title: Abnormal heart rate recovery after exercise predicts coronary artery disease severity.
abstract: BACKGROUND
  Slow heart rate recovery (HRR) after exercise is considered to represent impaired parasympathetic tone and to be a predictor of all-cause and cardiovascular mortality, but the independent value of abnormal HRR in predicting the presence and severity of coronary artery disease (CAD) is unknown. The aim of this study was to evaluate these relationships in our patients.
  
  
  METHODS
  This prospective cross-sectional study included 208 patients (67.3% men), aged 34 to 74 (mean 53) years. Patients who had an ischemic response during symptom-limited exercise testing underwent selective coronary angiography. The value for HRR was defined as the decrease in heart rate from peak exercise to one minute after the exercise ceased. Eighteen beats per minute was defined as the lowest normal value for HRR.
  
  
  RESULTS
  Significant CAD was detected in 140 (67.3%) patients. There were 66 (31.7%) patients with an abnormal HRR. In multivariable logistic regression analysis adjusted for established CAD risk factors, abnormal HRR was independently correlated with the extent of major epicardial coronary involvement (p = 0.04). The sensitivity, specificity, positive and negative predictive values, and accuracy of abnormal HRR for predicting extensive CAD were 48%, 83.3%, 72.7%, and 63.4%, respectively. There was also a significant correlation between HRR one minute after exercise and smoking (p = 0.004), chronotropic variables (p = 0.001), and the calculated risk score for the exercise test (p = 0.03). There was no significant correlation between HRR and other risk factors including age and gender, left ventricular systolic function, and history of myocardial infarction.
  
  
  CONCLUSIONS
  There is a significant correlation between abnormal post-exercise HRR at one minute and the extent of major epicardial coronary involvement.
authors.affiliation: Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Samad
authors.initials: S
authors.lastname: Ghaffari
authors.forename: Babak
authors.initials: B
authors.lastname: Kazemi
authors.forename: Parvaneh
authors.initials: P
authors.lastname: Aliakbarzadeh
mesh_terms: D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D007492:Iran; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013997:Time Factors