Jan 2, 2001
While it has become extremely commonplace to treat blocked coronary arteries with balloon angioplasty and the placement of a stent, the possibility of a renarrowing of an artery over time has remained a problem. Now, New York Weill Cornell Medical Center of NewYork-Presbyterian Hospital is one of the few centers in the United States to offer two newly approved devices for treating the area of the blockage with radiation. These techniques have been shown to reduce the likelihood of renarrowing of the artery by about 60 percent compared with currently available treatment approaches.
As explained by Dr. S. Chiu Wong, Director of New York Weill Cornell's Cardiac Catheterization Laboratory and Associate Professor of Medicine at Weill Cornell Medical College, coronary blockages are as commonplace as they are serious. "In this country alone, there are close to 800,000 interventional procedures done on arterial blockages each year," he says. "In our cath lab, we're approaching 15 hundred angioplasty procedures a year. Seventy or 80 percent of the procedures in this country involve a stent placement. Why? Because stents have been shown to decrease procedural complications as well as to decrease the chance of recurrence.
"But a stent is not a panacea. In about 20 percent of the cases, there is renarrowing in the area of the stent. Sometimes the blockage comes back over only a short segment. Those cases can be treated with a balloon or a rotor-blade or a laser. If these treatments are effective, there is a less than 30 percent chance the blockage will come back. However, if the narrowing within the original stent is long, meaning more than 10 millimeters, then, no matter what you use—a balloon, rotor, laser, or another stent—the chances of narrowing coming back are 60 to 70 percent. That's the dilemma: how to treat those patients with long lesions inside the stent. The most effective way in the year 2001 is radiation."
The Food and Drug Administration recently approved two devices of radiation therapy for coronary arteries: gamma radiation as supplied by Johnson & Johnson's Cordis Division and beta radiation as supplied by the Novoste Company. The gamma radiation device is a ribbon catheter inserted into the artery at the time of angioplasty and stent placement and left there for about 20 minutes. The beta radiation device consists of radioactive seeds in a "source train" that is inserted into the artery by a patented hydraulic device for three to five minutes and then withdrawn. New York Weill Cornell's cath lab was involved in the clinical trials of both radiation methods.
Dr. Wong points out that radiation has been used to treat more benign conditions, such as keloids, in which the radiation decreases the formation of scar tissue. He says that conceptually, the proliferation of smooth muscle tissue that takes place in a renarrowing of an artery is similar to scar formation.
While only a few hundred people have received radiation therapy so far, Dr. Wong says, the most important point is that "it works"—"That's why the FDA approved it."