Clinical evidence standards for high-risk endovascular devices in ischemic stroke: a European multisociety consensus

Clinical evidence requirements for high-risk endovascular stroke devices in Europe remain heterogeneous, reflecting limited indication-specific methodological guidance under the European Medical Device Regulation (MDR) and resulting in uncertainty regarding the design and appraisal of clinical investigations across jurisdictions. We combined a systematic review of clinical studies evaluating endovascular stroke devices with a European multisociety expert consensus using a modified Delphi process. Eighteen experts representing the European Society of Minimally Invasive Neurological Therapy (ESMINT), the European Stroke Organisation (ESO), and the European Society of Neuroradiology (ESNR) participated in three Delphi rounds to formulate clinically grounded methodological recommendations for regulatory device evaluation. Prospective observational studies, including externally controlled comparative designs and single-arm studies based on performance benchmarks or precision-based estimation, were considered appropriate for most regulatory and clinical scenarios. For conceptually novel devices, no consensus was reached on a single optimal study design, leaving room for both randomized trials and observational approaches depending on the level of uncertainty. Consensus was achieved on key elements of study design, including multicenter structure, center and operator requirements, independent monitoring, imaging core-laboratory adjudication, endpoint selection, and data transparency. Functional independence at 90 days, successful reperfusion, and symptomatic intracranial hemorrhage were identified as core outcome domains. This clinician-driven consensus provides practical, indication-specific methodological recommendations for the design and conduct of regulatory studies evaluating single-use endovascular stroke devices. It complements existing frameworks, including CORE-MD and ISO-based guidance, by translating general principles into clinically applicable standards for neurointerventional research and regulatory trial design.