Bioresorbable heart stent wars to heat up in U.S.

The idea of a permanent metallic implant being left in the coronary artery after a stent has been used to force it open following blockage has prompted many companies to look for solutions.

We have seen the partially absorbable polymer stent from Boston Scientific – Synergy – that won approval from the Food and Drug Administration back in October. On Tuesday, FDA approved the first fully-resorbable polymer stent from Abbott – Absorb.

“The FDA’s approval of the Absorb GT1 BVS (biovascular scaffold) 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, director of the division of cardiovascular devices at the FDA’s Center for Devices and Radiological Health, in a statement.

With Synergy and now Absorb’s approval, the bioresorbable polymer stent wars are sure to heat up in the U.S. Both these polymer stents elute the drug everolimus.

Absorb, which was already approved overseas, is designed to disappear into the body between two and three years following the procedure leaving no trace behind, unlike Synergy, which isn’t fully absorbable because while the polymer coating disappears, the metallic stent remains in the body.

Abbott’s device would certainly be an advance in treatment options currently available to patients suffering from coronary artery disease. The National Heart, Lung, and Blood Institute estimates that 370,000 deaths in the U.S. result from coronary artery disease.

However, interestingly enough, results for the ABSORB III pivotal clinical trial demonstrated that Absorb was no worse than Abbott’s own best-in-class drug-eluting stent, the Xience V. In other words, Absorb did not show clear superiority over existing standard of care.

Here’s how Absorb compared with Xience in the trial.

Results showed that the Absorb resorbable scaffold met its clinical endpoint of target lesion failure at one year, and there was no statistical difference between the Absorb and Xienze in other clinical outcomes.

However, numerically, Absorb’s results were worse off than Xience on a number of different outcomes, including in device thrombosis. That occurs where a thrombus or blood clot suddenly forms in a stented coronary artery impeding blood flow. It is considered a life-threatening complication.

Within one year, “device thrombosis had occurred in 1.5% of patients in the Absorb group and in 0.7% of those in the Xience group” according to results published in the New England Journal of Medicine. The Absorb III trial implanted 1,322 patients with the Absorb device and 686 with the Xience stent.

Cardiac death occurred in eight patients implanted with Absorb (0.6%) whereas only one in the Xience group (0.1%). Death from any cause in the Absorb group was 15 (1.1%) while with Xience it was 3 (0.4%).

Back in October, when the trial results were presented at the Transcatheter Cardiovascular Therapies meeting in San Francisco, a debate over Absorb’s value arose. The central question was whether promising first-gen technologies that show no immediate, clear clinical benefits should be adopted by the physician community.

A physician and chairman of Absorb’s clinical program issued a full-throated support in a news release from Abbott following the FDA announcement.

“No metal means the treated artery can pulse and flex naturally as demands on the heart change with everyday activities. No metal may also reduce the potential of future blockages that occur with permanent metallic stents, and allows easier access to other treatment options should they prove necessary in the patient’s future,” said Dr. Gregg W. Stone, director, cardiovascular research and education, Center for Interventional Vascular Therapy, Columbia University Medical Center, New York-Presbyterian Hospital.

An Abbott spokesman said that the product will find reimbursement using existing codes for drug-eluting stents.