ICDs are implanted in people who have had a life-threatening arrhythmia or have had a serious cardiac event like a cardiac arrest. ICDs may also be appropriate to use as a precaution when there is a considerable risk of developing a serious arrhythmia.
Many ICDs are inserted due to damage to the heart as a result of a heart attack.
Certain inherited heart conditions put people at risk of developing life-threatening arrhythmias. These include cardiomyopathy which is a heart muscle disease, Long QT Syndrome (LQTS) which is an inherited heart rhythm disorder, and rare conditions such as Brugada Syndrome.
Patients with heart failure may also require an ICD to be inserted, as this condition can increase the risk of developing heart rhythm problems.
ICDs treat life-threatening heart rhythm problems but they do not prevent a heart attack.