title: Occult T wave alternans in long QT syndrome.
abstract: T wave alternans that is visually apparent on the ECG is a known risk factor for sudden death in idiopathic long QT syndrome (LQTS). To determine if occult and visually undetectable forms of T wave alternans are also present in LQTS, we measured T wave alternans from a 16-year-old girl with LQTS during exercise using spectral analysis methods and a recording system designed to minimize exercise-related noise. While there was no alternans at rest, statistically significant, yet visually inapparent T wave alternans were measured both during exercise and recovery. Using identical recording techniques, no significant T wave alternans was detected from the subject's mother, who had a prolonged QT interval but was not experiencing arrhythmias, nor from five healthy volunteers with normal QT intervals. This report suggests that electrocardiographically occult, yet prognostically important forms of T wave alternans may be present in patients with LQTS.
authors.affiliation: Department of Medicine, Case Western Reserve University, Cleveland, Ohio, 441 USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Platt
authors.forename: J M
authors.initials: JM
authors.lastname: Vijgen
authors.forename: P
authors.initials: P
authors.lastname: Albrecht
authors.forename: G F
authors.initials: GF
authors.lastname: Van Hare
authors.forename: M D
authors.initials: MD
authors.lastname: Carlson
authors.forename: D S
authors.initials: DS
authors.lastname: Rosenbaum
mesh_terms: D000293:Adolescent; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis / Q000503:physiopathology*; D012307:Risk Factors