Using OCT, cardiac MRI can identify underlying causes of MINOCA in women
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Among women with MI with nonobstructive coronary arteries, approximately 85% had potential mechanisms identified when they underwent coronary OCT and cardiac MRI, according to results of the HARP-MINOCA study.
For the prospective observational study, researchers analyzed women with MI. All 301 women enrolled had invasive coronary angiography, which determined 170 had less than 50% stenosis in all major arteries. Women without obstructive CAD then underwent OCT to identify culprit lesions and CMR to identify ischemia-related and nonischemia-related myocardial injury, and the researchers combined all images to attempt to identify the mechanism of MINOCA, Harmony R. Reynolds, MD, associate professor of medicine, associate director of the Cardiovascular Clinical Research Center and director of the Sarah Ross Soter Center for Women’s Cardiovascular Disease at NYU Langone Health, said during a press conference at the virtual American Heart Association Scientific Sessions.
The findings were simultaneously published in Circulation.
Reynolds said approximately 1 in 10 MIs in women is MINOCA, but there are a wide range of causes including nonobstructive plaque rupture, coronary artery spasm, coronary dissection, thrombus or thromboembolism, myocarditis and takotsubo syndrome, so identifying the precise cause is important because the optimal treatments are likely to be different for each.
“In the 4 years after a MINOCA event, prior studies show that the risk of a major adverse cardiovascular event is 24%, and the risk of death over 5 years is 11%,” she said. “Right now, though, different doctors tell patients different messages about MINOCA, and may incorrectly say the event was not a heart attack. I had a patient who was told her arteries were open, and they gave her Xanax.”
Among the 170 women with MINOCA, 145 had OCT with adequate image quality and 116 of those who had OCT also had CMR.
Of the women who had OCT, 46.2% had a definite or probable culprit lesion identified, Reynolds said. Of the women who had CMR, 74.1% had abnormal findings and 53.4% had an ischemic cause for abnormalities such as infarction or myocardial edema in a coronary territory, while 20.7% had a nonischemic cause for abnormalities such as myocarditis, takotsubo syndrome or nonischemic cardiomyopathy, she said.
Using both OCT and CMR, 84.5% of women had a cause of MINOCA identified, higher than OCT only (P < .001) and CMR only (P = .001), according to the researchers.
Of the 116 women who had OCT and CMR, 63.8% had an ischemic etiology of MINOCA, 20.7% had a nonischemic etiology and 15.5% had no mechanism identified, Reynolds said.
“OCT and CMR provided useful diagnostic information independently and in combination,” Reynolds said during the press conference. “Identifying a detailed diagnosis helps doctors select treatment and helps patients understand which medications may be useful. OCT and CMR together provide strong scientific support to the hypothesis that plaque rupture can cause heart attacks, even in plaques that don’t block the artery badly. Approximately half of women [in this study] had no OCT culprit identified. This was likely due to coronary spasm or thromboembolism, or perhaps the OCT missed it. Mechanisms of MINOCA in women were often similar to mechanisms of MI with obstructive CAD, so it is important for these women to receive treatment for secondary prevention.”
During a discussant presentation at the press conference, Martha Gulati, MD, MS, FAHA, FACC, FASPC, division chief of cardiology for the University of Arizona College of Medicine, said the study is important because “MINOCA occurs in up to 15% of all heart attacks, and it’s far more frequent in women. Understanding the cause will hopefully help us treat them appropriately. The lack of obstruction does not mean the heart attack is benign. We really need this information to better treat these patients.”
Reference:
Perspective
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Julia Grapsa, MD, PhD, FACC
The findings of HARP-MINOCA have implications for secondary prevention in women with MINOCA, which may be targeted to the most likely underlying causes as demonstrated in this study. The results provide support to the recent European Society of Cardiology recommendation to follow a diagnostic algorithm to identify the underlying cause of a MINOCA presentation, to facilitate treatment according to the underlying cause or causes of MI.
OCT and CMR provided complementary, independent information about mechanisms of MI in women with MINOCA in this study. The finding that 56% of women with normal CMR had an OCT culprit lesion illustrates the potential for OCT findings to change management of MINOCA patients. However, clinical trials are needed to investigate the effects of specific therapies on outcomes.
Comprehensive imaging such as with OCT and CMR should be implemented in the guidelines as a part of MINOCA diagnostic algorithm. Nowadays, we detect a significant percentage of MINOCA in the community and careful history as well as imaging may provide the differential diagnosis with coronary artery disease.
MINOCA is an umbrella term used to describe heart attacks that aren’t caused by obstructed arteries — a comprehensive imaging algorithm is crucial in setting the differential diagnosis. This will facilitate clinical practice but also prevention in a significant percentage of women.
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Reynolds HR, et al. LBS.03: Current challenges in coronary and valve disease. Presented at: American Heart Association Scientific Sessions; Nov. 13-17, 2020 (virtual meeting).
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