Benefit of ICD Generator Replacement

Study Questions:

Is there any benefit from implantable cardioverter-defibrillator (ICD) generator replacement (GR) in patients whose ejection fraction (EF) is no longer ≤35% or who have not yet received an appropriate ICD therapy?


This was a retrospective cohort study of 173 patients with an ICD for primary prevention of sudden death who underwent GR and then were followed for a mean of 2.9 years. One hundred forty-four patients (Group A) still had an EF ≤35% or had received an appropriate ICD therapy before the GR, and 29 patients (Group B) had an EF >35% and had not received any appropriate ICD therapies. The main outcomes were mortality and appropriate ICD therapies.


During follow-up after ICD GR, the mortality rate was significantly lower in Group B than in Group A (hazard ratio [HR], 0.39), as was the rate of appropriate ICD therapies (HR, 0.30). Five of the 29 patients in Group B experienced an appropriate ICD therapy after ICD GR. Their EFs were 36%, 38%, and 47% in three patients, and not measured at the time of GR in the other two patients.


In patients who have received a primary prevention ICD, the risk of death or ventricular tachycardia/fibrillation is significantly lower after GR among patients who no longer have an EF ≤35% and did not receive an appropriate ICD therapy before the GR.


It is disconcerting that an appropriate ICD therapy occurred in 5/29 patients in Group B. Unfortunately, there were only 29 patients in Group B and there was no control group of patients similar to the ones in Group B except for not having undergone GR. Given these major limitations, a firm conclusion on the need for GR in patients who no longer meet primary prevention criteria is not possible from this study.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure

Keywords: Arrhythmias, Cardiac, Death, Sudden, Defibrillators, Implantable, Heart Failure, Primary Prevention, Stroke Volume, Tachycardia, Ventricular, Ventricular Fibrillation

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