USFDA gives nod to Abott's ABSORB stent

USFDA has approved the first fully absorbable stent to treat coronary artery disease. The Absorb GT1 Bioresorbable Vascular Scaffold System (BVS), which releases the drug everolimus to limit the growth of scar tissue, is gradually absorbed by the body in approximately three years.

The stent, called Absorb, is made of a plastic similar to dissolving sutures and offers patients an alternative to metal stents currently used to prop open arteries cleared of blockages.

The Absorb GT1 BVS offers a new treatment option for individuals who are candidates for angioplasty, but would prefer an absorbable device rather than a permanent metallic coronary stent,” said Bram Zuckerman, M.D., director of the division of cardiovascular devices at the FDA’s Center for Devices and Radiological Health.

Absorb’s appeal is that it allows the blood vessel to return to a natural state, free from a permanent metal implant. The approach holds particular promise for patients whose coronary artery disease could require multiple implants over the course of several decades, said Mitchell Krucoff, a professor at Duke University Medical Center who has advised Abbott on Absorb.

The Absorb GT1 BVS is manufactured from a biodegradable polymer called poly(L-lactide), which is similar to materials used in other types of absorbable medical devices, such as sutures. The device’s absorption by the body gradually eliminates the presence of foreign material in the artery once the stent is no longer needed. After absorption, there are only four very small platinum markers embedded in the walls of the artery, which help cardiologists identify where the Absorb GT1 BVS was originally placed.

Possible adverse events that may be associated with the procedure to insert the Absorb GT1 BVS or with the Absorb GT1 BVS itself include allergic reactions to materials in the device or medications used during the procedure, allergic reaction to the drug everolimus, infection or irritation at the catheter insertion site, internal bleeding, the development of abnormal connections between arteries and veins, embolism, or other coronary artery complications that may require medical intervention and that could lead to death.

The Absorb GT1 BVS is contraindicated for patients who have a known hypersensitivity or allergy to everolimus or the materials used in the device, such as poly(L-lactide), poly(D,L-lactide), or platinum. It is also contraindicated for those who are not candidates for angioplasty, have sensitivity to contrast, or who cannot take long-term aspirin therapy along with other blood-thinning medications (antiplatelet agents).

"No metal means the treated artery can pulse and flex naturally as demands on the heart change with everyday activities," said Gregg Stone of Columbia University Medical Center, who led clinical trials for Absorb. "No metal may also reduce the potential of future blockages that occur with permanent metallic stents."

Data released in October concluded Absorb was comparable to Abbott’s own Xience drug-coated metal stent in safety and effectiveness but showed a higher risk of heart attacks and blood clots. Abbott said it expects the risks to lessen as surgeons gain experience with it.

Absorb also will compete with Medtronic Plc's traditional drug-coated Resolute stent and Boston Scientific Corp's Synergy and Promus stents. Synergy’s polymer coating disappears over time after delivering a drug that helps prevent the artery from re-clogging, leaving a metal stent in place.

Abbott plans to roll out the device to about 100 hospitals in the next several months as it trains surgeons on the implant procedure before ramping up sales, said spokesman Jonathon Hamilton. Absorb will be priced at a "modest" premium to Xience, he said. Analysts have predicted Absorb will gain a market niche but not surpass drug-dispensing metal stents such as Xience in share until longer-term data show more favourable clinical results.

Coronary heart disease is responsible for about 370,000 deaths each year in the U.S., according to the National Heart, Lung, and Blood Institute. The condition develops when cholesterol-containing deposits build up and narrow the coronary arteries, decreasing blood flow to the heart. This can cause chest pain (angina), shortness of breath, fatigue or other heart disease symptoms. Doctors often treat coronary artery disease with a procedure called angioplasty to widen the artery using a metal stent. Scar tissue can form within the stent causing the artery to narrow again (restenosis). Drug-eluting stents temporarily release a drug, typically for a few months after stent placement, to combat the formation of scar tissue.

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