The MINOCA-GR registry will be the first nationwide study aiming to obtain data regarding prevalence, demographics, clinical profile, previous anginal status, presence of cardiovascular risk factors, management and outcomes in patients with Myocardial Infarction with Non-Obstructive Coronary Arteries. An additional purpose of the registry is to highlight, for the first time worldwide to the best of the investigator's knowledge, the role of cardiac computed tomography angiography for risk stratification and personalized therapeutic approach in MINOCA patients.

MINOCA occurs in 5%-10% of all patients with Acute Myocardial Infarction (AMI) and these patients are younger and more often women in comparison with patients with AMI and obstructive Coronary Artery Disease (CAD). The underlying pathophysiological mechanisms are poorly understood, although several different mechanisms have been proposed, including plaque disruption, spasm, thromboembolism, dissection, microvascular dysfunction and ischemic myocardial injury attributable to supply/demand mismatch. In most, but not all, studies of prognosis, MINOCA patients had better outcomes than their AMI counterparts with coronary artery disease but faced a high risk for recurrent events, with one study finding that 25% of patients with MINOCA experience angina in the following year. Optimal patient management requires early diagnosis as well as understanding which of the myriad of mechanisms (atherosclerotic or non-atherosclerotic as well as a combination of both) may be underlying the initial diagnosis. The effects of secondary preventive treatments proven beneficial in patients with classical type I AMI are unknown in MINOCA patients; randomized clinical trials, and large observational studies, as well, evaluating different treatments in MINOCA patients do not exist. Hence, evidence-based guidelines for treatment of MINOCA are lacking. Elucidating the associations between different treatments and outcome may also increase the understanding of underlying mechanisms of MINOCA. The underlying mechanisms strongly determine prognosis and more importantly, therapeutic interventions as well as their success.

Likewise, multimodality imaging could provide new insights into the management of MINOCA patients. The current research reveals the utility of Cardiac Magnetic Resonance for diagnosis and risk stratification of suspected MINOCA patients but at the same time shows how much more information is needed to further characterize risk and ultimately develop therapeutic approaches to alter its natural history. Computed tomography has a suite of strengths including diagnosis of CAD, identification of plaque characteristics, morphology and perfusion data, and even possibly delayed enhancement; its ability to detect nonobstructive coronary disease by way of visualizing not only the lumen but also plaques is very helpful in our efforts trying to understand microvascular disease, plaque erosion, and myocardial infarction with no obstructive coronary artery. Furthermore, up until recently, high-risk plaque features and lesion specific ischemia are thought to be not directly related. However, emerging evidence suggests a possible relationship between high-risk plaque features, particularly low attenuation plaque volume and positive remodeling, with lesion specific ischemia by fractional flow reserve. Such relationship is independent of degree of luminal stenosis. As a result of the above, it is obvious that Cardiac Computed Tomography Angiography (CCTA) may have a potential role in some selected patients with MINOCA, depending on their clinical picture and stability.

Regarding Greece, the MINOCA-GR registry will be the first prospectively enrolling medical database of this magnitude.

Inclusion Criteria:

1. Patients older than 18 years
2. Patients without known history of coronary artery disease
3. Patients with acute coronary syndrome with and/or without ST-segment elevation who underwent coronary angiography within 24h after onset of the disease
4. Absence of obstructive coronary atherosclerosis (normal coronary arteries or plaques <50% stenosis) based on the results of invasive coronary angiography
5. Subject has provided written informed consent
6. Subject is willing to comply with study follow-up requirements

Exclusion Criteria:

1. Patients < 18 years old at time of coronary angiography
2. Patients with a previous history of coronary artery disease and/or prior revascularization
3. Patients with serious concurrent disease and life expectancy of < 1 year
4. Patients who refuse to give written consent for participation in the study
5. In the investigator's opinion, subject will not be able to comply with the follow-up requirements
6. Subject is pregnant and/or breastfeeding or intends to become pregnant during the study
7. Subject has a known allergy to contrast agent that cannot be adequately pre-medicated

This study will enroll consecutive patients with MINOCA admitted to study clinical sites.