN-LATE. The MR CLEAN-LATE study is a prospective, randomized study, assessing the value of endovascular therapy (EVT) in patients with acute ischemic stroke due to a proximal occlusion presenting in the 6–24-hour time window. Over 500 patients were randomized across 18 centers. The study met its primary endpoint, showing that EVT provided a significant benefit on modified Rankin Scale score (mRS) after 90 days, compared to no EVT (odds ratio 1.68). Trial inclusion was based on the presence of collaterals, as previous analyses have demonstrated an association between the degree of collateral flow and the effect of EVT. Additionally, patients who met the CT perfusion criteria set out in the Dutch guidelines were excluded, as the recent DEFUSE 3 and DAWN trials demonstrated that these patients benefit from EVT in the late time window. In this way, MR CLEAN-LATE has defined a new group of patients that can be treated with EVT and has demonstrated that the presence of collateral flow on CT angiography is an adequate criterion for patient selection in the late time window. CTA is a much more widely available imaging modality compared to perfusion or diffusion imaging, enabling more centers to select patients and rapidly transfer them for intervention. This interview took place at the World Stroke Congress 2022 in Singapore.

Transcript (edited for clarity)

The MR CLEAN-LATE trial was presented yesterday, and it’s a trial looking at patients arriving beyond the six-hour time window and up to 24 hours after onset of symptoms or last seen well. We saw a treatment benefit with a common odds ratio of 1.68, which was coincidentally exactly the same as in the original MR CLEAN trial. It is a significant treatment benefit.

So we selected patients only on the presence of collaterals, so patients without any collaterals were excluded from the trial...

The MR CLEAN-LATE trial was presented yesterday, and it’s a trial looking at patients arriving beyond the six-hour time window and up to 24 hours after onset of symptoms or last seen well. We saw a treatment benefit with a common odds ratio of 1.68, which was coincidentally exactly the same as in the original MR CLEAN trial. It is a significant treatment benefit.

So we selected patients only on the presence of collaterals, so patients without any collaterals were excluded from the trial. So patients needed to have some collaterals. We also excluded patients that fulfilled the Dutch guideline criteria. Those guideline criteria are based on the DIFFUSE 3 and the DAWN trials that have been published in 2018. There it was shown that if you select patients based on some CT perfusion criteria, there is a benefit. So with that evidence from that time, we could not randomize those patients anymore. So those patients are excluded from the trial.

That means that the ones that we include are an additional cohort of patients that now can be treated because they do not fulfill the CT perfusion criteria as used in the guidelines, but still seem to benefit as long as there are collaterals. I think, well, it’s my opinion that those patients that we excluded because they had a favorable perfusion, I should say small core and some penumbra- those patients probably all have collaterals. That means that if you see patients with collaterals, you can treat them. We even mentioned at the end of the presentation that you can still do CT perfusion if you have doubt about collaterals or you don’t see any collaterals. But the easiest way to select patients for treatment in the late window for endovascular treatment now is I think looking at collaterals because we know that those patients with collaterals will benefit.

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Disclosures

Prof. van Zwam reports the following disclosures: speaker fees from Cerenovus, Stryker and Nicolab and consulting fees from Philips, all paid to institution.