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Potential alternative to metal stent dissolves leaving no foreign body inside the patient
Walnut Creek, Calif. (April 9, 2014) – John Muir Health is one of a very select group of health systems across the country participating in a clinical trial of a medical device that could change the way people are treated for coronary artery disease, which is the narrowing of one or more arteries that supply blood to the heart.
The ABSORB III clinical trial is focused on a new type of dissolvable scaffold, or stent, that is used to open blocked arteries and leaves no foreign body inside the patient.
"This is the Holy Grail of interventional cardiology," said Gary Gershony, M.D., interventional cardiologist and director of cardiovascular research, education and technology at John Muir Health's Cardiovascular Institute. "It's something that we dreamt about being able to offer patients for more than 20 years."
The device, called a Bioresorbable Vascular Scaffold (BVS), initially works much like its metallic counterpart, which is currently the standard of care, by opening a blocked artery and allowing blood to flow through to the heart. Also like the metallic stent, the BVS delivers medications that prevent the artery from scarring and re-narrowing.
Unlike the current devices in use, however, the BVS is made of polylactide, a naturally dissolvable material that is commonly used in medical implants like dissolving sutures, so that it dissolves harmlessly into water and carbon dioxide over the course of one to two years. This leaves the artery more physiologically healthy and able to expand and contract as it normally would during exercise or at other times and may ultimately shorten the time patients are required to take blood thinners.
In the 1970s, patients underwent open heart surgery for artery blockages, which meant a long recovery. Treatment then evolved into balloon angioplasty, but with unpredictable results. In the late 1980s and early 1990s, bare metal stents implanted using minimally invasive techniques became the standard with more positive results, but re-narrowing of arteries occurred 20-30% of the time. In 2003, drug eluting stents reduced that rate to less than 10%, but patients still have a permanent metal stent in their heart. A dissolvable stent is the latest innovation in the treatment of blocked arteries.
"This is the next quantum leap in interventional cardiology," Dr. Gershony said. "We've seen excellent results so far for patients involved in the study. The immediate results with the dissolvable stent appear to be at least as favorable as those with a metallic stent. We are carefully following all of the study patients to make sure that the results are durable long term. Even though patients don't know which stent they are receiving, they are excited to be part of the study and have a chance to receive something that won't remain in their body indefinitely."
The BVS dissolves completely except for two pairs of tiny metallic markers, which help guide placement and remain in the artery to enable a physician to see where the device was placed. From a patient perspective, the procedure that involves the new dissolvable stent is the same as the procedure used to place the older metallic stents. Both are placed using a minimally invasive surgical technique called percutaneous coronary intervention (PCI), which involves inserting a catheter through a small opening in a patient's groin or wrist. The stent is crimped onto a deflated balloon at the end of the catheter and moved into position at the blockage site where the balloon and stent are expanded. Once the stent is placed, the balloon is deflated and the catheter is removed. Patients generally spend a night in the hospital for observation and are released the next day.
The dissolvable stent is manufactured by Abbott Vascular and has been studied and approved in Europe, as well as parts of Asia and Latin America, but this the first major clinical trial in the United States. It is a multi-hospital, randomized, double blind controlled trial eventually involving 2,250 patients across the country. The U.S. Food and Drug Administration (FDA) will review the trial data after one year and consider approval. If approved by the FDA, the device will be the first biodegradable stent used in the United States and could be widely available by 2016.
John Muir Health has been involved in the study since August of 2013 and has so far enrolled 16 patients. The goal is to recruit a total of 50 patients. Patients interested in the trial who meet the clinical inclusion criteria should consult with their cardiologist about participating. More information is also available by calling the John Muir Health Clinical Research Center at (925) 674-2580.
Coronary Artery Disease is a leading cause of death for men and women in the United States. According to the Centers for Disease Control, 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 U.S.