Cardiac MIBG scintigraphy in pure autonomic failure: A systematic review.

[BACKGROUND] Pure autonomic failure (PAF) is an α-synucleinopathy affecting the autonomic nervous system, which may remain confined to the peripheral nervous system or represent a premotor/precognitive phase of Parkinson's disease (PD), dementia with Lewy bodies (DLB), or multiple system atrophy (MSA). Despite the recognised role of cardiac I-metaiodobenzylguanidine (MIBG) scintigraphy in central nervous system synucleinopathies, its application in PAF has been described only in a few case reports or small case series.

[OBJECTIVE] To assess the potential diagnostic and prognostic utility of cardiac MIBG scintigraphy in patients with PAF.

[METHODS] We conducted a systematic review of case reports and case series describing patients with a clinical diagnosis of PAF who underwent cardiac MIBG scintigraphy, in accordance with PRISMA guidelines. Demographic, clinical, and scintigraphic data were extracted and summarised.

[RESULTS] A total of 39 cases were included: 38 from the literature and one unpublished case from our centre. The cohort comprised 28 men and 11 women, with a mean age of 67.6 ± 8.1 years and a mean disease duration of 9.1 ± 6.2 years. Abnormal MIBG scintigraphy was observed in 33 patients (84.6 %). Following MIBG scintigraphy, phenoconversion to a central nervous system synucleinopathy was reported in 3 cases with abnormal MIBG uptake (2 to PD, 1 to DLB) and 5 cases with normal MIBG uptake (4 to MSA, 1 to PD).

[CONCLUSIONS] MIBG scintigraphy showed abnormal cardiac uptake in most patients with clinical PAF. Conversely, preserved MIBG uptake may be associated with a high probability of phenoconversion, particularly to MSA.