Key Points

• An arrhythmia is a change in the heart's rhythm that causes the heart to beat too fast, too slow, or irregularly. A heartbeat that is too fast is called tachycardia. A heartbeat that is too slow is called bradycardia.
• An arrhythmia happens when some part of the heart's electrical system doesn't function as it should.
• Most arrhythmias are harmless, but some can be serious or even life threatening.
• Millions of Americans have arrhythmias, and arrhythmias are especially common among older adults. About 2.2 million Americans have atrial fibrillation. Health experts think that most of the sudden cardiac deaths that occur every year (about 335,000) are due to ventricular fibrillation.
• Arrhythmias have many causes. Heart disease is a common cause of serious arrhythmias. Stress, smoking, heavy alcohol use, heavy exercise, some drugs (such as cocaine or amphetamines), and some medicines can lead to arrhythmias in some people.
• Signs and symptoms of an arrhythmia include:
  • Palpitations (an unpleasant feeling that your heart is skipping beats or beating too hard)
  • A fast or racing heartbeat, a slow heartbeat, or an irregular heartbeat
  • Weakness, dizziness, light-headedness, sweating, and fainting
  • Shortness of breath
  • Chest pain
  • Anxiety
• Usually the first test used to diagnose an arrhythmia is an EKG (electrocardiogram).
• Arrhythmias can be treated with medicines, medical procedures (for example, electrical energy delivered to the heart), and surgery.
• Serious arrhythmias can often be successfully treated. Most people with arrhythmias are able to live normal lives.