Mid-term morphological changes in Frozenix

The frozen elephant trunk is widely used for aortic arch aneurysms and DeBakey type I and III aortic dissections. However, radial force and spring-back of the stent can cause morphological changes, contributing to stent-induced new entry. This study aimed to evaluate postoperative morphological changes of frozen elephant trunk and provide biomechanical insights.

This retrospective study included 107 patients who underwent Frozenix placement between April 2014 and December 2023. Clinical outcomes and morphological changes of frozen elephant trunk were assessed. Morphological changes were evaluated by measuring the distal diameter and stent angle, defined as the angle between the lines perpendicular to the proximal and distal ends of the stent, via computed tomography, including angiographic imaging.

Thirty-day mortality was 3%. The median follow-up duration was 24 months, and the incidence of all-cause mortality was 9.69 events per 100 patient years. Stent-induced new entry occurred in seven patients (7%). The distal diameter was enlarged in all 95 evaluated patients; 59 (62%) exceeded the stent size. In these patients, the mean distal diameter reached 105% of the original stent size. Dissections demonstrated greater distal diameter expansion than thoracic aortic aneurysms. The stent angle, assessed in 33 patients, increased in all cases, with progressive changes observed over 3 years.

Postoperative enlargement of the distal diameter beyond the original stent size and progressive changes in stent angle should be taken into account when selecting the size of the frozen elephant trunk and planning the surgical strategy. Long-term computed tomography follow-up is also warranted.