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Critical Analysis of the Mid-term Results after Chimney EVAR: Cause for Concern
Salvatore T. Scali, Robert J. Feezor, Catherine K. Chang, Alyson Waterman-Pugh, Scott A. Berceli, Thomas S. Huber, Adam W. Beck
University of Florida- Gainesville, Gainesville, FL

INTRODUCTION: “Chimney” or “snorkel” techniques have been increasingly reported to extend landing zones during endovascular aortic repair(chEVAR); however, concerns about long-term durability and patency remain. The purpose of this analysis was to examine mid-term outcomes of chEVAR.
METHODS: All patients at a single institution treated with chEVAR for any indication were reviewed. Major adverse events (MAE) were recorded and defined as a composite end-point that included any chimney stent thrombosis, reintervention, 30-day/in-hospital death and/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 2008-2012, 41 patients [age ± standard deviation (SD); 72.7±8.3; male 65.9%(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 pathologic indications, including: juxtarenal aneurysm, 41.5% (N=17, 1 rupture); suprarenal aneurysm, 17.1% (N=7), thoracoabdominal aneurysm, 17.1% (N=7), aortic anastomotic pseudoaneurysm, 14.6% (N=6; 3 ruptures), type 1a endoleak after EVAR, 7.3% (N=3), and atheromatous disease, 2.4% (N=1). Two patients had a single target vessel abandoned due to cannulation failure and 1 patient had a type 1a endoleak at case completion (technical success = 92.7%). Intraoperative complications occurred in 7 (17.1%) cases: graft maldeployment with unplanned mesenteric chimney (N=2) and access vessel injury requiring repair (N=5). Major postoperative complications developed in 19.5% (N=8). 30-day and in-hospital mortality were 4.9% (N=2) and 7.3% (N=3), respectively.
At median follow-up of 18.2 (range 1.4-41.5) months, 22% (N=9) of patients developed endoleak at some point during follow-up [type 1a, 7.3% (N=3); type 2, 9.6% (N=4); indeterminate, 7.3% (N=3)]. One patient (2.4%) underwent surgical conversion who was initially treated for dissection-related suprarenal aneurysm. The estimated probability of freedom from reintervention (±standard error mean) was 96±4%
at both 1 and 3 years. Primary patency of all chimney stents was 88±5% and 85±5% at 1 and 3 years, respectively (Figure 1). Corresponding freedom from MAE was 83±7% and 57±10% at 1 and 3 years (Figure 2). The 1 and 5-year actuarial estimated survival for all patients was 85±6% and 65±8%, respectively.
CONCLUSIONS: These results demonstrate that chEVAR can be completed with a high degree of initial success. Significant rates of both perioperative complications and major adverse events during follow-up, including loss of chimney patency and endoleak, are not uncommon thus underscoring the critical need for close surveillance. Elective use of chEVAR should be performed with caution and comparison to open and/or fenestrated EVAR is needed to determine the long-term efficacy of this technique.


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