Wang S, Zou R, Cai H, et al. - The ability of heart rate (HR) and HR difference during head-up tilt test (HUTT) was investigated. In addition, clinical improvement related to metoprolol treatment was predicted in children and adolescents with postural tachycardia syndrome (POTS). Researchers conducted a retrospective cohort study including 53 children (27 males, aged 6-12 years old, mean age 11.79 ± 1.50 years old) with POTS treated with metoprolol and 52 children who underwent health examination during the same period as the control group. Calculation was done of the HR distance between 5 min and 0 min (HRD5) and between 10 min and 0 min (HRD10) during HUTT. Relative to control group, the POTS group was significantly higher in HR5, HR10, HRD5 and HRD10. Findings suggest the utility of HR and HRD in predicting the efficacy of metoprolol on POTS. The sensitivity and specificity were 82.50% and 69.23%, 84.62% and 69.70%, 85.29% and 89.47%, 97.56% and 64.86%, respectively, when HR5, HR10, HRD5 and HRD10 were ≥110, 112, 34 and 37 beats/min, respectively.