Heart failure has become a worldwide pandemic, with high morbidity and
mortality, and also high costs. While better therapies are improving outcomes, many of
the treatments are invasive and expensive, particularly cardiac implantable electronic
devices (CIEDs). As the effectiveness of many pharmacologic therapies are attributed
to their addressing the neurohormonal pathophysiology underlying heart failure, one
would expect that using CIEDs based on neurohormonal parameters would provide
more effective use of them. An important component of the neurohormonal system is
cardiac adrenergic innervation that can be imaged with single photon radiotracers such
as iodine-123 metaiodobenzylguanidine (123I-mIBG) and analogous positron emission
(PET) tracers such as carbon-11-metahydroxyephedrine (11C-HED). Adrenergic
imaging has consistently been shown to effectively risk stratify patients with heart
failure with reduced ejection fraction (HFrEF), and it does so independently of, and in
many cases better than, customarily used parameters. In addition, adrenergic imaging
has been shown to effectively and independently stratify HFrEF patients in terms of the
risk of a lethal ventricular arrhythmic event. For therapeutic guidance, while adrenergic
imaging is unlikely to influence institution of guidelines directed pharmacologic
treatments, there is much evidence of a potential to help guide use of CIEDs such as
biventricular pacemakers for cardiac resynchronization therapy (CRT), ventricular
assist devices for end-stage HFrEF (LVAD), and implantable cardioverter defibrillators
(ICDs). In particular, 123I-mIBG imaging parameters appear to follow a patient’s
clinical response to CRT and perhaps could better identify which patients are more
likely to benefit. 123I-mIBG imaging parameters, by identifying when pharmacologic
therapy is failing, could show earlier in the disease course when LVAD would be
beneficial, and then later help determine when or if patients who already have the
device have achieved reverse ventricular remodeling sufficient to consider LVAD
explantation. Finally, evidence indicates that adrenergic imaging should be able to
more effectively guide use of ICDs than current recommendations that are based
largely on ejection fraction, with imaging especially able to identify patients who are very unlikely to benefit from this device that has underappreciated morbidities. In
addition, with regard to addressing ventricular arrhythmias, there are studies reporting
benefits of adrenergic imaging for guidance of invasive electrophysiological
therapeutic procedures. Thus, while CIEDs have provided tremendous benefit to people
with advanced heart failure, with technologic advances continuously occurring,
radionuclide adrenergic imaging shows much promise in more effectively guiding use
of these devices.
Keywords: Adrenergic Innervation, Autonomic Nervous System, Cardiac
Resynchronization Therapy (CRT), Cardiac Implantable Electronic Device
(CIED), Heart Failure, 123I-mIBG, Implantable Cardioverter Defibrillator (ICD),
Left Ventricular Assist Device (LVAD), Radionuclide Adrenergic Imaging,
Ventricular Arrhythmias.
