Atrial infarction is an often-missed entity that has been described in association with ventricular infarction or as an isolated disease, which is mainly caused by atherosclerosis.The electrocardiographic diagnostic criteria were proposed more than fifty years ago and have not yet been validated.The diagnosis is based on elevations and depressions of the PTa segment and changes in the P wave morphology.However, supraventricular arrhythmias such as atrial fibrillation are the most common finding and often predominate in the clinical presentation.Early recognition and treatment may prevent serious complications such as mural thrombosis or atrial rupture.Further studies need to be carried out in order to establish unified criteria for the diagnosis and the actual prevalence of this entity.