Abstract Body: BACKGROUND:
Large vessel occlusion (LVO) is associated with high morbidity and mortality but has had major advances in treatment options. Prior studies in the United States have been limited by referral bias. We sought to study the population-based prevalence, presenting features, management, and mortality of LVO stroke.

METHODS:
From the Greater Cincinnati/Northern Kentucky Stroke Study (GCNKSS), we selected patients with a diagnosis of acute ischemic stroke (AIS) using ICD-10 codes in adults ≥18 years of age presenting with symptomatic intracranial LVO stroke confirmed on vessel imaging within study year 2020. LVO stroke was defined as occlusion limited to the intracranial internal carotid artery (ICA), the M1 segment of the middle cerebral artery (MCA), and the basilar artery (BA). Non-LVO stroke included events due to any other cause. All cases were physician reviewed using GCNKSS epidemiologic criteria. Demographic information, medical history, presenting features, use of advanced imaging, and treatment were collected for each patient. Prevalence was calculated with 95% confidence interval (CI) per 100,000 using 2020 census Demographic and Housing Characteristics in the GCNKSS region. Mortality from any cause within 30 days was calculated using the National Death Index.

RESULTS:
In 2020, 3,033 AIS events were ascertained in the GCNKSS, with a median age of 69 years (IQR 60-80), 24% black, and 52% female. Events with no vessel imaging available were excluded (n=283). Of the remaining 2,750 events, 279 (10.1%) presented with LVO stroke and had similar demographics to the overall cohort. The prevalence of LVO was 24.7 per 100,000 people (95% CI: 21.9, 27.8). In descriptive analysis, LVO stroke events presented earlier and with higher NIHSS than those without. 159 (14.1%) presented with an intracranial ICA, M1, or BA occlusion among all ischemic events within 6 hours of last known normal. Discharge mRS was also higher (TABLE 1). The 30-day mortality for first time stroke was 30.1% (95% CI: 24.6, 36.0) for stroke due to LVO compared to 8.1% (95% CI: 7.0, 9.2) in non-LVO stroke.

CONCLUSION:
One in ten ischemic stroke patients harbor an intracranial ICA, M1, or BA occlusion at the population level. They continue to demonstrate worse outcomes despite treatment advances.