title: Impact of CARDIOrespiratory FITness on Arrhythmia Recurrence in Obese Individuals With Atrial Fibrillation: The CARDIO-FIT Study.
abstract: BACKGROUND
  Obesity begets atrial fibrillation (AF). Although cardiorespiratory fitness is protective against incident AF in obese individuals, its effect on AF recurrence or the benefit of cardiorespiratory fitness gain is unknown.
  
  
  OBJECTIVE
  This study sought to evaluate the role of cardiorespiratory fitness and the incremental benefit of cardiorespiratory fitness improvement on rhythm control in obese individuals with AF.
  
  
  METHODS
  Of 1,415 consecutive patients with AF, 825 had a body mass index ≥27 kg/m(2) and were offered risk factor management and participation in a tailored exercise program. After exclusions, 308 patients were included in the analysis. Patients underwent exercise stress testing to determine peak metabolic equivalents (METs). To determine a dose response, cardiorespiratory fitness was categorized as: low (<85%), adequate (86% to 100%), and high (>100%). Impact of cardiorespiratory fitness gain was ascertained by the objective gain in fitness at final follow-up (≥2 METs vs. <2 METs). AF rhythm control was determined using 7-day Holter monitoring and AF severity scale questionnaire.
  
  
  RESULTS
  There were no differences in baseline characteristics or follow-up duration between the groups defined by cardiorespiratory fitness. Arrhythmia-free survival with and without rhythm control strategies was greatest in patients with high cardiorespiratory fitness compared to adequate or low cardiorespiratory fitness (p < 0.001 for both). AF burden and symptom severity decreased significantly in the group with cardiorespiratory fitness gain ≥2 METs as compared to <2 METs group (p < 0.001 for all). Arrhythmia-free survival with and without rhythm control strategies was greatest in those with METs gain ≥2 compared to those with METs gain <2 in cardiorespiratory fitness (p < 0.001 for both).
  
  
  CONCLUSIONS
  Cardiorespiratory fitness predicts arrhythmia recurrence in obese individuals with symptomatic AF. Improvement in cardiorespiratory fitness augments the beneficial effects of weight loss. (Evaluating the Impact of a Weight Loss on the Burden of Atrial Fibrillation [AF] in Obese Patients; ACTRN12614001123639).
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Rajeev K
authors.initials: RK
authors.lastname: Pathak
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Adrian
authors.initials: A
authors.lastname: Elliott
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Melissa E
authors.initials: ME
authors.lastname: Middeldorp
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Megan
authors.initials: M
authors.lastname: Meredith
authors.affiliation: Research School of Finance, Actuarial Studies and Applied Statistics, Australian National University, Canberra, Australia.
authors.forename: Abhinav B
authors.initials: AB
authors.lastname: Mehta
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Mahajan
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Jeroen M L
authors.initials: JM
authors.lastname: Hendriks
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Darragh
authors.initials: D
authors.lastname: Twomey
authors.affiliation: Department of Cardiology, Royal Melbourne Hospital and the Department of Medicine, University of Melbourne, Melbourne, Australia.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Kalman
authors.affiliation: College of Medicine, Biology and Environment, Australian National University and Canberra Hospital, Canberra, Australia.
authors.forename: Walter P
authors.initials: WP
authors.lastname: Abhayaratna
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Lau
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia. Electronic address: prash.sanders@adelaide.edu.au.
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
mesh_terms: D017677:Age Distribution; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000453:epidemiology* / Q000601:surgery; D001315:Australia; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000453:epidemiology; D017115:Catheter Ablation / Q000379:methods / Q000401:mortality; D015331:Cohort Studies; D015897:Comorbidity; D004562:Electrocardiography / Q000379:methods; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology*; D010809:Physical Fitness / Q000502:physiology*; D011379:Prognosis; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D016019:Survival Analysis
keywords: atrial fibrillation; fitness; obesity; physical activity; risk factors; weight loss