Evar For Infrarenal Aaa: Can Imaging Criteria Predict Cure?
Sheila M. Coogan, MD1, Harleen K. Sandhu, MD2, Charles C. Miller, III, PhD2.
1McGovern Medical School at UTHealth and Memorial Hermann Hospital at TMC, Houston, TX, USA, 2McGovern Medical School at UTHealth, Houston, TX, USA.
Introduction: Endovascular-repair (EVAR) for infrarenal-abdominal-aortic-aneurysms (AAA) has become the standard-of-care for patients who meet criteria based on device specifications. Success for aneurysm repair is defined as freedom from rupture. Early advantages of EVAR compared to open-AAA repair such as reduced initial hospital cost, shorter length-of-stay, and lower rate of myocardial-infarction are mitigated by increased re-intervention-rate at 4-years in EVAR-patients and cost of long-term follow-up. The goal of this study is to identify patients who are cured after EVAR.
Methods: We queried the M2S-Preview-database for isolated-AAAs that were not enrolled in a clinical-trial, had at least one pre-operative and one post-operative scan, and had maximum pre-intervention sac-diameters of 50mm or larger. The cohort was divided into patients that had maximum sac-diameters at the last post-operative scan of 35mm or less (cure cohort) and of greater than 4.5(control cohort) with a 4:1 control:test match.
Results: The M2S database contained 17,108 patients who met the criteria. 143/17,108 (0.84%) patients were identified as having reached the maximal diameter cure threshold, and these constituted the cure cohort. 579 controls were selected from the main cohort for a total case-control sample of 722. Median-age was 72.5 (IQR 62.5-77.5), and 89/722 (12%) were female. Pre-procedure radiologically-determined proximal neck seal-zone length was significantly longer in patients who reached cure goal (23.8 vs 19.2 mm, p<0.0001), and the seal-zone length achieved post-procedurally was also longer in the cure group (38.1 vs 23.5 mm, p<0.0001). Preoperative aortic common reference diameter (at a standardized difference of 15mm below the distal renal origin) was smaller in the cure group than the controls (22.5 vs 25.5mm, p<0.0001). Similarly, preoperative maximal sac-diameter was less in the cure group (54.3 vs 56.7mm, p<0.0001), and no patient in the cure group had a maximal diameter>70 mm.
Conclusion: Complete normalization of aortic-diameter is uncommon, having been observed in only 0.84% of a cohort of more than 17,000 patients. In this study, patient characteristics such as preoperative aortic-diameter and neck length were strong correlates of aortic-size normalization. This is unsurprising, but these patient characteristics are not modifiable. The most influential actionable determinant was length of the seal-zone actually achieved, and this was a statistically stronger predictor than potential zone size. Development of stent-grafts specifically engineered to maximize proximal seal-zone length may improve aortic-remodeling.
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