title: Abnormal heart-rate response during cardiopulmonary exercise testing identifies cardiac dysfunction in symptomatic patients with non-obstructive coronary artery disease.
abstract: BACKGROUND
  Symptomatic non-obstructive coronary artery disease is a growing clinical dilemma for which contemporary testing is proving to be of limited clinical utility. New methods are needed to identify cardiac dysfunction.
  
  
  RESULTS
  This is a prospective observational cohort study conducted from December 2013 to August 2015 in two outpatient cardiology clinics (symptomatic cohort) and 24 outpatient practices throughout the US (healthy cohort) with centralized methodology and monitoring to compare heart-rate responses during cardiopulmonary exercise testing (CPET). Participants were 208 consecutive patients (median age, 61; range, 32-86years) with exercise intolerance and without prior heart or lung disease in whom coronary anatomy was defined and 116 healthy subjects (median age, 45; range, 26-66years). Compared to stress ECG, the novel change in heart-rate as a function of work-rate parameter (ΔHR-WR Slope) demonstrated significantly higher sensitivity to detect under-treated atherosclerosis with similar specificity. In men, area under the ROC curve increased from 60% to 94% for non-obstructive CAD and from 64% to 80% for obstructive CAD. In women, AUC increased from 64% to 85% for non-obstructive CAD and from 66% to 90% for obstructive CAD. ΔHR-WR Slope correctly reclassified abnormal studies in the non-obstructive CAD group from 22% to 81%; in the obstructive CAD group from 18% to 84% and in the revascularization group from 35% to 78%.
  
  
  CONCLUSIONS
  Abnormal heart-rate response during CPET is more effective than stress ECG for identifying under-treated atherosclerosis and may be of utility to identify cardiac dysfunction in symptomatic patients with normal routine cardiac testing.
authors.affiliation: Research and Development, MET-TEST, Inc., Atlanta, GA, United States. Electronic address: schaudhry@mettest.net.
authors.forename: Sundeep
authors.initials: S
authors.lastname: Chaudhry
authors.affiliation: Research Division, Whitby Cardiovascular Institute, Whitby, Canada.
authors.forename: Naresh
authors.initials: N
authors.lastname: Kumar
authors.affiliation: Research Division, Whitby Cardiovascular Institute, Whitby, Canada.
authors.forename: Hushyar
authors.initials: H
authors.lastname: Behbahani
authors.affiliation: Division of Cardiology, St. Michael's Hospital, University of Toronto, Canada.
authors.forename: Akshay
authors.initials: A
authors.lastname: Bagai
authors.affiliation: Division of Cardiovascular Medicine, Hofstra Northwell School of Medicine, Hofstra University, New York, NY, United States.
authors.forename: Binoy K
authors.initials: BK
authors.lastname: Singh
authors.affiliation: Research and Development, MET-TEST, Inc., Atlanta, GA, United States.
authors.forename: Nick
authors.initials: N
authors.lastname: Menasco
authors.affiliation: Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, MA, United States.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Lewis
authors.affiliation: Division of Preventive Cardiology, Emory University, Atlanta, GA, United States.
authors.forename: Laurence
authors.initials: L
authors.lastname: Sperling
authors.affiliation: Division of Cardiovascular Medicine, Stanford University and Veterans Affairs, Palo Alto Health Care System, Palo Alto, CA, United States.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
mesh_terms: D000328:Adult; D000368:Aged; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000503:physiopathology; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D000070276:Heart Rate Determination / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D063189:Symptom Assessment / Q000379:methods; D014481:United States
keywords: Angina; Exercise testing; Ischemic heart disease; Women