Background: The treatment of acute coronary syndrome (ACS) is well defined by evidence and guidelines. However, in up to 10% of ACS patients there is no detectable obstructive coronary heart disease. This so-called myocardial infarction with non-obstructive coronary arteries (MINOCA), has gained clinical attention. However, scientific investigations are still rare and many clinical and pathophysiological issues as well as distinct disease definition remain unresolved.

Objective: We aimed (1) to evaluate the distribution and prevalence of the different entities of infarction (myocardial infarction with obstructive coronary arteries, MIOCA vs. MINOCA) in a 12 months period in a high-volume PCI center, and (2) to compare clinical characteristics and outcomes.

Methods: We established a retrospective registry based on all patients (N= 3,021) who received invasive coronary diagnostic in our center between 2017 and 2018. Patients with working diagnosis ACS and troponin elevation were included and further evaluated regarding final diagnosis. Various demographic, clinical and procedural parameters, as well as  laboratory parameters and diagnostic work-up were collected, anonymously registered and compared.

Results: Altogether, 760 ACS patients were included. There were 542 MIOCAs, 118 MINOCAs and 100 patients with troponin elevation without myocardial damage. Therefore, the prevalence of MINOCA in the analyzed patient population was 15.5% (Figure 1). Table 1 shows clinical characteristics of the different entities of infarction: MINOCA patients were more likely women (63,1% vs. 32.7% p<0.001), but showed no difference in age or other comorbidities except for a smaller incidence of structural heart disease (18.3 vs. 25.2 %, p < 0.001). In general, the presence of diabetes mellitus, hypertension or multimorbidity seem to be important co-factors for the occurrence of cardiovascular diseases in both groups, whereas frailty alone is not (Fig. 1). Overall, “true infarction” (MIOCA) patients were sicker, showing with 10.5% (N=57) a significant higher 30-day mortality (p = 0.047), and though leading to a higher need for advanced life support such as cardiopulmonary resuscitation, defibrillation or intubation (18.6% vs. 7.8%, p=0.007). Even though less, but the 30day-mortality rate of MINOCA patients has to be judged with 2.9 % as substantial. Additional imaging was used more often in the MINOCA group (17.5% vs. 4.8%, p<0.001). Among these, most had cardio-MRI. Utilization of intracoronary imaging was very low (2 %), and with no differences, between both groups (Tab.). ECGs of MINOCA patients were less frequently pathological (62.1% vs. 77.1%, p=0,001), but a specific pattern could not be observed.

Compared with true infarcts, MINOCAs had a significant lower levels of cardiac biomarkers and a higher left ventricular ejection fraction, both at admission (57.6 ± 15.4 vs. 52.4 ± 14.8 %, p=0,001) and at 1 year.

Conclusion: With a prevalence of more than 15%, MINOCA accounts for a significant proportion of ACS patients. MINOCA is a disease entity with significant differences in certain clinical characteristics and outcomes. However, MINOCA has a relevant 30-day mortality rate. Further research is needed to improve the understanding and to establish specific diagnostic and therapeutic strategies for MINOCA.