Absorb: Bioresorbable Vascular Scaffold System
Coronary artery disease (CAD) is one of the most common causes of death globally, taking millions of lives every year. Due to CAD arteries that supply blood to the heart become narrowed or blocked by a build-up of fatty deposits called plaque. This narrowing reduces the blood flow to your heart muscle, which causes oxygen deficit and makes it harder for the heart to work properly.
For the last few decades CAD is treated by performing an angioplasty – an endovascular procedure to widen narrowed or obstructed arteries or veins. During the procedure an empty, collapsed balloon, known as a balloon catheter, is passed over a wire into the narrowed locations and then inflated to a fixed size. The balloon forces expansion of the narrowing within the vessel and the surrounding muscular wall, opening up the blood vessel for improved flow. The balloon is then deflated and withdrawn. In some cases, a stent is inserted to ensure the vessel remains open.
Up until now there were two main types of stents: regular metallic stent and a drug eluting stent (which was introduces about 10-12 years ago). Both types are permanent and have serious possible complications, including: damaged artery flexibility, severe inflammatory reaction, restenosis, etc. These stents also require the patient to permanently take blood-thinning drugs in order to prevent blood clots formation on top of the stent.
Absorb: revolution in Interventional cardiology
In 09/2014 Abbott (the manufacturer of the Absorb scaffold) published positive one-year clinical results of follow-up on patients after angioplasty with a bioresorbable vascular scaffold system called Absorb. Absorb is a non-metallic mesh tube, made of polylactide, which is the same type of material used in other medical devices, such as dissolving stitches. Absorb was designed to treat CAD by opening the narrowed artery to restore blood flow to the heart. Once the artery has the ability and strength to stay open on its own Absorb gradually dissolves into natural substances already found in our body (water and carbon dioxide).
The trial included hundreds of patients and showed that people treated with Absorb were less likely to experience angina once they left the hospital than those treated with a regular DES (metal drug-eluting stents). In 12/2014 Absorb was approved for use in Israel by the Israeli Ministry of Health. Herzliya Medical Center is currently the only medical facility in Israel offering the option of angioplasty with Absorb performed by a cardiosurgeon of the patient’s choice.
The development of Bioresorbable Vascular Scaffolds was based on the premise that scaffolding and drug delivery to the diseased coronary vessel are only required on a temporary basis following coronary interventions. Several studies support this concept and indicate that there is no incremental clinical benefit of a permanent implant over time. Absorb, the world’s first commercially available drug-eluting coronary Bioresorbable Vascular Scaffold (BVS), is designed to deliver Vascular Reparative Therapy (VRT) by eliminating the presence of a permanent mechanical restraint (with the exception of two tiny markers, so that the implantation spot can be located in the future).
Unlike a metallic stent, which cages the vessel, Absorb is more flexible and dissolves over time (starting 3-6 months after the implantation), leaving behind a treated vessel free of a permanent implant with the potential to flex, pulse and dilate in response to various demands on the heart, based on people's lifestyle and activities, such as exercise. While stenting performance is characterized by a single phase of revascularisation, Absorb was designed with the premise of working in three phases to deliver VRT:
- Revascularisation - in this phase, Absorb revascularises like the best of DES do. Absorb achieves this goal by offering good deliverability, excellent conformability, a minimum of acute recoil, high radial strength, and controlled release of everolimus (an immunosuppressant meant to prevent restenosis).
- Restoration - this phase is meant to enable natural vessel function for improved long-term outcomes. Restoration of the vessel occurs as the scaffold benignly resorbs without inflammation.
- Resorption - Absorb gradually ceases providing luminal support and evolves from an intact scaffold to a discontinuous structure embedded within neointimal tissue. As the scaffold degrades, the polymer is converted into lactic acid, which is metabolized and ultimately converted into carbon dioxide and water.
Recovery from the procedure is usually quite quick. Absorb slowly releases medication to the diseased area and overtime it starts to dissolve. The process is individual: it start 3-6 month after the surgery and might take up to 3 years.
