Blunted tachycardia and cardiac sympathetic denervation in isolated rapid eye movement sleep behavior disorder

• Published in: BMC neurology 2024-09, Vol.24 (1), p.317-17, Article 317
• Main Authors: Saeda, Shota, Sumi, Yukiyoshi, Fujiwara, Koichi, Kadotani, Hiroshi
• Format: Article
• Language: English
• Subjects: 3-Iodobenzylguanidine; Aged; Aged, 80 and over; Autonomic dysfunction; Autonomic nervous system; Autonomic neuropathies; Behavior; Behavior disorders; Blood pressure; Blunted tachycardia; Cardiac arrhythmia; Cardiovascular disease; Comorbidity; Complications and side effects; Computed tomography; Coronary artery disease; Dementia; Dementia disorders; Demographic aspects; Denervation; Diabetes; Diabetes mellitus; Diagnosis; Dopamine transporter; Eye movements; Female; Follow-Up Studies; Health aspects; Heart - innervation; Heart beat; Heart diseases; Heart rate; Humans; Hypertension; Hypotension; Investigations; Lewy bodies; Longitudinal study; Male; Medical research; Medicine, Experimental; Mental disorders; Mental illness; Middle Aged; Mortality; Movement disorders; Nervous system; Neurodegeneration; Neurodegenerative diseases; Nuclear medicine; Older people; Orthostatic hypotension; Parkinson's disease; Patients; Phenoconversion; Pramipexole; Psychotropic drugs; Rapid eye movement sleep behavior disorder; REM sleep; REM sleep behavior disorder; REM Sleep Behavior Disorder - diagnosis; Risk factors; Scintigraphy; Single photon emission computed tomography; Sleep; Sleep disorders; SPECT imaging; Sympathectomy; Sympathectomy - methods; Tachycardia; Tachycardia - diagnosis; Tomography, Emission-Computed, Single-Photon - methods
• ISSN: 1471-2377; 1471-2377
• DOI: 10.1186/s12883-024-03822-w

Isolated rapid eye movement sleep behavior disorder (iRBD) serves as a prodromal phase of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Blunted tachycardia (BT) during postural changes indicates neurogenic orthostatic hypotension, a marker of autonomic dysfunction. We aimed to investigate whether BT is associated with cardiac sympathetic neurogenic denervation. Additionally, we conducted a preliminary short-term follow-up to examine the potential prognostic significance of BT regarding phenoconversion and mortality. Forty-three patients with iRBD at Shiga University of Medical Science Hospital underwent active standing tests to identify BT, defined by a specific ratio of decrease in systolic blood pressure to inadequate increase in heart rate after standing, and orthostatic hypotension. I-metaiodobenzylguanidine myocardial scintigraphy ( I-MIBG) and dopamine transporter single-photon emission computed tomography (DAT-SPECT) were performed. Participants were followed up for 3.4 ± 2.4 years for phenoconversion and 4.0 ± 2.3 years for mortality assessment, and the risk of events was analyzed using log-rank tests. Among the 43 participants (mean age, 72.3 ± 7.9 years; 8 female), 17 met the BT criteria. We found no significant comorbidity-related differences in hypertension or diabetes between the BT(+) and BT(-) groups. Orthostatic hypotension was more prevalent in the BT(+) group than in the BT(-) group (47.1% vs 7.7%, p = 0.003). BT(+) patients were older with a lower early and delayed MIBG uptake; however, no significant differences were observed in DAT accumulation. Phenoconversion was observed in seven (41.2%) BT(+) and seven (26.9%) BT(-) patients. Three deaths were recorded in the BT(+) group (17.6%) and three in the BT(-) group (11.5%). No significant differences were observed in the risk of phenoconversion or mortality between the groups. We have identified the possibility that BT reflects cardiac sympathetic neurogenic denervation in patients with iRBD. Future research is needed to elucidate the potential prognostic value of BT.