A Propensity Matched Comparison of Distal Active Fixation versus Standard Stent Graft Performances in Challenging Distal Landing Zone After Thoracic Endovascular Aortic Aneurysm Repair

Introduction: Current guidelines highlight thoracic endovascular aneurysm repair (TEVAR) as the first line treatment in patients presenting with descending thoracic aortic aneurysms (DTAAs). However, TEVAR has a higher re-intervention rate, primarily for endoleaks. This stands in stark contrast to the low rate of complications generally associated with TEVAR procedures for other disorders, such as traumatic aortic injuries. Owing to its relevance, the proximal landing zone (LZ) has been the main focus of several publications analysing TEVAR. Nevertheless, some authors have called attention to the relevance of specific issues of the thoracic distal LZ. The objective of this study was to evaluate the outcomes of the distal LZ in TEVAR patients with challenging aortic morphology treated with distal active fixation (DAF) stent grafts versus standard stent grafts. Methods: This was a retrospective, case–control, multicentre study of patients with DTAA treated by TEVAR comparing DAF stent grafts (study group) and standard stent grafts (control group). Five academic tertiary centres participated. Between 2006 and 31 December 2020, 138 TEVAR procedures were performed (n = 69 per group). The primary endpoints were distal endoleak and re-intervention. The secondary endpoints were distal segment migration, wedge apposition, and related complications. The distal LZ length and diameter, previous TEVAR, tortuosity index (TI), and maximum diameter were the covariates included in the propensity-scored model (1:1) after univariate and multivariate logistic regression. A linear regression model was applied to investigate the relationship between the wedge apposition, the aortic angulation, and the TI. Kaplan–Meier analysis was used to estimate freedom from distal endoleak and freedom from distal re-intervention, with their standard error (SE) and log rank test. Results: Results were reported for the DAF versus control group, and are summarised in the Table. Mean ± SD length of follow up was 3.3 ± 2.1 versus 3.7 ± 3.4 years. Distal LZ diameter and length were 32.6 ± 5.4 versus 31.1 ± 5.5 and 27.0 ± 23.5 versus 26.0 ± 11.3 mm, respectively. Distal endoleak rate was 7.3% versus 27.5% (p = .011). Freedom from distal endoleak was 95% (SE 2.7%), 95% (SE 2.7%), and 91% (SE 5.1%) versus 85% (SE 4.4%), 76% (SE 6.1%), and 73% (SE 6.6%) at one, three, and five years, respectively (log rank p = .011; Fig. 1). TI and distal thoracic aorta angulation were predictors of endoleak (p = .012 and p = .29, respectively). The distal re-intervention rate was 7.3% versus 20.3% (p = .026). Freedom from distal re-interventions was 95% (SE 2.7%), 95% (SE 2.7%), and 91% (SE 5.1%) versus 92% (SE 3.6%), 75% (SE 6.5%), and 75% (SE 6.5%) at one, three, and five years, respectively (log rank p = .041; Fig. 2). The wedge apposition was 5.8 versus 13.0 mm (p < .000). The distal thoracic aorta angulation, as well as the TI, were significant independent risk factor for wedge apposition (p = .000 and p = .010, respectively). A wedge apposition variation of > 10 mm was lower in the DAF group (p = .039). The distal segment migration was upward directed in all cases and was significant (>10 mm) in 13.0% versus 39.1% (p = .000). Conclusion: The DAF stent graft showed a significant reduction in both distal endoleak rates and distal re-interventions. Wedge apposition is a known risk factor for endoleak. A dedicated analysis outlined aortic angulation and the TI as risk factors for wedge apposition. DAF stent grafts appeared capable of significantly reducing both wedge apposition and its worsening during follow up. In addition, this type of fixation was able to prevent distal component migration. The relevance of these results should be emphasised owing to the treated patients’ adverse anatomy. Issues related to the thoracic distal LZ were not studied in depth, and should be further investigated given their considerable importance.