Abstract Number: Esoc2026a1808 Reverse Cherry Picking in Large Randomized Controlled Trials—results From the Distal Trial

Abstract Background and aims Randomized controlled trials failed to demonstrate a benefit of endovascular treatment (EVT) for medium or distal vessel occlusion (MDVO) strokes. A potential explanation is reverse cherry-picking, in which patients with higher expected treatment benefit are treated outside of the trial. Methods This is a retrospective analysis of non-randomized patients fulfilling the DISTAL trial inclusion criteria who received EVT at top enrolling centers during the trial. Baseline characteristics and 90-day functional outcomes were assessed using regression analysis. Second, all eligible patients at two participating centers were analyzed irrespective of treatment strategy. Results A total of 273 eligible patients were treated outside of the trial. Non-randomized patients presented with a more severe stroke profile, including higher baseline National Institute of Stroke Scale (NIHSS) scores (9 versus 6, P 0. 001), more frequent M2-segment occlusions (62% versus 44%, P 0. 001), and larger Tmax 6 s hypoperfusion volumes (50 mL versus 33 mL, P 0. 001). After adjusting for baseline NIHSS, pre-stroke mRS, occlusion location, and IVT, patients treated outside of the trial showed lower 90-day mRS outcomes (cOR 0. 68, 95% CI 0. 48–0. 97). In the secondary all-eligible cohort, EVT was preferentially performed in patients with higher NIHSS scores and more proximal occlusions, whereas patients with more distal occlusions were predominantly treated with best medical treatment alone. Conclusions Non-randomized MDVO stroke patients who received EVT had more M2-segment MCA occlusions and were more severely affected than the randomized EVT cohort, which could be considered when interpreting the trial results. Conflict of interest Alexander Stebner: nothing to disclose, Vera Aebischer: nothing to disclose, Michail Panagiotis Giannakakis: nothing to disclose, Nikki Rommers: nothing to disclose, Alex Brehm: nothing to disclose, Urs Fischer: reported research support of the Swiss National Science Foundation and the State Secretariat for Education, Research and Innovation; research support of the Swiss Heart Foundation, the Swiss Brain League and the Horton Foundation; research grants from Medtronic and from Stryker, Rapid medical, Penumbra, Medtronic and Phenox, Boehringer Ingelheim; consultancies for Medtronic, Bayer, Boehringer Ingelheim, Boston Scientific, CSL Behring, Merck, Siemens and Takeda (fees paid to institution). Participation in an advisory board for AstraZeneca (former Alexion/Portola), Auzone, Biogen, AbbVie, Siemens, Corxel (fees paid to institution). Member of a clinical event committee (CEC) of the COATING study (Phenox). Member of the data and safety monitoring committee (DSMB) of the TITAN, RESCIND, LATEMT, IN EXTREMIS and RapidPulse trials. Past president of the Swiss Neurological Society and president-elect of the European Stroke Organization. Marios Psychogios: received research grants from the Swiss National Science Foundation (SNF) and Bangerter-Rhyner Stiftung. Unrestricted grant support from Medtronic Inc. , Rapid Medical Inc. , Penumbra Inc. , Siemens Healthineers AG, Stryker Neurovascular Inc. , Phenox GmbH (paid to institution) received speaker fees from Stryker Neurovascular Inc. , Medtronic Inc. , Penumbra Inc. , Acandis GmbH, Phenox GmbH, Rapid Medical Inc. , Siemens Healthineers AG (paid to institution). Is Sponsor-PI of the DISTAL Trial, SPINNERS Trial and ICARUS Trial.