title: Stimulant therapy in children with attention-deficit/hyperactivity disorder and concomitant long QT syndrome: A safe combination?
abstract: BACKGROUND
  Attention-deficit/hyperactivity disorder (ADHD) is prevalent in about 11% of children in the United States. As such, ADHD is expected to be present in patients with long QT syndrome (LQTS), a rare, potentially lethal but highly treatable cardiac channelopathy. ADHD-directed stimulant therapy is relatively contraindicated in patients with LQTS because of concern for LQTS-triggered events.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the ADHD-directed treatment, outcome, and frequency of LQTS-triggered events in patients with LQTS and concomitant ADHD.
  
  
  METHODS
  A retrospective electronic medical record review of 357 pediatric patients with LQTS evaluated between 1999 and 2014 was performed to determine the prevalence of concomitant ADHD and the incidence of LQTS-triggered events in patients with LQTS, with or without concomitant ADHD.
  
  
  RESULTS
  Overall, 28 patients (8%) were diagnosed with LQTS concomitant ADHD. There were no phenotypic differences between patients with LQTS and ADHD, and LQTS alone. ADHD-directed stimulant therapy was stopped or advised against in 19 patients (68%) at the time of first evaluation or after diagnosis. None of the 15 stimulant-treated patients experienced LQTS-triggered events in a combined 56 person-years of treatment. Perhaps paradoxically, there was a statistically lower LQTS-triggered event rate in the stimulant-treated ADHD group compared to the LQTS alone cohort.
  
  
  CONCLUSIONS
  Among patients with mild- to moderate-risk LQTS, we found a prevalence of ADHD similar to that in the general population, which can be treated effectively and safely with stimulant therapy. Physicians should find reassurance in the low adverse event rate and should weigh the potential effects of suboptimal treatment of ADHD with the theoretical proarrhythmic risk from stimulant medications.
authors.affiliation: Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Ram K
authors.initials: RK
authors.lastname: Rohatgi
authors.affiliation: Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota.
authors.forename: J Martijn
authors.initials: JM
authors.lastname: Bos
authors.affiliation: Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota,; Department of Medicine/Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota. Electronic address: ackerman.michael@mayo.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ackerman
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000453:epidemiology; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D015994:Incidence; D008133:Long QT Syndrome / Q000139:chemically induced / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome; D014481:United States
chemical_list: D000697:Central Nervous System Stimulants
keywords: Attention-deficit/hyperactivity disorder; Long QT syndrome; Stimulant therapy