Which Works Better: Stents or Bypass Surgery?

The Controversy Continues

bypass surgery
bypass surgery. Thierry Dosogne/Getty Images

The controversy over whether patients with coronary artery disease (CAD) do better with stents or with bypass surgery (also called coronary artery bypass grafting, or CABG), has been going on ever since stents were invented. And today, despite the fact that clinical studies now have been published comparing stents to CABG, the question remains unsettled.

Invasive Treatment of CAD

Before discussing stents vs. CABG, we need to keep in mind that neither of these approaches is required in most patients with stable CAD.

In most patients, medical therapy is sufficient to relieve the symptom of angina, and yields equivalent results compared with invasive treatment in terms of subsequent mortality or heart attacks.

However, invasive therapy is clearly indicated in the following circumstances:

When Are Stents Preferred?

Stents are generally preferred over CABG in patients with ACS, or who have failed with medical therapy, and who have one- or two-vessel CAD.

For these patients, long-term outcomes with stents seem similar to outcomes with CABG.

However, the situation in patients with complex CAD is far less settled - and this is where the controversy remains.

Stents vs. CABG In Complex CAD - The Controversy

Doctors have known for a number of years that in patients with left main or triple-vessel CAD, survival is improved with CABG.

Indeed, these are the only patients with "stable" CAD (that is, CAD which is not currently causing ACS) who generally do better with invasive treatment than with medical therapy alone.

Accordingly, these cases of left main or triple-vessel CAD have remained something of a "last stand" for cardiac surgeons -- these patients are nearly the only ones the cardiologists still feel obligated to refer for CABG. And, as one might expect, the cardiologists have been busy conducting clinical trials designed to show that stents are as good as bypass surgery even in these patients.

The SYNTAX trial, published in 2009, was the major randomized clinical trial to compare stents to CABG in patients with complex CAD. This study showed that patients treated with CABG had significantly fewer endpoint events (a composite of death, stroke, myocardial infarction, and the need for repeat revascularization) than patients receiving stents (12.4% vs 17.8% after 12 months). Similar results were reported in the BEST trial in 2015.

So the two randomized clinical trials comparing stents to CABG in patients with complex CAD both came out in favor of CABG.

Cardiologists point out, however, that while the composite endpoint was worse with stents, the short-term risk of stroke appears higher after CABG (0.6% for stents vs. 2.2% for CABG) after 12 months. This is a legitimate point, though the risk of stroke was statistically equivalent in both groups after three years.

Investigators who ran the SYNTAX trial have since developed what they call a “SYNTAX score,” which essentially grades the characteristics of a patient’s CAD in terms of its complexity. Patients with lower SYNTAX scores appear to do relatively better with stents than those with higher SYNTAX scores. However, the SYNTAX score has never been tested in a clinical trial.

So the controversy continues.

The Bottom Line

The bottom line is that for most people who have severe triple-vessel CAD or significant blockage in their left main coronary artery, CABG still ought to be considered the primary mode of therapy.

Using stents instead of CABG for complex CAD ought to be reserved for patients who, after understanding all the risks and benefits, still opt for the less invasive approach.


Serruys P, Morice MC, Kappetein P, et al. Percutaneous coronary intervention versus coronary-artery bypass grafting for severe coronary artery disease. N Engl J Med 2009; 360:961-972.

Farooq V, van Klaveren D, Steyerberg EW, et al. Anatomical and clinical characteristics to guide decision making between coronary artery bypass surgery and percutaneous coronary intervention for individual patients: development and validation of SYNTAX score II. Lancet 2013; 381:639.

Park SJ, Ahn JM, Kim YH, et al. Trial of everolimus-eluting stents or bypass surgery for coronary disease. N Engl J Med 2015; 372:1204.

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