Two-year data from the Mimics study, presented at the late-breaking clinical trials session at the VIVA Symposium, have confirmed that BioMimics 3D provides a significant improvement in long-term primary patency compared to a straight nitinol control stent in patients undergoing femoropopliteal artery intervention.
A new 12-month analysis presented at the VIVA Symposium reinforces the longer term benefit of Veryan’s helical stent technology and showed a statistically significant improvement in the Kaplan Meier estimate of survival from clinical-driven TLR through 24 months, compared to the control stent (P<0.05).
BioMimics 3D, a nitinol stent with unique three-dimensional helical geometry, has been developed by Veryan, based on research by Colin Caro at Imperial College London into the link between blood flow mechanics and vascular disease. The BioMimics 3D nitinol stent has unique helical centre line geometry to mimic natural vascular curvature that promotes secondary (swirling) flow and elevated haemodynamic shear stress, which has a protective effect on the endothelium. The helical geometry of the BioMimics 3D femoropopliteal stent is also designed to enable coil-spring shortening of the stented segment during knee flexion and mitigate the risk of stented segment compression causing localised strains in a straight stent that may lead to stent fracture and chronic vascular injury.
The Mimics study is a prospective, randomised, multicentre controlled trial conducted at eight German investigational centres and supported by an independent core lab. A total of 76 patients were enrolled and randomised 2:1 (50 BioMimics 3D v 26 control) in subjects undergoing femoropopliteal artery intervention. Mimics’ investigators compared the safety, efficacy and vascular haemodynamics of the BioMimics 3D stent to straight nitinol stents (24/26 control subjects were treated with LifeStent (CR Bard)).
Mimics data were presented during the VIVA session by principal investigator Thomas Zeller, Universitäts-Herzzentrum, Freiburg-Bad Krozingen, Germany. The Kaplan Meier survival estimate of freedom from loss of primary patency at two years was 72% for BioMimics 3D subjects vs. 55.0% for the control arm. The difference in survival estimate between the two groups by log rank test was significant (P<0.05). Importantly, there was no increase in the Kaplan Meier estimate of clinically-driven target lesion revascularisation (CDTLR) rate in the BioMimics arm between 12 and 24 months (9% at both time-points) compared to a three-fold increase (8% at 12 months and 24% at 24 months) in the straight stent control arm.
An improvement of one or more Rutherford categories was observed in 87% of BioMimics 3D patients at 24-months compared to baseline. A core lab review of straight and flexed knee x-rays did not detect any stent fractures in any BioMimics 3D Stent. Bi-planar x-ray imaging data indicate the ability of the femoropopliteal artery to adopt the three-dimensional curvature of the BioMimics 3D stent and computational fluid dynamic modelling provided evidence of secondary flow within the stented segment and predicted zones of elevated wall shear stress.
Mimics study data indicate a correlation between primary patency and stent curvature. BioMimics 3D stented segments showed significantly greater curvature (P= 0.02) compared with the control, providing swirling blood flow and elevated wall shear, which may explain the longer term patency protective effect seen with BioMimics 3D. Across all patients, stent curvature was greater for BioMimics 3D stents compared to the straight control stents and no loss of patency was observed in patients with mean straight leg stent curvature above 0.02mm-1.
“These data suggest the existence of a patency protective effect provided by the biomimetic characteristics of the BioMimics 3D nitinol stent resulting in haemodynamic and biomechanical performance advantages over straight nitinol stents,” comments Zeller.
Veryan has received CE mark approval for the BioMimics 3D stent and is planning commercialisation through an international distributor starting in the first quarter of 2015.