For the past two decades, physicians have routinely used tiny metal stents to open up the blood vessels of patients suffering from a mild coronary blockage. These devices become permanent fixtures in the patients’ hearts and a forever reminder of their mortality.
But now cardiologists at Scripps Health and Kaiser Permanente have begun testing something different – a heart stent that gradually dissolves into the body over a two-year period.
Named the “Absorb,” the implant is a small mesh tube scaffold that is designed to open a blocked heart vessel, restore blood flow to the heart and then dissolve into the blood vessel over time. Scripps Health is the first site in San Diego to begin studying the implant in a clinical trial sponsored by the device’s creator, Abbott Vascular.
“Up until now, the drug-coated stent was the most advanced technology available to treat blocked vessels,” said Paul Teirstein, principal study investigator and director of interventional cardiology at Scripps Clinic. “The hope is that by using the Absorb scaffold, vessels can return to the state they were in before the blockage occurred. When more blood flow is needed, they will be able to expand, when less is needed they can contract.”
In the randomized trial, patients either receive the Absorb bioresorbable vascular scaffold (BVS) or a standard drug-coated stent. On July 31, the first patient at Scripps Clinic underwent the procedure. Since that time, Dr. Teirstein has had 15 more patients participate in the study. In a separate arm of the study, Kaiser Permanente interventional cardiologists Richard Fortuna, M.D., and Jeffrey Cavendish, M.D., expect to enroll their first patient in late October at Scripps Memorial Hospital La Jolla. Scripps is the exclusive provider of cardiac surgery and interventional cardiology to the more than 500,000 Kaiser members across San Diego County.
“The Absorb III trial is the first U.S. clinical trial to evaluate the potential benefits of Absorb in comparison to the commonly used drug-coated stent in patients with coronary artery disease,” said Dr. Cavendish. “This is an exciting technology that is currently being used across Europe and parts of Asia Pacific and Latin America, and it is the hope that this trial will clear its way to be used in the United States.”
Coronary artery disease (CAD), a form of heart disease, is a leading cause of death for men and women in the United States. Patients with CAD can experience symptoms such as chest pain and shortness of breath when the demand for blood to the heart is more than the heart’s ability to supply blood due to blockages in the vessels that supply blood to the heart. These blockages are caused by the build up of fat and cholesterol inside the vessel.
Since the 1970s, physicians have treated patients who have CAD with balloon angioplasty, and metallic and drug-coated metallic stents, allowing many patients to avoid open heart surgery.
About a decade ago, scientists at Abbott started development of Absorb and now Abbott is the first company in the world to begin testing a bioresorbable vascular scaffold in patients in the United States.
Unlike a metallic stent that remains permanently in the body, Absorb is referred to as a scaffold to indicate that it is a temporary structure. Absorb BVS is made of polylactide, a naturally dissolvable material that is commonly used in medical implants such as dissolving sutures. After the drug-coated stent dissolves only two pairs of tiny metallic markers are left behind to enable a physician to identify where the device was implanted.
“The patients treated with Absorb will be closely monitored to determine how much natural motion has returned to the vessel once the device has dissolved,” said Dr. Teirstein. “And because it eventually disappears, cardiologists could potentially line an entire artery with the scaffolds, which may preclude some patients from having to undergo bypass surgery.”
The Absorb III clinical trial will enroll approximately 2,250 patients at more than 100 locations throughout the United States. The Absorb III trial will provide the basis for an anticipated FDA approval. At Scripps, Dr. Teirstein expects to enroll 50 patients, and the Kaiser Permanente arm of the trial is slated to enroll 50 patients. Eligibility is based on non-emergency cases with simple blockages in the coronary arteries. Men or women over the age of 18, who are in need of stent implantation, may be eligible.
Each year, about 785,000 Americans have a first heart attack. Another 470,000 who have already experienced one or more heart attacks will have another. Heart disease accounts for one of every six deaths that take place in the United States.
- Lisa Ohmstede