Abstract A048: De Novo Pseudoaneurysm Formation After Cervical Artery Dissection: Incidence, Risk Factors, and Outcomes

Background: The clinical characteristics and complications associated with de novo pseudoaneurysm formation beyond the acute phase of cervical artery dissection remain poorly defined. In this study, we examined the incidence, risk factors, and related ischemic and hemorrhagic events of post-acute de novo pseudoaneurysm formation. Methods: We analyzed data from the STOP-CAD study (Antithrombotic Treatment for Stroke Prevention in Cervical Artery Dissection). A de novo pseudoaneurysm was defined as a new (not present on initial imaging) focal enlargement in the diameter of the artery, greater than the native lumen. The incidence of de novo pseudoaneurysm was assessed at 90 days, 180 days, and beyond 180 days of follow-up. Univariate and multivariate regression analyses were conducted to identify risk factors for post-acute de novo pseudoaneurysm formation. Kaplan-Meier survival estimates were used to compare ischemic and hemorrhagic events between patients with and without de novo pseudoaneurysms. Results: Among 4008 patients, 546 were excluded as they had dissecting pseudoaneursyms on initial presentation. Therefore, 3,462 patients were included in this analysis of whom 220 patients (6.35%) developed a de novo pseudoaneurysm over a maximum follow-up of 4.4 years. Of these, 127 (57.72%) were detected within the first 90 days, and 172 (78.18%) within the first 180 days. In multivariate regression analyses, in addition to hypertension, active smoking and Hispanic ethnicity, fibromuscular dysplasia (FMD) was an independent risk factor for post-acute de novo pseudoaneurysm formation (adjusted OR: 2.160; 95% CI: 1.408–3.315; p < 0.001). Notably, the presence of a de novo pseudoaneurysm was not associated with a significant increase in ischemic (hazard ratio HR 1.43 95% CI, 0.89–2.30; P=0.14) or hemorrhagic events (hazard ratio HR 1.42 95% CI, 0.43–4.69; P=0.57). Conclusion: De novo pseudoaneurysm formation following a diagnosis of a cervical artery dissection is not uncommon and most frequently occurs within the first 180 days. FMD was independently associated with this complication. The development of a de novo pseudoaneurysm did not significantly increase the risk of subsequent ischemic or hemorrhagic events.