Perimeter-based oversizing is associated with distal stent graft-induced new entry after frozen elephant trunk repair.

OBJECTIVES: Distal stent graft-induced new entry (d-SINE) is a relevant complication after frozen elephant trunk (FET) repair for aortic dissection. Oversizing has been implicated as a contributing factor, but the optimal method for its assessment remains unclear. This study compared different computed tomography-based methods to quantify oversizing and evaluated how measurement method influences the observed association between oversizing and d-SINE. METHODS: Between June 2019 and March 2026, 107 consecutive patients underwent FET repair at a single center. Among them, 97 patients with postoperative contrast-enhanced computed tomography were analyzed. Oversizing was calculated using three reference diameters: perimeter-based true lumen diameter, maximum true lumen diameter, and aortic diameter. Discriminatory performance was assessed using receiver operating characteristic analysis. Associations were evaluated using logistic regression, and time-to-event outcomes were assessed using Kaplan-Meier analysis. RESULTS: d-SINE occurred in 7 patients (7.2%). The evaluated measurement method yielded substantially different oversizing estimates and different discriminatory performance. Among them, perimeter-based oversizing showed the highest discriminatory ability (area under the curve [AUC], 0.72; 95% confidence interval [CI], 0.52-0.92), whereas aortic diameter-based oversizing showed little discriminatory ability. Using the exploratory cutoff derived from the study cohort, patients with perimeter-based oversizing ≥17% had a significantly higher incidence of d-SINE (log-rank p = 0.015). In multivariable Firth logistic regression analysis, perimeter-based oversizing remained associated with d-SINE. CONCLUSIONS: The method used to quantify oversizing may influence the observed association between oversizing and d-SINE after FET repair. Among the evaluated methods, perimeter-based oversizing showed the most promising discriminatory performance. These findings highlight the need for standardized methods to quantify oversizing and suggest that larger multicenter studies are necessary for the validation of specific sizing thresholds for routine clinical practice.