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The Aorfix AAA Endograft in Highly-angulated Aortic Necks: Performance in the Pythagoras U.S. Clinical Trial
Mahmoud B Malas, Umair Qazi, Adam W Beck, William D Jordan, Michael Belkin, Kim Hodgeson, William Robinson, Mark Fillinger
Johns Hopkins University, Baltimore, MD

The AORFIX endograft (Lombard Medical) is a highly-conformable modular nitinol/polyester device designed for infrarenal or transrenal fixation. PYTHAGORAS is the first clinical trial to evaluate outcomes for EVAR using AORFIX in highly-angulated infrarenal aortic necks (≥60°).
PYTHAGORAS is a prospective non-randomized clinical trial that enrolled and treated 151 patients with neck angles ≥ 60° (high-angle) and 67 patients with neck angles < 60° (low-angle) in the EVAR-group. The primary control were patients concurrently undergoing open repair (n=76), and a meta-analysis of 323 patients from US EVAR clinical trials (SVS Lifeline) served as the secondary control.
We compared both the high and low-angle EVAR groups to the open-group in PYTHAGORAS in terms of Mortality (30-Day and 1-Year) and Freedom from MAE (Major Adverse Events defined by the SVS: myocardial infarction, cerebrovascular accident, renal failure, respiratory failure, paralysis/paraparesis, bowel ischemia, death and bleeding) using the Fisher exact test (Table-1). Graft migration and Type I & III endoleak were compared between high-angle group and low-angle (Table 2).
Patient demographics and comorbidities were similar between the EVAR and open-group with the exception of age (EVAR 76 ± 8, vs 70 ± 7 years, p<0.05), CHF (EVAR 13% vs 7% p=0.015), neck angle (EVAR all 71° ± 23°, EVAR high angle 83° ± 15°, vs Open 48° ± 23°, p<0.05) and female gender (EVAR high angle 35% vs Open 17%, p<0.0001). Sac diameter and other anatomic variables were similar. Operative data favoured the EVAR group for procedure duration, blood loss, and hospital length of stay (all p<0.05).
There was no statistically significant difference between Freedom from MAE, 30-Day and 1-year mortality between of low or high angle EVAR groups when compared to the PYTHAGOAS open control group (Table-1). Also there was no difference between low and high-angle patients in regards to sac shrinkage, type I/III endoleak and endograft migration Table-2).
PYTHAGORAS is the first U.S clinical trial designed to evaluate the performance of EVAR in a population of patients with neck angles ≥60°. Despite significant predictors of worse short and long-term outcomes (female gender, CHF, neck angle), MAEs and other pertinent outcomes were either better or similar to open repair, and similar to trials with less severe anatomy. The results encourage the use of AORFIX in patients with highly angulated neck anatomy who may otherwise have no endovascular option.
PYTHAGORAS OpenSVS control group
p-value: Aorfix vs Open Control
Freedom from
SVS MAE (30 d)
92.5%81.5%57.9%56.3%<60: <0.001
>60: <0.001
Mortality (30 d)1.5%2.0%1.3%2.8%<60: 0.928
>60: 0.717
Mortality (1 yr)3.0%7.3%6.6%6.5%<60: 0.320
>60: 0.845

Table: 1
Sac shrinkage (5mm 1yr)36.7%44.1%0.7335
Sac expansion (5mm 1yr)0%1.8%1.000
Type I/III leak (1yr)0%1.9%1.000
Migration (10mm 1yr)0%1.9%1.000

Table: 2

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