Conventional radionuclide imaging of autonomic function in heart failure

Conventional nuclear imaging with single-photon emitting radionuclides can be used for qualitative and quantitative assessment of cardiac autonomic function in patients with heart failure. Status of sympathetic innervation can be assessed using [ ¹²³ I]-metaiodobenzylguanidine ([ ¹²³ I]-MIBG), an analogue of norepinephrine. Reduced myocardial [ ¹²³ I]-MIBG uptake is common in heart failure patients, and the severity of global and regional abnormalities is indicative of the level of risk for mortality and occurrence of ventricular arrhythmias. [ ¹²³ I]-MIBG imaging can identify early damage from cardiotoxic chemotherapy and early evidence of reinnervation in transplanted hearts. The extent of [ ¹²³ I]-MIBG tomographic defects provides an indicator of the likelihood of appropriate implantable cardioverter-defibrillator (ICD) activation and may be useful in assessment of patients being considered for these devices. In the future, [ ¹²³ I]-MIBG imaging may provide a non-invasive means to evaluate the effectiveness of heart failure treatments that reduce autonomic nervous system imbalances common in heart failure patients.