What do doctors say?
Dr. Michael Yonash, one of the best catheterization specialists in Israel, says: “this is every cardiosurgeon’s dream! It gives us the means to treat the diseased artery without all the side-effects of permanent stents”.
Professor Ran Kornovsky, Israel’s leading specialist in minimally invasive cardiosurgery, also commented: “Absorb is the beginning of a new era in the field of surgical CAD treatment. Israel’s cardiosurgeons are truly excited about it because it’s one of the most advanced technologies in the world for treating blocked coronary arteries”.
- Minimally invasive surgery with great results and minimal side-effects. No need for long-term blood anticoagulation therapy. Elimination of risks involved with a permanent stent.
- There are currently only several cardiosurgeons in Israel skilled at performing Absorb angioplasty, and they all work at HMC. HMC gives its patients the unique option of choosing their treating physician (this is not possible at public hospitals).
- Private hospital and VIP service. Being a private hospital allows HMC to schedule the necessary diagnostic and surgical procedures at the patient’s request. The whole process won’t take more than several days to a week. The hospitalization rooms offer a pleasant stay at the level of a 5 star hotel. Your case manager and the whole medical staff will make sure you get the best treatment possible.
*The materials for this article (text, images, video) were provided by Abbott.
The bioabsorbable coronary artery stent
Dr. Kornowski answered questions regarding the bioabsorbable coronary artery stent (BCAS) and its beneficial use in the treatment of coronary artery disease.
What are the indications for implanting a BCAS?
BCAS is suitable and recommended for patients that have significant arterial narrowing (stenosis) and atherosclerotic plaque of the coronary arteries. Coronary artery disease is graded using sophisticated medical imaging systems that measure stenosis precisely – this is essential in effectively fitting the BCAS in the correct position prior to surgery. This evaluation is also crucial for the success of this unique and innovative medical treatment. Patients that have irregular buildup of coronary plaque have the indications of high-grade disease complexity, they may benefit from an alternative procedure.
Are there any technical differences between the BCAS and a conventional stent procedure?
Generally speaking no. Both procedures involve the method of catheterization, which is routinely performed in the field of interventional cardiology. However, to ensure positive results, the implantation of a BCAS at the site of stenosis demands maximal accuracy and precision. Therefore, a highly trained interventional cardiologist and sophisticated catheterization lab are crucial for the optimum performance of a BCAS placement.
Does the placement of a BCAS require any special follow up?
The follow-up for both, a conventional coronary artery stent and BCAS is the same, following the procedure.
What are the possible complications of implanting a BCAS? Are they any different from the conventional coronary artery stent?
The procedure-related complications of a BCAS implantation are similar to the complications regarding the placement of a conventional coronary artery stent. Overall, the rate of major complications has decreased over the years and equates to less than 1%; this is due to the progression in medical innovation and research in the field of interventional cardiology. In rare cases (the aforementioned 1%), emergency surgery may be required because of critical coronary artery damage caused either by the invasive methods of the surgery itself; or mainly kidney damage and a stroke as a result of catheterization. According to numerous studies, following a BCAS implant, the recurrence of stenosis (restenosis) has a lower incident rate than conventional stents.
Is the medical treatment following the procedure of BCAS implantation any different from the conventional coronary artery stent?
The medical treatment following a BCAS and conventional coronary artery stent are identical. It involves dual antiplatelet therapy with aspirin for a lifetime and Plavix for 1 year.
What makes HMS unique regarding the treatment of Ischemic Heart Disease compared to other medical centers?
HMC was the first medical center in Israel to adopt the technology of BCAS implantation several years ago. As a result, we are the most experienced medical center in the placement of BCASs. The combination of a highly skilled interventional cardiology team, sophisticated catheterization labs and providing a personal and attentive care approach to each patient, make HMC a unique and excellent medical center for the treatment of coronary heart disease.