TUESDAY, March 28, 2023 (HealthDay News) – Millions of middle-aged folks may be walking around with no symptoms of heart disease, and yet they still face a higher risk for a heart attack, new research shows.

What gives? Subclinical or silent heart disease may be responsible. This is the early thickening or hardening of the heart arteries that can worsen over time and cause crushing chest pain, known as angina, or even a heart attack. Middle-aged folks with such subclinical heart disease face a much higher risk of a surprise heart attack, researchers discovered.

But they were quick to caution that the absolute risk of having a heart attack without any signs or symptoms remains low.

“Subclinical heart disease refers to changes of the circulatory system that are mainly seen with advanced age, and in some individuals may cause heart attack and premature death," explained study author Dr. Klaus Fuglsang Kofoed, a cardiologist at Copenhagen University Hospital in Denmark. “Importantly, many individuals may have these changes, yet will never have any clinical heart disease.”

For the study, more than 9,500 people aged 40 or older without known heart disease had scans to get a closer look at what was happening in their heart arteries. Of these, 54% of people showed no signs of subclinical heart disease; 36% had nonobstructive disease, and 10% had obstructive, or artery-clogging, disease. Folks with obstructive disease were more than eight times as likely to have a heart attack.

The study appears in the March 27 issue of the Annals of Internal Medicine.

These findings should serve as a wake-up call, said Dr. Evan Appelbaum, a cardiologist at Men's Health Boston. People may be walking around with the earliest stages of heart disease and don’t have a clue.

“For example, cholesterol builds up in the arteries before a blockage or narrowing of significance develops,” Appelbaum said. “It can affect anyone and is the reason that screening for cardiovascular disease is so important and can detect problems early enough to start on a preventive regimen that can save lives.”

Dr. Matthew Tomey, a cardiologist with the Mount Sinai Health System in New York City, agreed. Clinical disease -- such as heart attack, chest pains from blocked arteries and strokes -- represent only the tip of the iceberg.

Atherosclerosis, or the buildup of cholesterol plaque in the walls of arteries, progresses beneath the surface for years, Tomey said.

“Symptoms of atherosclerosis might not appear until an individual has a sudden obstruction of blood flow by a clot or the progressive narrowing of an artery by plaque, typically by 70% or more,” he said. “A person can be walking around with 69% blockages of all three major heart arteries with no clinical disease.”

These people may have normal results on a stress exercise test, which was commonly used to assess heart disease risk for years, he said.

“Computed tomography is a key tool available today that permits us to see beneath the surface and identify atherosclerosis in its subclinical phase,” Tomey said.

His advice? Have a conversation with your physician about how to best assess your risk of heart disease. “As part of this conversation, I would encourage patients to ask their doctors whether imaging to detect subclinical disease is appropriate for them,” Tomey added.

How else would you know if you had subclinical heart disease? You wouldn’t, added Dr. David Newby, the British Heart Foundation's John Wheatley Professor of Cardiology at the British Heart Foundation Centre of Research Excellence at the University of Edinburgh in Scotland.

“Having a healthy lifestyle is very important, and if you have any risk factor for heart disease, getting a health check is a good idea,” said Newby, who coauthored an editorial accompanying the new study.

More information

The U.S. Centers of Disease Control and Prevention has more on heart disease risks.

SOURCES: Klaus Fuglsang Kofoed, MD, PhD, cardiologist, Copenhagen University Hospital, Demark; Evan Appelbaum, MD, cardiologist, Men’s Health Boston; Matthew Tomey, MD, cardiologist, Mount Sinai Health System, New York City, David Newby, MD, PhD, British Heart Foundation John Wheatley Professor of Cardiology, British Heart Foundation Centre of Research Excellence, University of Edinburgh, Scotland; Annals of Internal Medicine, March 27, 2023