Predictors of functional outcome after thrombectomy for M2 occlusions: a large scale experience from clinical practice
Authors: Kniep Helge , Meyer Lukas , Broocks Gabriel , Bechstein Matthias , Guerreiro Helena , Winkelmeier Laurens , Brekenfeld Caspar , Flottmann Fabian , Deb-Chatterji Milani , Alegiani Anna , Hanning Uta , Thomalla Götz , Fiehler Jens , Gellißen Susanne ,   The German Stroke Registry – Endovascular Treatment (GSR – ET), Röther Joachim , Eckert Bernd , Braun Michael , Hamann Gerhard F. , Siebert Eberhard , Nolte Christian , Zweynert Sarah , Bohner Georg , Berrouschot Jörg , Bormann Albrecht , Kraemer Christoffer , Leischner Hannes , Hattingen Jörg , Petersen Martina , Stögbauer Florian , Boeckh-Behrens  , Wunderlich Silke , Ludolph Alexander , Henn Karl-Heinz , Gerloff Christian , Fiehler Jens , Thomalla Götz , Alegiani Anna , Schell Maximilian , Reich Arno , Nikoubashman Omid , Dorn Franziska , Petzold Gabor , Liman Jan , Schäfer Jan Hendrik , Keil Fee , Gröschel Klaus , Uphaus Timo , Schellinger Peter , Borggrefe Jan , Tiedt Steffen , Kellert Lars , Trumm Christoph , Ernemann Ulrike , Poli Sven , Riedel Christian , Ernst Marielle Sophie 
Published: October 2023

Mechanical thrombectomy (MT) for acute ischemic stroke with medium vessel occlusions is still a matter of debate. We sought to identify factors associated with clinical outcome after MT for M2-occlusions based on data from the German Stroke Registry-Endovascular Treatment (GSR-ET). All patients prospectively enrolled in the GSR-ET from 05/2015 to 12/2021 were analyzed (NCT03356392). Inclusion criteria were primary M2-occlusions and availability of relevant clinical data. Factors associated with excellent/good outcome (modified Rankin scale mRS 0–1/0–2), poor outcome/death (mRS 5–6) and mRS-increase pre-stroke to day 90 were determined in multivariable logistic regression. 1348 patients were included. 1128(84%) had successful recanalization, 595(44%) achieved good outcome, 402 (30%) had poor outcome. Successful recanalization (odds ratio [OR] 4.27 [95% confidence interval 3.12–5.91], p < 0.001), higher Alberta stroke program early CT score (OR 1.25 [1.18–1.32], p < 0.001) and i.v. thrombolysis (OR 1.28 [1.07–1.54], p < 0.01) increased probability of good outcome, while age (OR 0.95 [0.94–0.95], p < 0.001), higher pre-stroke-mRS (OR 0.36 [0.31–0.40], p < 0.001), higher baseline NIHSS (OR 0.89 [0.88–0.91], p < 0.001), diabetes (OR 0.52 [0.42–0.64], p < 0.001), higher number of passes (OR 0.75 [0.70–0.80], p < 0.001) and intracranial hemorrhage (OR 0.26 [0.14–0.46], p < 0.001) decreased the probability of good outcome. Additional predictors of mRS-increase pre-stroke to 90d were dissections, perforations (OR 1.59 [1.11–2.29], p < 0.05) and clot migration, embolization (OR 1.67 [1.21–2.30], p < 0.01). Corresponding to large-vessel-occlusions, younger age, low pre-stroke-mRS, low severity of acute clinical disability, i.v. thrombolysis and successful recanalization were associated with good outcome while diabetes and higher number of passes decreased probability of good outcome after MT in M2 occlusions. Treatment related complications increased probability of mRS increase pre-stroke to 90d.