Practical Graft Sizing Strategy Based on True Lumen Diameter Distal to the LSA in Fenestrated Frozen Elephant Trunk Procedures.

BACKGROUND

We aimed to describe a pragmatic graft-sizing strategy for fenestrated frozen elephant trunk procedures that aligns the sizing index with the proximal sealing or transition zone using the true lumen (TL) long-axis immediately distal to the left subclavian artery (LSA). This approach was evaluated against a pre-specified comparator at the seventh thoracic vertebral level (Th7).

METHODS

In this single-center retrospective cohort study (N = 24), the Frozenix graft diameter was determined by matching the device size to the LSA TL long-axis on centerline-orthogonal computed tomography. A virtual Th7 comparator was defined as the equivalent diameter (circumference/π) × 0.9, with sensitivity assessed using the Th7 long-axis × 0.9. The primary outcome was the agreement proportion (|Δ%|≤10%) between the actual and virtual sizes. Interobserver reliability was evaluated using the intraclass correlation coefficient (ICC; 2, 1) and Bland-Altman analysis. Safety outcomes included the type Ia endoleak, stent-graft-induced new entry (SINE), and staged thoracic endovascular aortic repair (TEVAR).

RESULTS

The median age of the cohort was 61.0 years (interquartile range (IQR): 56.0-66.0), and 66.7% were men. The median follow-up period was 682.0 days. The most frequently used graft size was 27 mm. Agreement between the actual and virtual Th7 (equivalent × 0.9) diameters was 4.2%, with a median Δ% of 30.5% (IQR: 18.3-39.5%), indicating systematic undersizing. Th7 diameter increased postoperatively, consistent with downstream remodeling. All staged TEVARs were preplanned (14/14, 100%). No type Ia endoleak or SINE occurred. Interobserver reliability was excellent (ICC: 0.98-0.99).

CONCLUSION

LSA-based sizing appears simple, reproducible, and anatomically aligned, warranting prospective multicenter validation.