Although aneurysm size has been categorized as a strong predictor of aortic dissection, its specific effect on the treatment of such complications has not been elucidated. As result, this study aimed to evaluate whether maximal aortic diameter affects outcomes after thoracic endovascular aneurysm repair (TEVAR) of type B dissection. Clinical data of patients undergoing TEVAR for elective type B dissections was extracted from the Vascular Quality Initiative (2012-2022). Patients were stratified into size groups according to aneurysm diameter: small ≤5.5 cm; 5.5 cm < medium ≤ 6.5 cm; and large > 6.5 cm. Inverse probability weights were calculated and used to balance the groups’ clinical characteristics. The small group was used as a reference point for comparing outcomes. The primary end points were all-cause mortality and thoracoabdominal life-altering events (TALE)—a composite of stroke, death, paraplegia, and dialysis. Secondary end points included major adverse cardiac events (MACE), a composite of stroke, myocardial infarction (MI), new dysrhythmia, chronic heart failure, major adverse limb events, leg amputation, embolization, spinal ischemia, and others. There were 1788 small, 667 medium, and 341 large patients included in the final analysis. TALE rates were statistically higher in the large vs small (P < .01: 24.3% vs 16.2%) and large vs medium groups (P < .001: 24.3% vs 15.9%) but not in the large vs small group (Table). The large vs small group also had a higher incidence of spinal ischemia, respiratory complications, MACE, and perioperative mortality. Although the Kaplan-Meier analysis did not show a statistically significant 8-year survival difference, it illustrated a clinically meaningful survival difference (P = .053: 77.0% small vs 74.2% medium vs 67.8% large). Logistic regression models adjusted for unbalanced characteristics showed higher odds of TALE in the large vs small (odds ratio, [OR] 2.2; 95% confidence interval [CI], 1.4-3.3; P < .001) and large vs medium groups (OR, 1.69; 95% CI, 1.2-2.5; P < .05). The large vs small group also demonstrated higher odds of spinal ischemia, respiratory complications, MACE, and perioperative mortality. Hazard analysis showed increased risk of 8-year mortality in the large vs small (hazard ratio, 1.8; 95% CI, 1.1-2.8; P < .05) and large vs medium groups (hazard ratio, 1.5; 95% CI, 1.1-2.1; P < .05). Larger maximum aortic diameters are associated with worse outcomes following TEVAR for type B dissections. The incidence of TALE and the long-term risk of mortality increases at the 6.5 cm size category; therefore, elective type B dissection repair with TEVAR should be considered at aortic diameters of 6.5 cm or greater in suitable-risk patients with appropriate anatomy.TableAdjusted logistic regression on outcomes of interestOutcomesSmall vs mediumSmall vs largeMedium vs largeSpinal ischemia at discharge1.4(0.38-5.24)NS3.5(1.12-10.73)aP < .052.5(0.82-7.37)NSRespiratory complication1.5(0.80-2.69)NS2.2(1.21-4.01)aP < .051.0(0.86-2.63)NSMACE1.9(1.09-3.39)aP < .052.1(1.15-3.72)aP < .051.1(0.68-1.71)NSTALE1.3(0.84-1.96)NS2.2(1.42-3.29)bP < .051.7(1.16-2.44)aP < .05Perioperative mortality1.9(0.95-3.97)NS2.6(1.31-5.14)aP < .051.3(0.69-2.61)NSMACE, Major adverse cardiac events; NS, nonsignificant; TALE, thoracoabdominal life-altering events. Values are odds ratios (95% confidence intervals).aP < .05, bP < .001. Open table in a new tab