Arrhythmogenic Cardiomyopathy/ Arrhythmogenic Right Ventricular Cardiomyopathy. Arrhythmogenic cardiomyopathy (ACM) is among the most common causes of sudden cardiac death in young patients, with males being affected more frequently. A familial occurrence with autosomal dominant inheritance as the most frequent pattern is reported. It is believed that a structural ventricular abnormality leads to arrhythmias, syncope, sudden cardiac death, and heart failure. The cardiac magnetic resonance imaging (CMR) diagnostic criteria and its role in evaluating ACM have altered notably in recent decades. Arrhythmogenic Right Ventricular cardiomyopathy (ARVC) is a subtype of ACM characterized by arrhythmias of right ventricular origin and ventricular pathology involving myocardial fibrosis and fatty replacement. Recent studies have shown that LV involvement in ARVC is not uncommon, particularly when evaluated by CMR, as a sensitive imaging modality. In some patients, LV might be the dominant involved ventricle, leading to the diagnosis of arrhythmogenic LV cardiomyopathy (ALVC). In this chapter we will review the CMR diagnostic approach including the required sequences and imaging findings in a patient with diagnosis of ARVC.