title: 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.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liao
authors.forename: Jinyan
authors.initials: J
authors.lastname: Yang
authors.forename: Fengwen
authors.initials: F
authors.lastname: Zhang
authors.forename: Stella
authors.initials: S
authors.lastname: Chen
authors.forename: Xueqin
authors.initials: X
authors.lastname: Liu
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Ai
authors.forename: Yuli
authors.initials: Y
authors.lastname: Wang
authors.forename: Chaoshu
authors.initials: C
authors.lastname: Tang
authors.forename: Junbao
authors.initials: J
authors.lastname: Du
authors.forename: Hongfang
authors.initials: H
authors.lastname: Jin
mesh_terms: D058646:Adrenergic alpha-1 Receptor Agonists / Q000008:administration & dosage / Q000627:therapeutic use; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology*; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002648:Child; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate; D006801:Humans; D008297:Male; D008879:Midodrine / Q000008:administration & dosage / Q000627:therapeutic use*; D054972:Postural Orthostatic Tachycardia Syndrome / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D012372:ROC Curve; D018667:Tilt-Table Test; D018615:Ultrasonography, Doppler, Color; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
chemical_list: D058646:Adrenergic alpha-1 Receptor Agonists; D008879:Midodrine