By Lauren Johnston
Doctors from UAB St. Vincent’s are impressed with the new AGENT drug-coated balloon technology and look forward to seeing how it will improve care for cardiac patients experiencing in-stent restenosis (ISR). ISR is a problem that occurs when a coronary artery that has been treated with a stent narrows or has blockage.
AGENT is Boston Scientific’s new coronary drug-coated balloon (DCB) and the first and only FDA approved coronary DCB on the market. This DCB delivers a targeted anti-proliferation drug dose without introducing an extra layer of metal. It’s designed to imprint the drug onto the inner surface of the coronary artery when the balloon is inflated.
UAB participated in the clinical trials that led to FDA approval. Josh Cockrell, MD at UAB St. Vincent’s East and David Cox, MD at UAB St. Vincent’s Birmingham were among the first in Alabama to deploy AGENT in qualifying patients in the fall of 2024.
“New technologies are always exciting, especially when it’s going to improve patient outcomes,” Cockrell said. “I’ve been practicing for 12 years, and you see this recurring problem with even the best stents. About 10 percent come back and need to be intervened on again inside the stents, so we’re happy to bring the AGENT to our patients.”
In the past, medical professionals had limited options when treating a patient with in-stent restenosis. This included balloon angioplasty, which allows a small balloon to be inflated in the artery without any drug coating. The other option was to add another layer of drug-coated stent into the artery, which leaves metal behind.
“When you leave metal behind, if you have to put another stent in, it becomes an issue of mechanics. You can dilate the vessel only so much, but you’re leaving another layer of metal,” Cox said. “The early stents were like folded up paper clips shoved in the artery. They were bulky, difficult to deliver, and difficult to get back across later on. The newer stents have become thinner and sleeker, but even with that, if you put two or three layers of stent in, the lumen of the vessel is going to be constricted.”
AGENT DCB provides an alternative to adding another metal stent inside the artery. Balloons with drug coating have been used for peripheral arterial disease for many years with good results, but this is a new technology for coronary artery disease. Both Cockrell and Cox have seen promising results in the patients that have received AGENT.
“It’s shown significant reductions of about 50 percent in both the need for repeat interventions and for stent thrombosis overall,” Cockrell said.
With a typical angioplasty, the balloon is inflated for about 10 to 15 seconds. With AGENT, the DCB needs to be inflated between 30 seconds to a minute to allow the anti-proliferation drug time to absorb and adhere to the vessel wall.
“The first coronary angioplasty was done in the late 1970s,” Cox said. “One of the big fallbacks about balloon angioplasty was that whenever you inflate a balloon in a coronary artery, there’s about a 40 to 50 percent chance that in six months that artery will restenose. That’s often a reaction to being stretched. That problem was improved upon with stents that came out and were used widely in the early 90s.”
One of the early pioneers of coronary stenting was Gary Roubin, MD when he was at UAB. As stent technology improved with different alloys of metal and later the addition of an antiproliferative drug coating, the percentage of restenosis dropped to about 10 percent. While the stents provided improvements, there were still limitations. If a second stent is needed because of in-stent restenosis, there’s about a 35 percent chance that restenosis will occur again.
Right now, AGENT DCB is only being deployed in patients with severe cases of restenosis who already have one or two prior stents. In the U.S., this is not being used on every blockage doctors encounter.
“In Europe, they're treating even de novo lesions with drug-coated balloons,” Cox said. “Sometimes you get a blockage in a main vessel, and you've got blockage extending into a branch vessel. They'll treat it with a drug-coated balloon up front, but we're not at that point in the United States.”
As this technology progresses and more studies are completed, Cox and Cockrell hope to see the cost of the balloon go down and expect to see a more widespread use in patients. They see the potential for AGENT to be used for patients with coronary disease who may have long legions that are too long for stents, who have multiple lengths of stents already, who have small vessel blockages that are too small for stents, or for bifurcation stenting.
“Bifurcation is a branch point stenting,” Cockrell said. “When you stent a vessel that's at a branch point, it becomes a lot more complicated if you're using two different stents. The idea is that maybe in the future, we could put a stent in one branch and then use the drug-coated balloon in the other branch.”
