BACKGROUND: This study aimed to assess the incidence, predictors, and clinical relevance of proximal aortic landing zone dilation (PALD) following thoracic endovascular aortic repair (TEVAR) for acute and chronic type B aortic dissection (TBAD). METHODS: A retrospective analysis of 47 patients who underwent TEVAR for TBAD at a single center was conducted. PALD was defined as a ≥5 mm increase in aortic diameter at 2 of 3 measurement sites (at 0, 1, and 2 cm distal to the stent graft proximal edge) at postoperative computed tomography angiography. The primary endpoint was the development of PALD. Secondary endpoints included entry fIow type IA, device migration and reintervention rates. Kaplan-Meier analyses was used to evaluate PALD-free survival. RESULTS: PALD occurred in 19% of patients (n = 9) during a median follow-up of 62 months. A stent graft diameter >
36 mm significantly predicted PALD (P = 0.022), with an area under the curve of 0.75 (sensitivity: 89%, specificity: 58%). No significant associations were found between PALD and reinterventions or type Ia entry flow. Kaplan-Meier analysis revealed a median PALD-free survival of 156 months (95% confidence interval: 92-210). Patients with PALD demonstrated a greater increase in aortic diameter at maximum follow-up compared to non-PALD patients (P <
0.001). Other demographic, anatomic, and procedural factors were not associated with PALD, and especially oversizing did not correlate with PALD development. CONCLUSION: PALD occurred in a significant proportion of patients following TEVAR for TBAD, with stent graft diameter serving as key predictor. PALD did not correlate with adverse clinical outcomes in this cohort.