Determinants of postexercise heart rate recovery in patients with the obstructive sleep apnea syndrome.

Abstract

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. 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)). 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. 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.