頭部傾斜試験に対する反応が異なる血管迷走神経失神患者における減速能力で定量化された迷走神経緊張との関連
Pakezhati Maimaitijiang1, Xinyi Wang1, Tao Zhang1
1Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, China.
Background:
Vasovagal syncope (VVS) involves autonomic dysregulation. Cardiac deceleration capacity (DC) is a metric of vagal activity with potential application in VVS. Although the head-up tilt test (HUT) categorizes VVS into vasodepressor, cardioinhibitory, and mixed subtypes, the characteristics of subtype-specific DC-quantified vagal tone remain unclear.
Objective:
This study aimed to investigate the relationship between DC and HUT-based VVS subtypes, elucidating discrepancies in vagal tone among patients with VVS.
Methods:
This observational study enrolled 264 patients with VVS and 127 asymptomatic controls. All participants underwent 24-hour Holter monitoring. Patients with VVS were classified by HUT responses. Multinomial logistic regression analysis was performed to assess DC's association with VVS subtypes. Receiver operating characteristic analysis was performed for DC to identify vasodepressor VVS.
Results:
Patients with VVS showed significantly higher DC than controls (8.28 ± 2.77 ms vs. 5.65 ± 1.07 ms; P < .001). Among patients with VVS, significantly lower DC was observed in vasodepressor VVS than cardioinhibitory, mixed, and HUT-negative VVS (P < .001). Multinomial analysis revealed DC's association with cardioinhibitory (odds ratio per 1-ms increase [95% confidence interval] 2.88 [2.17-3.82]), mixed (3.06 [2.32-4.04]), and HUT-negative VVS (3.12 [2.31-4.21]) was stronger than that with vasodepressor VVS (1.91 [1.42-2.58]). Receiver operating characteristic analysis showed DC's discriminative power for vasodepressor VVS (area under the curve 0.753), and DC of <7.8 ms achieved 82.5% sensitivity and 92.5% negative predictive value.
Conclusion:
Enhanced DC-quantified vagal tone is differentially associated with VVS subtypes. DC could serve as a practical tool for VVS classification without reproducing syncopal symptoms, potentially guiding phenotype-specific therapeutic strategies for VVS.
