Diagnosis and predictors of post-implantation syndrome following endovascular repair of aortic aneurysms – a narrative review

INTRODUCTION: After endovascular aortic repair (EVAR), many patients develop a systemic inflammatory response called post-implantation syndrome (PIS). AAA and procedure-related characteristics have been linked with increased odds of developing this syndrome. Similarly, some short- and long-term consequences have been associated with PIS. This study aims to review the literature on the diagnosis and predictors of post-implantation after endovascular repair of aortic aneurysms. RESULTS: A non-systematic review of the MEDLINE and Scopus databases was performed using the keywords "abdominal aortic aneurysm," "inflammation," and "endovascular techniques.” No time or language limitations were imposed. Manuscripts were considered irrespective of study design. Articles of interest were analyzed, and the relevant information was organized in tables. RESULTS: PIS is defined as a combination of constitutional symptoms, including fatigue and fever, and elevated inflammatory markers. There are several proposed diagnostic criteria, most including a combination of fever with leukocytosis and/or elevated C-reactive protein (CRP). These result in discrepant rates, as low as 2% and up to 100%. The typical evolution of this syndrome is spontaneous resolution, although pharmacologic measures for symptom relief may be needed. These symptoms often resolve within two weeks; no significant permanent complications remain. Most PIS cases will present up to the first 72 postoperative hours. Endograft material, particularly polyester-based stent grafts, has been consistently linked to increased odds of PIS, up to five-fold, compared to polytetrafluoroethylene (PTFE) grafts. Aneurysm thrombus load (both pre-existing and new-onset) has also been related to an increased odds of PIS. Bacterial translocation, contrast media, and other patient or procedure-related characteristics have not been linked to an increased risk of PIS. CONCLUSION: PIS is a common finding after EVAR. Universal diagnostic criteria for diagnosis are required. Polyester-based stent grafts present the highest risk of developing this syndrome. Aneurysm thrombus load may also relate to this increased risk. The impact of other clinical or anatomical factors remains undetermined.