title: Maximal Exercise-Corrected QT as a Predictor of Coronary Artery Disease: Comparison of Simpler Heart Rate Corrections.
abstract: OBJECTIVE
  The relationship between QT prolongation and myocardial ischemia is widely known. Due to the limited value of ST depression, we aimed to evaluate, by using four simpler heart rate corrections (Bazett, Framingham, Fridericia and Hodges), the value of maximal exercise-QTc prolongation in the diagnosis of coronary artery disease (CAD) presence and severity.
  
  
  METHODS
  We enrolled 234 subjects (mean age 57.3±9 years, 143 men) who had undergone exercise testing and coronary angiography due to a suspicion of CAD in the study. Evaluating CAD severity with Gensini scoring, the CAD group (n=122) and controls with non-CAD were compared in terms of corrected QT duration at maximal exercise.
  
  
  RESULTS
  Age, gender, hypertension, dyslipidemia, smoking, exercise duration, resting, and peak heart rate were similar between the two groups (all p>0.05). The CAD group had higher raw QT values than the controls {268 (169-438) vs. 240 (168-348), p<0.001}. Although Framingham QTc of ≥350 ms and Fridericia QTc of ≥340 ms were seen to be useful for the diagnosis of CAD, there was no additive diagnostic value of exercise QTc in addition to ST depression. Maximal exercise-QTc Bazett (r=0.163, p=0.01), Framingham (r=0.239, p=0.001), and Fridericia (r=0.206, p=0.001) equations were weakly positively correlated with Gensini scoring.
  
  
  CONCLUSIONS
  The patients with CAD have longer QTc intervals at peak heart rates during exercise. This finding provides insufficient evidence to support routine incorporation of QTc at peak heart rates into exercise test interpretation.
authors.affiliation: Department of Cardiology, Namık Kemal University Medical School, Tekirdag, Turkey.
authors.forename: Aydın
authors.initials: A
authors.lastname: Akyuz
authors.forename: Seref
authors.initials: S
authors.lastname: Alpsoy
authors.forename: Dursun Cayan
authors.initials: DC
authors.lastname: Akkoyun
authors.forename: Hasan
authors.initials: H
authors.lastname: Degirmenci
authors.forename: Niyazi
authors.initials: N
authors.lastname: Guler
keywords: Coronary artery disease; Corrected QT; Exercise test