Iodine-123-metaiodobenzylguanidine scintigraphy in risk stratification of sudden death in heart failure.

Metaiodobenzylguanidine (MIBG) is a false neurotransmitter noradrenaline analogue that is taken up by the 'uptake 1' transporter mechanism in the cell membrane of presynaptic adrenergic neurons and accumulates in catecholamine storage vesicles. Since it is practically unmetabolized, it can be labeled with a radioisotope (iodine-123) in scintigraphic exams to noninvasively assess the functional status of the sympathetic innervation of organs with a significant adrenergic component, including the heart. Studies of its application in nuclear cardiology appear to confirm its value in the assessment of conditions such as coronary artery disease, heart failure, arrhythmias and sudden death. Heart failure is a global problem, with an estimated prevalence of 2% in developed countries. Sudden cardiac death is the main cause of its high mortality. The autonomic nervous system dysfunction, including sympathetic hyperactivity, that accompanies chronic heart failure is associated with progressive myocardial remodeling, declining left ventricular function and worsening symptoms, and contributes to the development of ventricular arrhythmias and sudden death. Since 123I-MIBG cardiac scintigraphy can detect changes in the cardiac adrenergic system, there is considerable interest in its role in obtaining diagnostic and prognostic information in patients with heart failure. In this article we present a literature review on the use of 123I-MIBG scintigraphy for risk stratification of sudden death in patients with heart failure.