Abstract 2464: Severity of Obstructive Sleep Apnea Dependent upon Aldosterone Status in Subjects with Resistant Hypertension
Background: Obstructive sleep apnea (OSA) and hyperaldosteronism are common in subjects with resistant hypertension. Prior results from our laboratory relate severity of OSA to aldosterone levels in patients with resistant hypertension suggesting that the 2 disease entities may be mechanistically linked.
Objective: This study prospectively evaluated the relation between OSA severity and aldosterone status in subjects with resistant hypertension.
Methods: One hundred nine consecutive subjects (age 55.9±9.3 years; 50% male) with resistant hypertension referred to a university clinic for resistant hypertension were prospectively evaluated with plasma renin activity (PRA), plasma aldosterone concentration, and 24-hr urinary aldosterone excretion. Hyperaldosteronism was defined as a PRA <1.0 ng/mL/hr and 24-h urinary aldosterone excretion ≥ 12 μg/24-hr. Remaining patients were considered as having normal-aldosterone status. All subjects were evaluated by full-night attended diagnostic polysomnography. OSA was defined as an apnea-hypopnea index (AHI) ≥ 5 events/hr.
Results: Hyperaldosteronism was present in 28% of subjects. Overall, OSA was diagnosed in 77% of subjects; 81% of the high-aldosterone and 74% of the normal-aldosterone subjects. In subjects with hyperaldosteronism, plasma aldosterone and urinary aldosterone excretion correlated with AHI (r = 0.723, p <0.001 and r = 0.639, p <0.001, respectively) but not in the normal-aldosterone subjects (r = 0.008, p = 0.94 and r = 0.042, p = 0.71 respectively). Atrial natriuretic peptide (ANP) levels were significantly higher in the high-aldosterone compared to normal-aldosterone subjects (89±57 vs. 67±102 pg/ml; p = 0.03).
Conclusion: OSA is extraordinarily common in patients with resistant hypertension. A significant correlation between both plasma and urinary aldosterone levels and severity of OSA is observed in high-aldosterone but not normal-aldosterone subjects. The higher level of ANP in high-compared to normal-aldosterone subjects suggests greater intravascular fluid retention in the former subjects. These results suggest worsening of OSA in patients with hyperaldosteronism secondary to chronic aldosterone-induced intravascular fluid retention.