Editor's Choice – Influence of Proximal Aortic Neck Diameter on Durability of Aneurysm Sealing and Overall Survival in Patients Undergoing Endovascular Aneurysm Repair. Real World Data from the Gore Global Registry for Endovascular Aortic Treatment (GREAT)

Dominic P.J. Howard, Conor D. Marron, Ediri Sideso, Phillip J. Puckridge, Eric L.G. Verhoeven, James I. Spark
2018 European Journal of Vascular and Endovascular Surgery  
spark@sa.gov.au 24 25 26 What does this study/review add to the existing literature and how will it influence 27 future clinical practice? 29 Aortic neck diameter is an anatomical feature that is potentially linked to proximal seal failure 30 and adverse outcome following standard EVAR. We have shown that large aortic diameter 31 is independently associated with delayed type IA endoleak in patients undergoing standard 32 EVAR and is also associated with lower 5-year survival. With increasing
more » ... nical focus on 33 long-term stent-graft seal durability, aortic neck diameter is a parameter that should be 34 considered as more intensive long-term surveillance maybe required. 35 Abstract 36 Objective/Background: Aortic neck diameter is an independent anatomical feature that is 37 poorly understood, yet potentially linked to proximal seal failure and adverse outcome 38 following standard EVAR. The aim of this study was to assess whether large proximal aortic 39 neck (LAN) diameter is associated with adverse outcome using prospectively collected 40 individual patient data from The Global Registry for Endovascular Aortic Treatment 41 (GREAT). 42 Methods: 3166 consecutive patients, from 78 global centres, receiving Gore Excluder 43 stent-grafts for infra-renal abdominal aortic aneurysm repair between 2011 and 2017 were 44 included. Patient demographics, biometrics, operative details, and clinical outcome were 45 analyzed. Patients were divided into two groups; normal baseline proximal aortic neck 46 (NAN) diameter (<25mm on CT-aortography), and LAN (≥25mm). Clinical follow-up 47 (including imaging) was available for 76.5% of patients at 5-years post-intervention. Primary 48 endpoints analyzed were type IA endoleak and any aortic re-intervention out to 5 years 49 post-procedure. A composite endpoint of type IA endoleak, re-intervention, aortic rupture or 50 aortic-related mortality was also assessed. 51 Results: 1977 (62.4%) patients were classified NAN and 1189 (37.6%) were LAN. 52 Immediate technical success was achieved in 3164/3166 (>99.9%) of cases. Freedom from 53 type IA was achieved in 99.3% at 1-year and 97.3% at 5-years (lower in LAN vs NAN -54 96.8% (CI 93.7-98.4) vs 98.6% (CI 94.5-99.6), p=0.007). Freedom from aortic re-55 intervention was 93.7% at 1-year and 83.2% at 5-years (78.6% (CI 66.0-87.0) LAN vs 56 86.0% (CI 81.8-89.3) NAN, p=0.11). Freedom from primary composite endpoint was 95.9% 57 at one year and 84.9% at 5-years (81.3% (CI 69.2-89.0) LAN versus 87.0% (CI 81.6-91.0) 58 NAN, p=0.066). 5-year Survival was lower in the LAN group; 64.6% (CI 50.1-75.7) vs 59 76.5% (CI 70.7-81.3), p=0.03). 60 Conclusion: LAN is associated with delayed type IA endoleak occurrence and lower overall 61 survival. 62 Key words: Abdominal aortic aneurysm (AAA); Endovascular aneurysm repair 63 (EVAR); Aneurysm neck; Outcome analysis 65 66 Endovascular abdominal aortic aneurysm repair (EVAR) commenced in the early 1990s 1 and 67 is associated with short-term advantages compared to open repair, including shorter hospital 68 stay, more rapid return to independent activity, and early overall survival benefit. 2-4 These 69 benefits relate to the minimally invasive nature of the procedure. However, at the medium - 70 long-term follow up (4-15 years post procedure) benefits in terms of both aneurysm-related 71 and overall mortality are lost. 5-6 High-pressure endoleaks and graft migration are the key 72 culprits for stent-graft failure, aneurysm re-pressurization, and subsequent morbidity. 5-7 With 73 increasing awareness of this, there is a recent shift in focus to achieving long-term durability 74 rather than just immediate operative sealing following stent-graft deployment. Operating 75 within "instructions for use" (IFU) and performing detailed planning in order to choose optimal 76 sealing zones are crucial, 8 but the understanding of patient factors associated with endoleak 77 formation are limited. These include progressive aneurysmal degeneration and sealing zone 78 dilatation, both of which lead to subsequent EVAR failure, in addition the potential impact of 79 cardiovascular co-morbidity and medication use on endoleak formation are poorly 80 understood. 82 The infra-renal aortic neck is arguably the most important feature to consider when planning 83 endovascular intervention and the exact nature of its morphology often dictates both 84 immediate and long-term aneurysm sealing success. Several adverse aortic neck features 85 are known to be associated with poor proximal seal durability, including short neck length, 86 excessive angulation, circumferential thrombus, and reverse tapering. 