Oct. 26, 2024
Myocardial infarction with no obstructive coronary artery disease (MINOCA) can be an invisible diagnosis and is often untreated. MINOCA represents 6% to 15% of all myocardial infarctions in patients. A new clinical practice update published in the Canadian Journal of Cardiology offers guidance for diagnosing the disease.
"This clinical practice update is particularly relevant for women's cardiovascular health because MINOCA is more likely to affect women than men. Approximately 61% of MINOCA patients are women. In the VIRGO study of young patients with myocardial infarction, women had five times higher odds of presenting with MINOCA than men," says Thais D. Coutinho, M.D., a cardiologist at Mayo Clinic in Rochester, Minnesota, and co-chair of the clinical practice update.
Discovering a diagnosis
MINOCA is a good example of how cardiovascular disease pathophysiology is not always the same between men and women. "The true reasons for the sex difference in MINOCA incidence are not fully understood, but we know that women are more likely than men to have coronary microvascular dysfunction, which is one of the known pathophysiological mechanisms of MINOCA. The issue with misdiagnosis of myocardial infarction in women is not unique to MINOCA, but it is further exacerbated because the coronary arteries look normal or near normal on coronary angiography, which can 'fool' clinicians to think that the patient's presentation is not a myocardial infarction," says Dr. Coutinho.
Women are disproportionately represented and more likely undiagnosed. There is a gap in clinical outcomes observed in women diagnosed with myocardial infarction (MI) including:
- Increased risk of in-hospital deaths.
- Recurrent myocardial infarction (MI).
- Higher mortality rates after MI.
Optimizing treatment
The clinical practice update covers key areas such as excluding diagnostic "mimickers" and understanding the underlying pathophysiology causing the MINOCA event, to optimize treatment.
"Pursue the correct diagnosis and cause of the MINOCA. Based on the HARP study, we know that if a patient with MINOCA can have a cardiac MRI and intracoronary imaging, we can identify the cause of MINOCA 85% of the time, as compared to never, if these studies are not done," says Dr. Coutinho. "And we also know that among patients with MINOCA who have the pathophysiology for their event diagnosed and understood, the prognosis is better. It's important not to stop the evaluation at the normal coronary angiogram. If the clinical suspicion for myocardial infarction persists, we must do additional evaluation."
The update shows two flexible diagnostic pathways to choose. Both are focused on laboratory testing, noninvasive and invasive imaging that can be adapted based on each institution's expertise. The guide also describes the benefit of post-acute care resources, including referring to cardiac rehabilitation, and cardiac centers of excellence.
Looking ahead
"A MINOCA diagnosis is not benign despite the apparently normal coronary arteries. Rates of mortality, reinfarction, rehospitalization and recurrent angina are not low," says Dr. Coutinho. "We hope this update will offer guidance in a diagnosis that is still mysterious and confusing to many clinicians. By advancing our understanding, diagnosis and treatment of MINOCA, we will improve women's cardiovascular health."
For more information
Pacheco C, et al. Canadian Cardiovascular Society/Canadian Women's Heart Health Alliance Clinical Practice Update on Myocardial Infarction with No Obstructive Coronary Artery Disease (MINOCA). Canadian Journal of Cardiology. 2024;40:953.
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