Myocardial Infarction with Obstructive, Non-Obstructive, and Mimicking Conditions: Clinical Phenotypes, Diagnostic Imaging, Management, and Prognosis

<b>Background/Objectives:</b> Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogenous clinical entity that differs in pathophysiology, treatment, and prognosis from myocardial infarction with obstructive coronary artery disease (MI-CAD) and MINOCA mimickers, such as myocarditis or Takotsubo syndrome. This study aimed to compare the clinical characteristics, imaging findings, management strategies, and long-term outcomes of patients with true MINOCA, MI-CAD, and MINOCA mimickers. <b>Methods:</b> This retrospective cohort study included 1596 patients hospitalized with acute myocardial infarction (AMI) between 2012 and 2024 at a tertiary university hospital. Patients were classified as having true MINOCA, MI-CAD, or MINOCA mimickers based on coronary angiography and advanced cardiac imaging. Data included clinical and laboratory variables, echocardiography, cardiac magnetic resonance (CMR), and coronary computed tomography angiography (CCTA). All-cause mortality was analyzed using Cox regression. <b>Results:</b> Of 1596 AMI patients, 111 (7.0%) had true MINOCA, 1359 (85.1%) had MI-CAD, and 127 (8.0%) had MINOCA mimickers. Mimicker patients were significantly younger and had fewer cardiovascular risk factors. True MINOCA was more frequent in females and associated with preserved left ventricular ejection fraction and lower high-sensitivity troponin T levels compared to MI-CAD. CMR and CCTA contributed to etiological clarification in over 70% of MINOCA and mimicker patients. High-risk plaque features were observed in 42.9% of CCTA scans, suggesting but not confirming an atherosclerotic mechanism. Long-term all-cause mortality in MINOCA was similar to MI-CAD (32.1% vs. 30.9%, <i>p</i> = 0.764) and significantly higher than in mimickers (5.9%, <i>p</i> < 0.001). <b>Conclusions:</b> True MINOCA is a distinct clinical entity with diagnostic and prognostic implications. Its comparable mortality to MI-CAD highlights the need for accurate diagnosis and targeted secondary prevention strategies.