title: Determinants of postexercise heart rate recovery in patients with the obstructive sleep apnea syndrome.
abstract: BACKGROUND
  Young patients with obstructive sleep apnea syndrome (OSAS) display an attenuated heart rate recovery (HRR) during the first minute (HRR-1) and the first 2 min (HRR-2) postexercise. We sought to compare determinants of HRR-1 and HRR-2 in OSAS and to assess whether these associations depend on age.
  
  
  METHODS
  Exercise testing with measurements of HRR-1 and HRR-2 was performed in 54 patients with untreated OSAS (median [interquartile range] apnea-hypopnea index 27.5 [12.0-42.4] h(-1), desaturation index [DSI] 10.6 [5.1-25.0] h(-1)).
  
  
  RESULTS
  Overall, higher DSI (P < .001) and higher total cholesterol ([TC] P = .02) were independent predictors of lower HRR-1, whereas lower peak heart rate (P < .001), higher resting heart rate (P = .006), and higher DSI (P = .01) were independently associated with lower HRR-2. In the below-median age group (age <or= 48 years; n = 27), higher DSI (P = .002) was the only independent predictor of lower HRR-1, and lower peak heart rate (P < .001) and higher DSI (P = .003) were independently associated with lower HRR-2. In contrast, in the above-median age group (age > 48 years; n = 27) higher TC (P = .006), higher insulin resistance (P = .009), and higher resting heart rate (P = .048) were independently associated with lower HRR-1, and lower estimated glomerular filtration rate (P = .001), higher resting heart rate (P = .002), higher TC (P = .005), and lower peak heart rate (P = .01) were independently associated with HRR-2.
  
  
  CONCLUSIONS
  Assessment of HRR-2 provides additional information on different aspects of OSAS compared with HRR-1. Markers of OSAS severity, such as DSI, are independently associated with HRR in younger patients only, whereas in older patients, HRR reflects OSAS-related metabolic and renal dysfunction.
authors.affiliation: Baker IDI Heart and Diabetes Institute, Melbourne, Australia. micha.maeder@bluewin.ch
authors.forename: Micha T
authors.initials: MT
authors.lastname: Maeder
authors.forename: Peter
authors.initials: P
authors.lastname: Ammann
authors.forename: Otto D
authors.initials: OD
authors.lastname: Schoch
authors.forename: Hans
authors.initials: H
authors.lastname: Rickli
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Korte
authors.forename: Christoph
authors.initials: C
authors.lastname: Hürny
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
authors.forename: Thomas
authors.initials: T
authors.lastname: Münzer
mesh_terms: D000328:Adult; D001823:Body Composition; D004562:Electrocardiography; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011379:Prognosis; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D013147:Spirometry; D016276:Ventricular Function / Q000502:physiology*; D055815:Young Adult