ABSTRACT NUMBER: ESOC2026A1076 PERI-INTERVENTIONAL COVERT STROKE IN PATIENTS UNDERGOING MECHANICAL THROMBECTOMY: A SERIAL MRI STUDY

Abstract Background and aims We investigated the occurrence of covert brain infarcts (CBIs) on DWI in stroke patients undergoing mechanical thrombectomy (MT) and its association with clinical, radiological and procedural variables. Methods In this prospective longitudinal study, we included patients with anterior arterial occlusion who underwent MT between April 2015 and October 2018. Serial MRI was performed on admission (pre-MT), <2 hours post-MT, and on day 5, including DWI- and perfusion imaging. CBIs were defined as new DWI lesions, absent on pre-MT DWI, and located outside the initial hypoperfusion area. Poor outcome, defined as mRS > 2 at 3 months, was tested using multivariable logistic regression adjusted for relevant confounders. Results Ninety-eight patients were included; mean age 70y, median NIHSS 18, mean onset-to-groin time 424.6 min, average initial lesion volume of 22 ml and final mTICI 2b-3 in 86%. At <2 hours, 8/92 (8.7%) patients had ≥ 1 CBI; at day 5, 24/71 (33.8%) patients had ≥ 1 CBI, mostly located in frontal and parietal regions of both hemispheres. Six patients (6.9%) presented DWI lesion reversal on day 5. No radiological or procedural variables were associated with CBIs at both timepoints. In a multivariable analysis, CBIs at 5 days, but not at <2 hours, were independently associated with poor outcome (OR 0.21, 95% CI 0.05-0.76). Conclusions CBIs are common following MT, affecting one third of patients by day 5. Their presence is independently associated with worse functional outcome at 3 months, underscoring their potential clinical relevance. Conflict of interest Luna Jongenotter: nothing to disclose, Adrián Valls: nothing to disclose, Sebastià Remollo: nothing to disclose, Laura Dorado: nothing to disclose, Josep Munuera del Cerro: nothing to disclose, Meritxell Gomis: nothing to disclose, Lucia Muñoz-Narbona: nothing to disclose, Yolanda Silva: nothing to disclose, Mikel Terceño: nothing to disclose, Alejandro Bustamante: nothing to disclose, Malgorzata Stachno: nothing to disclose, Bárbara Yugueros-Baena: nothing to disclose, Monica Millan: nothing to disclose, Maria Hernandez Perez: nothing to disclose