Abstract Case description In November 2020, a 55-years-old female with no significant past medical history, was admitted to our Emergency Department for chest pain after acute stressful event. She had a significant family history of ischemic heart disease, and unclear comatose status of her sister. At admission, she was asymptomatic, blood pressure was 115/80 mmHg, and oxygen saturation was 96%. An electrocardiogram (ECG) showed biphasic T wave in anterolateral leads. Elevated levels of troponin I (hs-TnI of 900 ng/L) and B-type natriuretic peptide (BNP) of 864 pg/mL were detected. Transthoracic echocardiogram (TTE) revealed an ejection fraction (EF) of 30% with apical ballooning of mid and apical segments of the left ventricle (LV) along with a sizable apical thrombus. Aspirin, iv diuretics, iv nitrates and unfractioned heparin were started. After 13 hours, she suffered a sudden transient neurological sign of decreased level of consciousness. Cranial MRI revealed an ischemic lesion in the territory of the apex of basilar artery (thalamic region). After 7 days from stroke, the patients underwent coronary angiography demonstrating unobstructed coronaries. Thus, the diagnosis of takotsubo syndrome was confirmed. During hospitalization, ECG evolution showed T wave inversion in precordial and lateral leads. Hs-TnI declining within normal values. Of note, ventricular arrhythmias burden with polymorphic ventricular contraction (PVC) emerged on continuous ECG-monitoring. Despite resolution of apical balloning and apical thrombosis, there were persistent wall-motion abnormalities in infero-lateral walls and mild LV dysfunction. This was also confirmed by cardiac magnetic resonance (CMR). Further, CMR also showed an intense myocardial edema with elevated LV mass. The patients was discharged on Warfarin, Bisoprolol 2.5 mg/die, Ramipril 5 mg/die, Eplerenone 25 mg/die. A clinical documentation was required to further investigate history of her sister, and neurological sequelae after cardiac arrest at 28s related to ventricular fibrillation emerged. However, no deeply evaluation of underlining heart disease was available. Despite an early favorable follow-up of patient, after six months, she suffered from palpitations and heart failure requiring diuretic therapy. Persistent repolarization abnormalities in infero-lateral leads, and low-voltage in precordial leads were noted. An extensive wall-motion abnormalities and moderate LV dysfunction were detected. Importantly, significant arrhythmic burden with PVC (13%) at 24-hr ECG monitoring was recorded. CMR was requested to further investigate the possibility of underlining coexisting cardiomyopathy. Mild LV dilation, moderate dysfunction (LVEF 39%), wall motion abnormalities and thinning of the inferior wall middle segments were reported. Surprisingly, fibro-fatty replacement in infero-lateral of LV wall was detected, and unexpectedly, right ventricular (RV) fibro-fatty replacement and mild RV dysfunction were also described. Hence, diagnosis of arrhythmogenic cardiomyopathy was made. Since persistent arrhythmic burden despite optimized medical treatment, biventricular involvement, family history of SCD, an implantable cardioverter defibrillator in primary prevention was placed. Furthermore, genetic testing was required and extensive clinical family screening was suggested. Conclusion According to the clinical data collected, takotsubo and arrhytmogenic cardiomyopathy can coexist. A potential link between two myocardial heart disease may be identified in the future, especially among patients presenting takotsubo and long-term unfavorable outcome.