9 However progressive 87 aortic neck dilatation due to underlying aneurysmal degeneration is an independent feature 88 that is poorly understood, yet potentially linked to proximal seal failure and adverse short-89 term outcome. 10-12 Eurostar analysis has shown that up to 32% of patients experience neck 90 dilatation following EVAR and risk factors for this include the use of larger diameter main 91 body devices and excessive device oversizing. 13 At 2 year follow-up Cao et al. found 92 preoperative proximal neck diameter to be correlated with future aortic neck dilatation. 11 93 Despite this link, immediate technical success and short-term re-intervention rates have not 94 been found to be influenced by pre-operative neck diameter. 14-15 Mid-to long-term data are 95 scarce, conflicting, and limited to studies with less than 300 subjects. 16-17 As neck dilatation 96 is a slow process, issues with proximal fixation and sealing may not become apparent for 97 several years after the initial procedure. 99 The aim of this study was to assess whether large proximal aortic neck diameter is associated 100 with stent-graft failure at mid-long term follow-up. Particular outcomes focused on were type 101 IA endoleak occurrence, requirement for endovascular re-intervention, aortic rupture and 102 overall survival. As an aortic diameter of 25mm or greater is considered abnormal and 103 potentially pre-aneurysmal, 18 we used this diameter as a cut-off for defining large proximal 104 aortic necks. Current AAA screening policies use 25mm diameter as the cut-off for abnormal 105 aortic diameter, and 30mm for the definition of an aortic aneurysm. Therefore, to understand 106 aortic disease progression and what influences EVAR failure, we aimed to compare patients 107 with a normal aortic neck diameter sealing zone to those with an abnormal pre-aneurysmal 108 diameter. Prospectively collected individual patient data from The Global Registry for 109 Endovascular Aortic Treatment (GREAT) were used for this study. 19 110 111 112 113 114 115 116 117 118 119 120 121 142 3. Distal segment iliac vessel lengths of less than 30 mm with less than 10 mm less 143 than or equal to 18.5 mm in diameter. 144 4. The main body was sized of less than 10% (undersize) or greater than 21% 145 (oversize) compared to the aortic inner diameter. 146 5. The iliac limb extensions were sized less than 7% or greater than 25% compared 147 to the iliac inner diameter. 148 149 Data collection and processing 157 York, NY, USA) to ensure reliability, and secure authentication and traceability. Data 161 of the authors. There was an a priori analysis plan agreed upon and executed by GORE. The 260 GREAT registry since 2011, of which 3166 consecutive patients received a Gore Excluder 261 stent-graft for treatment of an infra-renal abdominal aortic aneurysm. 85.6% of subjects were 262 male, and mean (SD) age at time of procedure was 73.4 (8.3) years. 89.5% of patients were 263 Caucasian, 3.3% African American, and 0.6% Asian/Oriental (Table 1) . Prior cardiovascular 264 disease and the prevalence of vascular risk factors were significant, with 81.1% of subjects 265 having known pre-morbid hypertension, 56.2% having a smoking history, 18.8% with treated 266 diabetes mellitus, and 16.1% having pre-intervention renal impairment (Table 1). 267 268 1977 (62.4%) patients were classified as having normal proximal aortic neck (NAN) diameters 269 (<25mm maximal cross-sectional diameter on CT angiography) and 1189 (37.6%) were 270 deemed to have large proximal aortic necks (LAN) (≥25mm). Some significant differences 271 were found in patient demographics, past medical history, and risk factor burden between 272 the NAN and LAN groups. In particular, patients in the LAN group were slightly older (mean 273 age 73.9 versus 73.0, p=0.008), with higher male predominance (88.6% versus 83.8%, 274 p<0.001). Risk factors and cardiovascular disease burden were substantial in both groups. 275 The majority of variables were similar between groups, with the notable exceptions of renal 276 insufficiency (more common in the LAN group -19.3% versus 14.2%, p<0.001), and a history 277 of COPD, previous malignancy, stroke, and congestive cardiac failure, all of which were both 278 more common in the LAN group (table 1). 