title: Usefulness of metoprolol for unexplained syncope and positive response to tilt testing in young persons.
abstract: The efficacy of intravenous metoprolol in preventing symptoms during a repeat tilt test was compared with the outcome of chronic oral treatment in 21 patients (14 female, 7 male), age 8 to 20 years (mean 13 +/- 3) with unexplained syncope (> or = 1 episode) and a positive response to tilt testing. A positive response was defined as the development of either syncope or presyncope. During the initial tilt test, a positive response occurred during baseline (14 patients) or isoproterenol (0.03 to 0.1 microgram/kg/min) infusion (7 patients) with a cardioinhibitory (1 patient), vasodepressor (5 patients) or mixed (15 patients) pattern. Metoprolol (0.1 to 0.2 mg/kg) was administered intravenously. During the repeat tilt test, response was negative in 18 patients, including 11 of 14 patients with a positive response in the baseline and 7 of 7 patients with a positive response during isoproterenol infusion. Metoprolol (0.8 to 2.8 mg/kg/day) was administered orally to 15 patients for an average of 10 months. Symptoms were absent (7 patients) or improved (2 patients); metoprolol was discontinued because of adverse effects (3 patients) or recurrence of symptoms (3 patients). In 7 of 12 patients with a negative response and 2 of 3 patients with a positive response after intravenous metoprolol, oral administration of metoprolol prevented or improved symptoms without adverse effects. Many young patients (60%) with recurrent syncope obtained symptomatic improvement from chronic oral metoprolol treatment without adverse effects; repeat tilt testing after intravenous metoprolol did not appear to offer any additional information than would have been obtained from a trial of chronic oral treatment.
authors.affiliation: Division of Cardiology, Children's Memorial Hospital, Chicago, Illinois.
authors.forename: G
authors.initials: G
authors.lastname: Müller
authors.forename: B J
authors.initials: BJ
authors.lastname: Deal
authors.forename: J F
authors.initials: JF
authors.lastname: Strasburger
authors.forename: D W
authors.initials: DW
authors.lastname: Benson
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage*; D011187:Posture / Q000502:physiology; D013575:Syncope / Q000517:prevention & control*
chemical_list: D008790:Metoprolol