Abstract Introduction Patients with persistent chest discomfort or other symptoms suggestive of ischaemia and ST segment elevation in two contiguous leads on electrocardiography should be prompt managed to revascularization and emergent angiography for percutaneous intervention in two hours is the preferred reperfusion strategy. Purpose Our aim is to show the importance of differential diagnosis in a patient with an initial diagnosis of ST segment elevation myocardial infarction (STEMI). Clinical case We present a case of 67 years old women with a past medical history of dyslipidemia and polymyalgia rheumatica, treated with rosuvastatin 10mg id and prednisolone 5 mg id. The patient was admitted to emergency department complaining of chest pain with 3 hours of evolution that started after a period of nausea and vomiting. Physical examination showed slight tachypnea with 22 breath per minute, blood pressure 93/40 mmHg, heart rate 110 beats per minute, oxygen saturation in room air 90%, heart sounds with a systolic murmur II/VI and lung crackles in inferior lobes, with no peripheral oedema. Electrocardiography showed sinus rhythm and ST segment elevation in DI, DII and V2-6. Patient was treated with aspirin 300mg, ticagrelor 180mg, furosemide 40mg, oxygen therapy and was scheduled for emergent coronariography. This procedure revealed no significant coronary lesions and ventriculography identified apical ballooning, diagnosing takotsubo myocardiopathy. Clinical condition starts to deteriorate, and an echocardiography identified akinetic apical and midventricular segments and hyperkinetic basal segments with systolic anterior motion of mitral valve, significant mitral regurgitation and left ventricular outflow tract obstruction (LVOTO) with an intraventricular gradient superior to 60 mmHg. Adequate hemodynamic monitoring and heart rate control allowed a substantial clinical improvement. Two days later a cardiac magnetic ressonance was done, confirmed the diagnosis and identified an apical thrombus. The patient was later discharged stable with oral hypocoagulation with anti-vitamin K antagonist. Discussion and Conclusion Takotsubo cardiomyopathy is a unique cardiac syndrome characterized by transient systolic dysfunction witch often mimics acute coronary syndromes (ACS). After exclusion of an ACS, echocardiography is of primordial importance in the assessment of these patients. Left heart failure with pulmonar oedema, mitral regurgitation, LVOTO and thrombus formation were all complications that were present in this clinical case and established the indication to proper therapeutic attitudes. Abstract P184 Figure.