Background <p>Giant coronary aneurysms are rarely described in current literature, with an incidence of only 0.02%. Treatment strategies vary and there is no definitive recommendation; however, surgical treatment should be considered to prevent future complications.</p> Case presentation <p>We report the case of a 58-year-old patient with a history of hypertension, diabetes, and obesity who presented with non-ST-segment elevation myocardial infarction (NSTEMI), ischemic cardiomyopathy with reduced ejection fraction, coronary artery disease, and a giant right coronary artery (RCA) aneurysm with compressive effects and secondary hemodynamic repercussions, requiring surgical management.</p> Conclusion <p>This case describes an acute myocardial infarction associated with a giant compressive RCA aneurysm initially mistaken for a mediastinal mass. It highlights its challenge as a differential diagnosis and the importance of early surgical intervention and literature production on this rare entity.</p>