The impact of bird-beak configuration on aortic remodeling of distal arch pathology after thoracic endovascular aortic repair with the zenith pro-form tx2 thoracic endograft

Objective Structural changes and incomplete endograft apposition to the aortic arch (bird-beak configuration) after thoracic endovascular aortic repair are poorly understood. The aim of this study was to analyze the morphologic changes, conformability, and angulation factors in patients who underwent stainless steel-based stent graft repair of thoracic aortic pathology. Methods From March 2011 to March 2012, the study enrolled 19 patients with aortic pathology requiring proximal fixation in zones 2 and 3 who underwent stent graft repair using Zenith Pro-Form TX2 stent grafts (Cook Medical, Bloomington, Ind). For comparison, another 19 patients who received Zenith Z-Trak stent grafts were selected from December 2009 to February 2011. Chest computed tomography scans were analyzed at baseline, and then at 1, 6, and 12 months postoperatively. Arch angulation and bird-beak configuration were evaluated according to sealing zones of attachment by Aquarius iNtuition software (TeraRecon, San Mateo, Calif). Results The treated diseases included chronic type B aortic dissection in 17 patients and degenerative aneurysms in 21. Significant arch angle transformation was noted at the zone 2 level between the Pro-Form and Z-Trak treated groups (150 ± 11 vs 158 ± 6; P =.033) and left subclavian artery level (152 ± 12 vs 160 ± 8; P =.031) during 1 year of follow-up. The bird-beak configuration was detected in six patients (32%) in the Pro-Form group and in 11 (58%) in the Z-Trak group (P =.096) at 1 month, and in six (32%) in the Pro-Form group and in 14 (74%) in the Z-Trak group (P =.022) at 12 months. The mean bird-beak angle was significantly less in Pro-Form-treated patients at 1 month (5 ± 9 vs 15 ± 13; P =.019) and at 1 year (6 ± 10 vs 18 ± 15; P =.033). In the Pro-Form platform, a preoperative zone 2 angle <151.1 was a better estimation of the presence of a postoperative bird-beak configuration, with a sensitivity of 86% and specificity of 83%. Conclusions Aortic remodeling after stainless steel stent graft repair of thoracic aortic pathology is a continuous process. Significant arch angle transformation was discovered over the zone 2 and left subclavian artery levels. TX2 Pro-Form stent grafts improved arch conformation after 1 year of follow-up. Furthermore, in the patients with dissection, a preoperative distal arch angle of zone 2 was predictive of postoperative bird-beak configuration, regardless of whether they were treated with a Pro-Form stent graft.