Abstract
Background:
Myocardial Infarction with Non-Obstructive Coronary arteries (MINOCA) is defined as acute Myocardial Infarction (MI) despite the absence of severe coronary artery stenosis on angiography (i.e., stenosis severity <50%) and no specific alternative diagnosis (e.g., sepsis, pulmonary embolism). MINOCA remains a serious diagnostic and therapeutic challenge given the various possible underlying etiologies. Cardiac Magnetic Resonance Imaging (CMR) can distinguish between acute myocarditis (AM), MI, and Takotsubo cardiomyopathy (TCM) which are some of the commonest causes of MINOCA. Hence, The European Society of Cardiology (ESC) recommend CMR in all MINOCA patients with an unclear etiology. Intracoronary Optical coherence tomography (OCT) is a high-resolution imaging modality that allows for assessment of the integrity of the atheroma. We aimed to study the efficacy of CMR and OCT in detecting the etiology in MINOCA patients, which has the potential to guide medical therapy.
Methods:
A systematic search was made in PubMed, Medline and Cochrane database. Search terms used: Myocardial infarction, Coronary angiography, Normal coronary arteries, CMR, and OCT. Inclusion criteria was fulfilled by 18 studies. Meta-analysis and meta-regression was performed with 14 studies due to increased heterogeneity.
Results:
A total of 2474 patients were included in the meta-analysis. The mean age of all the patients was 51.5 and 56.4% were men. CMR was able to establish diagnosis in 74% of the patients; 30.4% had AM, 21.3% had true MI and 12% had TCM. Upon meta-regression the demographic variables, cardiovascular risk factors, troponin levels and C-reactive protein levels did not have any association with AM or MI. Incorporation of OCT with CMR was better at finding the etiology than either modalities individually.
Conclusion:
CMR is integral in finding the cause of MINOCA. Coupling coronary OCT and CMR is better than either techniques alone at identifying the etiology.