Baroreflex sensitivity predicts therapeutic effects of metoprolol on pediatric postural orthostatic tachycardia syndrome

Abstract

Objective: To determine if the baseline baroreflex sensitivity (BRS) could be a useful predictor for the metoprolol therapeutic efficacy on postural orthostatic tachycardia syndrome (POTS) in children. Methods: In this retrospective case-control study, 54 children suffering from POTS treated with metoprolol were recruited from the pediatric department of Peking University First Hospital. After 2–3 months of metoprolol treatment, all subjects were divided into responders and non-responders based on whether the symptom score (SS) was decreased by over 50% after metoprolol treatment at the follow-up. The baseline demographic parameters and the supine BRS during the head-up tilt test (HUTT) obtained by Finapres Medical System (FMS) were compared between the two groups. The value of BRS to predict the effectiveness of POTS was analyzed by a receiver-operating characteristic (ROC) curve. Results: The age, sex, height, weight, body mass index (BMI), course of the disease, baseline SS, medication time, metoprolol dose, and follow-up time of the subjects were not statistically different between the responders and non-responders (P > 0.05). The decline in symptom scores (ΔSS) of the responders was more obvious than that of the non-responders (P < 0.01). The supine BRS, BRS at maximum HR, supine heart rate (HR), and maximum HR were different between responders and non-responders (P < 0.01, P = 0.022, P < 0.01, P = 0.047). The binary multivariable analysis showed that baseline supine BRS was significantly associated with the response to metoprolol therapy [OR: 2.079, 95% CI: (1.077, 4.015), P = 0.029]. According to the ROC curve, the area under the curve (AUC) of baseline BRS was 0.912 (95% CI, 0.840–0.984), with a cut-off value of 8.045 ms/mmHg, yielding a sensitivity and specificity of 75.8% and 95.2%, respectively, in predicting the effectiveness of POTS. Conclusion: The baseline supine BRS level > 8.045 ms/mmHg can predict a good therapeutic response to metoprolol and the results would assist in guiding the individualized β-adrenoceptor blocker use in pediatric patients suffering from POTS.