title: Effect of exercise-based cardiac rehabilitation following coronary artery bypass surgery on ventricular repolarization indices.
abstract: OBJECTIVE
  Indices of ventricular repolarization heterogeneity are associated with future arrhythmias and sudden cardiac death. We investigated the effect of exercise-based cardiac rehabilitation (CR) on these indices in a sample of Iranian patients.
  
  
  METHODS
  Patients (N 122), who had undergone coronary artery bypass surgery (CABGS), were enrolled in this cohort study. Sixty patients attended 15 or more sessions of CR (CR group) and the remaining 62 patients attended 5 or fewer sessions of CR (control group). A standard 12-lead electrocardiogram was recorded for each patient. QT interval dispersion (QTd), RR interval variability (RRV), and heart rate-corrected QTd (QTc-d) were measured 3 times as follow: just before surgery, at the beginning of the first session of the CR program, and at the end of the 15th session for the CR group or the last session for the control group.
  
  
  RESULTS
  Following completion of the exercise-training program, the CR group showed a significant decrease in QTd (Δ = -49.4%, P < .0001) and QTc-d (Δ = 52.8%, P .0001), but not in the control group (Δ = 13.4% and 17.9%, respectively, P > .05 for both). In both groups, no statistically significant change in RRV was observed. After adjustment for variables such as age, gender, digoxin use, β-blocker use, and prerehabilitation ejection fraction, CR remained the independent predictor of QTd and QTc-d.
  
  
  CONCLUSIONS
  Results suggest that cardiac rehabilitation and exercise training programs significantly improve the indices of ventricular repolarization heterogeneity in patients with coronary artery disease who received CABGS.
authors.affiliation: Department of Cardiology, Tehran Heart Center, Jalal al-Ahmad CrossTehran, Iran. avasheghani@sina.tums.ac.ir
authors.forename: Ali
authors.initials: A
authors.lastname: Vasheghani-Farahani
authors.forename: Leila
authors.initials: L
authors.lastname: Asef-Kabiri
authors.forename: Farzad
authors.initials: F
authors.lastname: Masoudkabir
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Davoodi
authors.forename: Mostafa
authors.initials: M
authors.lastname: Nejatian
authors.forename: Soheil
authors.initials: S
authors.lastname: Saadat
authors.forename: Tahereh
authors.initials: T
authors.lastname: Yazdani
authors.forename: Baharak
authors.initials: B
authors.lastname: Mehdipoor
authors.forename: Ahmad
authors.initials: A
authors.lastname: Yaminisharif
mesh_terms: D001145:Arrhythmias, Cardiac / Q000473:pathology*; D016009:Chi-Square Distribution; D001026:Coronary Artery Bypass; D003324:Coronary Artery Disease / Q000534:rehabilitation*; D004562:Electrocardiography; D005081:Exercise Therapy / Q000379:methods*; D017079:Exercise Tolerance; D005260:Female; D006305:Health Status Indicators; D006339:Heart Rate; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D013318:Stroke Volume; D016896:Treatment Outcome; D016277:Ventricular Function, Left