Imaging Duo Impresses in Women with MINOCA

Cardiac MRI paired with optical coherence tomography (OCT) in women who presented with myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) on angiography identified potential mechanisms of injury in almost 85% of women, according to results from the HARP study.

In the prospective, multicenter, international, observational study of over 300 women with a diagnosis of MINOCA, multimodality imaging found possible mechanisms in 84.5%, with three-quarters being ischemic and one-quarter being non-ischemic, alternate diagnoses to MI, reported Harmony R. Reynolds, MD, of the Sarah Ross Soter Center for Women's Cardiovascular Research at NYU Langone Health in New York City, at the American Heart Association (AHA) virtual meeting. The study results were simultaneously published in Circulation.

Reynolds also reported that of the 116 women in the study who underwent multimodality imaging, a cause was determined in 98:

• 64% MIs
• 15% myocarditis
• 3% Takotsubo syndrome
• 3% non-ischemic cardiomyopathy
• 15% no cause identified

"Identification of the etiology of MINOCA is feasible and has the potential to guide medical therapy for secondary prevention," Reynolds and colleagues wrote.

However, she cautioned that "Not every form of imaging testing is available at every medical center. Coronary OCT "is not currently available at most centers where heart attack patients are taken, but it is available at specialized centers. In time, I anticipate coronary OCT may be more widely used as routine care for MINOCA patients."

And "These tests do add costs," Reynolds told MedPage Today, but noted that "There is value in having diagnosis to the patient as has cascade implications for treatment."

During an AHA press conference, Reynolds said the findings were important "because women with MINOCA have historically been told that, since the angiogram is okay, they never had a heart attack. This is entirely wrong for about two-thirds of the women who had both imaging tests, and misleading for one-quarter of the women because we found they had another problem that was not related to blood flow and could be diagnosed via cardiac MRI."

"One of every 10 heart attacks in women is MINOCA -- three times the number that occur in men," she stated. "In the 4 years after MINOCA, the risk of a major cardiovascular event is 24%. The risk of death within 5 years of the event is 11%."

For the HARP study, Reynolds and colleagues enrolled 301 women (median age 60; 50% non-Hispanic white) with a clinical diagnosis of MI. Among those, 170 were diagnosed with MINOCA, and 145 had adequate OCT image quality for analysis, while 116 of these patients underwent cardiac MRI.

"If invasive coronary angiography revealed <50% stenosis in all major arteries, multi-vessel OCT was performed, followed by CMR...Angiography, OCT, and CMR were evaluated at blinded, independent core laboratories. Culprit lesions identified by OCT were classified as definite or possible. The CMR core laboratory identified ischemia-related and non-ischemic myocardial," the authors explained.

When possible, the imaging results were combined to pinpoint the mechanism of MINOCA, they added.

The authors reported that a definite or possible culprit lesion was identified by OCT in 46.2% of participants, most commonly plaque rupture, intraplaque cavity, or layered plaque. CMR was abnormal in 74.1% of participants, and an ischemic pattern of CMR abnormalities (infarction or myocardial edema in a coronary territory) was present in 53.4%.

Study limitations included the relatively small sample size, few patients with ST-elevation MI, and the fact that three-vessel OCT was incomplete in some cases that may have led to the underestimation of the prevalence of culprit lesion, the authors explained.

AHA discussant Martha Gulati, MD, of the University of Arizona in Phoenix, said, "MINOCA occurs in up to 15% of heart attacks, especially in women. Understanding the cause of MINOCA will help us treat these patients appropriately. Lack of obstruction does not mean that the heart attack is benign."

However, Gulati said the lack of male participants did hamper generalization. Future studies should look into ways to optimally treat MINOCA, with an eye toward improving outcomes, she added.