If you don’t have signs of heart disease, there is no evidence to suggest that getting heart tests like CT scans or echocardiography will do you much good, researchers say.

“It is shocking how little evidence there is,” Dr. Patrick O’Malley of the Uniformed Services University in Bethesda, Maryland, who wrote an editorial in the Archives of Internal Medicine, where the new report was published.

Looking at earlier studies, the authors found screening people with such tests didn’t seem to change what drugs doctors prescribed, nor the patients’ diet and exercise habits or whether they smoked.

These are all factors that could influence a person’s risk of heart disease, which accounts for more than one out of every three deaths in the U.S., according to the American Heart Association.

The hope is that taking a piercing look at the heart will spot problems like calcium buildups that might one day block its blood supply. In principle, that would allow patients and their doctors to take steps to avert heart attacks, strokes and similar conditions down the road.

CT scans may cost anywhere between a few hundred dollars to a couple of thousand, and expose patients to radiation. But like other tests for heart disease, they have never been proven to improve health in patients without symptoms.

Still, the number of Americans who get these tests has been climbing fast in recent years. Every year, for instance, hundreds of thousands of people get CT scans, an imaging technique based high-dose x-rays. No one knows how many of those are done to look for heart problems in patients who don’t have any symptoms.

O’Malley said the tests shouldn’t be used on people without chest pain and other symptoms of heart disease outside of clinical experiments.

The report is based on a review of seven earlier studies - all the authors could find - that tested whether heart imaging had an impact on people’s lifestyle and the treatment they got.

The original studies included a broad swath of people without symptoms of heart disease - some had major risk factors like diabetes and some were healthy middle-aged people.

Across the board, Dr. Daniel Hackam of the University of Western Ontario in London, Canada, and colleagues found no differences between those who had their heart tested and those who didn’t.

But they add the studies were so small - most included only a few hundred individuals - that a possible impact couldn’t be entirely ruled out.