Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA) Diagnosed by Cardiac MRI: A Case Report

Background: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a distinct clinical entity where patients meet infarction criteria but show no obstructive disease on angiography. The condition is heterogeneous, encompassing diverse underlying mechanisms that may clinically mimic myocardial infarction. Identifying the underlying cause using conventional angiography alone remains insufficient for definitive diagnosis. Cardiac Magnetic Resonance Imaging (CMR) is a valuable non-invasive tool that aids in characterizing myocardial injury and supporting a definitive diagnosis. This case demonstrates the diagnostic delay arising from relying on angiography alone in MINOCA, which can miss the underlying etiology, whereas a multimodal approach such as CMR and thrombophilia screening can uncover the mechanism, underscoring angiography's limitation as a standalone tool. Case presentation: We report a 38-year-old male who presented to the emergency department with severe pressure-like chest pain for 60 minutes. He had hereditary hypercholesterolemia. Electrocardiogram showed sinus tachycardia with no ischemic changes, and initial labs revealed elevated inflammatory markers with normal cardiac injury markers. Empirical management led to clinical improvement. The next day, repeated labs showed no significant changes except troponin rising to 3072 ng/L (normal<19 ng/L). Coronary angiography remained unchanged compared with a study three years prior, which showed mild coronary artery disease, except for a mild atherosclerotic plaque from proximal to mid segment with sluggish flow in the left anterior descending artery. With no definitive diagnosis, the patient sought another opinion, and CMR revealed hypokinesia of the mid-anterior segment and increased signal within the endocardial layer, consistent with a mid-anterior myocardial infarction in the setting of MINOCA. Conclusion: This case highlights the importance of considering CMR and other imaging methods in patients with myocardial infarction symptoms, especially when obstructive coronary disease is absent. CMR helped avoid misdiagnosis and accurately identified MINOCA. However, the lack of optical coherence tomography and intravascular ultrasound during initial angiography delayed definitive diagnosis; further integration of advanced cardiac imaging may improve diagnostic accuracy in similar cases.