ICD Patients

This is a Phase 2 study evaluating the positron-emitting radiopharmaceutical 18F-mFBG as an imaging agent for quantification of myocardial sympathetic innervation. The study will examine a group of stable patients with heart failure (HF) from ischemic cardiomyopathy. All subjects will have left ventricular ejection fraction (LVEF) ≤35% and implantable cardioverter-defibrillators (ICD). The primary objectives of the study will be to: * document the degree to which 18F-mFBG uptake in the heart is reduced (compared to historical controls) * characterize the distribution of regional abnormalities in relation to findings on rest/stress positron-emission tomography (PET) myocardial perfusion imaging (MPI) * determine if there are global and/or regional differences in myocardial sympathetic innervation between subjects who have and have not experienced an appropriate ICD activation within the previous 12 months Effectiveness of 18F-mFBG will be judged in relation to historical experience with other nuclear imaging agents for cardiac sympathetic innervation imaging such as a 123I-meta-iodobenzylguanidine (mIBG) and 11C-hydroxyephedrine (HED). Safety data will be collected to identify adverse events \[AEs\] and serious adverse events \[SAEs\] and characterize the safety profile of 18F-mFBG.