Imaging of Cardiac Autonomic Innervation with SPECT and PET

Heart failure (HF) is a condition with high mortality and morbidity. A major component of HF pathophysiology is the body’s neurohormonal response that includes activation of the sympathetic nervous system. Imaging of cardiac sympathetic innervation with a radionuclide tracer, such as the extensively studied norepinephrine analogue ¹²³I-meta-iodiobenzylguanidine (¹²³I-mIBG), provides unique insights into a patient’s condition. Cardiac uptake of ¹²³I-mIBG, measured as a heart to mediastinal ratio (H/M), has consistently been shown to correlate with poor outcome and predisposition to cardiac arrhythmias independent of conventional clinical, laboratory, and heart function parameters. ¹²³I-mIBG imaging promises to help monitor a patient’s clinical course and response to therapy, and shows potential to improve patient selection for advanced therapies such as ICDs, LVADs, and transplant. Imaging regional abnormalities, although less studied, shows promise for more precisely identifying patients at risk for arrhythmias, and higher resolution PET tracers such as ¹¹C-HED and ¹⁸ F-LMI1195 show potential.