Abstract Number: Esoc2026a2473 Impact of Seasonal Respiratory Virus Circulation on Clinical Characteristics and Outcomes in Ischemic Stroke

Abstract Background and aims Seasonal peaks of influenza and other respiratory viruses have been associated with an increased risk of ischemic stroke. However, the impact of high virus circulation on acute stroke care and outcomes remains unclear. Methods We retrospectively analyzed ischemic stroke patients admitted for acute-phase treatment at a tertiary center in 2025, comparing periods of high (HA) and low (LA) respiratory virus activity, as determined from national epidemiological surveillance data. We assessed demographics, vascular risk factors, stroke severity (NIHSS), and functional outcomes (mRS) for potential seasonal variation. Results We included 624 patients in the analysis, 280 (44,9%) during HA season. Mean age was 77 years (SD: 12,95), 53% were female and mean NIHSS was 14,07 (SD: 7,32). Atrial fibrillation was more prevalent in the HA group (p-value= 0.004), whereas other vascular risk factors, stroke etiology, admission NIHSS and pre-stroke mRS were comparable between HA and LA seasons. Procedural metrics such as door-to-needle and door-to-groin times, as well as hemorrhagic transformation were similar between groups. Functional outcomes (mRS at 3 months) were poorer among patients admitted during the HA period (p-value 0.04). Conclusions Despite similar baseline characteristics, stroke severity, and treatment metrics, HA period admissions register a higher prevalence of poorer functional outcomes. Notably, increased healthcare system pressure during respiratory virus peak season did not adversely affect acute stroke workflow. Conflict of interest Teresa Morais: nothing to disclose