Association of Severe Sleep Apnoea in Patients with Primary Aldosteronism: A Cross-sectional Study Using the Oxygen Desaturation Index

Objective: Sleep apnoea is frequently observed in patients with primary aldosteronism (PA), but the extent to which aldosterone excess contributes to sleep apnoea severity remains unclear. This study investigated the association between sleep apnoea and endocrine, cardiac, renal, and hemodynamic parameters in patients with PA. Methods: We assessed the 3% oxygen desaturation index (ODI) via overnight pulse oximetry in 50 patients (54% male, 49 ± 7.3 years) with biochemically confirmed PA scheduled for adrenal vein sampling between 2017 and 2020. Based on ODI, patients were categorized as having mild, moderate, or severe sleep apnoea. We compared clinical and laboratory parameters including plasma aldosterone, renin activity, aldosterone-to-renin ratio (ARR), left ventricular mass index (LVMI), brain natriuretic peptide (BNP), estimated glomerular filtration rate (eGFR), and blood pressure between the severe group and the other groups. Results: Systolic blood pressure was significantly higher in the severe group than in the mild (175.3 ± 25.7 vs 144.8 ± 18.7 mmHg, p = 0.003) and moderate (143.0 ± 18.5 mmHg, p = 0.003) groups. BNP levels were also significantly elevated in the severe group compared to both the mild (p = 0.020) and moderate (p = 0.014) groups. Aldosterone, renin activity, and ARR did not differ significantly among groups. No significant differences were found in LVMI or eGFR. Conclusions: In patients with PA, aldosterone levels were not associated with sleep apnoea severity. However, severe sleep apnoea was significantly associated with elevated blood pressure and BNP levels, indicating possible hemodynamic and cardiac strain independent of aldosterone excess.