Continuous positive airway pressure improves blood pressure and serum cardiovascular biomarkers in obstructive sleep apnoea and hypertension

Abstract

Rationale The impact of treatment for obstructive sleep apnoea (OSA) on reduction of cardiovascular risk is unclear. This study aimed to examine the effect of continuous positive airway pressure (CPAP) on ambulatory blood pressure (BP) and subclinical myocardial injury in subjects with OSA and hypertension. Methods Subjects with hypertension requiring at least three anti-hypertensive medications and moderate-severe OSA were enrolled. Eligible subjects were randomized (1:1) to receive either CPAP treatment or control (no CPAP) for eight weeks. Changes in ambulatory BP and serum biomarkers were compared. Stratified analysis according to circadian BP pattern was performed. Main results Ninety two subjects (75% men; age, 51+/- 8 years; apnoea-hypopnoea index 40+/- 8 events/hour, taking average of 3.4 anti-hypertensive drugs [range 3-6]) were randomised. The group on CPAP treatment, compared to the control group, demonstrated significant reduction in 24-hour systolic BP (-4.4 mmHg,95% CI -8.7 to -0.1, p=0.046), 24-hour diastolic BP (-2.9mmHg,95% CI -5.5 to -0.2,p=0.032), daytime systolic BP (-5.4mmHg, -9.7 to -1.0,p=0.016) and daytime diastolic BP (-3.4mmHg,95% CI -6.1 to -0.8,p=0.012). CPAP treatment was associated with significant BP lowering only in non-dippers, but not in dippers. Serum troponin I (mean difference -1.74 pg/ml,95% CI -2.97 to -0.5,p=0.006) and brain natriuretic peptide (-9.1 pg/ml, 95% CI -17.6 to -0.6,p=0.036) were significantly reduced in CPAP compared to control group. Conclusion In a cohort with OSA and multiple cardiovascular risk factors including difficult-to-control hypertension, short-term CPAP treatment improved ambulatory BP and alleviated subclinical myocardial injury and strain.