Abstract TP001: Mechanisms of Brain Ischemia in Dolichoectasia-Related Stroke

Background: Dolichoectasia (DE) is frequently identified in patients with acute ischemic stroke (AIS), yet its role as a direct pathogenic cause of brain ischemia remains unclear. We aim to determine the frequency of DE-related stroke and characterize ischemic mechanisms based on infarct patterns. Methods: Consecutive AIS admissions to a large comprehensive stroke center (August 2024–July 2025) were screened for presence of DE. We defined DE as a brain arterial luminal diameter greater than two SD above sex-specific stroke population means. DE-related stroke was determined when AIS occurred in the territory of a dolichoectatic artery without an alternative etiology. Brain MRI acute infarcts were classified as thromboembolic (cortical [including isolated cerebellar], territorial, or multiple lesions in one vascular territory), hypoperfusion (≥1 borderzone infarct), or small vessel occlusion (SVO)—subclassified as lacunar (≤20 mm) or penetrating artery disease (PAD, >20 mm). Demographics, vascular risk factors, and arterial diameters were recorded. Results: Among 654 consecutive stroke admissions, 494 were diagnosed with AIS. Ninety-four (19.0%) had DE, with 59 (11.9%) cases suspected to have DE directly involved in the mechanism of brain ischemia. Patients with DE-related stroke had a mean age of 70.2 ± 12.5 years, 54.2% were men, and commonly had hypertension (88.1%), diabetes (32.2%), and hyperlipidemia (49.2%), with 74.6% having two or more vascular risk factors. Infarct patterns included thromboembolism in 30 cases (6.1% of all AIS), SVO in 27 cases (5.5% of all AIS), further classified into lacunar (n=14) and PAD (n=13), and hypoperfusion in two cases (0.4% of all AIS). Compared to SVO, thromboembolic DE-related strokes were associated to higher median NIHSS scores (9.5 vs. 3, p=0.02), greater frequency of hemorrhagic transformation (26.7% vs. 0.0%, p=0.01), and larger arterial diameters (median Z-score 3.4 vs. 2.5, p=0.01). Conclusions: Dolichoectasia directly contributes to the ischemic mechanism in about one in ten AIS cases, most often through thromboembolism or SVO, and less frequently through hypoperfusion. Thromboembolic DE-related strokes present with greater severity and are associated with larger arterial diameters. These findings provide a framework for prospective studies focused on DE-related stroke.