COURAGE
New study challenges use of stents in stable CAD patients
By Richard N. Fogoros, M.D., About.com
The most noteworthy results to come out of the 2007 American College of Cardiology Scientific Sessions in New Orleans were from the COURAGE trial (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation). The results of this trial, also published this week in the online version of the New England Journal of Medicine, have American cardiologists debating, once again, their use of stents in treating patients with coronary artery disease (CAD).
In COURAGE, 2,287 patients with stable CAD ("stable" CAD means that acute heart attacks and unstable angina are not occurring) were randomized to receive either aggressive drug therapy alone, or aggressive 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 aggressive 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 is estimated that up to 40 percent of stents being used in the U.S. today are in patients with stable CAD.
DrRich Comments:
Should cardiologists stop inserting stents in patients with stable CAD? Or should they just continue business as usual? (Business as usual: 1) Patient with or without symptoms of angina receives a screening stress test, and it is positive. 2) Coronary angiogram is done, and it shows at least one partial blockage of greater than 60 to 70 percent. 3) Cardiologist informs patient he/she is "sitting on a time bomb," and recommends stent. 4) Stent is placed.)
We can say, after the COURAGE trial, that business as usual (at least as formulated above) should stop. Stents should not be used to defuse "time bombs" (i.e., to prevent heart attacks) because this strategy does not work. Patients receiving stents for stable CAD are just as likely to have a heart attack or die as patients treated with aggressive drug therapy alone. This is the message of the COURAGE trial.
The COURAGE trial also tells us, however, that if a stable coronary artery blockage is great enough to be causing symptoms of angina with exertion, then a stent is likely to relieve the angina better than drug therapy alone. It is still OK to use stents for this purpose, as long as everyone realizes that it is symptoms--not life or death--that the stent is affecting. Furthermore, stents have been shown in other clinical trials to improve outcomes in patients having acute heart attacks or unstable angina, and should generally be used in these clinical circumstances.
Explaining COURAGE:
The results of the COURAGE trial are compatible with current conceptions of how heart attacks occur. Heart attacks are not caused by a stable plaque that grows to gradually occlude 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 occludes the artery. Rupturing and clotting is probably just as likely to happen in a plaque that is causing only a 10-percent fixed blockage as in one that is causing an 80-percent blockage. So stenting the plaques that are causing greater degrees of fixed blockages will 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). This approach, and probably not stents, may be the best way to lengthen the fuse -- or even douse the fuse -- on the time bomb.link |