279 280 Specific aortic aneurysm anatomical details are documented in table 2. Mean (SD) maximal 281 aneurysm diameter was 57.2 (10.6) mm, and this was greater in the LAN group (59.3mm 282 versus 55.7mm, p<0.001). Mean neck length was 29.7mm, averaging 28.1mm in the LAN 283 group and 30.0mm in the NAN group. Distal iliac diameters averaged between 13.8 and 284 15.3mm, and were marginally larger in the LAN group (table 2). Mean (SD) infra-renal neck intervention or aortic-related surgical procedure, 9 patients who had a cerebrovascular event, 309 and 17 patients who died from any cause. Device-specific complications of any type at 30-310 days (any endoleak, migration, compression, fracture, or aortic rupture) occurred in 52/3166 311 (1.6%) patients, with the majority being type I or II endoleaks. These were similar between 312 groups. 313 314 Hospital readmission and mortality was flagged and recorded for all cases. Freedom from from other medical registries by minimal exclusion criteria, having over 5000 consecutive 348 patients enrolled, and extended length of follow-up. The active tracking of long-term device 349 performance and associated patient outcomes will continue to provide key insights into real-350 world clinical practice, which is vital to advancing the future of endovascular repair and 351 improving outcome. Patient ascertainment from 78 centres in Europe, the United States, 352 Australia, New Zealand and Brazil should ensure robust and representative data is collected 353 on patients from a variety of demographic backgrounds. 355 This is the first study to use a cut-off at 25mm for aortic neck diameter, and this is because 356 an aortic diameter of 25mm or greater is abnormal and pre-aneurysmal tissue. In accordance 357 with this, all current AAA screening policies use 25mm diameter as the cut-off for abnormal 358 aortic diameter. If one wants to truly understand aortic disease progression and what 359 influences EVAR failure, it is essential to compare normal sealing zones with abnormal. We, 360 therefore, feel that this is the correct anatomical distinction to use. All previous studies 361 investigating aortic neck diameter, have used larger cut-offs, such as using 36mm diameter 362 stent-grafts. 23,24 These cases represent a very small minority of patients undergoing EVAR in 363 the real-world (only 177/3166 (5.6%) of patients in GREAT had aortic neck diameters greater 364 or equal to 30mm) which leads to limited study numbers, reduced power for useful analysis, 365 and limited overall clinical relevance. 367 Several key findings should be mentioned. First, a third of patients were found to have large 368 proximal aortic neck diameters (≥25mm). This is, therefore, a relatively common finding and 369 is associated with other anatomical features, including a larger maximal aortic aneurysm 370 diameter and slightly larger distal iliac diameters. However, adverse neck length and neck 371 angulation were not found to be associated with neck diameter. Subjects with larger proximal 372 aortic necks tended to require additional device components, particularly a higher likelihood 433 Adverse outcome, re-intervention, and aortic-related mortality out to five years were low 434 overall. However, patients with large proximal aortic neck diameters were found to have 435 higher rates of delayed type IA endoleak and reduced survival out to five years follow-up. 436 There was also a trend towards greater re-intervention and aortic-related complications in 437 these patients. These findings may be explained by progressive aortic neck dilatation and 438 subsequent proximal seal failure. With increasing clinical focus now on long-term stent-graft 439 seal durability, proximal aortic neck diameter is a parameter that should be considered as 440 more intensive long-term surveillance will be required in these patients. Our findings raise 441 the question as to whether young patients, with predicted life expectancies exceeding 10 442 years, should receive standard endovascular intervention if they have large aortic neck 443 diameters at baseline. 444 445 446 Acknowledgements: Many thanks to Beth Tohill at the Gore Clinical Research Office for 447 data extraction. 448 449 References 454 1. Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for 455 abdominal aortic aneurysms. Ann Vasc Surg,1991;5:491-499 456 2. Greenhalgh RM, Brown LC, Kwong GP, et al. Comparison of endovascular 457 aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR 458 trial 1), 30-day operative mortality results: randomised controlled trial Lancet. 14. Chisci E, Kristmundsson T, de Donato G, et al. The AAA with a challenging neck: 491 outcome of open versus endovascular repair with standard and fenestrated stent-492 grafts. JEVT. 2009;16:137-46. 493 15. Verhoeven BA, Waasdorp EJ, Gorrepati ML, et al. Long-term results of Talent 494 endografts for endovascular abdominal aortic aneurysm repair. JVS. 2011;53:293-8. 495 16. Jim J, Rubin BG, Geraghty PJ, Criado FJ, Fajardo A and Sanchez LA. A 5-year 496 comparison of EVAR for large and small aortic necks. JEVT. 2010;17:575-84. 497 17. Jordan WD, Jr., Ouriel K, Mehta M, Varnagy D, Moore WM, Jr., Arko FR, et al.
doi:10.1016/j.ejvs.2018.03.027 pmid:29764709 fatcat:cjyc5d2n3vgcratbv6hcxtdhhy