A ventricular aneurysm entails well-known risks for the patient such as heart failure, potentially lethal arrhythmias, and systemic embolic phenomena. The submitral or posterolateral ventricular aneurysm is a very rare variety, usually of congenital etiology, which may also have other causes, including ischemic heart disease. The present case is about a 76-year-old male with the antecedent of an acute myocardial infarction 3 years ago. He presented with intermittent, brief, and self-limiting episodes of severe dyspnea, intense desperation, and accelerated palpitations, with a nonspecific electrocardiogram. An echocardiography revealed a large submitral aneurysm, with a good clinical response to the specific treatment of heart failure, antiarrhythmics, and oral anticoagulation therapy. We analyze the implications of an aneurysm in the context of an ischemic etiology, with special attention to the limitations of the electrocardiogram in the diagnosis of occlusions of the circumflex artery that irrigates the posterolateral region of the heart. We suspect that a greater number of patients with a culprit circumflex artery could receive appropriate coronary interventionism or thrombolysis if decision-making in the emergency room would not depend mainly on the electrocardiogram. Better stratification tools are needed to prevent late complications of infarction, such as those observed in this patient.