Endovascular aortic repair with aneurysm sealing system and parallel grafts: is it the solution for type I endoleaks and target vessels’ thrombosis?

BACKGROUND Type I endoleaks (EL) from “gutters” and stent-graft compression represent the two main issues of the endovascular aortic repair (EVAR) using the chimney/snorkel technique. The potential impact of these complications would probably be reduced in presence of a sealing polymer, which could fill the “gutters” and can conform more precisely around the grafts without any adjunctive radial force. Aim of the study was to assess the reported rate of type I EL and target vessels’ thrombosis occurring after chimney/snorkel EVAR using traditional endografts (Ch-EVAR) and those reported after EVAR with chimney using an Endovascular Aneurysm Sealing system (Ch-EVAS). METHODS Analysis of the literature on Pubmed and Medline with the terms “Chimney” and “Parallel grafts” was performed. Case series of either Ch-EVAR or Ch-EVAS of juxtarenal/pararenal aneurysms, pseudoaneurysms and type Ia EL following EVAR were considered. Only papers with full text available in English and reporting complete data about the occurrence of endoleaks and stent-graft thrombosis with at least 1 month of follow-up were included in the analysis. Exclusion criteria were papers with incomplete data, inadequate follow-up or reporting less than 5 cases. For both Ch-EVAR and Ch-EVAS, the total proportion of type I EL and target vessels’ thrombosis occurring during the follow-up was calculated, along with the respective 95% confidence intervals (CI). The R program (http://CRAR.R-project.org) with “Metaprop” package was used. RESULTS The search on Pubmed retrieved 173 papers. Of these, only 24 papers were included in the analysis (20 in the Ch-EVAR group and 4 in the Ch-EVAS group). Data about 563 Ch-EVAR and 61 Ch-EVAS performed from January 2008 to December 2016 were analyzed. During the follow-up, a type I EL occurred in 10% of patients submitted to Ch-EVAR (95% CI: 8%-13%) and in 8% of patients submitted to Ch-EVAS (95% CI: 4%-19%). Target vessels thrombosis occurred in 9% of cases after Ch-EVAR (95% CI: 7%-12%) and in 6% of cases after Ch-EVAS (95% CI: 2%-17%). The nature of the reported studies did not allow the assessment of any statistically significant difference between the outcomes of both techniques. CONCLUSIONS The reported rate of type I EL and target vessels’ thrombosis occurring after Ch-EVAR tended to be slightly higher than those reported after Ch-EVAS, however it was not possible to assess if these data differed significantly. A randomized controlled trial comparing the outcomes of Ch-EVAR and Ch-EVAS is then needed to improve the knowledge about this topic.