MRI-based blood flow testing offers better answers for unexplained chest pain

Chest pain may still be angina even when coronary angiogram testing shows the main heart arteries look clear. Using stress cardiac stress MRI testing to measure blood flow around the heart appears to improve diagnosis and patient quality of life. These finding were shared at a late-breaking science presentation today at the American Heart Association's Scientific Sessions 2025. The meeting, Nov. 7-10, in New Orleans, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

People may have real angina even when the main arteries appear wide open. By measuring blood flow with a stress cardiac MRI test, we found that small vessel problems were common. Our findings show that an angiogram alone is not always enough to explain chest pain. A functional test of blood flow should be considered before sending people home, especially women, who are more likely to have small vessel angina that otherwise goes unrecognized."

Colin Berry, M.B.Ch.B., Ph.D., study author, professor of cardiology, University of Glasgow and consultant at Golden Jubilee University National Hospital

According to the American Heart Association, angina is chest pain that occurs if the heart is not getting enough oxygen-rich blood. About half of all patients with angina who undergo coronary angiogram testing have no obstructive coronary artery disease identified. This study aimed to determine if stress cardiac MRI testing (a heart scan that measures blood flow with magnetic resonance imaging) could help improve diagnosis and treatment for people with suspected angina.

A total of 250 adults with chest pain but no blocked coronary arteries based on testing were enrolled in the CorCMR trial. All of the participants had a coronary angiogram test within three months prior to enrollment in the study, with the results indicating they had suspected angina and no obstructive coronary arteries (ANOCA). The study participants were randomly assigned to one of two groups. People in both groups had a stress cardiac MRI test. In one group, the stress cardiac MRI results were shared with doctors and patients to help guide diagnosis and treatment. In the other group, results of the stress cardiac MRI were not disclosed to the doctors or the patients, and treatment decisions were based only on the results of the angiogram conducted before enrolling in the study. Neither the participants nor their doctors knew which group they were assigned to until after the one-year study ended.

After following all participants for at least 12 months, the analysis found:

• About half of all participants (53%) had a diagnosis change after the stress cardiac MRI was completed.
• About 1 in 2 participants had chest pain from small vessels in the heart (microvascular angina); about 1 in 2 (48%) had chest pain not linked to the heart; and a few (2%) had other conditions, such as heart muscle inflammation (myocarditis) or thickened heart muscle (hypertrophic cardiomyopathy).
• When doctors reviewed the stress cardiac MRI images, about 1 in 2 participants were diagnosed with microvascular angina, compared with fewer than 1 in 100 when doctors relied only on angiogram tests.
• More than half of those diagnosed with microvascular angina were women.
• After six- and twelve- months, all participants were surveyed using the Seattle Angina Questionnaire, a commonly used evaluation of 19 questions to assess individual levels of physical mobility or limitations, frequency and severity of chest pain, and quality of life (treatment satisfaction and disease perception).
• Quality-of-life scores were improved in the stress cardiac MRI group, with small improvements at six months that became more pronounced after a year.
  • Participants in the stress cardiac MRI group improved by an average of 18 points at six months, and 22 points at one year on the Questionnaire.
  • People in the angiogram-guided group improved by less than 1 point.
  • After one year, the difference in the Questionnaire results between the two groups increased to about 21 points.
• No participants had any serious side effects from the stress cardiac MRI screening, and there were no deaths during the year of follow-up.

"The results of our study open a new path for people with chest pain," Berry said. "It indicates that symptoms and well-being are worse when diagnoses are made based only on an angiogram. Clinical practice should now change to include a stress cardiac MRI test for angina, especially for women with chest pain and no blockages in the main arteries. These results may also help inform future clinical recommendations for anyone presenting with angina, and help improve clinical outcomes."

Study details, background and design:

• Out of 273 people screened to join the trial, 250 adults were enrolled. Participants were an average age of 63 years old, about half were women, and about 1 in 6 had Type 2 diabetes. All had a recent angiogram to indicate their main arteries were visibly clear with no blockages.
• All participants then had a stress cardiac MRI scan to measure blood flow in the heart's arteries, and a medication was given to mimic the effects of exercise on the heart while the scan was being done.
• Participants were randomly assigned to one of two groups. In one group, doctors saw the scan results and used them to make the final diagnosis and choose treatment. In the second group, doctors did not see the results and made decisions based only on the cardiac angiogram. Neither participants nor their doctors knew which group they were in until the trial ended.
• Enrollment for the study began in February 2021, and follow-up began in 2024, at three hospitals in the West of Scotland.
• All participants were followed for 12 months after enrollment, and there were no dropouts in either group.
• The study was coordinated by an independent clinical trials unit, data were collected centrally, and results were analyzed by a blinded statistician to minimize bias.

The study had some limitations to note. More research is needed to confirm these findings in different health care settings and to test whether this approach may improve longer-term outcomes for patients, such as re-hospitalization and survival. Because chest pain from small vessels is often under-recognized, especially in women and among people in groups historically excluded from scientific research studies, future trials should ensure these populations are well represented.
After physical injuries, chest pain is the second most common reason adults visit hospital emergency departments in the U.S., accounting for more than 6.5 million visits each year (about 1 in 20 ED visits). Chest pain also leads to nearly four million outpatient visits annually, according to the American Heart Association's Heart Disease and Stroke Statistics – 2025 Update.