Applications of PET Cardiac Neurotransmission Imaging in Heart Failure

Congestive heart failure is a very serious disease that affects many people. Increased sympathetic tone, noradrenaline release, decreased neuronal noradrenaline transporter function and noradrenaline concentration are present in the failing heart. An impairment of sympathetic and parasympathetic function increases the risk of mortality in patients with heart disease. Non invasive imaging modalities are used to evaluate heart failure patients like echocardiography, magnetic resonance imaging and radioisotopique techniques. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are now used for the assessment of the cardiac sympathetic and parasympathetic function. SPECT imaging with 123I metaiodobenzylguanidine is a very useful modality for patients with abnormal cardiac sympathetic function but its role in the quantitative assessment of myocardial autonomic nervous system is limited due to the relative low spatial resolution. PET, the new functional imaging modality, offers more detailed information about the biology of the heart failure helping to the accurate detection, and monitoring of dedicated therapeutic procedures. Another advantage of PET is that multiple tracers may be used providing deeper insights into nerve biology, such as tracers of sympathetic neuronal integrity [11C-hydroxyephedrine (11C-HED), 11C-epinephrine (11C-EPI), 11C-phenyl- -phrine (11C-PHE) etc.], tracers of adrenergic receptors (11C-CGP12177, 11C-CGP 12388, 11C-GB 67), and tracers of parasympathetic integrity (vesamicol derivatives etc.). PET can assess the sympathetic innervation and activation of the heart. Therefore, clinical applications in heart failure patients include risk stratification, assessment of ventricular arrhythmias and of risk of sudden cardiac death, identification of patients who should undergo implantation of defibrillators and therapy assessment.