When are stents really needed?
Updated December 04, 2014.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
The "routine" use of stents for coronary artery disease (CAD) was challenged in the COURAGE trial, reported in 2007. The COURAGE trial should have made all cardiologists re-evaluate when, and in which patients, they use stenting. However, recent evidence strongly suggests that stenting of stable CAD is still "business as usual."
If you have CAD, you should be aware of the COURAGE trial and its implications.
In the COURAGE trial, 2,287 patients with stable CAD ("stable" CAD means that acute coronary syndrome is not occurring) were randomized to receive either optimal drug therapy alone, or optimal drug therapy along with stents. The patients were then followed for up to 7 years, and the incidence of subsequent heart attacks and deaths was tabulated. To the surprise of at least some cardiologists, there was no difference in outcomes between the groups. In other words, the addition of stents did not improve the ability of optimal drug therapy to prevent heart attacks and death in patients with stable CAD. Patients receiving stents did, however, have better control of their angina symptoms than patients on drug therapy alone.
It was estimated at the time this trial was conducted that more than 40 percent of stents being used in the U.S. were in patients with stable CAD. And it was widely anticipated that this rate would fall. However, a new study suggests that, at least through 2009, cardiologists still hadn't altered their pattern of stent usage.
In this follow-up study, an analysis of 500,000 patients in a national registry showed that in 2009, only 45% of patients who received stents for stable CAD had been tried on optimal medical therapy beforehand. Prior to the COURAGE trial, this proportion had been 44%. So it appears that the COURAGE trial has changed the routine use of stents in the U.S. by only a trivial amount.
When Should Stents Be Used?
After the COURAGE trial, it became apparent that stents should not be used as first-line therapy in stable CAD to prevent heart attacks- - because stents are no more effective at preventing heart attacks in this circumstance than optimal medical therapy. Stents should be used, in stable CAD, when angina is still occurring despite optimal medical therapy.
How Can The COURAGE Results Be Explained?
The results of the COURAGE trial are compatible with the "new thinking" on CAD and how heart attacks occur. Heart attacks are not caused by a stable plaque that gradually grows to block an artery. Instead, they are caused by a plaque that partially ruptures, thus causing the sudden formation of a blood clot inside the artery, which then suddenly blocks the artery. Rupturing and clotting is probably just as likely to happen in a plaque that is blocking only 10 percent of the artery as in one that is blocking 80 percent.
So, stenting the "significant" plaques will help to relieve any angina being caused by the blockage itself, but apparently will not reduce the risk of acute heart attacks -- especially since many of these heart attacks are associated with plaques that cardiologists traditionally call "insignificant."
Preventing the acute rupture of plaques, and thus preventing heart attacks, is looking more and more like a medical problem instead of a "plumbing problem" -- and a problem best treated with drugs and lifestyle changes. "Stablilizing" coronary artery plaques (making them less likely to rupture) requires aggressive control of cholesterol, blood pressure, and inflammation, regular exercise, and making clotting less likely. Aggressive drug therapy will include aspirin, statins, beta blockers, and blood pressure medication (when necessary).
If you have stable CAD -- whether or not a stent is necessary to treat your angina -- to really prevent heart attacks you will need to be on this aggressive medical therapy. You should be sure to discuss with your cardiologist what would constitute optimal medical therapy in your own case.
Sources:
Boden WE, O'Rourke RA, Teo KK, et al. Optimal medical therapy with or without PCI for stable coronary disease. N Engl J Med 2007; DOI:10.1056/NEJMe070829.
Borden WB, Redberg RF, Mushlin AI, et al. Patterns and intensity of medical therapy in patients undergoing percutaneous coronary intervention. JAMA 2011; 305:1882-1889.
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