As a result of safety issues with DES — recently reinforced by the COURAGE study, and others, indicating that PCI/stenting may offer no greater length of life than medical therapy — utilization has declined substantially, particularly in the U.S. where usage has slumped from 87% of procedures in 2005 to the current rate of 64%, according to cardiologists at the ESC congress.

As one example, Q207 DES worldwide sales for Boston Scientific (Natick, Massachusetts) was $437 million, a 32% decrease from Q206 sales of $647 million.

The market is unlikely to recover in the near future, but a number of new stents described at the congress appear to hold the promise of reversing this decline by resolving safety issues via, perhaps, bioabsorbable stent materials.

Patrick Serruys, MD, PhD presented results from the ABSORB trial employing a bioabsorbable polylactic acid (PLA) stent under development by Abbott Vascular (Redwood City, California), a unit of Abbott Labs (Abbott Park, Illinois).

The Abbott stent has been designed for improved radial strength, and also includes an overcoat of PLA loaded with Everolimus for inhibiting restenosis.

At six-month follow-up, late loss was 0.44 mm, between that for a bare metal DES of 0.21 mm and a bare metal stent (BMS) of 0.85 mm. The binary restenosis rate at six months was 11.5%, but there were no target lesion revascularizations and no stent thrombosis events. The stent begins to absorb after six months and is designed to be completely absorbed in two years. Abbott said it is continuing to modify the design to reduce late loss.

Miodrag Ostojic, MD, of Clinical Center of Serbia (Belgrade, Serbia), presented results of a trial of the Nobori Core DES from Terumo Medical (Somerset, New Jersey), a unit of Terumo (Japan). The Terumo stent was compared to the Cypher from Cordis (Miami Lakes, Florida) in a non-randomized study that included 54 patients treated with the Nobori Core and 53 treated with Cypher.

The Nobori Core consists of a BMS employing Terumo's S-Stent platform, coated with a polylactic acid layer containing Biolimus A9. At nine-month follow-up, the restenosis rate for the Nobori stent was only 1.7% compared to 4.2% for Cypher, and late loss was 0.1 mm compared to 0.12 mm for Cypher. And evaluation of endothelial function revealed no abnormalities for patients receiving the Terumo stent while there was some evidence of dysfunction for the Cypher.

Another bioabsorbable stent, the Absorbable Metal Stent from Biotronik (Berlin, Germany), is being evaluated in the PROGRESS-1 first-in-man trial for use in the coronary arteries.

As discussed by Ron Waksman, MD, at the congress, results with the initial version of the device, which is fabricated from magnesium, are disappointing, with a 27.9% target lesion revascularization rate at one year and late loss of 1.0 mm. However, no long-term adverse events have occurred with the device, and it is completely bioabsorbed at 28 months post-implant.

Biotronik is now developing a second generation version of the device, the AMS2, which has a modified alloy for added strength, since the primary cause of the high restenosis rate is elastic recoil. A third version, the AMS3, will provide drug elution for further reduction of restenosis.

— MICHAEL SIMONSEN, PhD

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