Importantly, MINOCA is just an initial and general diagnosis which does not describe underlying pathophysiology. The potential pathophysiological mechanisms of clinical scenario when MI may be diagnosed according to the definition but there is a lack of the obstructive coronary artery disease are quite complex. These include both coronary and non-coronary pathologies. The coronary causes comprise of several different mechanisms. Thromboembolism may be an underlying pathological factor by itself or may be caused by plaque rupture or coronary spasm. This includes also thrombotic disorders (hereditary or acquire) [
6]. Plaque disruption may be caused by erosion, ulceration, plaque rupture, and intraplaque hemorrhage. Coronary artery spasm may be present not only due to endogenous causes but may be provoked by exogenous substances like cocaine [
7,
8]. Non-coronary etiologies are also frequent in MINOCA patients. It is important to recognize well-defined diseases with described etiopathologies like myocarditis, pulmonary embolism or Takotsubo cardiomyopathy in patients initially described as MINOCA. Importantly, some of those causes are treatable, so well planned diagnostics seems to be crucial for the final diagnosis, treatment selection and outcome of these patients. According to 2017 European Society of Cardiology Clinical Practice Guidelines on STEMI, failure to identify the underlying cause may result in inadequate and inappropriate therapy in MINOCA patients [
1]. The diagnostic algorithm based on suspected diagnosis and corresponding diagnostics modalities (non-invasive and invasive) was proposed. This includes myocarditis (with echocardiography, cardiac magnetic resonance and endomyocardial biopsy), coronary epicardial/microvascular etiology (with intravascular ultrasound (IVUS), ergonovine/acetylocholine test, pressure/doppler wire), myocardial disease (with echocardiography and cardiac magnetic resonance), pulmonary embolism (with D-dimer, CT scan, thrombophilia screening) and type 2 MI (with extracardiac investigation) [
1]. In the individual patients’ data meta-analysis of MINOCA patients diagnosed with cardiac magnetic resonance one-third of patients had myocarditis, whereas 21% had infarction in delayed enhancement imaging [
9]. Intracoronary imaging is important in selected cases since plaque rupture, ulceration, erosion or intraplaque hemorrhage are rarely visible in angiography in non-obstructive CAD. Reynolds et al. showed that plaque disruption confirmed by IVUS was observed in 38% of women with MINOCA. Interestingly, in some cases, plaque rupture was identified by IVUS even in angiographically normal-appearing segments [
10]. In addition, in patients with MINOCA invasive coronary provocative tests may be considered. Montone et al. showed acetylcholine and ergonovine tests to be safe in patients with MINOCA and suspected coronary vasomotor abnormalities. Moreover, test results correlated with clinical symptoms and outcome in follow-up [
11]. In the meta-analysis of MINOCA studies, coronary artery spasm was inducible in 27% of patients [
6]. In our analysis (patients undergoing coronary angiography in the year 2016) additional invasive imaging during coronary angiography was marginally used. However, the current upgrade of the reimbursement program in Poland should solve this diagnostics limitation.
In line with previous reports, we found MINOCA patients to be younger, rather with an initial diagnosis of NSTEMI than STEMI and to be more often female comparing to patients with obstructive CAD. Our analysis also showed that MINOCA patients had a lower risk profile concerning other CAD risk factors. However, in meta-analysis of MINOCA studies there was no significant difference in arterial hypertension, diabetes mellitus, smoking, and family history of CAD comparing to obstructive CAD patients [
6].
Patients with MINOCA have lower mortality comparing to obstructive CAD patients with MI in 12-month follow-up. However, in-hospital mortality of about 1% and 3.5% at 12-month is still high especially as compared to stable non-MI patients with normal coronaries in angiography [
6]. This underlines the need for precise diagnosis and dedicated treatment of MINOCA patients. In our analysis, only periprocedural mortality data were available with significantly lower rates found in MINOCA comparing to MI patients with obstructive CAD.
Presented analysis has several limitations. Angiograms were assessed locally by operators, and not by an independent image analysis core laboratory. The ORPKI for the moment does not collect data beyond the cathlab. So, it was impossible to assess further diagnostics done during hospitalization and after discharge and to analyze data according to final diagnosis as well as provide event rates at follow-up. In addition, there is a potential bias from unmeasured confounding factors not included in this analysis. Despite all these limitations our study reflects the outcome of a “real-world”. Thus, data could be extrapolated to the general population.