Dual imaging reveals hidden causes of heart attacks without blockages

When Ashley Perlow felt a sharp pain shoot across her chest and into both wrists, she didn't think it could be a heart attack. She was 36, a new mom, and otherwise healthy.

At the hospital, blood tests showed signs of a heart attack, but her arteries appeared normal.

Now, new research led by clinicians and researchers at NYU Grossman School of Medicine shows that in cases like hers, using two complementary heart imaging tests can identify the underlying cause of these heart attacks in most patients without coronary artery narrowing, helping guide diagnosis and medical treatment in a condition that often leaves patients without clear answers. The study is among the largest and most comprehensive to examine MINOCA, or myocardial infarction with non-obstructive coronary arteries, a condition that accounts for 6 to 15 percent of heart attacks and is about three times more common in women than men.

When arteries are not badly blocked, it can be unclear what caused the event. What we show is that in most cases, we can find the underlying explanation, and most often it is a true heart attack. Our results support the need to do specialized imaging in all patients with MINOCA, because we could not reliably predict who will have specific imaging findings."

Harmony R. Reynolds, MD, lead author and director of the Cardiovascular Clinical Research Center in the Leon H. Charney Division of Cardiology at NYU Langone Health

The findings come from the Heart Attack Research Program (HARP), a large international, prospective study. The latest results were presented by Dr. Reynolds as featured clinical research at the American College of Cardiology's 2026 Annual Scientific Session and simultaneously published March 28 in Circulation.

Dr. Reynolds and the team found that combining coronary optical coherence tomography (OCT) and a cardiac magnetic resonance imaging (MRI) identified the underlying cause of the heart event in 79 percent of study participants.

How advanced diagnostic imaging reveals the cause

To better understand these cases in both women and men, researchers enrolled 336 patients across 28 international sites in the Unites States, Canada, and the United Kingdom. The median age of participants was 58 years, including 270 women and 66 men.

Using coronary OCT and cardiac MRI, researchers identified underlying causes, assessed how often each test provided a diagnosis, and examined differences between sexes.

During coronary OCT, a thin catheter is placed inside the coronary arteries to capture high-resolution images of the artery wall, helping detect plaque buildup or blood clots that may not appear on a standard angiogram. Cardiac MRI provides detailed images of the heart muscle, showing where damage has occurred and whether it is related to reduced blood flow, inflammation, or another cause.

Using both imaging techniques together, researchers identified a likely cause in 79 percent of patients.

Most—59 percent—had a typical heart attack mechanism related to reduced blood flow from plaque buildup, artery spasm or blood clotting, while 20 percent (67 patients) had conditions that mimic a heart attack, such as myocarditis, takotsubo syndrome, or other cardiomyopathies. These nonischemic conditions require different treatment approaches than traditional heart attacks.

The new research builds on earlier work by Dr. Reynolds and colleagues, published in 2020 in Circulation, that demonstrated the value of using the same imaging methods in a smaller group of women. The current study expands those findings to a larger, more diverse international population.

Implications for patient care

The findings provide important support for current clinical guidelines, which recommend additional imaging in these patients but have largely been based on expert consensus rather than large-scale data. The results also highlight the limitations of standard angiography, which shows blood flow but cannot detect problems within the artery wall or subtle heart muscle injuries.

The combination of OCT and cardiac MRI provided a significantly higher diagnostic yield than either test alone. The study also found that doctors cannot reliably predict which patients will benefit from one imaging test versus another based on symptoms, blood tests, or initial findings. Even patients with relatively low levels of cardiac biomarkers frequently had detectable heart damage on imaging.

"We had hoped to be able to tailor testing to individual patients," said Dr. Reynolds. "Instead, we found that comprehensive imaging is often necessary to get the full answer."

Although MINOCA occurs more frequently in women, researchers found no significant differences in the underlying causes between women and men once the condition developed. This suggests that the disease process itself is similar once it occurs.

From uncertainty to answers

For Perlow, that clarity was critical. After months of unanswered questions, she was referred to Dr. Reynolds at NYU Langone, where further evaluation and testing helped officially diagnose her condition as MINOCA and guide her care.

Perlow now travels from New Hampshire to New York for follow-ups with Dr. Reynolds, whom she trusts with her heart care. Perlow's journey reflects the importance of specialized expertise in diagnosing these complex cases.

"This is a scary type of heart attack," said Perlow. "When you don't know what caused it, you worry anything could trigger it again."

Her experience reflects a broader shift in how clinicians understand heart disease, particularly in women and younger patients, who don't always display symptoms that align with traditional expectations.

"This is part of a broader shift in how we think about heart disease," said Dr. Reynolds. "Heart attack is not the same for everyone. There is a spectrum of conditions that don't look like the traditional heart attack but are just as real and important to diagnose."

Future research will focus on developing treatment strategies tailored to the specific causes identified through imaging.

The study was funded by the American Heart Association grants 812162 and 16SFRN27810006.

In addition to Dr. Reynolds, NYU Langone researchers involved with the study were Nathaniel R. Smilowitz, MD; Anais Hausvater, MD; Atul Sharma, MD; Yuhe Xia, MSc; Sripal Bangalore, MD; Michael J. Attubato, MD; Lori L. Vales, MD; Alair Holden; Chang Yu, PhD; and Judith S. Hochman, MD.

Additional authors from participating institutions across the United States, Canada, and Japan include Akiko Maehara, MD; Bobby Heydari, MD; Tara Sedlak, MD; Yader Sandoval, MD; Hayder D. Hashim, MD; Kevin R. Bainey, MD; Akl C. Fahed, MD; Natalia Pinilla Echeverri, MD, PhD; Mitsuaki Matsumura; Mobeen Ahmed, MD; Jacqueline Saw, MD; Aun-Yeong Chong, MD; Jennifer A. Tremmel, MD; Shuangbo Liu, MD; Puja K. Mehta, MD; and Bryan Har, MD, on behalf of the HARP Research Group.

NYU Langone is ranked No. 1 in the nation for cardiology, heart, and vascular surgery by U.S. News & World Report and has some of the nation's highest success rates for treating heart rhythm disorders, coronary artery disease, valve disease, heart failure, and congenital heart disease.