Introduction: Myocardial involvement in systemic sclerosis (SSc) is generally the result of a primary fibrotic process, but sometimes it can be caused by infectious myocarditis due to an aggressive immunosuppressive treatment. Differentiating between these 2 forms of myocardial involvement is important, since the therapeutic approaches are different. Cardiac magnetic resonance imaging (CMRI) is an accurate non-invasive procedure useful in distinguishing between these two types of myocarditis. Methods: We present the case of a 32 year old female patient with a 3 year history of SSc, who presented with dyspnea on exertion, othopnea and dry cough, which appeared a few days after flu like symptoms. Physical exam revealed bilateral crepitant rales and peripheral edema. The ECG showed frequent premature ventricular contractions and echocardiography demonstrated a moderately reduced ejection fraction (EF) of 40%, compared to her last examination of 60%. The diagnosis of heart failure (HF) was established and treatment with diuretics, aldosterone antagonists, ACE inhibitors and nitrates was started. Three days later, the patient developed three episodes of ventricular fibrillation, which were successfully resuscitated. Control echocardiography showed an EF of 15%. Results: A CMRI was performed, which showed myocardial inflammation and extensive endocardial fibrosis involving the lateral wall of the right ventricle, the apex and lateral wall of the left ventricle (LV), the anterior and posterior septum and papillary muscles. This pattern of extensive endocardial rather than epicardial fibrosis was in favor of a primary myocardial involvement. Infective myocarditis was excluded based on negative serum markers. Immunosuppressive treatment with dexamethasone, methotrexate and cyclophosphamide was initiated and an ICD was implanted. Despite an increase in the EF% to 23% in the following days, the patient developed multiple organ failure and died 2 weeks later. Conclusions: CMRI has the ability to suggest the specific etiology of myocarditis: a focal pattern of fibrosis is usually found in infectious myocarditis, while a more diffuse pattern is present in primary myocardial involvement. Patients with infectious myocarditis may benefit from specific therapy, while patients with primary myocardial involvement may require an aggressive immunosuppressive treatment. Primary myocardial involvement should be considered in patients with SSc who present with either severe ventricular arrhythmias of congestive HF. Cardiac MRI is a valuable tool for establishing the diagnosis of myocarditis and identifying the underlying cause.