An old friend gets a new look

Drug-coated stents may revolutionize treatment

By Brian Hoyle

Modern medicine has a whole slew of techniques to intervene and repair damaged or malfunctioning body parts. One of these modern-day marvels is the stent, first introduced less than 20 years ago. These expandable, slotted metal tubes are inserted into a weakened artery to provide structural support, clear blockages, and improve the flow of blood to the heart.

Stents work fine, but they're not perfect. There's always a possibility of restenosis, the re-narrowing of the artery where it was treated. Recently, stents coated with certain antibodies or with a fungal compound, called sirolimus (also known as rapamycin), have shown promise in reducing restenosis by slowly releasing the antibody or drug which helps prevent the re-growth of cells that could block the artery again. In the past few years, several clinical studies have produced encouraging results for sirolimus-coated stents. But the patients in these studies were healthier than people who typically require stent implantation. Because of this, the significance of the study results has been debatable.

Now, a study published online in the December issue of Circulation reports on the use of sirolimus-coated stents in patients who were sicker or older than the patients in past studies. The study shows that sirolimus-coated stents are safe and effective at preventing heart attacks, repeated restenosis, and even death in "real world" patients.

This latest study comes from a team at the Eramus Medical Center in Rotterdam led by cardiologist Dr Patrick Serruys. The study assessed the performance of the drug-coated stents in 508 patients, and non-coated "bare" stents in 450 patients.

About half the patients in each group had experienced a heart attack or heart pain, and over 15% of each group was diabetic. In addition, both sets of patients had blocked arteries that had not been treated before the use of the stents. "Sixty-eight percent of the patients in this study did not meet the selection criteria for the [previous] clinical trials," said Dr Serruys. In general, the patients who received the coated stents were more likely to have more complicated heart problems involving more than one cardiac artery than patients who had been assessed in the previous clinical trials. Data collected over one year were assembled in a registry. While almost 10% of the patients using the sirolimus-coated stents experienced an "adverse cardiac event," the number rose to almost 15% for patients using bare stents.

The effectiveness of the coated stents may actually have been an underestimate. Some patients were not treated with the stents because of their larger diameter vessels. The size of stent required was unavailable at the time of the study. "As large [blood] vessels have been shown to present a lower risk of restenosis, it is quite possible that the noninclusion of patients with larger vessels may have resulted in an underestimation of the overall treatment," write the authors.

The trend that Dr Serruys and his colleagues observed -- that people treated with the coated stent fared better than those treated with an uncoated stent -- mirrors the findings of those earlier clinical trials of coated stents. Now it is apparent that the observations from the healthier patients have merit. Not only that, the present study establishes that the drug-coated stents could well become a useful tool in the clinician's arsenal against heart maladies.

The drug eluting stent is "the next major step" in the treatment of heart problems, according to Serruys. The modified stent follows on the heels of the 1977 introduction of balloon angioplasty and the 1986 introduction of the stent.