Self-expanding nitinol stents must be oversized at least by a minimal amount to ensure contact with the vessel wall and prevent migration. Once the stent is deployed it exerts a continuous force upon the vascular wall, termed chronic outward force (COF). Data about COF and neointimal hyperplasia in humans are currently lacking. Some animal studies, though, found a markedly increased neointimal hyperplasia in stents with high oversizing and thus high COF. The objective of the BIOFLEX-COF trial is to investigate differences in formation of intimal hyperplasia at one and two years after implantation of nitinol-stents with high vs. low COF in de-novo femoropopliteal occlusive lesions in patients with symptomatic peripheral arterial disease.~The BIOFLEX-COF trial is a prospective, randomized controlled trial. 80 subjects will be enrolled and randomly assigned to either a high COF group (LifeStent Vascular Stent) or low COF group (Pulsar). Diameter of implanted stents will be measured at every two millimetres along the stent axis on DICOM images of the respective completion angiography using image processing software.~The scheduled time for recruitment is 2 years. There will be two follow-up evaluations at 12 and 24 months.~Primary endpoint is the amount of in-stent neointima at one year, assessed by contrast-enhanced CT angiography (CTA). Secondary objectives are the amount of in-stent neointima at two years, device- and procedure-related adverse events and target lesion revascularisation (TLR) rate.~In the control examinations stent diameter and true lumen diameter will be measured on DICOM images every two millimetres along the stent axis to quantify the relative amount of in-stent restenosis.~The present study is challenging in that it compares two different self-expanding nitinol-stents head-to-head against each other. To optimize the power of this study, both clinical TLR and binary re-stenosis at Colour flow Doppler Ultrasound were dropped as primary endpoints. Instead the amount of neointima inside the stent accessed by CTA was selected as outcome parameter.~The study differs further from similar previous trials in its generous inclusions criteria. This was done in effort to perform the trial on a patient sample that closely represents real-world patients of a specialised endovascular centre.
The objective of the BIOFLEX-COF trial is to investigate differences in formation of intimal hyperplasia at one and two years after implantation of nitinol-stents with high vs. low COF in de-novo femoropopliteal occlusive lesions in patients with symptomatic peripheral arterial disease.~The BIOFLEX-COF trial is a prospective, randomized controlled trial. 80 subjects will be enrolled and randomly assigned to either a high COF group (LifeStent Vascular Stent) or low COF group (Pulsar).