What is the main indication for an ICD in CHF?

• A. Primary prevention in HFrEF with EF ≤ 35% who are expected to survive with good functional status
• B. Secondary prevention after ventricular tachycardia
• C. In all patients with CHF
• D. For HFpEF patients only

Answer: (A)

The main use of an implantable cardioverter-defibrillator (ICD) in heart failure is to prevent sudden cardiac death from dangerous ventricular rhythms in patients with reduced systolic function. Specifically, it’s indicated for primary prevention in patients with heart failure with reduced ejection fraction (HFrEF) and an ejection fraction ≤35% who are on optimal medical therapy and are likely to live with a good functional status for more than about a year. ICDs reduce the risk of death from ventricular arrhythmias in this group, even though they don’t improve symptoms of heart failure itself.

This is not applied to all heart failure patients, nor to those with heart failure with preserved ejection fraction (HFpEF), where benefits have not shown the same level of evidence. ICDs are also used for secondary prevention in patients who have survived a ventricular tachycardia or ventricular fibrillation, but the scenario described targets the primary prevention indication.