Heart failure is a progressive, heterogeneous form of cardiovascular disease that requires treatment to be individualized depending on the presenting symptoms. A decision to use an implantable cardioverter'defibrillator (ICD) is based on chronic heart failure patients presenting with a New York Heart Association classification of II or III and a left ventricular ejection fraction (LVEF) less than or equal to 30%'35%. A large percentage of ICD devices, however, never deliver therapy during their lifetime, and as many as 33% of patients ineligible for an ICD (LVEF > 35%) die of sudden cardiac death. 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy identifies sympathetic nervous system dysfunction and has been shown to lead to better patient stratification. This article reviews the role of planar 123I-MIBG global quantitation in improving differentiation of heart failure, regardless of the LVEF, to better identify those in whom an ICD is more likely to reap benefits. It goes on to explore the potential incremental benefit of SPECT-based regional quantitation to risk stratification and provides a case example in which 123I-MIBG SPECT was used to inform a decision to not use an ICD in a patient eligible under the standard criteria.