Atherosclerosis common in adults without heart disease, symptoms

• A study conducted in Sweden found that about 42% of the participants without known heart disease or symptoms had fatty deposits in the arteries of their heart, which experts call atherosclerosis.
• Approximately 5% of the participants had significant obstruction of blood flow in one or more of the three coronary arteries, while 2% had severe disease.
• Older male participants of the study had a higher prevalence of atherosclerosis.
• Long-term follow-up data are necessary to establish the clinical relevance of these findings and to determine the best high risk screening strategies.

The number of deaths from coronary heart disease (CHD) in the United States decreased 9.8% in years 2008–2018.

However, CHD remained the number one cause of death in the U.S. in 2018, leading to about 366,000 deaths. CHD occurs as a result of coronary artery disease (CAD).

In atherosclerosis, deposits of cholesterol and other substances accumulate as plaque on the walls of arteries, which supply blood to the heart and rest of the body. These plaques can narrow the arteries, impeding or blocking blood flow. This can eventually lead to heart attack.

Doctors commonly check for plaque and calcium deposits in the coronary arteries through a type of CT scan called coronary artery calcium (CAC) scan.

Based on the scan results, doctors assign CAC scores, or Agatston scores, to estimate the person’s risk of CHD.

CAC scores are as follows:

Although CAC scores are helpful to ascertain risk, they do not detect all types of plaque. Importantly, they cannot detect noncalcified atherosclerosis, which also increases CHD risk.

Evolving cardiovascular risk pattern

This blind spot in CAC scores led researchers to conduct the prospective population-based Swedish CArdioPulmonary BioImage Study (SCAPIS).

Dr. Göran Bergström, Ph.D., a professor at the University of Gothenburg in Sweden and principal investigator of the study, spoke with Medical News Today.

Dr. Bergström, who is also head of the Physiology Group at Wallenberg Laboratory and senior consultant in clinical physiology at the Vascular Diagnostic Unit, Sahlgrenska University Hospital, explained,

“We see a changing risk pattern for cardiovascular disease [(CVD)], and a new cohort study aimed at CVD was needed.”

He added: “Risk factors used to be smoking and high cholesterol. In addition to that, we now have sedentary behavior, low physical activity, and a low quality diet leading to obesity and diabetes resulting in CVD. SCAPIS aims to address this new cardiometabolic risk pattern using state-of-the-art techniques.”

The results of the study appear in the journal Circulation.

The study used coronary computed tomography angiography (CCTA) to determine the prevalence, characteristics, and severity of atherosclerosis in people without diagnosed CHD. The researchers also looked for correlations between CCTA and CAC scores.

CCTA uses CT scanning and a contrast material to create 3D images of the arteries that supply the heart.

The study randomly recruited 30,154 participants aged 50–64 years from the census register at six sites in Sweden from 2013–2018. The study included 25,182 participants without CHD, of whom 50.6% were women.

The study scored CCTA scans and classified them into three categories of stenosis, which is the narrowing of blood vessels:

• no atherosclerosis
• 1–49% stenosis
• 50% or more stenosis

Above 50% stenosis would cause a clinically significant obstruction of blood flow.

Silent disease

CCTA detected atherosclerosis in 42.1% of the participants. In all, 5.2% of the participants had significant obstruction of blood flow in one or more of the three coronary arteries, and 8.3% of the participants had noncalcified plaques.

Overall, 1.9% of the participants had severe disease, which means it affected either the left main artery, the proximal left anterior descending artery, or all three coronary arteries.

The prevalence of atherosclerosis was almost twice as high in men than in women, with about a 10-year onset delay in women.

The incidence of atherosclerosis increased with age, with a 1.8 times greater prevalence of atherosclerosis in the participants aged 50–54 years compared with those aged 60–64 years.

Increasing CAC scores correlated with an increased prevalence of CCTA-detected atherosclerosis.

In all, 5.5% of the participants with a CAC score of 0 had atherosclerosis, with 0.4% experiencing a significant obstruction of blood flow.

All of the participants with a CAC score over 400 had atherosclerosis, with 45.7% having significant obstruction.

“[The study] is confirming what we had suspected all along based on prior population studies: Atherosclerosis or [CAD] is actually quite prevalent,” said Dr. Hoang Nguyen, an interventional cardiologist at MemorialCare Heart & Vascular Institute at Orange Coast Medical Center in Fountain Valley, CA, in an interview with MNT.

“It was really astounding that if you took a random group of 10 [relatively healthy people in their 50s into their 60s], four of these would have some degree of atherosclerosis, […] up to 5% of these people [would have] significant coronary artery disease — meaning 50% stenosis in their arteries — and around 2% of these people [would have] significant disease that we would consider very dangerous.”

Dr. Nguyen commented: “So this puts you at kind of a conundrum — if you have this information, how aggressive should we be in treating this patient? Should we start these patients on medication like statins earlier?”

He continued, “Is this going to be a bigger burden to the healthcare system — meaning that if we […] identify a lot more patients, [will] we be forced to do more invasive testing, like an angiogram, assessing the blockage in these patients?”

“Maybe we’ll do more harm when we intervene, so that’s the bigger question — we don’t know, and [so we will need] a longer-term follow-up.”

Strengths and limitations

Commenting on the study’s strengths and limitations, Dr. Bergström explained that one of the strengths is that the population sample is “representative of the background population, which makes our data generalizable.”

However, it is important to note that it may not be generalizable to populations beyond Sweden with different demographics.

As for limitations, Dr. Bergström mentioned “the lack of follow-up data.” He continued: “What is needed now is follow-up data on hard events to test whether CCTA can outperform CAC scoring in identifying people at high risk of disease. We expect this follow-up data to be available in SCAPIS in 2024–2025.”

Dr. Nguyen concluded that “this [study] gives us a lot more ammunition and a lot more certainty that we should be more aggressive in controlling atherosclerosis risk factors [in] patients or even the general population. There should be more education about healthy diet and exercise, and [people should be] cognizant of their family history.”

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