The aim of the study was to assess the reproducibility of quantitative measurements of myocardial uptake of Iobenguane I 123 on planar and single photon emission computed tomography (SPECT) imaging following intravenous (i.v.) administration of AdreView. Efficacy was assessed based upon the absolute differences between quantitative analyses of imaging data on 2 scans performed 5 to 14 days apart.

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.

Safety population defined as all enrolled participants who received at least 1 administration of AdreView (Iobenguane I 123 Injection).

From Baseline up to discharge from hospital on each dosing.

Adverse events (AEs) reported were treatment emergent adverse events (TEAEs) that were AEs that begins (or a pre-existing AE that worsens) after receiving investigational medicinal product through the time of discharge on each dosing day.