Fig 1. Symptom scores and heart rate changes of patients with POTS after metoprolol treatment.

Compared to the symptom scores before treatment, the scores were significantly decreased after treatment in 34 children with POTS [(5.7 ± 2.2) vs. (2.9 ± 2.5), t = 9.232, P <0.001)]. Twenty-three patients repeated the head-up test, showing that the increment in heart rate induced by postural changes was significantly reduced after treatment [(41 ± 11) vs. (28 ± 13) beats/min, t = 3.476, P = 0.002]. * P < 0.01 compared with before treatment.