The participants in Ischemia were not experiencing a heart attack, like Senator Bernie Sanders, nor did they have blockages of the left main coronary artery, two situations in which opening arteries with stents can be lifesaving. Instead, the patients had narrowed arteries that were discovered with exercise stress tests.

With 5,179 participants followed for a median of three and a half years, Ischemia is the largest trial to address the effect of opening blocked arteries in nonemergency situations and the first to include today’s powerful drug regimens, which doctors refer to as medical therapy.

All the patients had moderate to severe blockages in coronary arteries. Most had some history of chest pain, although one in three had no chest pain in the month before enrollment in the study. One in five experienced chest pain at least once a week.

All participants were regularly counseled to adhere to medical therapy. Depending on the patient’s condition, the therapy variously included high doses of statins and other cholesterol-lowering drugs, blood pressure medications, aspirin and, for those with heart damage, a drug to slow the heart rate. Those who got stents also took powerful anti-clotting drugs for six months to a year.

Patients were randomly assigned to have medical therapy alone or an intervention and medical therapy. Of those in the intervention group, three-quarters received stents; the others received bypass surgery.

The number of deaths among those who had stents or bypass was 145, compared to 144 among the patients who received medication alone. The number of patients who had heart attacks was 276 in the stent and bypass group, compared with 314 in the medication group, an insignificant difference.