Here is some very recent related information that you might find useful.
Please note that this is not a drug-coated stent - it is a nickel-titanium (NINTINOL) self-expanding stent used in the peripheral vasculature.
Side Note: ASTM F1980 is the most commonly used standard I have seen for accelerated aging (AA) of medical devices, and it points out the need to also perform real time aging to confirm the AA results.
FDA PMA Summary of Safety and Effectiveness: ev3 EverFlex(tm) Self-Expanding Peripheral Stent System
For those involved with NiTi self-expanding devices (particularly implantable ones), this PMA summary has some useful information.
http://www.accessdata.fda.gov/cdrh_docs/pdf11/P110023b.pdf
Highlights
- Biocompatibility tests performed and rationale for tests not performed
- Animal and in vitro test results including acceptance criteria
- Clinical study design and results
- High fracture rate seen in animal studies - swine and sheep (>50% rate up to 180 days)
- Relatively low fracture rate in human experience at 1 year (1 out of 260 patients - trans-axial spiral fracture)
- Human fracture analysis table breaks down different fracture modes into 5 classes
- Existence of a "Stent Fracture Committee"
- Significant post-market study commitments (2 studies)
--- new study requires 169 patients followed up to 36 months post-procedure (sample size determined to detect stent fractures)
--- following patients from earlier studies up to 36 months post-procedure
Excerpt
High fracture rates were observed in both animal studies; however, animal studies
often present worst case conditions for fracture. For this PMA, the animal testing was
comprised of long length stenting and overlapped configurations representing severe
anatomic conditions. In addition, experimental studies in small research undulates
are often limited by anatomic challenges such as angularity, curvature and taper of the
femoral and iliac arteries. Because of the high fracture rates observed in these animal
studies and in light of the limitations posed, the available clinical data on stent
fracture for the EverFlex stent weighed heavily in the evaluation of fracture rate.