Study Validates Bioabsorbable Stents
A mid-March issue of the Lancet published findings from a trial to examine use of bioabsorbable stents. The endpoints that were considered include the safety and feasibility of this stent. A group of researchers from New Zealand assessed Abbott Vascular’s bioabsorbable everolimus-eluting stent (BVS).
This stent has a poly-L-lactic acid backbone, which provides support for the BVS stent. It is coated with poly-D L-lactic acid, which helps to control the means by which the everolimus is releases. The drug is an antiproliferative agent.
The prospective, multi-center, open-label trial enrolled a total of 30 patients. All the patients who participated were over age 18 and were diagnosed with silent, stable, or unstable ischemia and a single de novo lesion amenable to treatment with either a 3×18mm or 3×12 mm stent. Patients were recruited at one of four different participating academic medical centers.
The primary endpoints for the study were ischemia-driven target lesion revascularization (TLR), myocardial infarction, and cardiac death, which were assessed at six and twelve months. These were evaluated in 26 of the patients. Intravascular ultrasound was completed in 24 patients. As well, 13 patients underwent examination with optical coherence tomography.
The researchers also assessed the number of patients that required additional stenting. For such patients, the physicians employed the Cypher sirolimus-eluting stent from Cordis, a Johnson & Johnson subsidiary. Patients were also treated with a minimum of 75 mg of aspirin every day during the five year study period in additional to 75 mg of clopidogrel for a minimum of six months.
The reference-vessel diameter level for target lesions considered for this trial was 3 mm. Target stenosis diameter was 50 percent or more but less than 100 percent. The target for thrombolysis in MI flow grade was more than one.
The success rate of stent placement was 100 percent. Device success was 94 percent. At six months, the angiographic in-stent late loss was 0.44 mm. The clinicians noted that this was attributed to a mild reduction in the area of the stent which was measured with intravascular ultrasound.
One year following stent placement, 3.3 percent of patients had a major cardiac event. Only one patient had a non-Q wave MI and none of the patients had TLRs. There were no instances of late stent thromboses. This study indicates that the BVS stent has an excellent safety profile at one year after placement.
The researchers declared no conflict of interest in completing the trial. Funding for the study was, notably, provided by Abbott. The team is planning further studies to gather follow-up from a longer time period, noting that all side effects might not be captured during the first year.
March 27, 2008 Related topics: New Technology & Innovation, Quality, Safety, Errors, Cardiology