Cardiac autonomic imaging may play an important role in the management of heart disease, and it can be imaged with the norepinephrine radiotracer analogue iodine-123 meta-iodobenzylguanidine (123I-mIBG) and analogous positron emission tomography (PET) tracers.
Global and regional cardiac uptake and retention of 123I-mIBG and PET tracers have been robustly shown to effectively and independently risk stratify patients who have heart failure with reduced ejection fraction for occurrence of adverse cardiac events including potentially lethal ventricular arrhythmias.
Cardiac adrenergic imaging shows promise for guiding therapy, particularly for use of an implantable cardioverter defibrillator.
There is potential to use adrenergic imaging in a multimodality imaging protocol for improving the effectiveness of invasive antiarrhythmic therapeutic procedures.
It is recognized by many in the field of nuclear cardiology that in order to thrive and advance, the discipline needs to go beyond myocardial perfusion imaging (MPI). The high diagnostic and risk stratification utilities of radionuclide single-photon emission computed tomography (SPECT) and positron emission tomography (PET) MPI are well established, with numerous studies providing evidence that performing and properly acting upon the results of MPI can lead to improved patient outcome.1–7 Nevertheless, there is an increased focus on developing techniques that rely on the ability of the imaging modality to depict underlying molecular processes of cardiac disease, thereby expanding the field beyond imaging myocardial perfusion for assessment of coronary artery disease.8 For example, there is much current focus on heart failure (HF), left ventricular dysfunction and structural abnormalities, and associated arrhythmias, conditions that are widely and increasingly prevalent, and that cause much cardiovascular morbidity and mortality. The ability of radiotracer imaging to assess the underlying pathophysiology of these conditions is potentially extremely advantageous in managing patients.9 Among such radionuclide imaging techniques is the assessment of cardiac autonomic innervation that portrays aspects of cardiac pathophysiology not detected by conventional evaluation methods, thereby promising to better direct therapies, particularly invasive and costly cardiac implantable electronic devices (CIEDs).10,11 Radionuclide imaging of myocardial innervation has shown promise for uniquely helping to manage patients with cardiac disease in ways that that can lengthen life, reduce adverse events, and improve well-being. This chapter will describe the scientific basis of SPECT and PET radionuclide adrenergic neuronal imaging, detail the methodology of image acquisition and interpretation, and discuss the evidence for the ability of this imaging technique to evaluate and risk stratify patients with HF and associated ventricular arrhythmias, with a focus on how such image findings could potentially guide patient management better than current techniques. Discussions will also briefly mention other cardiac conditions for which adrenergic imaging might be helpful, and touch on technologic advances that promise to enhance the technique’s clinical utility.
NEUROHORMONAL REGULATION OF THE CARDIOVASCULAR SYSTEM
Regulation of the cardiovascular system involves both circulating hormones and direct innervation.12,13 Hormones include epinephrine, norepinephrine (NE), arginine vasopressin, ...