An ICD is generally needed for those at high risk of cardiac arrest due to a ventricular arrhythmia. This includes people with heart failure who have problems with the contraction of the heart, such as abnormal left ventricular ejection fraction. There may be other reasons for your doctor to recommend an ICD.

Why would a doctor implant an ICD in a patient?

It helps when your heart stops beating effectively (cardiac arrest), even when you're not near a hospital. Your doctor may recommend an ICD if you've had signs or symptoms of certain abnormal heartbeats called sustained ventricular tachycardia, including fainting.

Why would a person need a defibrillator?

You need an ICD if you have ventricular fibrillation (VF). That's when the heart's lower chambers don't contract hard enough to pump blood throughout the body, triggering cardiac arrest. You also need one if you've already suffered cardiac arrest, from VF or another cause.