Introduction: Acute myocardial infarction with non-obstructive coronary arteries (MINOCA) is a frequent condition caused by a wide array of diseases. Absence of a definitive diagnosis can difficult proper treatment and may worsen prognosis. Given its unique ability to achieve tissue characterization, cardiac magnetic resonance (CMR) can be extremely useful in these patients. We sought to describe the use of CMR in a tertiary care center in Latin-America for the evaluation of MINOCA and its impact in patient management. Methods: Cross-sectional study of all hospitalized patients with MINOCA undergoing CMR and impact in medical management at discharge based on its result. Results: A total of 3283 patients underwent CMR between 2016 and 2020 in our institution. Of these, 144 had MINOCA (without IVUS/OCT imaging) as the main indication for the study. Mean age was 50.7 ± 14.8 years and 56.9% were females. The most frequent diagnosis after CMR was myocarditis in 50% of cases (n=71) followed by AMI in 22% (n=31) and Tako-Tsubo Syndrome in 12% (n=17). Only 11% (n=15) of CMR were normal (Fig 1). There were significant changes in prescription before and after CMR of ASA, dual-antiplatelet therapy (DAPT), anticoagulants (AC), betablockers (BB), statins, colchicine and NSAIDs (Fig 2). Conclusions: CMR is critical for making a definitive diagnosis in a substantial proportion of MINOCA patients and its use has a significant impact in medical regimen optimization at discharge. Figure 1. Definite diagnosis achieved after CMR. AMI: Acute Myocardial Infarction. CMP: Cardiomyopathies. HCM: Hypertrophic Cardiomyopathy. TS: Takotsubo Syndrome.Figure 2. Changes in prescription before and after CMR.