Hello Mr. Segundo, enlarged heart, or called cardiomegaly, is not a disease, but a symptom of other conditions, the conditions may be one or more of the below: high blood pressure, heart valve disease, heart muscle disease, pulmonary hypertension, fluid around your heart, anemia, thyroid disorder(both overactive and underactive), too much iron in the blood. Generally, a certain condition made your heart pump harder, this damages the heart muscle, as a result the heart chamber is enlarged.