MINOCA: unravelling the enigma

Patients with acute chest pain and elevated troponin concentrations usually undergo invasive coronary angiography unless there are obvious non-coronary causes of this constellation. It thus became apparent that up to 10% of such patients do not have obstructive coronary artery disease. In women, this group may even be larger. The catchy name for this phenomenon is MINOCA (Myocardial Infarction with Non-Obstructed Coronary Arteries). Although the definition seems straightforward, MINOCA is a heterogeneous entity comprising takotsubo syndrome (TTS), myocarditis, plaque rupture with embolisation, coronary dissection, etc. Scientific information about MINOCA patients suffers from variable inclusion and exclusion criteria. For instance, studies differ with respect to the proportion of patients with smooth coronary arteries and those with plaque up to 50% diameter stenosis. In many studies, the cause of MINOCA has not been systematically identified, for instance, by using cardiac magnetic resonance (CMR). Consequently, recent data on the prognosis of MINOCA patients show a huge variation in annual mortality from 0.6% up to 8.1%. CMR is helpful to elucidate the underlying causes leading to a MINOCA presentation. It is the method of choice for the non-invasive diagnosis of myocarditis which is difficult to make on clinical grounds alone. Furthermore, if performed as early as possible following coronary angiography (which is nowadays often done without a left ventricular angiogram), it is ideally suited to detect the typical wall motion abnormalities and absence of late gadolinium enhancement associated with TTS. CMR can also detect minute subendocardial areas of acute myocardial infarction. Surprisingly, such areas have been found in a rather constant proportion of 20%–25% in all-comer studies of MINOCA patients using this technique.1–3 Our knowledge of the diagnostic spectrum found in MINOCA patients who were systematically studied by CMR within …