The symptoms of an enlarged heart are observed when the heart can no longer pump the amount of the blood the body needs to function adequately. Here are some of the signs and symptoms of an enlarged heart: 1  Swollen legs. 2  Increased abdominal girth. 3  Thyroid problems. 4  Weight gain. 5  Edema. 6  Shortness of breath. 7  Abnormal heart rhythms. 8  Palpitations. 9  Cough. 10  Chest Pain.