Myocardial infarction with non-obstructive coronary arteries: A comprehensive review and future research directions

Abstract

Acute coronary syndromes constitute a variety of myocardial injury presentations that include a subset of patients presenting with myocardial infarction with non-obstructive coronary arteries (MINOCA). This acute coronary syndrome differs from type 1 myocardial infarction (MI) regarding patient characteristics, presentation, physiopathology, management, treatment, and prognosis. Two-thirds of MINOCA subjects present ST-segment elevation; MINOCA patients are younger, are more often female and tend to have fewer cardiovascular risk factors. Moreover, MINOCA is a working diagnosis, and defining the aetiologic mechanism is relevant because it affects patient care and prognosis. In the absence of relevant coronary artery disease, myocardial ischaemia might be triggered by an acute event in epicardial coronary arteries, coronary microcirculation, or both. Epicardial causes of MINOCA include coronary plaque disruption, coronary dissection, and coronary spasm. Microvascular MINOCA mechanisms involve microvascular coronary spasm, takotsubo syndrome (TTS), myocarditis, and coronary thromboembolism. Coronary angiography with non-significant coronary stenosis and left ventriculography are first-line tests in the differential study of MINOCA patients. The diagnostic arsenal includes invasive and non-invasive techniques. Medical history and echocardiography can help indicate vasospasm or thrombosis, if one finite coronary territory is affected, or specify TTS if apical ballooning is present. Intravascular ultrasound, optical coherence tomography, and provocative testing are encouraged. Cardiac magnetic resonance is a cornerstone in myocarditis diagnosis. MINOCA is not a benign diagnosis, and its polymorphic forms differ in prognosis. MINOCA care varies across centres, and future multi-centre clinical trials with standardized criteria may have a positive impact on defining optimal cardiovascular care for MINOCA patients.

Keywords: Management; Myocardial infarction; Myocardial infarction with non-obstructive coronary arteries; Non-obstructive coronary; Prognosis.

Figure 1

Diagnostic and therapeutic workup for myocardial infarction with non-obstructive coronary arteries. STEMI: ST segment elevation myocardial infarction; NSTEMI: Non-ST segment elevation myocardial infarction; Ach: Acetylcholine; CMR: Cardiac magnetic resonance; EMB: Endomyocardial biopsy; TTE: Transthoracic echocardiography; TOE: Transoesophageal echocardiography; ACEi: Angiotensin-converting-enzyme inhibitors; ARB: Angiotensin II receptor blockers; MINOCA: Myocardial infarction with non-obstructive coronary arteries; ECG: Electrocardiogram; iFR: Instantaneous wave-free ratio; OCT: Optical coherence tomography; FFR: Fractional flow reserve; IVUS: Intravascular ultrasound; PET: Positron emission tomography.