A "first-in-man" study has found that drug-eluting stents that are made with natural materials and not polymers are just as effective in treating blocked coronary arteries. Furthermore this stent also uses 60 percent less drug that its polymer counterpart.
The breakthrough reported by MIV Therapeutics Inc., a company based at Atlanta in Georgia, attains significance because it shows a possibility of doing away with stents made of materials that are believed to be a cause of restenosis, re-blocking of arteries, after the treatment.
The Brazilian study was conducted by Dr. Alexandre Abizaid at Institute Dante Pazzanese of Cardiology in Sao Paolo, during which the researchers implanted stents in fifteen patients.
The team measured the extent of restenosis at four and nine months using two independent measures-an imaging technique called intravascular ultrasound and quantitative coronary angiography, which uses a radioactive tracer injected into the heart to detect blockages through an X-ray camera positioned outside the body.
The first four months were allowed for healing, while the subsequent time point was chosen for inflammatory or cell-proliferative responses.
The researchers used the ultrasound to measure "volumetric obstruction" that relates to the percentage of the stent volume that has filled, and the angiography to measure "late-lumen loss" that signifies the reduction of the free path through the stent area at its narrowest.
There was not statistically significant narrowing of blood vessels inside the VESTASync stent at nine months, compared to the results of the patients at four months.
According to the researchers, both volumetric obstruction and late lumen loss were comparable with restenosis measures for conventional drug-eluting stents, and there was no evidence of "incomplete stent apposition"-a measure of incomplete attachment of the stent to the blood vessel.
Dr. Costa, who presented the data at the annual meeting of the American College of Cardiology, said that there was no evidence of stent-related thrombosis (blood clot), and no major adverse coronary events over the study period.
"Our nine month data are very encouraging and reaffirm our positive findings at four months. What is remarkable is these results were obtained with 60% less drug delivered from an ultra-thin 0.6 micron coating that is entirely polymer-free," Dr. Costa added.
Instead of coating the metal with polymers, as is the case with conventional stents, MIV manufactures its new vascular stents by coating the metal with hydroxyapatite, one of the building blocks of bones and teeth.
"The human body treats hydroxyapatite as part of itself, rather than as a foreign material," says MIV President and Chief Executive Officer, Dr. Mark Landy.
MIV is now planning additional studies to verify these exciting nine month results found in this study.