Cardiac arrhythmia, also known as cardiac dysrhythmia or irregular heartbeat, is a group of conditions in which the heartbeat is irregular, too fast, or too slow. A heart rate that is too fast - above 100 beats per minute in adults - is called tachycardia and a heart rate that is too slow - below 60 beats per minute - is called bradycardia.

Many types of arrhythmia have no symptoms. When symptoms are present these may include palpitations or feeling a pause between heartbeats. More seriously there may be lightheadedness, passing out, shortness of breath, or chest pain.

While most types of arrhythmia are not serious, some predispose a person to complications such as stroke or heart failure.

Others may result in cardiac arrest.