title: Association between coronary flow reserve and exercise capacity.
abstract: BACKGROUND
  Reduced exercise capacity is of clinical importance. Sometimes no corresponding cardiovascular disease can be found to explain this condition. We hypothesized that coronary microvascular dysfunction may have an effect on exercise capacity in patients without apparent cardiovascular disease.
  
  
  METHODS
  Fifty patients (33 female, mean age 46.8 ± 12.4 years) without coronary artery or other cardiac disease were enrolled. Coronary microvascular function was evaluated by measurement of coronary flow reserve (CFR) during transthoracic pulsed-wave Doppler echocardiography with pharmacological stress. CFR was calculated as the ratio of hyperemic to baseline peak diastolic velocities after dipyridamole infusion. Exercise capacity was determined by treadmill exercise testing. Exercise time, metabolic equivalent (MET), and Duke treadmill score (DTS) were recorded and compared with the CFR data.
  
  
  RESULTS
  CFR was correlated with exercise time (r=0.376, p=0.007), MET (r=0.435, p=0.002) and DTS (r=0.458, p=0.001). Exercise time, MET, and DTS were lower in patients with impaired CFR (<2) than in those with normal CFR (2) (5.3 ± 1.8 min vs. 8.6 ± 2.7 min, p<0.001; 7.3 ± 3.1 vs. 11.4 ± 2.8, p=0.002; -1.75 (-5.9, 5.0) vs. 7.5 (5.2, 9.41), p<0.001; respectively). CFR was lower in patients with MET7 as compared to patients with MET>7 (2.0 ± 0.5 vs. 2.6 ± 0.6, p=0.015).
  
  
  CONCLUSIONS
  CFR is associated with exercise capacity. Thus coronary microvascular dysfunction may be a reason for reduced exercise capacity in patients who have no apparent cardiovascular disease.
authors.affiliation: University of Baskent, Faculty of Medicine, Department of Cardiology, Ankara, Turkey.
authors.forename: Serpil
authors.initials: S
authors.lastname: Eroglu
authors.forename: Leyla Elif
authors.initials: LE
authors.lastname: Sade
authors.forename: Ezgi
authors.initials: E
authors.lastname: Polat
authors.forename: Huseyin
authors.initials: H
authors.lastname: Bozbas
authors.forename: Haldun
authors.initials: H
authors.lastname: Muderrisoğlu
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology; D003331:Coronary Vessels / Q000503:physiopathology; D003971:Diastole / Q000187:drug effects / Q000502:physiology; D004176:Dipyridamole / Q000008:administration & dosage / Q000009:adverse effects; D015150:Echocardiography, Doppler / Q000379:methods; D018619:Echocardiography, Doppler, Pulsed; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D055806:Microvessels / Q000503:physiopathology; D008875:Middle Aged; D015588:Observer Variation
chemical_list: D004176:Dipyridamole