In which scenario are ICDs indicated?

The indication for implantable cardioverter-defibrillators (ICDs) is primarily based on the prevention of sudden cardiac death, especially in patients who exhibit a high incidence of ventricular tachycardia (VT) or have a history of life-threatening arrhythmias. In the context of heart failure, particularly when there's a significant risk for ventricular arrhythmias, ICDs can be life-saving. They are designed to monitor the heart rhythm continuously and deliver appropriate therapy (such as shocks) to restore normal rhythm when dangerous arrhythmias are detected.

Patients with frequent ventricular tachycardia are at a greater risk for life-threatening cardiac events, making the use of an ICD appropriate to help manage these potentially fatal rhythms. The device serves as a critical intervention, allowing those with recurrent VT to maintain a safer cardiac rhythm and ultimately reducing the risk of sudden cardiac death.

On the other hand, scenarios such as severe stage D heart failure, a low risk of sudden cardiac death, or no prior history of cardiac arrest do not usually qualify for ICD placement, as these situations do not typically indicate a high enough risk of life-threatening arrhythmias that the ICD would effectively mitigate.