Systematic review and meta-analysis of incidence, indications, and outcomes of early open conversions after EVAR for abdominal aortic aneurysms

Introduction: The purpose of this study is to report incidence, indications, and outcomes of early open conversions (EOC) after endovascular aortic repair (EVAR), defined as surgical conversion performed within 30 days from the initial EVAR. Evidence aquisition: A systematic review of the literature was performed (database searched: PubMed, Web of Science, Scopus, Cochrane Library; last search April 2023). Articles reporting EOC after EVAR comprising at least five patients were included. Meta-analyses of proportions were performed using a random-effects model. Evidence synthesis: Seventeen non-randomized studies, published between 1999 and 2022, were included. A total of 35,970 patients had previously undergone EVAR, of these 438 patients underwent EOC. Estimated incidence of EOC was 1.4% (95% CI 1.1-1.4; I2=81.66%). Specifically, in the works published before 2010 the incidence was 1.8% (95% CI 1.3-2.4; I2=74.25) while for subsequent ones it was 0.9% (95% CI 0.6-1.1; I2=69.82). Weighted mean age was 74.91 years (95% CI 72.42-77.39; I2=83.11%). Estimated rate of cause determining EOC were: access issue in 27.7% of patients (95% CI 13.8-41.6; I2=88.14%), incorrect placement of the endograft in 20.1% (95% CI 10.2-30.0; I2=76,9%), problems with "delivery system" in 9.0% (95% CI 4.9-13.1; I2=0%), aorto-iliac rupture in 8.6% (95% CI 4.5-12.6; I2=0%), endoprosthesis migration in 7.9% of cases (95% CI 3.3-12.4; I2=22.96%), failure in engaging the contralateral gate in 4.8% (95% CI 1.6-8; I2=0%), "kinking" or "twisting" of endoprosthesis in 3.3% (95% CI 0.6-5.9; I2=0%), graft thrombosis in 3.2% (95% CI 0.6-5.7; I2=0%), type Ia endoleak in 2.9% (95% CI 0.4-5.4; I2=0%), type III endoleak in 2.8% (95% CI 0.3-5.3; I2=0%) and endograft infection in 2.7% (95% CI 0.3-5.2; I2=0%). Intraoperative conversion rate was 91.1% (95% CI 85.8-96.4; I2=66.01%). Early mortality rate after EOC was 14.5% (95% CI 9.1-19.9; I2=48.31%). Mean length of stay (LOS) was 11.94 days (95% CI 6.718-17.172; I2=92.34%). Conclusions: The incidence of EOC seems to decrease over time. Causes of EOC were mainly related to access problems and incorrect positioning of the endograft. Most of the EOC were performed intraoperatively carrying a high mortality rate.