Objective: The high prevalence of obstructive sleep apnea in patients with resistant hypertension could be mediated by an activation of the renin-angiotensin-aldosterone system. This study assessed the impact of continuous positive airway pressure (CPAP) treatment on plasma aldosterone concentration (PAC).
Methods: One hundred and twenty-four patients with resistant hypertension were assessed, and those who fulfilled inclusion criteria (n = 116) underwent full night polysomnography, 24-h ambulatory blood pressure monitoring, and PAC measurement. Patients with an apnea–hypopnea index above 15 (n = 102) were randomized to CPAP (n = 50) or to conventional treatment (n = 52) for 3 months.
Results: Seventy-eight patients completed the follow-up (36 CPAP, 42 conventional treatment); 58 had true resistant hypertension (74.3%), whereas 20 had white-coat resistant hypertension (25.6%). Most patients were men (70.7%), age 58.3 ± 9.4 years, and the mean apnea–hypopnea index was 50.1 ± 21.6. In patients with true resistant hypertension, CPAP achieved a significant decrease in most 24-h BP measurements and a nonsignificant decrease in PAC (25 ± 8.7 vs. 22.7 ± 9 ng/dl; P < 0.182). In patients with white-coat resistant hypertension, CPAP achieved a significant decrease in PAC (26.1 ± 11.2 vs. 18.9 ± 10.1 ng/dl; P < 0.041) and in night-time DBP. After adjustment, a weak but significant association was found between cumulative time spent with SaO2 below 90% (CT90%) and baseline PAC (P < 0.047, R2 0.019), and between changes in PAC and changes in office DBP (P < 0.020, R2 0.083)
Conclusions: Night-time hypoxemia and changes in DBP showed an association with baseline and changes in PAC, respectively. CPAP achieved a significant reduction in PAC only in patients with white-coat resistant hypertension, although the CPAP effect on BP was highest in patients with true resistant hypertension.
aServei de Pneumologia, Sleep Unit, Hospital Universitari Vall d’Hebron, Universitat Autònoma de Barcelona, Barcelona
bCIBER de Enfermedades Respiratorias (CIBERES), Instituto Nacional de Salud Carlos III, Madrid
cServei de Nefrologia
dServei de Neurofisiologia Clínica, Sleep Unit
eServei d’Anàlisis Clíniques, Hospital Universitari Vall d’Hebron, Barcelona
fServicio de Neumología, Hospital Universitari i Politècnic La Fe, Valencia, Spain
Correspondence to Dr Patricia Lloberes, Servei de Pneumologia, Hospital Universitari Vall d’Hebron, Passeig Vall d’Hebron, 119-129, 08035 Barcelona, Spain. Tel: +34 932746157; fax: +34 93 2746083; e-mail: firstname.lastname@example.org
Abbreviations: ABPM, ambulatory blood pressure monitoring; AHI, apnea–hypopnea index; CPAP, continuous positive airway pressure; CT90%, percentage of cumulative time spent with SaO2 below 90%; OSA, obstructive sleep apnea; PAC, plasma aldosterone concentration; RAAS, renin–angiotensin–aldosterone system; SaO2, arterial oxygen saturation
Received 14 November, 2013
Revised 7 April, 2014
Accepted 7 April, 2014