Flow-mediated vasodilation as a predictor of therapeutic response to midodrine hydrochloride in children with postural orthostatic tachycardia syndrome.

Abstract

This study was designed to explore the value of flow-mediated vasodilation (FMD) as a predictor of therapeutic response to midodrine hydrochloride (MD) in children with postural orthostatic tachycardia syndrome (POTS). One hundred and eight children diagnosed with POTS and 20 healthy control children were enrolled. All children with POTS received MD and were followed up for 3 months. FMD of brachial artery for each participant was measured by vascular ultrasound. Symptom scores, FMD values, and head-up test (HUT)/head-up tilt test (HUTT) outcomes were investigated before and after treatment. A receiver operating characteristic curve was used to explore the value of FMD as a predictor. Baseline FMD (%) and increased heart rate (beats per minute) during HUT/HUTT were significantly greater in children with POTS compared with control children (FMD: 11 ± 3% vs 6 ± 2%, p <0.001; increased heart rate: 38 ± 9 vs 7 ± 7 beats/min, p <0.001, respectively). Before treatment, MD responders had greater FMD values than MD nonresponders (p <0.05). Symptom scores, excessive increases in heart rate during HUT, and increased FMD values were all reduced significantly after treatment (all p <0.05). The receiver operating characteristic curve for the predictive value of FMD showed the area under the curve to be 0.790 (95% confidence interval: 0.679 to 0.902; p <0.001) at 1-month and 0.803 (95% confidence interval: 0.669 to 0.936; p <0.01) at 3-month therapy. FMD of 9.85% had a high sensitivity (1-month therapy: 71.6%; 3-month therapy: 74.4%) and specificity (1-month therapy 77.8%; 3-month therapy: 80%). In conclusion, FMD is a predictor of the efficacy of MD for treating children with POTS.

• Authors: Ying Liao, Jinyan Yang, Fengwen Zhang, Stella Chen, Xueqin Liu, Qingyou Zhang, Yi Ai, Yuli Wang, Chaoshu Tang, Junbao Du, Hongfang Jin
• Journal: The American journal of cardiology (Am J Cardiol) Vol. 112 Issue 6 Pg. 816-20 (Sep 15 2013) ISSN: 1879-1913 [Electronic] United States
• PMID: 23735645 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2013 Elsevier Inc. All rights reserved.

Chemical References

• Adrenergic alpha-1 Receptor Agonists
• Midodrine

Topics

• Adrenergic alpha-1 Receptor Agonists (administration & dosage, therapeutic use)
• Blood Flow Velocity (drug effects, physiology)
• Brachial Artery (diagnostic imaging, physiopathology)
• Child
• Dose-Response Relationship, Drug
• Female
• Follow-Up Studies
• Heart Rate
• Humans
• Male
• Midodrine (administration & dosage, therapeutic use)
• Postural Orthostatic Tachycardia Syndrome (diagnosis, drug therapy, physiopathology)
• Posture (physiology)
• Prospective Studies
• ROC Curve
• Tilt-Table Test
• Ultrasonography, Doppler, Color
• Vasodilation (drug effects, physiology)