Bradycardia is defined as a resting heart rate of less than 60 beats per minute. The average resting heart rate is between 60 and 100 beats per minute.
Bradycardia can be normal. Healthy young adults and athletes often have resting heart rates of less than 60 beats per minute.
The condition is abnormal when the heart's own pacemaker doesn't work as it should, or when the electrical system of the heart has been damaged. Often, abnormal bradycardia arises from certain underlying medical conditions, such as heart disease, hypothyroidism and electrolyte imbalances.
Bradycardia can go away on its own if the underlying condition is reversed. If heart disease is the cause, a pacemaker is usually needed to restore normal heart rate.