title: Effect of physical training on ventricular repolarization in type 1 long QT syndrome: a pilot study in asymptomatic carriers of the G589D KCNQ1 mutation.
abstract: OBJECTIVE
  High-intensity physical exercise and competitive sports have been traditionally avoided in long QT syndrome. However, endurance training increases vagal activity and thus may improve cardiac electrical stability in healthy subjects. We hypothesized that controlled submaximal endurance training would not adversely affect ventricular repolarization in asymptomatic carriers of a KCNQ1 gene mutation of type 1 long QT syndrome (LQT1).
  
  
  RESULTS
  Previously, sedentary carriers of a missense mutation of KCNQ1 gene (LQT1, n=7) and healthy controls (n=8) exercised on a bicycle ergometer 3-4 times a week, 30 min a day at 60-75% of maximal heart rate (HR) for a maximum of 3 months. Body surface potential mapping (BSPM) was recorded and QT intervals were determined automatically from 14 channels over the left chest area. Maximal work capacity increased by 4+/-1% in LQT1 and by 14+/-2% in controls (both P<0.05), and left ventricular (LV) mass by 8+/-1% and 9+/-1%, respectively (P<0.05). Resting corrected QT interval shortened by 10+/-1% (P<0.05) and QT interval dispersion by 25+/-9% (P<0.05) in LQT1, but not significantly in controls. QT intervals at specified HRs during workload and recovery phases were not changed in either group.
  
  
  CONCLUSIONS
  In this pilot study of asymptomatic carriers of a KNCQ1 gene mutation, submaximal endurance training did not harmfully affect arrhythmia risk markers. Confirmatory studies in a broader spectrum of LQT1 genotypes are needed before any generalization can be made.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Helsinki University Hospital, Haartmaninkatu 4, FI-00290 Helsinki, Finland.
authors.forename: Merja A
authors.initials: MA
authors.lastname: Perhonen
authors.forename: Petri
authors.initials: P
authors.lastname: Haapalahti
authors.forename: Sari
authors.initials: S
authors.lastname: Kivistö
authors.forename: Anna-Mari
authors.initials: AM
authors.lastname: Hekkala
authors.forename: Heikki
authors.initials: H
authors.lastname: Väänänen
authors.forename: Heikki
authors.initials: H
authors.lastname: Swan
authors.forename: Lauri
authors.initials: L
authors.lastname: Toivonen
mesh_terms: D000328:Adult; D004562:Electrocardiography; D015444:Exercise; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006579:Heterozygote; D006801:Humans; D008133:Long QT Syndrome / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D010807:Physical Endurance / Q000502:physiology; D010865:Pilot Projects; D015221:Potassium Channels / Q000235:genetics*
chemical_list: D015221:Potassium Channels