Key result
Lower 24-hour average heart rate is linked to ~7% higher odds of vasovagal syncope.
Why the study?
Heart rate variability may have practical value in identifying vasovagal syncope and its subtypes, but its predictive utility has not been fully elucidated.
Do heart rate variability parameters predict the occurrence and subtypes of vasovagal syncope in patients with syncope symptoms?
Case-Control (n=415)
No
Do heart rate variability parameters predict the occurrence and subtypes of vasovagal syncope in patients with syncope symptoms?
Odds Ratio: 0.935 (95% CI 0.912–0.959)
Absolute Event Rate: 72% vs 77%
p-value: p=<0.001
Heart rate variability parameters, particularly 24-hour average heart rate and SDNN, are independently associated with vasovagal syncope and may aid in its noninvasive clinical screening and phenotypic classification.
May support HRV in VVS risk assessment; hypothesis-generating and requires prospective validation.
Background Vasovagal syncope (VVS) is the most common type of reflex syncope. Although typically benign in its clinical course, VVS may lead to injury and reduced quality of life. Autonomic nervous system imbalance is considered the core pathophysiological mechanism of VVS. Heart rate variability (HRV), a noninvasive marker of autonomic regulation, may have practical value in identifying VVS and its subtypes; however, its predictive utility has not been fully elucidated. Methods In this single-center retrospective case-control study, we included 415 patients with syncope symptoms who underwent both 24-hour Holter monitoring and a head-up tilt test (HUTT) between January 2021 and December 2024. Based on HUTT results, patients were classified into a VVS-positive group ( n = 279) and a control group ( n = 136). HRV parameters extracted from Holter recordings included 24 h average, maximum and minimum heart rates (HRs), standard deviation of NN intervals (SDNN), triangular index (TI), root mean square of successive differences (rMSSD), and the percentage of NN intervals differing by more than 50 ms (pNN50). Associations and predictive performance were assessed using logistic regression and receiver operating characteristic (ROC) analysis. Results Multivariable logistic regression revealed that 24 h average HRs (OR: 0.935; 95% CI: 0.912–0.959; P < 0.001), 24 h maximum HRs (OR: 0.976; 95% CI: 0.964–0.989; P < 0.001), 24 h minimum HRs (OR: 0.947; 95% CI: 0.915–0.980; P = 0.002), TI (OR: 1.032; 95% CI: 1.009–1.056; P = 0.006), SDNN (OR: 1.029; 95% CI: 1.016–1.043; P < 0.001), rMSSD (OR: 1.023; 95% CI: 1.007–1.038; P = 0.004), and pNN50 (OR: 1.028; 95% CI: 1.006–1.051; P = 0.013) were independently associated with the occurrence of VVS. ROC analysis showed that 24 h average HRs (AUC: 0.688; 95% CI: 0.632–0.744), 24 h maximum HRs (AUC: 0.652; 95% CI: 0.594–0.709), and SDNN (AUC: 0.614; 95% CI: 0.557–0.672) exhibited moderate predictive ability for VVS. Conclusion HRV parameters are associated with the occurrence of VVS. As a noninvasive and continuous physiological biomarker, HRV may aid in the clinical screening, risk stratification, and phenotypic classification of patients with suspected VVS.
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Yusufuaji et al. (2026) conducted a case-control in Vasovagal syncope (n=415). Heart rate variability parameters (e.g., 24 h average HR) vs. Patients with negative head-up tilt test (control group) was evaluated on Occurrence of vasovagal syncope (positive head-up tilt test) (OR 0.935, 95% CI 0.912-0.959, p=<0.001). Lower 24-hour average heart rate (OR 0.935) and higher SDNN (OR 1.029) were independently associated with the occurrence of vasovagal syncope.
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