Introduction: Arrhytmogenic cardiomyopathy (AC) is a genetic disease, associated with arrhythmic sudden death in young people. Since inflammation might be also present, differential diagnosis with myocarditis is necessary. We present a challenging case initially di-agnosed with ventricular tachycardia (VT) and acute myocardial infarction (AMI), in which multimodality imaging changed the initial diagnosis.

Methods: A 68-year old woman with dyslipidaemia and hypertension was admitted with chest pain, abnor-mal ECG (negative T waves in anterior leads, epsilon wave in V1, V2), negative troponin I (TnI) and elevated NT-proBNP (342ng/ml). One month before, she was hospitalized for a monomorphic VT with left bundle branch block (LBBB) pattern, with hemodynamic in-stability, cardioverted electrically to sinus rhythm. In-creased TnI suggesting an AMI. She recalls an episode of flu with high fever (39°C) before admission.

Results: At current admission, transthoracic echo re-vealed LVEF 52%, severe lateral wall (LW) hypokine-sia, severe RV dysfunction with fractional area change of 23%, TAPSE 15 mm. Coronary angiography exclu-ded significant lesions. Speckle tracking echo revealed patchy areas of decreased myocardial deformation in LV and basal segment of RV free wall. Cardiac mag-netic resonance (CMR) revealed LVEF 59%, LW and septal wall hypokinesia with late gadolinium enhance-ment (LGE) in mid-ventricular layer, with increased extracellular volume (ECV) >30%, increased native T1 time and T2 mapping and pericardial effusion (7mm); dilated RV (diastolic volume of 107 ml/m² and systolic volume of 69 ml/m²), with decreased RV ejection frac-tion 35% with hypokinesia of free wall, dyssynchrono-us contractions and microaneurysms. Diagnosis was concluded for AC with delayed onset, revealed by acute myocarditis. Betablocker, ACEI and implantable car-dioverter defibrillator (ICD) in secondary prevention were decided. We also screened the patient’s relatives. Her daughter has 8000 monomorphic ventricular ecto-pic beats with LV origin and incipient signs of AC on CMR (increased ECV on T1 mapping – 7 LV segments, without LGE).

Conclusions: We presented a rare case of late arrhyth-mic onset of AC in a patient, in which the first aetiology of VT was considered to be ischaemic. VT with LBBB morphology can be caused by myocarditis, AMI or AC. Similarly, epsilon wave with negative T waves in pre-cordial leads may have multiple aetiologies. In our case, multimodality imaging approach excluded AMI and suggested an inflammatory cause for VT. CMR allowed the identification of morphologic condition AC and the trigger condition myocarditis. Our case highlights the importance of a multimodality imaging approach in diagnosing AC and myocarditis, for a correct and complete management.