When Should Stents Be Used in Coronary Artery Disease?

COURAGE study challenges use of stents in stable CAD patients

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The routine use of stents in patients with stable coronary artery disease (CAD) was strongly challenged in the COURAGE trial, first reported in 2007. In this trial, patients with stable CAD were randomized to receive optimal medical therapy alone or optimal medical therapy along with stents. The study showed no difference in outcomes between the two groups after 4.6 years.


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Resistance to the Results of the COURAGE Trial

The results of the COURAGE trial should have made all cardiologists re-evaluate when they use stents and in which patients. But many cardiologists did not change their practices regarding stents. Their rationale was that many believed that opening blockages with stents simply must be more effective than medical therapy in preventing heart attacks and death. Therefore, the results from COURAGE must be wrong. They believed it was likely that the longer-term follow-up would reveal the truth.

But in November 2015, the final long-term results of COURAGE were published. After nearly 12 years of follow-up, stents still provided no benefit over optimal medical therapy.

Details of the COURAGE Trial

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 incidence of subsequent heart attacks and deaths was tabulated.

There was no difference in outcomes between the groups. Patients receiving stents did, however, have better control of their angina symptoms than patients on drug therapy alone, but their risk of heart attack and death was not improved.

The 2015 follow-up analysis looked at long-term mortality differences between the two groups. After an average of 11.9 years, there was no significant difference. Twenty-five percent of patients receiving stents had died, compared to 24% of patients treated with medical therapy alone.

Investigators looked at numerous subgroups of patients to see whether some subset might have done better with stents. They found none that did.

When Should Stents Be Used?

It now seems clear 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. In fact, there is a real question as to how much stents are useful at all for treating stable angina.

Stents should be used, in stable CAD, only when significant 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 are probably just as likely to happen in a plaque that is blocking only 10% of the artery as in one that is blocking 80%.

Stenting the "significant" plaques will help to relieve any angina being caused by the blockage itself. But, apparently, it 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." It's best treated with drugs and lifestyle changes. "Stabilizing" coronary artery plaques (making them less likely to rupture) requires aggressive control of cholesterol, blood pressure, and inflammation. It also requires 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 case.

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By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.