Dissolving Heart Stent passes first major test

Abbott Vascular’s dissolving Absorb stent did the job as good as a conventional stent in the one-year study, but a few experts are suspicious because of the fact that it did not prove superior.

Around 850,000 heart disease patients in the US are given stents each year.

Stents are tiny mesh tubes meant to keep blood vessels open and unclogged after angioplasty, a procedure to open narrowed or obstructed arteries. They are generally coated with a material that oozes medicine, but at times they lead to inflammation and other problems after a few years.

Abbott’s Absorb stent, already sold in Europe, is made of a material that degrades over several years.

The dissolving stent, which has a plastic that is similar to the kind used in sutures that dissolve, has been created to disappear completely within three years of implantation, which returns the blood vessel treated to its flexible, natural state. A longer study underway now of 5,000 patients “will go a long way toward determining whether this promise will become a reality”.

The study involved about 2,000 patients with chest pain due to one or two clogged arteries, and was aimed at winning Food and Drug Administration approval to sell Absorb in the U.S.

That difference was not considered statistically significant, said researches. Specifically, the target lesion failure rate (the primary endpoint) for Absorb and XIENCE was 7.8% and 6.1%, respectively (non-inferiority p 0.007).

On a number of secondary type measures, numerically it appeared Xience was also better at the one year point, but none of the differences were statistically significant. Of the 2008 patients at 193 sites who underwent randomization, 1322 were assigned to receive the Absorb scaffold, and 686 to receive the Xience stent.

“The trial met all its major endpoints, and given all the attributes my opinion is that it should be approvable”, said global study chairman Dr. Gregg Stone. Although Absorb is already in use in 100 countries, both the United States and China have yet to approve the stent for widespread use with patients. This makes it different from Boston Scientific’s newly-approved Synergy stent, where the polymer coating that delivers the drug disappears in time, but leaves a bare metal stent after the coating dissolves.

“A lot of patients would much rather have a dissolving stent that returns arteries back to their normal condition”, he says. “It will be very good for young patients who will live 30 or 40 years with this decision”.