This new finding stems from the largest and most comprehensive study of ICD use to prevent sudden death in patients with mild to moderate heart failure --Sudden Cardiac Death in Heart Failure Trial, SCD-HeFT-- the results of which were published in the New England Journal of Medicine in 2005. Implantable heart defibrillators or implantable cardioverter-defibrillators (ICDs), as they are known, are small battery-powered generators that are implanted in patients who are at risk of sudden cardiac death due to ventricular fibrillation.

That study demonstrated a clear survival advantage for patients treated with an ICD and medications for heart failure therapy compared to patients treated only with medications for heart failure.