Value of difference in diameters between Pipeline embolization device and parent artery in assessing aneurysm outcome

OBJECTIVE In vitro trials have demonstrated that oversized stents are associated with reduced metal coverage and increased porosity. However, the relationship between stent selection and aneurysm outcome is inconclusive, and determination of this was the authors’ purpose in conducting this study. METHODS This was a single-center retrospective study. Patients who underwent Pipeline embolization device treatment at the authors’ center between January 1, 2018, and June 15, 2023, were enrolled. The authors constructed multiple logistic regression models and restricted cubic spline plots to examine the effect of the difference in diameters between the stent and parent artery (Dd) on aneurysm outcome. The authors also performed stratified analyses. Then, Dd was included in the logistic regression analysis as a categorical variable. The cutoff value for Dd was determined according to the principle of the maximum Youden’s index. RESULTS In total, 302 patients were included in this study. The median Dd was 0.52 mm. With a median follow-up time of 7 months, the aneurysm occlusion rate was 80.1%. The restricted cubic spline plots showed a decreasing aneurysm occlusion rate as Dd increased. After stratification by age and adjunctive embolization, the restricted cubic splines aligned with the results of the main analysis. Compared with the group with a smaller Dd (Dd < 0.3625 mm), the group with a larger Dd showed an OR of 0.439 (p = 0.026). Additionally, patients with diabetes mellitus (OR 0.306, p = 0.018), age ≥ 65 years (OR 0.968, p = 0.03), aneurysm incorporation with a branch (OR 0.253, p < 0.001), and aneurysm neck ≥ 4 mm (OR 0.872, p = 0.003) were independent predictors of aneurysm persistence, whereas Pipeline embolization device plus coiling (OR 4.949, p < 0.001) and smoking history (OR 5.86, p = 0.025) were predictors of aneurysm occlusion. CONCLUSIONS The authors’ retrospective analysis demonstrated that the aneurysm occlusion rate declined when Dd increased within a certain range. The authors suggested that Dd with an interval of −0.25 to 0.5 mm may be proper in clinical practice.