This Is MS Multiple Sclerosis Community: Knowledge & Support

For thirty years since the invention of angioplasty, cardiologists have been using stents to repair arteries. First was the balloon stent, then the metal stent, then the drug eluting metal stent. Next it will be the bioabsorbable stent, or should I say now it is the bioabsorbable stent?

Phase I of Abbott's new ABSORB has just been published in The Lancet and the results were very successful. After two years, 30 patients that participated in the trial showed reduction in plaque, no stent thrombosis, no major cardiac events from 6 months to 2 years, and successful absorption of the stent. There was one more result and this one amazed me: the patients' coronary arteries
were virtually restored to normalcy, having regained their ability to contract and expand.

The ABSORB coronary device is made of polylactic acid, a proven biocompatible material that is commonly used in medical implants such as dissolvable sutures. The drug that is eluted by the ABSORB stent is everolimus, an immunosuppressant to prevent the body's rejection of the stent.

Not only is ABSORB the first successful bioabsorbable stent, but the imaging technology that is used to mark its progress is also new, as well as essential to the observability of ABSORB's success. Multislice CT angiography, intravascular ultrasound, and Optical Coherence Tomography (OCT), which were used to measure ABSORB's results, did not exist when stents were first invented.

ABSORB is now going into Phase II trials which will enroll about 80 patients
from European countries, Australia and New Zealand. Drug delivery and vessel support enhancements will be made to the ABSORB stents. It will be at least three years before ABSORB is market-ready.

via PCTA.org

Results
The AMS was well-expanded upon deployment without immediate recoil. The major contributors for restenosis as detected by IVUS at 4 months were: decrease of external elastic membrane volume (42%), extra-stent neointima (13%), and intra-stent neointima (45%). From 4 months to late follow-up, paired IVUS analysis demonstrated complete stent degradation with durability of the 4-month IVUS indexes. The neointima was reduced by 3.6 ± 5.2 mm3, with an increase in the stent cross sectional area of 0.5 ± 1.0 mm2 (p = NS). The median in-stent minimal lumen diameter was increased from 1.87 to 2.17 mm at long-term follow-up. The median angiographic late loss was reduced from 0.62 to 0.40 mm by quantitative coronary angiography from 4 months to late follow-up.

"For coronary stents, there is an incredible premium on stent performance," said Campbell Rogers, chief scientific officer for J&J's Cordis unit, in a telephone interview. "You need a Ferrari. The bioresorbable stent is a larger, bulkier stent. The likelihood of it being a significant advance for patients and clinicians in coronary use is not great."

Abbott's main competitors in the stent market are in the early stages of evaluating dissolving devices. Most of their work is in places such as the leg where the larger size of an absorbable stent isn't a problem.

Stress and pressure on the legs can cause metal stents to fracture, making an absorbable device more attractive, said Sean Salmon, vice president and general manager of Minneapolis-based Medtronic's coronary and peripheral division.

Biodegradable Self-expanding Stents for the Treatment of Benign Cardia Stricture in a Dog Model

Presented During: Non-vascular Interventions: GI/GU

Mon, 3/26: 8:24 AM - 8:32 AM

Abstract No: 105

Authors: Y. Zhu2, Y. Cheng1

Author(s)

Dr. Ying-Sheng Cheng, MD, PhD - View Disclosure
Shanghai Tenth Hospital of Tongji University
Shanghai, China

Purpose:

To assess the efficacy of a newly designed biodegradable self-expanding stent for the treatment of benign cardia stricture in a canine model versus group that received normal metallic stent insertion.

Materials:

Forty-eight dog models induced by LES circumferential injection of benzyl-dimethyltetradecylammonium chloride (BAC, 4 mmol/L, 16 ml) were randomly divided into a control group (CG; no stent insertion; n=16), a metallic stent group (MSG, n=16) and a biodegradable stent group (BSG, n=12). Metallic stents were retrieved four days after insertion. Lower-esophageal-sphincter pressures (LESP) and the 5-min barium height (5-mBH) were assessed before and immediately after the procedure, and at 1-week, 1-, 3- and 6-month follow-up. Four dogs in each group were sacrificed for histological examination.

Results:

Stent insertion was tolerated by all subjects. At the 6-month follow-up, the values of LESP and 5-mBH in the BSG is more stable compared to those in the MSG (p<0.05). Immunohistochemistry for mouse anti–proliferating cell nuclear antigen (PCNA) and a-smooth muscle actin revealed stronger inflammatory reaction in the BSG than in the MSG (p<0.05). Collagen proliferation was more severe after 6 months in the BSG (p<0.05).

Conclusions:

The novel biodegradable self-expanding stent was more effective than normal metallic stent for the treatment of this benign cardia stricture canine model despite it induced stronger inflammation reaction. Further studies are required to assess if drug-eluting biodegradable stents may reduce inflammation reaction and provide more stable treatment outcomes in a long-term.