Friedman DJ, et al. - Researchers explored the link between baseline and long-term follow-up left ventricular ejection fraction (LVEF) and clinical outcomes among patients with a primary prevention implantable cardioverter defibrillator (ICD). Follow-up LVEF was examined 1–3 years after ICD implantation using 2 definitions: ≥10% improvement compared to baseline or actual value of ≥40%. Both baseline and follow-up LVEF were found to be independently related to long-term risk for appropriate ICD therapy, but not to time to the composite of left ventricular assist device (LVAD), transplant, or death among patients with a baseline LVEF≤35% ≤6 months prior to ICD implantation. Among primary prevention ICD recipients, both baseline and follow-up LVEF were independently associated with long-term risk for appropriate ICD therapy, but they were not associated with time to the composite of LVAD, transplant, or death.