This review focuses on myocardial [(123)I]mIBG imaging in patients with cardiomyopathy and heart failure (HF). In particular, the potential role of myocardial (123)I-mIBG scintigraphy in the prediction of potentially fatal arrhythmic events is described. A growing body of evidence supports the use of cardiac sympathetic innervation imaging, specifically using (123)I-mIBG, to risk stratify patients with HF. Cardiac sympathetic imaging can help to improve understanding of the mechanisms responsible for increased sympathetic activity in HF, and how sympathetic over-activity exerts its deleterious actions. Eventually, this may result in more effective therapies and, thereby, better outcome for these patients. Assessment of cardiac sympathetic activity could also contribute to a more appropriate selection of individual patients for implantable cardioverter-defibrillators (ICD).