MINOCA… What is it?

A 54-year-old woman with no past medical history presents to the emergency department with a 2-hour history of substernal chest pain, rated 8/10, related to sweating and shortness of breath. She appears to be in a mildly agitated state and is pale. Her electrocardiogram shows ST-segment elevation within the precordial leads. Her initial high-sensitivity cardiac troponin level was 225 ng/L; her laboratory results were otherwise unremarkable. She has a big past medical history of hypertension, and he or she was recently diagnosed with breast cancer 3 weeks ago. She is urgently transferred to the cardiac catheterization laboratory. It was anticipated that coronary atherosclerosis could be identified because the explanation for her acute myocardial infarction and life-saving percutaneous coronary intervention with stent placement could be performed. However, her coronary arteries were angiographically normal with no evidence of obstructive disease. A transthoracic echocardiogram was performed, which noted apical ballooning and akinesia, with an estimated ejection fraction of 35%. Troponin levels continued to rise and peaked at 1550 ng/L. This patient was diagnosed with myocardial infarction without obstructive coronary artery disease, more specifically, takotsubo cardiomyopathy. A serious life stressor, namely a recent diagnosis of cancer, was identified because the trigger for this acute medical diagnosis. Takotsubo cardiomyopathy is a condition that falls inside the category of myocardial infarction without obstructive coronary artery disease (MINOCA).

Definition

MINOCA is a term used to explain a puzzling clinical condition that has been documented for over 75 years but has gained popularity in recent times (Pasupathy et al., 2017). A patient with MINOCA meets the diagnostic criteria for traditional myocardial infarction (MI), including an increase or fall in cardiac troponin related to any of the next: evidence of myocardial ischemia, electrocardiographic changes consistent with ischemia (recent ST changes or recent left bundle branch block), recent pathological Q waves, lack of viable myocardium or recent wall motion abnormality, and identification of intravascular clot by angiography or autopsy (Crea and Niccoli, 2017). MINOCA is distinguished from typical MI by angiographic evidence of normal or near-normal coronary arteries (Crea and Niccoli, 2017).

Occurrence and prognosis

MINOCA accounts for 6-8% of all acute myocardial infarctions and will account for 50% of all myocardial infarctions in women <55 years of age (Parwani et al.). African-American and Latino patients are probably the most common ethnic groups diagnosed with MINOCA (Crea and Niccoli, 2024). The risk factor profile was similar in those diagnosed with heart problems, including diabetes, smoking, hypertension, hyperlipidemia, and family history (Crea and Niccoli, 2017). The prognosis for MINOCA is best than for MI attributable to coronary artery disease (CAD), but it surely is way from benign. MINOCA is related to a 12-month mortality rate of 4.7%, and as much as 25% of MINOCA patients report persistent angina after the primary event (Claudio et al., 2018).

Causes

There are many potential pathophysiological etiologies related to the acute clinical presentation of MINOCA. The graphic below shows coronary and non-coronary causes (Pasupathy et al., 2017).
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Diagnosis

MINOCA can’t be diagnosed with no thorough history and coronary angiography (Pasupathy et al., 2017). Given that the classic clinical presentation of MINOCA resembles MI attributable to coronary artery disease (CAD), these patients are sometimes referred to the cardiology laboratory urgently as standard of care. In the absence of coronary artery occlusion (<50% stenosis), additional testing is mandatory to discover the underlying cause. During the stay within the cardiology laboratory, intravascular ultrasound (IVUS) or optical coherence tomography (OCT) may be performed inside the epicardial arteries to discover plaque disruption, rupture, ulceration, or dissection. Additionally, ergonovine challenge testing can be performed within the catheterization laboratory to help within the diagnosis of coronary vasospasm (Pasupathy et al., 2017; Crea and Niccoli, 2017). One of probably the most useful noninvasive tests used to find out the explanation for MINOCA is transthoracic echocardiography to evaluate the left ventricle. Regional wall motion abnormalities may indicate an epicardial cause akin to vasospasm, thrombosis, or plaque rupture. Apical ballooning with apical akinesia suggests Takotsubo cardiomyopathy (Pasupathy et al., 2017). Coronary artery embolism/microembolism must be considered in patients with prosthetic heart valves, atrial fibrillation, dilated cardiomyopathy with apical thrombus, infective endocarditis, and atrial myoma. In such cases, contrast transthoracic echocardiogram or transesophageal echocardiogram could also be helpful in elucidating the etiology (Pasupathy et al., 2017). Cardiac MRI is a useful test to discover myocardial edema, scarring, or other myocardial abnormalities (Pasupathy et al., 2017). Current data estimate that cardiac MRI can discover the cause in roughly 90% of patients with MINOCA (Crea and Niccoli, 2017). Virologic testing for parvovirus, human herpes virus 6, and coxsackievirus is indicated when the suspicion for viral myocarditis is high. A hypercoagulable state may predispose the patient to coronary thrombosis; factor V Leiden, prothrombin gene mutation, protein C and S, and factor VII are mostly tested when a hematologic cause is high on the differential diagnosis list (Pasupathy et al., 2017).

Management

MINOCA patients profit from treatment directed on the cause. There is currently no consensus advice from society guidelines (Parwani et al., 2023). For example, within the context of the etiology of plaque disruption, treatment may include aspirin, a statin, an ACE inhibitor or an angiotensin receptor blocker, and cardiac rehabilitation including a beta-blocker and a P2Y12 inhibitor. Other therapies include lifestyle changes, risk factor management, weight reduction/weight-reduction plan modification, smoking cessation, and regular physical activity (Claudio et al., 2018). Two ongoing trials, MINOCA-BAT (Randomized Evaluation of Beta Blocker and ACEI/ARB Treatment in MINOCA Patients) and WARRIOR (Women’s Ischemia Trial to Reduce Events In Non-Obstructive CAD), are expected to discover optimal treatment strategies in lots of them (Parwani et al., 2023).

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Pacheco Claudio, C., Quesada, O., Pepine, C.J., and Noel Bairey Merz, C. (2018). Why names matter to women: MINOCA/INOCA (myocardial infarction/ischemia and non-obstructive coronary artery disease). , (2), 185–193. https://doi.org/10.1002/clc.22894

Crea, F. & Niccoli, G. (2024, February 2). Myocardial infarction or ischemia without obstructive coronary atherosclerosis. Â https://www.uptodate.com/contents/myocardial-infarction-with-no-obstructive-coronary-atherosclerosis

Parwani, P., Kang, N., Safaeipour, M., Mamas, M. A., Wei, J., Gulati, M., Naidu, S. S., and Merz, N. B. (2023). Contemporary diagnosis and treatment of patients with MINOCA. (6), 561–570. https://doi.org/10.1007/s11886-023-01874-x

Pasupathy, S., Tavella, R., and Beltrame, J. (2017, September 14). American College of Cardiology. https://www.acc.org/latest-in-cardiology/articles/2017/09/14/08/44/unraveling-the-enigma-of-mi-with-nonobstructive-coronary-arteries

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