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Coated inserts keep vessels unclogged.

Doctors started opening blocked coronary art/des with balloon-tipped catheters in the 1970s, but repeat narrowing of those vessels sent many patients back to the hospital. In the 1980s, scientists devised mesh cylinders called stents that prop open the arteries after the balloon is withdrawn. Even with stents, however, one-fourth of reopened vessels become obstructed again within 6 months.

Researchers now report that stents coated with a drug that inhibits cell migration and growth sharply reduce blockages in repaired arteries. The report appears in the Oct. 2 New England Journal of Medicine.

Inserting a balloon into an artery, inflating the balloon, and installing a stent traumatize the inner reaches of a blood vessel. The trauma stimulates the body's tissue-repair system to send muscle cells to the site, where they then proliferate. The stent-coating drug, called sirolimus or rapamycin, discourages both these actions, says study coauthor Jeffrey W. Moses of the Lenox Hill Heart and Vascular Institute of New York. He estimates that about 60 percent of U.S. patients receiving a stent in a blocked coronary artery are now getting a sirolimus-coated device.

Moses and his colleagues randomly assigned 1,058 heart patients to receive uncoated stents or drag-coated devices after their artery-widening procedures. The patients, average age 62, all entered the study with a coronary artery more than half blocked, and many had chest pain. Roughly one-fourth of the patients in each group also had diabetes, and nearly one-third had had a previous heart attack.

During the 9 months after stent placement, 21 percent of the patients with uncoated stents either had a heart attack or required a procedure to correct blockage of the same artery. Only 8.6 percent of people in the coated-stent group faced such consequences.

Richard A. Schatz of Scripps Clinic in La Jolla, Calif., a codeveloper of the original coronary artery stent, calls the study "a tremendous advance. It shows a clear reduction in [blockage] recurrence rates, which has always been the negative of our business."

Alan W. Heldman of Johns Hopkins Medical Institutions in Baltimore says the coated stents represent a "whole new paradigm of combining a device with a biological agent to treat coronary disease."

Other researchers are seeing similar benefits using stents coated with the anticancer drug taxol, which also blocks cell migration and growth. The Food and Drug Administration approved sirolimus-coated stents in April but has yet to rule on taxol-coated stents.

The direct effects of both drugs wear off in a matter of weeks, but by stopping early on the process that initiates blockage, the coating has a lasting benefit, says Andrew R. Marks of Columbia University.

The sirolimus-coated stents cost more than $2,500 apiece, roughly three times the price of bare-metal stents. Moses argues that the lower rate of artery renarrowing with coated stents will save money over time, as people have fewer complications and need fewer additional procedures.

In some hospitals, however, coated stents aren't always available because supply lags behind demand, Marks says.
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Title Annotation:Coronary Fix
Author:Seppa, N.
Publication:Science News
Date:Oct 4, 2003
Words:498
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