A faster, more accurate way to diagnose heart disease?

Image from a coronary CT angiography showing areas of plaque along an artery (left) and a three-dimensional rendering of the left anterior descending artery (right). If you experience a short-lived squeezing sensation or discomfort in your chest when you exercise or feel stress, one possible cause is insufficient blood flow to your heart. Known as stable angina, this condition indicates you may be at risk for a heart attack.

To diagnose (or rule out) potential heart problems, doctors used to start with a stress test. This test monitors the heart's electrical activity, muscle function, and blood flow patterns while the heart is under stress from exercise or medication. But there's a downside: stress tests only detect when a person has one or more severely narrowed arteries (typically more than 70% blocked) that restrict blood flow, triggering symptoms and abnormal findings during the test.

"We now know that most heart attacks occur not from those serious blockages but when smaller, nonobstructive plaques rupture and form a clot that triggers a heart attack," says Dr. Ron Blankstein, a senior preventive cardiologist and director of cardiac computed tomography at Brigham and Women's Hospital. An alternative test, called coronary computed tomography angiography (CCTA), creates a three-dimensional image of the heart and its blood vessels. The image reveals both obstructive and nonobstructive plaque, he explains. Growing evidence suggests that CCTA may improve how cardiologists find and treat heart disease (see "How high-tech heart scans may clarify heart attack risk").

How high-tech heart scans may clarify heart attack risk

Advances in x-ray and computing technology have enabled us to see increasingly detailed images of the body, including the arteries of the heart. In 1999, the first use of coronary CT angiography (CCTA) combined just four cross-sectional images, each called a slice. Modern multi-detector scanners now generate more than 64 slices, and some — known as photon-counting CT scanners — operate at faster speeds and provide better resolution. These higher-quality images can now more accurately predict who might benefit from medications to detect early coronary artery disease and prevent its progression, thereby reducing the odds of a heart attack.

In 2018, a study called SCOT-HEART compared standard care (which typically included stress testing plus recommended medications) to standard care plus CCTA. While early results showed that people who had CCTA scans were more likely to undergo additional procedures in the first year after their scan, the number of procedures had evened out between the groups five years into the study. However, those in the CCTA group were more likely to be taking preventive drugs and were 41% less likely to die of cardiovascular disease or to have had a heart attack.

Ten years into the study, 56% of the CCTA group were taking medications (including aspirin and statins) to reduce their risk of a heart attack compared to 49% in the standard test group. What's more, the rate of nonfatal heart attacks was 28% lower in the CCTA group compared with those who had standard tests. The findings were published Jan. 25, 2025, in The Lancet. "It's the first study to show that the type of test used to evaluate chest pain may have a direct impact on a person's health outcomes," says Harvard Medical School professor Dr. Ron Blankstein.

What is CCTA?

CCTA uses a special CT scanner to take multiple, high-speed x-rays to create three-dimensional views of the blood vessels and other heart structures (see photos). Before the scan, you receive an injection of contrast dye into your arm or hand that "lights up" the blood vessels. You may also be given medications to slow your heart rate and widen your blood vessels. During the scan, you lie on a table that moves through a donut-shaped opening in the scanner. While the preparation and setup may take up to an hour, the actual scan lasts just seconds.

CCTA has a "Class 1" indication and an "A" level of evidence — the strongest possible recommendation — for use as a first-line tool to evaluate people with chest discomfort or those coming to the emergency room with chest pain, says Dr. Blankstein. Most cases of chest pain seen in emergency rooms end up having nothing to do with the heart, so CCTA can be helpful to rule out a possible heart attack in people who may be at risk for one. However, the test is more commonly used to assess people with stable angina.

The most common symptom of stable angina is a feeling of pressure, tightness, or squeezing in the center of the chest that typically subsides within a few minutes. Some people feel discomfort that spreads to the shoulder, arm, neck, back, upper abdomen, or jaw, and some may feel short of breath (what doctors refer to as dyspnea).

Advice about CCTA

"There's tremendous excitement about increasing the use of CCTA. But the benefit depends heavily on the quality of the image, and not all scanners are the same," says Dr. Blankstein.

Certain people aren't good candidates for CCTA. These include people who have a very high heart rate that can't be effectively lowered with medication, or a very high body mass index (40 or higher). Both conditions can hinder image quality. Some people should avoid the test because they have an allergy to the contrast material.

People with known coronary artery disease may be less likely to benefit from CCTA because the results might not change how they're treated, says Dr. Blankstein. But as the technology advances, repeat scans might one day help physicians see how well specific therapies are working and if adjustments are needed.

Future refinements?

Two medical device companies, HeartFlow and Cleerly, use artificial intelligence to analyze CCTA results in greater detail. In theory, quantifying the exact amount of plaque a person has — especially the nonobstructive type — could further refine a person's risk calculation. But we don't yet know whether that information adds any value on top of a visual inspection of the scan, Dr. Blankstein says. Still, the current CCTA technology helps doctors provide a more personalized approach to preventive cardiology. "In general, the more plaque someone has, the more likely we are to suggest aggressive therapies," he says.

Image courtesy of Ron Blankstein, MDT