Share on Pinterest
Some screenings for atherosclerosis can miss non-calcified deposits in blood vessels. Getty Images
  • Researchers say atherosclerosis can still be a risk for people who have no known heart disease.
  • That’s because screening done for the disease can sometimes miss non-calcified deposits in blood vessels.
  • Experts say more advanced tests should be used when assessing a person’s heart health.

Heart disease is often called a “silent killer.”

That description is backed up by a new study showing that even many people who have no symptoms can have potentially deadly atherosclerosis, or hardening of the arteries.

Researchers in Sweden said that more than 42 percent of study participants ages 50 to 64 who had no known heart disease were found to have some degree of fatty deposits in their blood vessels.

Dr. Donald Lloyd-Jones, the chair of the department of preventive medicine at Northwestern Medicine in Illinois and the president of the American Heart Association, told Healthline that the research is important because it looks at the general population rather than just people with known risk of heart disease.

Lloyd-Jones said the findings were not surprising, “given the prevalence of risk factors in our society, that these middle-aged people have some degree of atherosclerosis.”

The research, published today in the journal Circulation, found that while common screening tests for atherosclerosis capture calcium-containing plaques in the arteries, they can miss non-calcified deposits.

“Measuring the amount of calcification is important, yet it does not give information about non-calcified atherosclerosis, which also increases heart attack risk,” said Dr. Göran Bergström, the lead study author and a professor and senior consultant in clinical physiology in the department of molecular and clinical medicine at the University of Gothenburg’s Institute of Medicine in Sweden.

“It is important to know that silent coronary atherosclerosis is common among middle-aged adults, and it increases sharply with sex, age, and risk factors,” he said.

Cardiac CT scans are commonly used as part of assessing cardiac risk.

The cross-sectional scan of the blood vessels yields what’s known as a coronary artery calcification (CAC) score, which can range from 0 to 400. The higher the number, the greater the risk of having a heart attack in the next 10 years.

Yet the study by Bergström and colleagues found that even some people with a low CAC score can have significant atherosclerosis.

“Someone experiencing chest pain may seem safe if they have a CAC score of zero but could still be at risk,” Dr. Renee Bullock-Palmer, a cardiologist and the director of Non-Invasive Cardiac Imaging at Deborah Heart and Lung Center in New Jersey, told Healthline.

Researchers analyzed data on more than 25,000 people with no history of heart disease who had undergone both cardiac CT scans and coronary CT angiography (CCTA) scans.

CCTA provides more advanced radiologic imaging than the cardiac CT scans used to generate CAC scores.

The CCTA scans found that higher CAC scores generally corresponded with higher detected levels of atherosclerosis.

For example, among study participants with a CAC score closer to 400, nearly half had significant blockage, where more than 50 percent of the blood flow was obstructed in one of the coronary arteries.

However, CCTA scans found that atherosclerosis could also occur in people with a CAC score of zero.

The study showed that 5 percent of people with a zero CAC score had atherosclerosis detected by CCTA, and 0.4 percent had significant obstruction of blood flow.

“A high CAC score means there is a high likelihood of having obstruction of the coronary arteries,” Bergström said. “However, more importantly, a zero CAC score does not exclude adults from having atherosclerosis, especially if they have many traditional risk factors of coronary disease.”

Bergström noted that current American Heart Association and American College of Cardiology guidelines for heart attack prevention say that adults with a zero CAC score and intermediate levels of risk factors are at low risk of a future heart attack.

However, he said, “We found that 9.2 percent of people who fit that description had atherosclerosis in their coronary arteries visible by CCTA.”

Bergström noted that the non-calcified atherosclerosis detected by CCTA is believed to be more prone to cause heart attacks than calcified atherosclerosis.

Overall, the study found that 8 percent of adults in the study had one or more non-calcified plaques.

Bergström said follow-up studies will look at whether people with non-calcified atherosclerosis are at higher future risk of heart attack.

CCTA, which involves a higher dose of radiological imaging and the injection of contrast dye, is not currently a recommended part of heart attack prevention protocols.

However, Lloyd-Jones said the findings support broader use of CAC scoring — which can cost as little as $75 — for people with no known risk factors of heart disease.

“CAC gives us the vast majority of the information we need,” he said.