title: Prognostic value of submaximal exercise data for cardiac morbidity in Fontan patients.
abstract: BACKGROUND
  Submaximal exercise parameters are associated with an increased risk of hospitalization in patients with heart failure, but the implication in patients with Fontan circulation remains unknown. We investigated the prognostic value of these parameters in a Fontan cohort, in whom maximal exercise effort is often limited.
  
  
  METHODS
  Fifty-two Fontan patients received cardiopulmonary exercise tests at least 12 months after Fontan completion. We evaluated two maximal parameters (peak oxygen consumption (V˙O2) and HR reserve) and two submaximal parameters (oxygen uptake efficiency slope (OUES) and minute ventilation (V˙E) to carbon dioxide elimination (V˙CO2) slope).
  
  
  RESULTS
  The peak V˙O2 and OUES were 58.0% ± 11.2% and 56.6% ± 14.5% of the age- and sex-related predicted values. In the subsequent follow-up (median, 22.7 months), 11 patients (21%, including one death) exhibited cardiac morbidity, defined as cardiac-related hospitalization. Time-dependent receiver operating characteristic curve analysis demonstrated that only submaximal parameters were related to 2-yr cardiac morbidity (area under the curve for OUES 0.781, P = 0.018; for V˙E/V˙CO2 slope 0.714, P = 0.04), even in the subgroup achieved maximal exercise effort. The optimal threshold value for OUES was 45%, and for the V˙E/V˙CO2 slope, it was 37. Furthermore, the OUES conveyed independent prognostic information beyond resting oxygen saturation and a history of heart failure or protein-losing enteropathy.
  
  
  CONCLUSIONS
  Submaximal exercise parameters provide superior prognostic information to maximal exercise data for predicting cardiac morbidity in Fontan patients. Moreover, the association between the OUES and cardiac morbidity is independent of relevant baseline clinical information.
authors.affiliation: 1Department of Pediatrics, National Taiwan University Hospital, Taipei, TAIWAN; 2Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, TAIWAN; 3Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei, TAIWAN; 4Cardiac Children's Foundation, TAIWAN; and 5Department of Surgery, National Taiwan University Hospital, Taipei, TAIWAN.
authors.forename: Chun-An
authors.initials: CA
authors.lastname: Chen
authors.forename: Ssu-Yuan
authors.initials: SY
authors.lastname: Chen
authors.forename: Hsin-Hui
authors.initials: HH
authors.lastname: Chiu
authors.forename: Jou-Kou
authors.initials: JK
authors.lastname: Wang
authors.forename: Chung-I
authors.initials: CI
authors.lastname: Chang
authors.forename: Ing-Sh
authors.initials: IS
authors.lastname: Chiu
authors.forename: Yih-Sharng
authors.initials: YS
authors.lastname: Chen
authors.forename: Chun-Wei
authors.initials: CW
authors.lastname: Lu
authors.forename: Ming-Tai
authors.initials: MT
authors.lastname: Lin
authors.forename: Hung-Chi
authors.initials: HC
authors.lastname: Lue
authors.forename: Yu-Chuan
authors.initials: YC
authors.lastname: Hua
authors.forename: Mei-Hwan
authors.initials: MH
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D002648:Child; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000379:methods*; D005260:Female; D018729:Fontan Procedure / Q000009:adverse effects; D006333:Heart Failure / Q000503:physiopathology*; D006339:Heart Rate; D006760:Hospitalization; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011237:Predictive Value of Tests; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology; D012372:ROC Curve; D018570:Risk Assessment / Q000379:methods; D055815:Young Adult