Open-label, Test-retest Study Assessing Reproducibility of Quantitative Measurements of Myocardial Uptake of AdreView.

Inclusion Criteria: * The participant was originally diagnosed with New York Heart Association (NYHA) Class II-III HF due to ischemic heart disease at least 3 months or due to non-ischemic cardiomyopathy at least 6 months before enrollment into the study. * The participant had Left Ventricular (LV) dysfunction with Left Ventricular Ejection Fraction (LVEF) less than or equal to 35% measured by an appropriate method (e.g., radionuclide or contrast ventriculography, electrocardiogram \[ECG\]-gated SPECT myocardial perfusion imaging \[MPI\], magnetic resonance \[MR\] imaging, computed tomography \[CT\] or echocardiography) within 6 months of enrollment into the study and documented in the participant's medical record. * The participant had a history of compliance with prescribed heart failure (HF) medications and took HF guidelines-based medication at study entry including at a minimum a beta-blocker and either an angiotensin converting enzyme inhibitor or angiotensin receptor antagonist unless documented to be intolerant to any of these classes of medications. * The participant had been on a stable medical regimen for a minimum of 3 months, with no hospitalizations or change in HF medications or HF symptoms. * Participants must be clinically stable for at least 7 days before enrolling into the study (e.g., not experiencing continuing chest pain or hemodynamic instability). Exclusion Criteria: * The participant had previously received 123 I-mIBG or 131 I-mIBG. * The participant had known or suspected hypersensitivity/allergy to iodine, Iobenguane or to any of the excipients in AdreView. * The participant had a heart transplant at any time prior to enrollment. * The participant had LVEF \>35% as measured by an appropriate method (e.g., radionuclide or contrast ventriculography, ECG-gated SPECT MPI, MR, CT, or echocardiography) within 30 days prior to enrollment into the study. * The participant had received defibrillation either external or via an implantable cardioverter defibrillator (ICD), anti-tachycardia pacing, or cardioversion to treat an arrhythmic event in the previous 90 days. * The participant had a cardiac revascularization, insertion of an ICD, or acute myocardial infarction within 30 days before study entry. * The participant used any of the following medications: Amitriptyline and derivatives, imipramine and derivatives, other antidepressants that inhibit the norepinephrine transporter, antihypertensives that deplete norepinephrine stores or inhibit reuptake, sympathomimetic amines and cocaine. * The participant had either NYHA Class I or NYHA Class IV HF at the time of study entry. * The participant had renal insufficiency (creatinine \>3 mg/dl). * The participant had participated in a clinical trial involving IMP or devices within 30 days prior to first administration of AdreView™. * In the investigator's opinion, the participant's medical history included either extensive lifetime exposure to ionizing radiation (medical, occupational, other) or documented total radiation dose \>50 mSv during the previous 5 years. * The participant had experienced HF hospitalization, increased HF symptoms without hospitalization, or had a change or increase in HF medications during the previous 3 months. * The participant had a serious non-cardiac medical condition associated with significant elevation of plasma catecholamines, including pheochromocytoma.