Data from the US PYTHAGORAS clinical trial show that major adverse events are lower in patients treated with Aorfix than with open repair, and similar in patients with less severe anatomies treated with other EVAR devices. Results from the trial were presented by Mark Fillinger MD, for the PYTHAGORAS Investigators, at the Society for Vascular Surgery Annual Meeting (5–7 June, Boston, USA).
Fillinger, who is principal investigator for the US PYTHAGORAS clinical trial, stated, “The highly conformable design of the Aorfix endograft allows for the treatment of a wide range of abdominal aortic aneurysm anatomies. The PYTHAGORAS trial was unique in its focus on challenging anatomy that has never been studied before in an FDA-approved trial, yet Aorfix delivered results comparable to competitor devices used in much less challenging cases.”
Aorfix (Lombard Medical) was designed to treat abdominal aortic aneurysms with highly angulated aortic necks. It is a highly flexible, soft, conformable device, made of polyester fabric and nitinol rings, with four pair of hooks proximally and an 8mm-long primary seal zone. It is commonly placed in a transrenal position.
Fillinger told delegates that type I endoleaks increase with neck angle in most EVAR devices, and that neck angle has an effect on seal zone. He noted that in highly angulated aortic necks, the central lumen line is not a good indicator of the actual seal zone, where the seal zone available on the inner curve might be 8 mm in a neck with a central lumen line length of 15 mm.
The US PYTHAGORAS clinical trial is the first EVAR pivotal trial focusing on highly-angulated aortic necks 60–90°. In the roll-in group, 65 EVAR patients with aneurysm neck angle <60° were treated, and in the primary study group, 150 EVAR patients with neck angles 60–90° and higher were included. The US trial enrolled 205 patients on an intention-to-treat basis. The control arms were the SVS Registry meta-analysis of control patients from US EVAR clinical trials (n=323) and the trial concurrently enrolled open surgical controls (n=76) for neck angulation and other variables not in the SVS Registry.
In terms of demographics, comorbidities and anatomy in the PYTHAGORAS trial, EVAR and open control patients had similar aneurysm sac diameter (5.8cm in each group) but the two groups differed with regards to four factors previously shown to adversely affect outcomes: age (EVAR 75.4±8 vs. 69.2±7 years, p=0.001), female gender (EVAR high angle 35% (51/145) vs. 20%, p=0.017), congestive heart failure history (EVAR 12.6% vs. 6.5% p<0.05, SVS controls), and neck angle (EVAR all 72°±22°, EVAR high angle 83°±15° vs. open repair 48°±22°, p<0.001) ; EVAR 69% >60°, open 27% >60° (p<0.05).
The open cohort had shorter necks on average.“This is the first trial with more female patients in the test group, and the first trial with more severe neck angles in the test group,” Fillinger said.
Aortic endografts were successfully implanted in 197/205 cases according to the intention-to-treat analysis (all eight cases were access-related, and device was not attempted in four cases). The mortality rate was 2% for the entire cohort (4/205), 1% for the 60–90° angle group (1/103), and 2.6% for the open controls (9/323, p=ns). Thirty 30-day outcomes favoured the test group for procedure duration, estimated blood loss, transfusion, and hospital length of stay (all p<0.05). Freedom from major adverse events with Aorfix was superior to open controls at 30 days and one year. Amongst patients treated with Aorfix, those with aneurysm neck angles 60–110°had low rates of sac expansion (1.8% had 5mm expansion at one year), type I/III endoleak at one year (2%) and migration (1.7% 10mm at one year).
In conclusion, Fillinger said, despite significant predictors of worse short and long-term outcomes, major adverse events were better for Aorfix than for open repair, and similar to EVAR trials with much less severe anatomy. “This device provides a less invasive on-label option for patients with highly angulated neck anatomy who would otherwise have poor endovascular options or open repair,” he added.