How do we establish cardiac sympathetic nervous system imaging with ¹²³I-mIBG in clinical practice? Perspectives and lessons from Japan and the US

Cardiac denervation is associated with progressive left ventricular (LV) dysfunction, ventricular arrhythmias, and sudden cardiac death (SCD) in heart failure (HF). In this regard, it is important to evaluate cardiac-specific sympathetic nervous system (SNS) function. The radiotracer Iodine-123 meta-iodobenzylguanidine (¹²³I-mIBG) can noninvasively evaluate pre-synaptic SNS function. Recent multicenter trials have shown ¹²³I-mIBG to have strong predictive value for fatal arrhythmias and cardiac death in HF. ¹²³I-mIBG was initially developed in the USA in the 1970s. In 1992, the Japanese Ministry of Health and Labour approved ¹²³I-mIBG for the assessment of cardiac function. Following approval, the Japanese nuclear cardiology community developed ¹²³I-mIBG imaging services in various medical centers. Japanese groups have been trying to establish the clinical utility of ¹²³I-mIBG and standardize parameters for data acquisition and image analysis. The US Food and Drug Administration (FDA) has approved clinical use of ¹²³I-mIBG for cardiac and non-cardiac imaging. However, clinical use of ¹²³I-mIBG in the US has been very limited. The number of ¹²³I-mIBG studies in Japan has also been limited. There are similarities and differences between the two countries. To establish the clinical utility of ¹²³I-mIBG in both countries, it is important to characterize the situations of ¹²³I-mIBG in each.