title: Peak oxygen uptake, ventilatory efficiency and QRS-duration predict event free survival in patients late after surgical repair of tetralogy of Fallot.
abstract: OBJECTIVE
  Patients with repaired tetralogy of Fallot (ToF) have an increased long-term risk of cardiovascular morbidity and mortality. Risk stratification in this population is difficult. Initial evidence suggests that cardiopulmonary exercise testing (CPET) may be helpful to risk-stratify patients with repaired ToF.
  
  
  RESULTS
  We studied 875 patients after surgical repair for ToF (358 females, age 25.5 ± 11.7 year, range 7-75 years) who underwent CPET between 1999 and 2009. During a mean follow-up of 4.1 ± 2.6 years after CPET, 30 patients (3.4%) died or had sustained ventricular tachycardia (VT). 225 patients (25.7%) had other cardiac related events (emergency admission, surgery, or catheter interventions). On multivariable Cox regression-analysis, %predicted peak oxygen uptake (V˙O2 %) (p=0.001), resting QRS duration (p=0.030) and age (p<0.001) emerged as independent predictors of mortality or sustained VT. Patients with a peak V˙O2 ≤ 65% of predicted and a resting QRS duration ≥ 170 ms had a 11.4-fold risk of death or sustained VT. Ventilatory efficiency expressed as V˙E/V˙CO2 slope (p<0.001), peak V˙O2 % (p=.001), QRS duration (p=.001) and age (p=0.046) independently predicted event free survival. V˙E/V˙CO2 slope ≥ 31.0, peak V˙O2 % ≤ 65% and QRS duration ≥ 170 ms were the cut-off points with best sensitivity and specificity to detect an unfavorable outcome.
  
  
  CONCLUSIONS
  CPET is an important predictive tool that may assist in the risk stratification of patients with ToF. Subjects with a poor exercise capacity in addition to a prolonged QRS duration have a substantially increased risk for death or sustained ventricular tachycardia, as well as for cardiac-related hospitalizations.
authors.affiliation: Department of Pediatric Cardiology and Congenital Heart Disease, Deutsches Herzzentrum München, Technische Universität München, Germany. Electronic address: j.mueller@tum.de.
authors.forename: Jan
authors.initials: J
authors.lastname: Müller
authors.affiliation: Department of Pediatric Cardiology and Congenital Heart Disease, Deutsches Herzzentrum München, Technische Universität München, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Hager
authors.affiliation: Adult Congenital Heart Center and Center for Pulmonary Hypertension, Royal Brompton Hospital and the National Heart & Lung Institute, Imperial College, London, United Kingdom; Adult Congenital and Valvular Heart Disease Center, Department of Cardiology and Angiology, University Hospital of Muenster, Muenster, Germany.
authors.forename: Gerhard-Paul
authors.initials: GP
authors.lastname: Diller
authors.affiliation: Cardiorespiratory Unit, Great Ormond Street Hospital for Children, London, United Kingdom.
authors.forename: Graham
authors.initials: G
authors.lastname: Derrick
authors.affiliation: Research Centre for Cardiovascular and Respiratory Rehabilitation, Department of Rehabilitation Sciences, Katholieke Universiteit Leuven, Belgium.
authors.forename: Roselien
authors.initials: R
authors.lastname: Buys
authors.affiliation: Department of Paediatric Cardiology and Congenital Heart Disease, Heart and Diabetes Center of North Rhine-Westphalia, University of Bochum, Bad Oeynhausen, Germany.
authors.forename: Karl-Otto
authors.initials: KO
authors.lastname: Dubowy
authors.affiliation: Child Development & Exercise Centre, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, The Netherlands.
authors.forename: Tim
authors.initials: T
authors.lastname: Takken
authors.affiliation: Adult Congenital and Valvular Heart Disease Center, Department of Cardiology and Angiology, University Hospital of Muenster, Muenster, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Orwat
authors.affiliation: Adult Congenital Heart Center and Center for Pulmonary Hypertension, Royal Brompton Hospital and the National Heart & Lung Institute, Imperial College, London, United Kingdom.
authors.forename: Ryo
authors.initials: R
authors.lastname: Inuzuka
authors.affiliation: Research Centre for Cardiovascular and Respiratory Rehabilitation, Department of Rehabilitation Sciences, Katholieke Universiteit Leuven, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Vanhees
authors.affiliation: Adult Congenital Heart Center and Center for Pulmonary Hypertension, Royal Brompton Hospital and the National Heart & Lung Institute, Imperial College, London, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Gatzoulis
authors.affiliation: Cardiorespiratory Unit, Great Ormond Street Hospital for Children, London, United Kingdom.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Giardini
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D018572:Disease-Free Survival; D004562:Electrocardiography; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012189:Retrospective Studies; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000453:epidemiology; D013771:Tetralogy of Fallot / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D055815:Young Adult
keywords: Event free survival; Exercise testing; Peak VO(2); QRS duration; Tetralogy of Fallot; Ventilatory efficiency