International Study to Determine if AdreView Heart Function Scan Can be Used to Identify Patients With Mild or Moderate Heart Failure (HF) That Benefit From Implanted Medical Device

Inclusion Criteria:

• Participants >=18 years of age at the time dated informed consent was obtained.

• Female participants must be pre-menarchal, surgically sterile (had a documentedbilateral oophorectomy and/or documented hysterectomy), postmenopausal (cessation ofmenses for more than 1 year), non-lactating, or, if of childbearing potential, a serumor urine pregnancy test with the results known prior to AdreView (Iobenguane I-123Injection) administration) was negative.

• Participants willing and able to comply with all study procedures and a signed anddated informed consent was obtained before any study-procedure was carried out.

• Heart failure NYHA class II or III for symptoms, participants with ischemic ornon-ischemic heart disease, eligible for ICD implantation as per each site's standardof practice.

• Non-ischemic dilated cardiomyopathy or ischemic heart disease of at least 3 monthsduration receiving guideline-directed optimal medical therapy.

• 25%≤LVEF≤35%, performed within 3 months before or at time of enrollment, as measuredby radionuclide ventriculography, or electrocardiogram [ECG]-gated SPECT myocardialperfusion imaging [MPI], or magnetic resonance imaging [MR], computed tomography [CT],or 3D or 2D echocardiography [Simpson's or multidisc method only, M-modeechocardiography was not accepted]. In case LVEF measurement was performed within 3 months before enrollment, measurementshould be performed at least 40 days after a hospitalization for HF or acute coronarysyndrome (including myocardial infarction), and to be valid, method of measurement shouldbe in accordance with the protocol and the imaging exam should be made available to theSponsor in digital format. In case several valid LVEF measurements are available, theclosest to enrollment will be used for inclusion determination.

• Clinically stable heart failure in the medical judgment of the investigator (i.e. nosignificant changes in medication, no worsening of symptoms, no unscheduled visits tothe doctor's office) for the past 30 days and no hospitalization for heart failure oracute coronary syndrome (including myocardial infarction) in the past 40 days.

• Reasonable expectation of meaningful survival for at least 1 year.

Exclusion Criteria:

• Participants with existing ICD or participant having an indication of ICD implantationfor secondary prevention of sudden cardiac death.

• Hospitalization for HF or for acute coronary syndrome in the previous 40 days.

• Participants where a cardiac resynchronisation therapy (CRT) was planned or indicated.

• Other indication for placement of device (sustained ventricular tachycardia,resuscitated sudden death, need for atrioventricular pacing).

• NYHA class I or class IV symptoms at the time of study entry.

• Participants with chronic renal insufficiency defined as serum creatinine ≥ 3 mg/dl (or ≥ 265.2 µmol/L).

• American College of College-American Heart Association (ACC-AHA) class III or class IV (unstable) angina.

• Known or suspected hypersensitivity/allergy to Iobenguane or to any of the excipientsan Adreview (Iobenguane I-131 injection).

• Participant who was pregnant or plans to become pregnant within 2 weeks after AdreView (Iobenguane I-123 Injection) administration.

• Participant who had used any medication in the 2 weeks before AdreView (IobenguaneI-123 Injection) that could interfere with the test: e.g. but not limited toamitriptyline or derivatives, imipramine or derivatives, other antidepressants ordrugs known or suspected to inhibit the norepinephrine transporter, antihypertensivesthat deplete norepinephrine stores or inhibit reuptake, sympathomimetic amines orcocaine.

• Participants that had a medical condition that could interfere with the AdreView test (e.g. but not limited to left ventricular assist device (LVAD), or prior hearttransplant).

• Participants who participated in a clinical study involving a drug or device within 30days prior to study entry and participants participating in any other clinical study.

• Participants having serious non-cardiac medical condition associated with significantelevation of plasma catecholamines, including pheochromocytoma.

• Participants with a clinical diagnosis of (or being treated for) Parkinson's diseaseor Multiple System Atrophy.

• The participant had participated in a research study using ionizing radiation in theprevious 12 months.

• Participants previously randomized in this study.