The study was designed to reflect current clinical practice, in which patients with severe blockages in their arteries often undergo an angiogram and revascularization with a stent implant or bypass surgery. Until now, there has been little scientific evidence to support whether these procedures are more effective in preventing adverse heart events than simply treating patients with medications such as aspirin and statins.

“If you think about it, there’s an intuitiveness that if there is blockage in an artery and evidence that that blockage is causing a problem, opening that blockage is going to make people feel better and live longer,” said Harrington, who regularly sees patients with cardiovascular disease at Stanford Health Care. “But there has been no evidence that this is necessarily true. That’s why we did this study.”

Invasive treatments involve catheterization, a procedure in which a tube-like catheter is slipped into an artery in the groin or arm and is threaded through blood vessels to the heart. This is followed by revascularization, as needed: placement of a stent, which is inserted through the catheter to open a blood vessel, or cardiac bypass surgery, in which another artery or a vein is redeployed to bypass the area of blockage.

Investigators studied heart patients who were in stable condition but living with moderate to severe ischemia caused primarily by atherosclerosis — deposits of plaque in the arteries. Ischemic heart disease, also known as coronary artery disease or coronary heart disease, is the most common type of heart disease. Patients with the disease have narrowed heart vessels that, when completely blocked, cause a heart attack. About 17.6 million Americans live with the condition, which results in about 450,000 deaths each year, according to the American Heart Association.

Ischemia, which is reduced blood flow, often causes symptoms of chest pain known as angina. About two-thirds of those heart patients enrolled in the study suffered symptoms of chest pain.

The results of this study do not apply to people with acute heart conditions, such as those having a heart attack, the researchers said. People experiencing acute heart events should immediately seek appropriate medical care.

Study randomized

To conduct the study, investigators randomly divided the patients into two groups. Both groups received medications and lifestyle advice, but only one of the groups underwent invasive procedures. The study followed patients between 1½ and seven years, keeping tabs on any cardiac events.

Results showed that those who underwent an invasive procedure had roughly a 2% higher rate of heart events within the first year when compared with those on medical therapy alone. This was attributed to the additional risks that come with having invasive procedures, the researchers said. By the second year, no difference was shown. By the fourth year, the rate of events was 2% lower in patients treated with heart procedures than in those on medication and lifestyle advice alone. This trend resulted in no significant overall difference between the two treatment strategies, the investigators said.

Among patients who reported daily or weekly chest pain at the start of the study, 50% of those treated invasively were found to be angina-free after a year, compared with 20% of those treated with lifestyle and medication alone.

“Based on our results, we recommend that all patients take medications proven to reduce risk of heart attack, be physically active, eat a healthy diet and quit smoking,” Maron said. “Patients without angina will not see an improvement, but those with angina of any severity will tend to have a greater, lasting improvement in quality of life if they have an invasive heart procedure. They should talk with their physicians to decide whether to undergo revascularization.”

Investigators plan to continue to follow the study participants for another five years to determine whether the results change over a longer period of time.

“It will be important to follow up to see if, over time, there will be a difference. For the period that we followed participants, there was absolutely no survival beneift from the invasive strategy,” Maron said. “I think these results should change clinical practice. A lot of procedures are performed on people who have no symptoms. It’s hard to justify putting stents into patients who are stable and have no symptoms.”