Trials find invasive surgery is no better than medication at reducing heart attack risk

By Sally Robertson, B.Sc.Mar 30 2020

Findings from two milestone studies suggest that among patients with stable ischemic heart disease, invasive procedures such as bypass surgery and stent placement do not reduce the risk for heart attack and death any more than the use of medication and lifestyle changes.

Image Credits: crystal light / Shutterstock.com

However, the studies, which were recently published in the New England Journal of Medicine, did suggest that such procedures provide more relief from symptoms and a better quality of life.

The International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA), which is one of the largest trials of its kind, followed more than 5,000 patients with stable ischemic heart disease and moderate-to-severe disease over a median of 3.2 years. Funding was provided by the National Heart, Lung, and Blood Institute (NHLBI), which is part of the National Institutes of Health.

Comparing invasive and conservative treatment approaches

The study compared a conservative treatment approach that included blood pressure, cholesterol and angina medications, as well as information on diet and exercise with an invasive approach that involved surgical procedures, medications, and information about diet and exercise.

Participants underwent stress tests and evaluation of coronary blood flow restriction to assess the severity of ischemia.

"Previous studies have reached similar conclusions as ISCHEMIA, but they were criticized for not including patients who had severe enough disease to benefit from the procedures. ISCHEMIA studied only patients with the most abnormal stress tests," says study author Yves Rosenberg from the NHLBI. "These findings should be applied in the context of careful attention to lifestyle behaviors and guideline-based adherence to medical therapy, and will likely change clinical guidelines and influence clinical practice."

Rosenberg adds that in the meantime, patients should consult their doctors about which treatment approaches are most suitable for them.

In the United States, coronary heart disease affects approximately 18 million individuals and is the most common cause of death. Symptoms vary, but sometimes people do not experience any symptoms at all and are unaware that they have the condition until they suddenly have chest pain, myocardial infarction or cardiac arrest.

To investigate whether an invasive or conservative approach to treatment is better at lowering the risk of such events, researchers assessed the effect of both strategies on heart attack, heart failure, cardiac arrest, cardiovascular death and hospitalization for angina. Another primary outcome was patients’ quality of life.

The study included 5,179 patients (aged an average of 64 years), who were enrolled at 320 sites across 37 countries between August 2012 and January 2018. The majority had a history of chest pain, with one-fifth reporting that they experienced the pain on a daily or weekly basis. Approximately 35% of patients said they had not experienced any pain in the month before being enrolled.

What did the study find?

During the five-year study period, about one-fifth of participants receiving conservative treatment required a stent or bypass, while the remainder stayed on medication. Among those in the invasive group, almost 80% underwent revascularization procedures, with 75% of those individuals receiving a stent implant and the remainder receiving bypass surgery.

At the end of the study, the researchers found no significant between-group differences in death rate, which was 145 among the invasive group and 144 among the conservative group.

The rate of events such as heart attack was similar between the two groups, at 352 in the medication-only group and 318 in the invasive procedures group.

One caveat the researchers acknowledge is that those in the conservative group experienced fewer cardiovascular events during the study’s first two years. However, those in the invasive group experienced fewer events during the final two years due to an increase in heart attacks during the first six months.

"We have known and confirmed in this study that stent and surgical procedures have a risk of some heart damage," says study chair Judith Hochman, 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."

Long-term follow-up will be required to better establish the true difference in patient outcomes between the two groups.

The benefits for people with angina

The researchers say that among patients who had angina, the benefits of invasive procedures were more beneficial throughout the trial than medication alone.

"ISCHEMIA showed an impressive, sustainable improvement in patients' symptoms, function and quality of life with an invasive strategy for up to four years of follow-up," says John Spertus, from Saint Luke's Mid America Heart Institute in Kansas City. "However, this benefit was only observed in roughly two-thirds of those who had angina at baseline and no benefit was seen in those who had no symptoms."

Lead author David Maron from Stanford University says the clinical results and the quality of life assessments indicate that patients who are not experiencing symptoms do not need to undergo invasive procedures.

For those with angina, our results show it is just as safe to begin treating with medication and lifestyle change, and then if symptoms persist, discuss invasive treatment options.”

David Maron, Stanford University