Risk factors and treatment outcomes for stent graft infection after endovascular aortic aneurysm repair

Abstract

Objective: We aimed to retrospectively analyze incidence, risk factors, and management of postoperative stent graft (SG) infection after endovascular aneurysm repair (EVAR).

Methods: We evaluated patients who underwent EVAR for infrarenal abdominal aortic aneurysm at our institution between July 2006 and December 2014. The primary end point was SG infection. We compared patients' demographics between the infection (group I) and noninfection (group NI) groups and reviewed management and outcomes in group I. A risk factor for SG infection was assessed by multivariable logistic regression. Patients without aortoenteric fistula (AEF) were treated with conservative therapy for SG infection.

Results: A total of 1202 patients underwent EVAR for infrarenal abdominal aortic aneurysm. During a mean follow-up of 43.9 ± 30.4 months, SG infection occurred in 15 cases (incidence, 3.5/1000 person-years). The median time between initial EVAR and detection of infection was 30 months (range, 14 days-86 months). Freedom from SG infection at 1 year, 3 years, and 5 years was 99.5%, 99.2%, and 98.2%, respectively. There were no differences in age, sex, comorbidities, and SG type between the groups. Coil embolization of the hypogastric artery was more frequent in group I (60% vs 31%). During follow-up before infection, type II endoleak (47% vs 24%), sac enlargement (40% vs 16%), and multiple reinterventions (13% vs 2%) were significantly higher in group I; however, after multivariate analysis, only coil embolization of the hypogastric artery (odds ratio, 3.22; 95% confidence interval, 1.12-9.24; P = .029) remained a significant predictor. Among the 15 patients, four had AEF and six bacteriologic species were detected in five patients (33%). Twelve patients (80%) were treated with conservative therapy; three underwent surgical therapy (two patients with SG resection, omentum patching, and extra-anatomic bypass with fistula closure or partial duodenectomy and one patient with graft preservation, irrigation, omentum patching, and aneurysmorrhaphy). In-hospital mortality occurred in three cases; two cases were due to sepsis after conservative therapy, and one case was due to aortic stump rupture after surgical therapy. Excluding in-hospital mortality cases, during a median follow-up of 31 (range, 2-76) months, five patients were lost because of cancer or senility. There was no aneurysm-related death or recurrence of SG infection.

Conclusions: Concomitant coil embolization was a risk factor for SG infection. For patients with AEF, surgical therapy remains the first-line treatment of SG infection after EVAR; however, conservative therapy is a viable option for SG infection in patients without AEF, particularly considering patients' comorbidities and limited life expectancy.

Keywords: Abdominal aortic aneurysm; Conservative therapy; Endovascular aneurysm repair; Infection; Stent graft.