Excerpt

Heart failure (HF) affects over 5 million people in the United States, and while survival has improved, mortality remains high, with approximately 50% survival within 5 years of diagnosis.1 The American Heart Association estimates that prevalence of HF will increase 25% by 2030.1 Patients with HF and reduced ejection fraction are at risk of ventricular arrhythmias and sudden cardiac death (SCD), and current guidelines on treatment of systolic heart failure recommend implantable cardioverter defibrillator (ICD) for primary prevention of SCD in a select group of patients.2,3 The decision-making regarding placement of ICD is complex because the therapy is invasive and associated with risks, is expensive, and is not suitable for every patient. A large proportion of patients (≈80%) with HF and reduced EF never require an ICD shock,4 and in ≈15% of patients, inappropriate ICD therapy occurs.5 Thus, tools to help further risk stratify which HF patient is at high risk of SCD and is likely to benefit from an ICD placement would be invaluable. It has been shown that cardiac innervation is an important factor related to lethal arrhythmias.6 Myocardial scintigraphy performed with Iodine-123-meta-iodobenzylguanidine (MIBG) is an imaging technique developed over 3 decades ago, capable of assessing the sympathetic denervation of the heart.7 MIBG is a well-established analog of norepinephrine, and abnormal MIBG uptake indicates abnormal cardiac sympathetic activity. Several large studies have evaluated the relationship between MIBG and EF with respect to adverse cardiac outcomes.8,9 These studies have shown that MIBG provides incremental prognostic information over EF in predicting cardiac death. Further, results of MIBG imaging have been shown to correlate with the occurrence of appropriate ICD shocks—patients with appropriate device discharges had significantly lower MIBG uptake as measured by traditional planar techniques.10,11 …