Coronary artery disease, which is caused by narrowed arteries that reduce blood to the heart, is the most common type of heart disease. It affects about 18 million Americans and is the leading cause of death in the United States. Symptoms can vary, but some people do not have them at all and may not know they have heart disease until they experience chest pain, a heart attack, or sudden cardiac arrest.

To find out whether an invasive or conservative strategy would be more effective in reducing these kinds of events, researchers studied the impact of both on heart attack, hospitalization for unstable angina, heart failure, resuscitated cardiac arrest, and cardiovascular death. An additional key outcome of study was quality of life.

From August 2012 to January 2018, ISCHEMIA enrolled 5,179 patients who were an average of 64 years old, at 320 sites in 37 countries. Most participants had a history of chest pain, with 21% reporting daily or weekly chest pain. About 35% had no chest pain one month prior to enrollment.

The patients then were randomly assigned to receive either the conservative, medical therapy alone (unless their symptoms worsened), or medical therapy and an invasive intervention soon after having an abnormal stress test. Over the five years of the trial, 21% of patients in the conservative treatment group ended up having a stent implant or bypass surgery; the rest continued medication alone. Of those in the intervention group, revascularization was performed in 79%, three-quarters of them receiving stents and the others, bypass surgery.

By the end of the trial, the death rate between the two groups proved to be essentially the same: among the participants who had invasive procedures, 145 died, compared to 144 who received medication alone. The overall rate of disease-related events was similar among those who took medication alone: 352 experienced an event such as heart attack, compared to 318 who had invasive procedures.

Researchers noted one caveat; patients in the conservative strategy had fewer cardiovascular events during the first two years of the study. However, the invasive strategy patients had fewer events during the last two years, researchers noted, because of an uptick in heart attacks in that group in the first six months.

"We have known and confirmed in this study that stent and surgical procedures have a risk of some heart damage," said Judith Hochman, M.D., study chair, co-lead author and Senior Associate Dean for Clinical Sciences NYU Grossman School of Medicine. "However, we saw that the heart damage related to a procedure was not as serious in terms of the risk of subsequent death compared to heart attacks that occurred spontaneously, unrelated to any procedure."

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