Endovascular Repair of Small Abdominal Aortic Aneurysms: A Paradigm Shift?

Abstract

Recent reports have documented poor long-term results following endovascular aneurysm repair (EVAR) of large abdominal aortic aneurysms (AAA). EVAR of small AAAs may result in improved long-term results compared to large AAAs. It is not known whether the frequency of anatomic suitability for EVAR is increased for small compared to large AAAs. This study compared the anatomic suitability of large and small AAAs for EVAR in an unselected patient population. Radiology reports for all computed tomography (CT) scans in a single hospital over a recent 3-year period were reviewed. AAAs diagnosed by contrasted CT scans with cuts >7 mm were excluded. Suitability for EVAR was determined by neck diameter, length, and angulation. In addition, iliac diameters and common iliac distal landing zone lengths were determined. Computerized 3-dimensional (3D) reconstruction was used to measure neck angulation and total aortic tortuosity. One hundred ninety-one patients were found to have AAAs with adequate CT scans for evaluation. Suitability for EVAR was highest in patients with AAA diameters of 3-4 cm and declined with increasing size of the AAA. Dividing AAAs into sizes greater than or less than 5.5 cm revealed that small AAAs had significantly longer necks, less neck angulation, longer common iliac landing zones, and less total aortic tortuosity. Multivariable analysis revealed that maximal aortic diameter was the only independent predictor of suitability for EVAR (p = 0.005, odds ratio 1.67, CI 95% = 1.17 to 2.38). The odds ratio predicts that with each 1 cm increase in size, the likelihood of suitability decreased by 5.3-fold. Small AAAs have less complex anatomy with longer aortic necks, less neck angulation, and less tortuosity. The poor outcomes following the treatment of large AAAs is thought to be due to complex anatomy. EVAR of less anatomically challenging small AAAs may improve long-term outcomes.

The Powerlink system for endovascular abdominal aortic aneurysm repair: Six-year results

“…14 Welborn et al performed an anatomic study, which showed that small AAAs had significantly longer necks, less neck angulation, longer common iliac landing zones, and less aortic tortuosity. 15 The smaller aneurysm diameter in the test group in this study thus may have contributed to the excellent success of endovascular repair.…”

The PIVOTAL study: A randomized comparison of endovascular repair versus surveillance in patients with smaller abdominal aortic aneurysms

“…ADAM and UKSAT demonstrated similar long-term results after open operation vs surveillance in patients with smaller aneurysms. If outcomes after EVAR are better in patients with smaller vs larger aneurysms as suggested from retrospective database analyses, 11,12,[19][20][21] then survival after EVAR might actually be improved in patients with small aneurysms.…”

“…In one study, AAAs Ͻ5.5 cm had longer necks, less angulation, less tortuosity, and longer iliac landing zones than AAAs Ͼ5.5 cm. 20 With each 1-cm increase in diameter, anatomic suitability for EVAR decreased fivefold. Thus, some candidates for EVAR at AAA diameters of 4 to 5.5 cm might no longer be suitable when diameters are Ͼ5.5 cm and thus might be subject to the increased risks of open repair performed at a time when the patients are older and less fit for a major invasive procedure.…”

Limited Feasibility in Endovascular Aneurysm Repair Using Currently Available Graft in Korea

“…Welborn et al (19) showed that the aneurysm size is intimately correlated with short neck, steep neck angulation, decreased CIA landing zones and more tortuosity, which should be decreased suitability of EVAR. Ouriel et al (14) also described that as aneurysm size increased, several morphologic features including aneurysm length, angulation, and iliac artery size might be changed.…”