Aortic Diameter Effect in Patients Undergoing Thoracic Endovascular Aneurysm Repair for Elective Chronic Type B Dissection

Aneurysmal degeneration following type B aortic dissection is a known natural history of the disease; however, the appropriate threshold to treat these aneurysms has not been well studied. This study evaluated whether maximal aortic diameter (MAD) affects survival outcomes after elective thoracic endovascular aneurysm repair (TEVAR) for chronic type B dissection. Clinical data of patients undergoing elective TEVAR for chronic type B aortic dissections were extracted from the Vascular Quality Initiative (2012-2022). Patients were stratified into groups according to MAD: small ≤ 40 mm; 40 mm < medium < 55 mm; and large ≥ 55 mm. Inverse probability weights were calculated to balance the groups’ clinical characteristics. We used a proportional hazard model with TAA diameter as a continuous variable to assess 10-year mortality. The primary end points were all-cause mortality and thoracoabdominal life-altering events—a composite of stroke, death, paraplegia, and dialysis. Secondary end points included major adverse cardiac event, a composite of stroke, myocardial infarction, new dysrhythmia, chronic heart failure; major adverse limb events, leg amputation, embolization; spinal ischemia; others. We included 68 small, 231 medium, and 564 large patients in the final analysis. The weight-adjusted χ2 analysis showed no correlation between MAD and perioperative thoracoabdominal life-altering events, major adverse cardiac event, or major adverse limb events. There was no difference in the weighted 8-year survival among stratified (small, medium, large) MAD groups. Hazard ratio analysis demonstrated that a diameter of 50 mm represented a threshold where mortality began to increase stepwise (50 mm vs 55 mm; hazard ratio, 1.3; 95% confidence interval, 1.1-1.4; P = .01) (Figure). The risk of mortality after elective TEVAR for type B aortic dissection increases as MAD increases over 50 mm. Therefore, early, elective chronic type B dissection repair with TEVAR should be considered for patients with aneurysms <50 mm at a high risk of progression to >50 mm as mortality risk may increase with progressive aortic degeneration. Future survival analyses, including a comparison to patients with type B dissections that are medically managed, may allow for more treatment-directing recommendations for high-risk surgical candidates being considered for elective TEVAR with aortic diameters <50 mm.