Abstract
Objective: To explore the role of baroreflex sensitivity (BRS) in the head-up tilt test (HUTT) in predicting the therapeutic response of vasovagal syncope (VVS) patients to metoprolol.Materials and Methods: Vasovagal syncope patients treated with metoprolol were enrolled in this study and were classified as responders or non-responders according to changes in their symptom scores before and after metoprolol treatment. Values of BRS in the supine position and at positive response occurrence in the HUTT were obtained, and BRS changes from supine to positive response occurrence were calculated. Differences between responders and non-responders were analyzed. Receiver operating characteristic curve analysis was performed to assess the value of BRS for predicting the therapeutic efficacy of metoprolol in pediatric patients with VVS.Results: Forty patients (14 boys; 11.8 ± 2.5 years) diagnosed with VVS were recruited in the study, 28 of whom were verified to be responders to metoprolol and 12 of whom were verified as non-responders. They did not show any differences in baseline characteristics and hemodynamics in the HUTT (p > 0.05). However, the responders had an obviously increased supine BRS value compared to the non-responders (16.9 ± 7.7 ms/mmHg vs. 7.6 ± 3.8 ms/mmHg; p < 0.01). No difference in BRS at positive response occurrence was observed between the two groups (8.9 ± 8.5 ms/mmHg vs. 10.6 ± 9.8 ms/mmHg; p > 0.05). Accordingly, the changes in the BRS of responders were more obvious than in non-responders (8.0 ± 7.8 ms/mmHg vs. −3.0 ± 10.4 ms/mmHg; p < 0.01). The area under the receiver operating characteristic curve for the predictive value of supine BRS was 0.887 (95% CI, 0.779–0.995; p < 0.01). A cut-off value of 10 ms/mmHg yielded a sensitivity and specificity of 82 and 83%, respectively, in predicting the therapeutic efficacy of metoprolol in pediatric VVS patients. The area under the receiver operating characteristic curve for the predictive value of BRS changes was 0.827 (95% CI, 0.693–0.962; p < 0.01). A cut-off value of 4 ms/mmHg yielded a sensitivity and specificity of 71 and 83%, respectively.Conclusion: Baroreflex sensitivity may predict the response of children with VVS to metoprolol.
Highlights
Vasovagal syncope (VVS) is common in children and significantly affects their quality of life (Ng et al, 2019)
The inclusion criteria were as follows: (1) diagnosed with vasovagal syncope (VVS) based on existing guidelines (Wang et al, 2018); (2) having received metoprolol treatment after diagnosis; (3) complete data available on baroreflex sensitivity (BRS) and head-up tilt test (HUTT); and (4) having completed the followup process
A total of 40 children (14 boys; 11.8 ± 2.5 years) suffering from VVS with positive responses to HUTT were included in the study in accordance with the inclusion criteria
Summary
Vasovagal syncope (VVS) is common in children and significantly affects their quality of life (Ng et al, 2019). The mechanisms of VVS are not fully understood, excessive sympathetic tone is considered to be important in some cases, which provides a rationale for the use of beta-blockers as an indispensable therapeutic strategy (Sehra et al, 1999; Alehan et al, 2002; Pitzalis et al, 2003; Raj et al, 2016; Lee et al, 2017; Li et al, 2018; Tao et al, 2019c). There are some pediatric patients with VVS that have no obvious sympathetic activation (Hayoz et al, 1996; Mosqueda-Garcia et al, 1997; Thomson et al, 1997; Flevari et al, 2002; Huang et al, 2017), and beta-blockers only have a class III recommendation in pediatric VVS because of their inconsistent efficacy as well as their adverse effects (Shen et al, 2017; Brignole et al, 2018). The above facts suggest that there be an urgent need to seek out useful indicators to predict the patients who will respond to beta-blocker therapy before treatment
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