 [ Symptoms ] what is cardiomegaly [ Disease ] cardiomegaly is an enlarged heart in most cases enlargement of the heart occurs over an extended period of time weeks or more often years due to an injury to the heart the heart responds to the injury by remodeling itself in a way that lets it continue to do its job of pumping blood this sometimes results in a stretching of the heart muscle the condition may also be called dilated cardiomyopathy the most common causes of cardiomegaly are high blood pressure that is inadequately treated for a long time coronary artery disease or heart attacks alcohol abuse viral myocarditis heart infection by a virus postpartum cardiomyopathy unexplained heart enlargement after delivering a baby in many cases no cause can be identified which is called idiopathic dilated cardiomyopathy the heart may also only appear enlarged on a chest x ray the traditional way doctors have diagnosed cardiomegaly an abnormal amount of fluid around a normal sized heart pericardial effusion will deceptively enlarge the heart is shadow on a chest x ray film an echocardiogram heart ultrasound is usually recommended for people with an enlarged heart an echocardiogram can tell the difference between a pericardial effusion and true cardiomegaly and can provide additional information about the heart is shape and function