title: Usefulness of exercise test in the diagnosis of short QT syndrome.
abstract: OBJECTIVE
  Short QT syndrome (SQTS) is a rare arrhythmogenic inherited heart disease. Diagnosis can be challenging in subjects with slightly shortened QT interval at electrocardiogram. In this study we compared the QT interval behaviour during exercise in a cohort of SQTS patients with a control group, to evaluate the usefulness of exercise test in the diagnosis of SQTS.
  
  
  RESULTS
  Twenty-one SQTS patients and 20 matched control subjects underwent an exercise test. QT interval was measured at different heart rates (HRs), at rest and during effort. The relation between QT interval and HR was evaluated by linear regression analysis according to the formula: QT = β ×HR + α, where β is the slope of the linear relation, and α is the intercept. Rest and peak exercise HRs were not different in the two groups. Short QT syndrome patients showed lower QT intervals as compared with controls both at rest (276 ± 27 ms vs. 364 ± 25 ms, P < 0.0001) and at peak exercise (228 ± 27 ms vs. 245 ± 26 ms, P = 0.05), with a mean variation from rest to peak effort of 48 ± 14 ms vs. 120 ± 20 ms (P < 0.0001). Regression analysis of QT/HR relationship revealed a less steep slope for SQTS patients compared with the control group, never exceeding the value of -0.90 ms/beat/min (mean value -0.53 ± 0.15 ms/beat/min vs. -1.29 ± 0.30 ms/beat/min, P < 0.0001).
  
  
  CONCLUSIONS
  Short QT syndrome patients show a reduced adaptation of the QT interval to HR. Exercise test can be a useful tool in the diagnosis of SQTS.
authors.affiliation: Division of Cardiology, Department of Medical Sciences, University of Torino, 'Città della Salute e della Scienza' Hospital, C.so Bramante 88, 10126 Torino, Italy carla.giustetto@unito.it.
authors.forename: Carla
authors.initials: C
authors.lastname: Giustetto
authors.affiliation: Division of Cardiology, Department of Medical Sciences, University of Torino, 'Città della Salute e della Scienza' Hospital, C.so Bramante 88, 10126 Torino, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Scrocco
authors.affiliation: 1st Department of Medicine-Cardiology, University Hospital Mannheim, Mannheim, Germany DZHK (German Centre for Cardiovascular Research) partner site Mannheim, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Schimpf
authors.affiliation: Department of Cardiology, Rangueil University Hospital, Toulouse, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Maury
authors.affiliation: Division of Cardiology, Department of Medical Sciences, University of Torino, 'Città della Salute e della Scienza' Hospital, C.so Bramante 88, 10126 Torino, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Mazzanti
authors.affiliation: Sport Medicine Unit, ASL TO1, Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Levetto
authors.affiliation: Department of Medicine, Päijät-Häme Central Hospital, Lahti, Finland.
authors.forename: Olli
authors.initials: O
authors.lastname: Anttonen
authors.affiliation: Medical Statistics Unit, Department of Public Health and Paediatrics, University of Torino, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Dalmasso
authors.affiliation: Division of Cardiology, Department of Medical Sciences, University of Torino, 'Città della Salute e della Scienza' Hospital, C.so Bramante 88, 10126 Torino, Italy.
authors.forename: Natascia
authors.initials: N
authors.lastname: Cerrato
authors.affiliation: Division of Cardiology, Department of Medical Sciences, University of Torino, 'Città della Salute e della Scienza' Hospital, C.so Bramante 88, 10126 Torino, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Gribaudo
authors.affiliation: Department of Medicine-Cardiology, Nephrology and Internal Intensive Care Medicine, Ludwigsburg, Klinikum Ludwigsburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wolpert
authors.affiliation: Medical Genetics Unit, University of Torino, San Luigi Hospital, Orbassano (TO), Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Giachino
authors.affiliation: Masonic Medical Research Laboratory, Utica, NY, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Antzelevitch
authors.affiliation: 1st Department of Medicine-Cardiology, University Hospital Mannheim, Mannheim, Germany DZHK (German Centre for Cardiovascular Research) partner site Mannheim, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Borggrefe
authors.affiliation: Division of Cardiology, Department of Medical Sciences, University of Torino, 'Città della Salute e della Scienza' Hospital, C.so Bramante 88, 10126 Torino, Italy.
authors.forename: Fiorenzo
authors.initials: F
authors.lastname: Gaita
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Exercise test; Genetics; Short QT syndrome