Is an abnormal heartbeat a heart abnormality?

Abnormal heartbeats or heart rhythms are a class of heart abnormalities often caused by other kinds of heart abnormalities. If you have an abnormal heartbeat, your heart may beat too fast, too slow, or irregularly. Most abnormal heartbeats themselves are not life-threatening and will not interfere with normal physical activity. An abnormal heartbeat may, however, be a symptom of a more serious heart abnormality, such as coronary artery disease or heart failure. Coronary artery disease kills more people in the United States than any other cause of death.