Critical analysis of results after chimney endovascular aortic aneurysm repair raises cause for concern

Abstract

Objective: "Chimney" techniques used to extend landing zones for endovascular aortic repair (chEVAR) have been increasingly reported; however, concerns about durability and patency remain. The purpose of this analysis was to examine midterm outcomes of chEVAR.

Methods: All patients at the University of Florida treated with chEVAR were reviewed. Major adverse events (MAEs) were recorded and defined as any chimney stent thrombosis, type Ia endoleak in follow-up, reintervention, 30-day/in-hospital death, or ≥25% decrease in estimated glomerular filtration rate after discharge. Primary end points included chimney stent patency and freedom from MAE. Secondary end points included complications and long-term survival.

Results: From 2008 to 2012, 41 patients (age ± standard deviation, 73 ± 8 years; male, 66% [n = 27]) were treated with a total of 76 chimney stents (renal, n = 51; superior mesenteric artery, n = 16; celiac artery, n = 9) for a variety of indications: juxtarenal, 42% (n = 17, one rupture), suprarenal, 17% (n = 7), and thoracoabdominal aneurysm, 17% (n = 7); aortic anastomotic pseudoaneurysm, 15% (n = 6; three ruptures); type Ia endoleak after EVAR, 7% (n = 3); and atheromatous disease, 2% (n = 1). Two patients had a single target vessel abandoned because of cannulation failure, and one had a type Ia endoleak at case completion (technical success, 93%). Intraoperative complications occurred in seven patients (17%), including graft maldeployment with unplanned mesenteric chimney (n = 2) and access vessel injury requiring repair (n = 5). Major postoperative complications developed in 20% (n = 8). The 30-day mortality and in-hospital mortality were 5% (n = 2) and 7% (n = 3), respectively. At median follow-up of 18.2 months (range, 1.4-41.5 months), 28 of 33 patients (85%) with available postoperative imaging experienced stabilization or reduction of abdominal aortic aneurysm sac diameters. Nine patients (32%) developed endoleak at some point during follow-up (type Ia, 7% [n = 3]; type II, 10% [n = 4]; indeterminate, 7% [n = 3]), and one patient underwent open, surgical conversion. The estimated probability of freedom from reintervention (±standard error mean) was 96% ± 4% at both 1 year and 3 years. Primary patency of all chimney stents was 88% ± 5% and 85% ± 5% at 1 year and 3 years, respectively. Corresponding freedom from MAEs was 83% ± 7% and 57% ± 10% at 1 year and 3 years. The actuarial estimated survival for all patients at 1 year and 5 years was 85% ± 6% and 65% ± 8%, respectively.

Conclusions: These results demonstrate that chEVAR can be completed with a high degree of success; however, perioperative complications and MAEs during follow-up, including loss of chimney patency and endoleak, may occur at a higher rate than previously reported. Elective use of chEVAR should be performed with caution, and comparison to open and fenestrated EVAR is needed to determine long-term efficacy of this technique.