The tiny stent already might consume half the supply budget of a cardiac catheterization laboratory, but it's destined for even greater use.
Future coronary stents will fit the smallest arteries, instead of just larger vessels, physicians say. In addition, there will be more stents for more conditions, such as blocked veins, prostate ducts and urinary canals.
The most popular coronary stent is a $1,600 half-inch, stainless-steel mesh sleeve, generally used to keep an artery from reclosing after angioplasty. In angioplasty, a small balloon is blown up inside an artery to compress plaque that's blocking blood flow.
The Food and Drug Administration approved the Johnson & Johnson stent in 1994. Worldwide stent sales subsequently tripled to $645 million in 1995 and are expected to total $1 billion this year, according to Cowen & Co., a Boston-based investment banking firm.
By 1999, stents will be an almost
$2 billion annual product. Coronary stents will make up more than 75% of total sales, Cowen predicted.
A $1,150 coronary stent manufactured by Cook, a cardiac products company, also has FDA marketing approval but only to repair abrupt vessel closure during angioplasty instead of preventing long-term failure.
At least 12 other companies are working on new stents. Many of their products already are on sale in Europe.
Coronary stents have two roles. They prop up arteries that suddenly close during angioplasty, which occurs in about 2% to 4% of cases. Also, they limit the long-term buildup of plaque and scar tissue in arteries after angioplasty. The condition, called restenosis, is common. Without stents, about 40% of patients will need a second procedure within six months.
Because of their size, the stents now marketed usually are implanted in larger arteries, which aren't as prone to restenosis as smaller vessels, said David Yardley, M.D., who runs the cardiac catheterization lab at 451-bed Rockford (Ill.) Memorial Hospital. Without stents, studies show 30% of these arteries must be cleared again within six months. Stents result in repeat rates of 14% to 19%, Yardley said.
Generally, at least two stents are needed to cross the previously blocked area of the artery, where restenosis will occur. On occasion, Yardley has implanted as many as five stents.
The next generation of stents will be a tremendous advance, Yardley said.
"What is coming are designs that will allow us to go to smaller-diameter arteries, that allow us to stent on bends and then deliver drugs and radiation," he said. "The newer stents are going to be coming in a variety of lengths. Rather than buy two $1,600 stents, we may buy one for less."
FDA approval of new stents might be less than 16 months away, although companies publicly predict about two years, said Ed Schrader, director of cardiology-clinical markets at VHA, an Irving, Texas-based hospital alliance.
Stents were implanted in more than 225,000 patients worldwide in 1995, or about 25% of interventional angioplasty procedures, Cowen estimated in a recent report. With the advent of improved stents that could grow to 65% by 1999.
Fortunately, reimbursement for stents-once sparse-seems to be improving as evidence of their clinical payoff mounts. "Now that data show these patients might not be coming back for procedures, the insurance industry is getting kind of enthused about stents," Yardley said.
Although the current Medicare angioplasty reimbursement rate doesn't account for the extra cost of stents, HCFA likely will offer additional reimbursement during fiscal 1997, Schrader said.
"Depending on terms and market conditions, we've seen up to a $500 variance in individual hospital pricing for stents," Schrader said. New stents probably won't cost less, but on the bright side, they shouldn't get pricier, he said. Per-procedure costs even might decline slightly due to longer stents.
"This technology is worth a lot as far as what it has done in angioplasty," Schrader said. "I think what you are going to see is value packaging around stent technology." For example, companies might market balloons and stents together or sell stents for a set payment per procedure, he said.
Companies are readying for fierce competition. Johnson & Johnson recently spent $1.8 billion to acquire Cordis, a Miami-based firm that makes angioplasty balloons (Nov. 13, 1995, p. 25). In March, Medtronic agreed to acquire InStent of Eden Prairie, Minn., in a $215 million stock swap. And just last week, Boston Scientific announced plans to buy another stent developer, MinTec of Freeport, Bahamas, for about $70 million.
One problem with stents is it's hard to pinpoint who needs them. Cardiometrics of Mountain View, Calif., said its technology can weed out at least some of the patients who don't. "Some hospitals you go to, you probably will get a stent; in some, the odds are you won't," said Robert Newell, its chief financial officer.
Cardiometrics makes a $60,000 ultrasound system that measures blood flow impairment in arteries. Each use requires a $450 disposable guide wire.
The device-approved for marketing in 1992-initially was marketed as a way for doctors to judge if patients needed angioplasty. Cardiometrics now wants doctors to use it in conjunction with angiography to objectively justify the use of stents. Angiography measures the blockage remaining after angioplasty.
The combination identifies a subset of patients, about 22% of the total, who are less likely to benefit from stents. According to its studies, 16% of those patients will need a second angioplasty within six months.
Many other studies are under way to clarify the best use of stents. "We are in a state of new technology, and we're trying to determine what is best for patients," said William Knopf, M.D., an interventional cardiologist at 346-bed Saint Joseph's Hospital of Atlanta.*n