ABSTRACT NUMBER: ESOC2026A2051 LONG-TERM EXPOSURE TO AIR POLLUTION (PM2.5 AND NO2) AND ITS ASSOCIATION WITH CLINICAL OUTCOMES AFTER ACUTE ISCHAEMIC STROKE

Abstract Background and aims Exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) contributes to stroke burden, but their impact on aetiology, severity, and outcomes remains underexplored in Switzerland. Methods We included 1446 acute ischaemic stroke patients (2015-2022). Annual mean PM2.5 and NO2 exposures were assigned at 100×100 m resolution using geocoded residential addresses. Patients were stratified into exposure groups. Multivariable regression models were performed adjusted for age, arterial hypertension, heart failure, and renal insufficiency. Results High (>10 μg/m3;n=434;30.0%) vs. low (<7 μg/m3;n=135;9.3%) PM2.5 exposure was associated with higher median admission NIHSS (14 vs. 13;p=0.008), more cardioembolic aetiology (50.2% vs. 22.2%;p<0.001), and more ICA/MCA tandem occlusions (8.8% vs. 3.7%;p<0.001). This group had shorter prehospital delays (46 min;p<0.001), longer acute care stays (+1.2 days;p<0.001), and fewer EVT complications (20.7% vs. 32.6%;adjusted OR 0.921;95%CI:0.869-0.975). Despite greater stroke severity, patients with higher PM2.5 exposure showed better adjusted 3-month functional recovery (mRS 0-2:OR 1.052;95%CI:1.001-1.106). High (>10 μg/m3;n=611;42.3%) vs. low (<7 μg/m3;n=211;14.6%) NO2 exposure was linked to poorer excellent outcome (mRS 0-1:OR 0.975;95%CI:0.951-1.000) and more recurrent strokes (16.7% vs. 14.7%;p=0.005). Conclusions PM2.5 was associated with greater stroke severity but better organized acute care and recovery. NO2 predicted worse functional outcomes and recurrence. These findings highlight pollutant-specific pathways and reinforce air pollution as stroke risk factor. Conflict of interest Fiona Huber; Claudine Bouverat; Charlotte Berger; Marino Costa; Kateryna Antonenko; Lilla Gurtner; Kees de Hoogh; Benjamin Flückiger; Tatiana Bremova-Ertl; Mirjam R. Heldner: Nothing to disclose.