Aneurysm shape and sac shrinkage after total arch replacement with frozen elephant trunk for true aortic arch aneurysm

Objectives This study aimed to evaluate midterm outcomes and identify predictors of sac shrinkage following total arch replacement with a frozen elephant trunk (TAR-FET) for true aortic arch aneurysms. Methods A retrospective analysis was conducted on 28 patients who underwent elective TAR-FET for true arch aneurysms between July 2014 and March 2022. Postoperative sac changes on CT were categorized as shrinkage (≥5 mm reduction), enlargement (≥5 mm increase), or no change (<5 mm change). The sphericity index, a novel morphological parameter, was calculated by dividing the average axial and sagittal sac diameters by sac length. Results The median age was 74 years, and 23 were male. No operative deaths or recurrent laryngeal nerve palsy occurred. Among 28 patients, 12 experienced sac shrinkage attributable to the initial TAR-FET. Over a median follow-up of 3.6 years, 12 cases showed shrinkage, 2 enlargement, and 14 no change. Cumulative shrinkage rates at 1, 2, and 3 years were 42%, 47%, and 47%, respectively. Additional TEVAR was required in 5 patients (22% at 3 years). Multivariable analysis showed that shorter preoperative sac length (subdistribution hazard ratio 0.96; 95% CI, 0.93–0.99) and a higher sphericity index (per 0.1 increment: subdistribution hazard ratio 1.38; 95% CI, 1.21–1.57) were independently associated with sac shrinkage. Conclusions TAR-FET resulted in sac shrinkage in a substantial proportion of patients. Aneurysms that were shorter and more protruding, as indicated by a higher sphericity index, may be more likely to exhibit postoperative sac shrinkage.