Weighing the Risks: The Impact of Body Mass Index on Outcomes After Frozen Elephant Trunk Aortic Arch Repair.

Background and

Objectives

This study aimed to evaluate the impact of body mass index (BMI) on post- operative outcomes in patients undergoing aortic arch repair with the frozen elephant trunk technique (FET). Materials and

Methods

A total of 387 patients who underwent an FET procedure between 04/2014 and 11/2024 were retrospectively analyzed. Patients were divided into four groups according to BMI: underweight (BMI < 18.5, n = 12) normal weight (BMI: 18.5 to <25, n = 150), overweight (BMI: 25 to <30, n = 154), and obese (BMI: ≥30, n = 71). Patient characteristics and clinical outcomes were compared across groups. Multivariable Cox regression, interaction analysis, and restricted cubic spline modelling were performed using R (Version 4.4.3).

Results

Interaction analysis revealed BMI-dependent effect modification for several predictors. Insulin-dependent diabetes mellitus was associated with increased mortality only in patients with BMI < 25 kg/m2 (interaction p = 0.003). Transfusion of packed red blood cells (PRBCs) also showed a significant interaction with BMI (p = 0.016), with a stronger effect in patients with BMI < 25 kg/m2, although significant in both strata. Moreover, cross-clamp time demonstrated a BMI-dependent interaction (p = 0.047), with numerically higher mortality hazards in overweight patients (BMI > 25 kg/m2), but without statistically significant subgroup effects. Spline analysis indicated a non-linear, threshold-based association between overall mortality and BMI but does not reach statistical significance. Kaplan-Meier analysis showed no significant difference in 5-year survival among BMI categories.

Conclusions

BMI should not be used as a primary risk stratification tool for survival after an FET procedure. Rather, attention should be paid to comorbid conditions and intraoperative factors that interact with BMI. For patients with lower BMI (<25 kg/m2), optimizing glycemic control and minimizing transfusion may improve outcomes. Data suggests that a reduction in cross-clamp time may be particularly beneficial in patients with higher BMI (>25 kg/m2). Future studies should aim to clarify the impact of BMI on outcomes after FET, particularly in the context of patient selection and perioperative optimization strategies.