Classification and Outcomes of Distal Stent Graft-Induced New Entry After Frozen Elephant Trunk Procedure

Background: Distal stent graft induced new entry (dSINE) is an early or late complication after frozen elephant trunk (FET) procedure that negatively influences aortic remodeling leading to high reintervention rates. The purpose of this study was to identify incidences, risk factors, and different presentations of dSINE.

Methods: Between 2005 and 2024, 512 patients underwent FET surgery at our institution. Postoperative computed tomography angiography (CTA) scans were analyzed to evaluate the morphological characteristics and to identify different presentations of dSINE. Aortic parameters at the distal landing zone, including the residual stent graft expansion capacity, a parameter of the remaining unfolding potential of the stent graft (SG), were assessed in the postoperative CTAs in the dSINE cases.

Results: Distal SINE occurred in 39 (7.6%) of the patients, after a mean time of 3.0 ± 2.8 years. Freedom from dSINE was 89% at 5 years and 85% at 10 years. Incidences varied based on aortic pathology: 5% (15/295) in acute aortic dissection (AD), 23% (22/97) in chronic AD, and 2% (2/120) in aortic aneurysms. CTA analysis of the dSINE cases revealed that 74% (29/39) had a new intimal wall entry and false lumen formation, 5% (2/39) showed new type B aortic dissection, 13% (5/39) had endoleaks, and 8% (3/39) experienced a contained aortic rupture. Aortic measurements at the distal landing zone of dSINE patients demonstrated an aortic area of 11.6 ± 4.2 cm² and a true lumen area of 4.0 ± 1.6 cm². Predefined area of the SG graft was 5.5 ± 1.2 cm², resulting in a residual SG expansion capacity of 1.5 ± 1.3 cm². Aortic reinterventions were performed in 36 of 39 cases, with 80% (31/39) undergoing endovascular reintervention and 5 patients (13%) requiring open surgery.

Conclusion: This study introduces a new CTA-based classification system for dSINE, categorizing cases by the presence of new entry tears, aortic dissection, endoleaks, and contained aortic rupture. dSINE occurred in 7.6% of FET patients, with higher incidence in chronic aortic dissection. Close imaging follow-up is essential for timely intervention.