What indication warrants the use of an implantable cardioverter-defibrillator (AICD)?

The indication for using an implantable cardioverter-defibrillator (AICD) is primarily associated with the risk of life-threatening arrhythmias, particularly in patients with a significantly reduced ejection fraction. When a patient's ejection fraction falls below 35%, it indicates a severe reduction in the heart's ability to pump blood effectively, often related to heart failure or prior myocardial infarctions. This diminished cardiac function is a significant risk factor for the development of ventricular tachycardia or ventricular fibrillation, which can lead to sudden cardiac death.

The AICD serves to monitor the heart's rhythm continuously and can deliver shocks to restore a normal rhythm if a dangerous arrhythmia is detected. This capability is critical for patients with compromised ventricular function, providing a preventive measure against the potentially fatal outcomes associated with these arrhythmias.

In contrast, conditions like stable angina, intolerable bradycardia, and hypertension do not inherently carry the same high risk of sudden cardiac death or malignant arrhythmias that would necessitate the implantation of an AICD. Stable angina typically indicates coronary artery disease but doesn't alone warrant arrhythmia risk management through an AICD. Intolerable bradycardia may be managed with pacing devices