When is ICD therapy recommended for primary prevention?

ICD therapy, or Implantable Cardioverter Defibrillator therapy, is recommended for primary prevention in patients who have a left ventricular ejection fraction (LVEF) of 35% or less and are experiencing symptoms classified as New York Heart Association (NYHA) class 2 or 3, despite being treated with guideline-directed medical therapy. This patient population is at a higher risk for sudden cardiac death due to ventricular arrhythmias, and the use of an ICD can help prevent these fatal arrhythmias from occurring.

Patients who meet these criteria show that they have a significant reduction in their heart's pumping ability (as indicated by the low LVEF) and still present with mild to moderate symptoms such as fatigue or shortness of breath during ordinary physical activity (NYHA class 2-3). The combination of these factors justifies the proactive approach of placing an ICD in order to reduce the risk of sudden cardiac death even before a patient experiences life-threatening arrhythmias.

In contrast, the other options do not meet the established criteria for ICD therapy in primary prevention. For example, having an LVEF greater than 35% means that the patient is at a lower risk for sudden death and would not typically warrant an ICD