Your health care provider may advise a CRT for the following reasons:

• Prior attack of ventricular arrhythmia
• Previous history of heart attack
• Suffered a sudden cardiac arrest and survived
• Long QT syndrome
• Brugada syndrome
• Congenital heart disease or other underlying conditions for sudden cardiac arrest.

Reference : Implantable cardioverter-defibrillator: MedlinePlus Medical Encyclopedia. (n.d.). Retrieved from https://medlineplus.gov/ency/article/007370.htm