A higher peak heart rate during head-up tilt test predicts the therapeutic efficacy of metoprolol in vasovagal syncope

BACKGROUND: Although beta blockers, such as metoprolol, have been widely used in the management of vasovagal syncope (VVS), their efficacy remains debated, with larger studies showing limited benefit. Identifying patient-specific characteristics that predict a positive response to metoprolol could optimize its use. This study aims to investigate the key factors that may determine which VVS patients are suitable candidates for metoprolol treatment. METHODS: This retrospective study was conducted at a single center. Patients diagnosed with VVS and treated with metoprolol for a minimum of three months were included. A 50% reduction in syncope symptom score (SS) after three months of metoprolol treatment was used to define metoprolol responders, while those who did not achieve this reduction were classified as non-responders. After a three-month follow-up, patients were divided into two groups: responders and non-responders. Baseline data-including age, gender, comorbidities, laboratory tests, and the type of VVS-were analyzed for each patient. Changes in heart rate (HR) and blood pressure during the head-up tilt test (HUTT) were also evaluated between the two groups. Logistic regression analysis was performed to identify potential predictors of metoprolol response, and receiver operating characteristic (ROC) curve analysis was used to assess the value of these predictors in selecting potential responders. RESULTS: A total of 168 VVS patients were enrolled between January 2016 and December 2020. Of these, 100 patients responded positively to metoprolol, while 68 did not. No significant differences in baseline characteristics or HUTT results were observed between the two groups (p > 0.05). However, responders exhibited a significantly higher peak HR compared to non-responders during the HUTT (120.13 ± 19.33 vs. 106.60 ± 22.32, p < 0.001). The increase in HR was also more pronounced in responders (0.60 ± 0.23 vs. 0.41 ± 0.25, p < 0.001). Additionally, HR variability was significantly greater in responders than in non-responders (16.18 ± 5.51 vs. 12.61 ± 5.50, p < 0.001). CONCLUSION: Higher peak HR, larger increases in HR, and greater HR variability during the HUTT may serve as reliable predictors of a positive response to metoprolol in patients with VVS.