Doctor's View ArchiveMedical Author: Frederick Hecht, M.D.
Medical Editor: Barbara K. Hecht, Ph.D.
Oct. 3, 2003 -- This week has been an auspicious one for medicated stents in coronary arteries. Two important reports have appeared about these stents. One report is of a large trial of medicated versus nonmedicated stents. It was published in The New England Journal of Medicine together with an excellent editorial on the topic. The other report appeared in the London-based journal The Lancet, and is about the use of medicated stents for long narrowed areas in small coronary arteries. It, too, was accompanied by a valuable editorial.
A Substance from the Soil of Easter Island
A naturally occurring substance called sirolimus was discovered in a soil sample from Easter Island. Sirolimus first was thought to have some promise as an antifungal antibiotic but this idea was jettisoned when sirolimus was unexpectedly found to have immunosuppressive activity. After the usual delays inherent in drug research and development, the US Food and Drug Administration in 1999 approved the use of sirolimus as an immunosuppressant agent.
But evidence had been uncovered earlier in the nineties that sirolimus was also a potent inhibitor of the growth of smooth muscle cells in blood vessels. The idea was then "hatched" that sirolimus might be used to inhibit the restenosis (reclosure) of coronary arteries
Today, after a balloon angioplasty has been done to open a clogged coronary artery, a mesh tube called a stent is often inserted to keep the artery open. However, restenosis occurs in up to a third of cases when smooth muscle cells migrate from the vessel wall into the stent. The muscle cells proliferate there and narrow the interior diameter of the stent.
Sirolimus Stents Show Considerable Promise
Stents medicated with sirolimus have shown promise in the prevention of restenosis after balloon dilation of simple coronary lesions. By "simple" coronary lesions is meant, for example, a short area of narrowing in one coronary artery. The clinical trial reported yesterday in The New England Journal compared the sirolimus stent with a standard stent in patients with complex coronary lesions.
The research was done at 53 centers in the US. In the trial there were 1,058 patients with "complex" coronary lesions. The coronary disease in these patients was considered "complex" because of the frequent presence of diabetes, the high percentage of patients with longer lesions, and small vessels.
The sirolimus stent proved to be superior to standard stents in the prevention of restenosis. The rate of failure of the vessel was reduced from 21% with a standard stent to 8.6% with a sirolimus stent. The investigators conclude with typical scientific understatement that: " Coronary stents coated with sirolimus have considerable promise in the treatment of simple and complex coronary stenoses."
Sirolimus Stents Good for Long Narrowed Areas
The Lancet report focuses on the use of sirolimus stents compared with bare-metal stents in long narrowed areas in the coronary arteries. The research was done in Europe. There were 352 patients in the trial. All had a long narrow segment in a single coronary artery that need to be treated.
Eight months after the stents were put it, the minimum diameter was significantly greater within sirolimus stents than in the standard bare metal stents. The rate of restenosis was significantly reduced with the sirolimus stents compared with the bare metal stents. And at 9 months, fewer patients with sirolimus stents had had major adverse cardiac events than did controls.
The researchers conclude with precision that: "Sirolimus-eluting stents are better than bare-metal stents for treatment of single long atherosclerotic lesions in a coronary vessel smaller than 3 mm in diameter."
A Note to Our Cardiologist
If one of us needs a stent in a coronary artery tomorrow, please forget the old bare metal stent and put in a medicated stent instead.
And for more information on these topics, please see the following features in MedicineNet.com:
- Heart Attack Risks and Medicated Stents
- Heart Attack Warning Signs
- Heart Attack Symptoms in Women
- Heart Attack Pathology
Sources: This article is based upon information in the following references:
- JW Moses and Others. Sirolimus-Eluting Stents versus Standard Stents in Patients with Stenosis in a Native Coronary Artery. New Engl J Med 2003; 349: 1315-1323. (Original article)
- AR Marks. Sirolimus for the Prevention of In-Stent Restenosis in a Coronary Artery. New Engl J Med 2003; 349: 1307-1309. (Editorial Perspective)
- J Schofer and Others. Sirolimus-eluting stents for treatment of patients with long atherosclerotic lesions in small coronary arteries: double-blind, randomised controlled trial (E-SIRIUS). Lancet 2003; 362: 1093-99. Published online Sept 30, 2003. (Original article)
- U Sigwart. Drug-delivering coronary artery stents: bare metal threatened by extinction? Lancet 2003; 362: Published online Sept 30, 2003. (Editorial Commentary)