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Commentary: Postimplantation Syndrome: An Underrecognized EVAR Complication

Inflammation seems to play an important role both in the pathogenesis of an abdominal aortic aneurysm (AAA) and following endovascular aneurysm repair (EVAR). The systemic inflammatory response immediately following EVAR, known as the postimplantation syndrome (PIS), has not been studied adequately despite its presence in approximately a third of EVAR patients. Endovascular aneurysm sealing (EVAS) has introduced a totally novel technology in AAA treatment that completely seals the aneurysm sac from the systemic circulation with the use of polymer-filled endobags surrounding the endograft lumen. In the October 2017 issue of the JEVT, Berg et al compared the risk of PIS after EVAR and EVAS, finding a trend toward a lower incidence of PIS in the EVAS group. The 30-day clinical outcome was worse in patients who received a polyester stent-graft, while there was also a trend toward fewer adverse events and endoleaks in patients without PIS. The exact effect of the EVAS endobags on thrombus remodeling and their relation to thrombotic and inflammatory properties remains unknown. It has been proposed that aneurysm thrombus has a role in the inflammatory response. In the early days of EVAR, it was shown that AAA mural thrombus contains high amounts of interleukin (IL)-6, which might be released during manipulations with endovascular instruments. A recent report found no differences in either total preoperative AAA volume or in the amount of newly formed thrombus between PIS and non-PIS groups. These results have also been confirmed by Voûte et al in 136 patients, weakening the theory that AAA mural thrombus was the cause of PIS. In the present study, the EVAS approach showed a diminished inflammatory response compared to EVAR overall (5.1% vs 20.5%) and especially to polyester endografts (5.1% vs 31%). However, no data are provided to elucidate potential pathophysiological factors that may contribute to these results. The relation of PIS to patient outcomes has not been adequately established. In most studies PIS is considered a benign condition, although it may lead to more intense postoperative care, resulting in prolonged hospitalization. In a prospective study of 214 EVAR patients, those with PIS were more likely to suffer from an adverse event during the 30 days after the procedure. Adverse events occurred in 25.9% of the PIS group compared with 2.9% of the non-PIS group and included any major cardiovascular event, acute renal failure, readmission, or death from any cause. In the present study, Berg et al also found a higher incidence of serious adverse events (20% vs 4%, p=0.12) and endoleak (20% vs 3%, p=0.08) in patients with PIS, though these did not reach statistical significance probably because of the small sample size and the retrospective study design. Considering the effect of PIS on patient outcomes, the main question remains whether we should alter our approach and treat patients with PIS focusing on the elimination of the inflammatory response. Literature data are scarce, and no therapeutic algorithm has ever been established. Preoperative high-dose glucocorticoid administration in a randomized trial reduced systematic inflammatory response after EVAR but had no effect on 30-day surgical or medical morbidity. Interestingly, Bischoff et al reported that 71% of the German 727279 JETXXX10.1177/1526602817727279Journal of Endovascular TherapyKouvelos et al research-article2017