In patients with new-onset hypertension and obstructive sleep apnea, continuous positive airway pressure (CPAP) therapy plus antihypertensive treatment with losartan led to reductions in systolic blood pressure beyond those achieved with losartan alone, a two-phase study found.
“Adding CPAP treatment to losartan may reduce blood pressure in a clinically relevant way if the patients are compliant with the device,” said Dr. Erik Thunström of the Sahlgrenska Academy at the University of Gothenburg, Sweden, and his associates.
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In their open-label study, 89 men and women with new-onset untreated hypertension – 54 of whom were found to have obstructive sleep apnea (OSA) through a home sleep study and 35 of whom were determined to not have OSA – were treated for 6 weeks with losartan, 50 mg daily. Ambulatory 24-hour blood pressure monitoring was performed before and after treatment.
The patients with OSA were then randomized to receive 6 weeks of nightly add-on CPAP therapy or to continue losartan alone. Ambulatory 24-hour blood pressure monitoring was performed again.
Losartan alone reduced blood pressure in patients with hypertension and concomitant OSA, but the effect was smaller than that seen in patients without OSA. Statistically significant differences were seen in the mean net reduction in morning systolic blood pressure and morning mean arterial pressure. Overall, losartan appeared to be less effective at night and during the early morning hours in patients with OSA, the researchers reported.
After 6 weeks of losartan alone, a blood pressure less than 130/80 mm Hg was achieved by 12.5% of the patients with OSA and by 29% of the patients without OSA.
After 6 weeks of add-on CPAP therapy, 25% of patients with OSA achieved blood pressures less than 130/80 mm Hg. The differences in blood pressures for the OSA patients receiving CPAP plus losartan and those receiving losartan alone were 4.4 mm Hg for 24-hour systolic blood pressure, 1.9 mm Hg for diastolic, and 2.5 mm Hg for mean arterial pressure.
The most “robust” blood pressure changes were seen in the patients who used CPAP therapy for more than 4 hours every night, reducing the mean 24-hour systolic blood pressure by 6.5 mm Hg, the diastolic pressure by 3.8 mm Hg, and the mean arterial blood pressure by 4.6 mm Hg, the researchers reported (Am J Respir Crit Care Med. 2016 Feb.;193:310-20). “Adding CPAP to treatment with losartan reduced the mean 24-hour systolic blood pressure by 6.5 mm Hg in the subgroup of patients with OSA who were adherent with CPAP,” they wrote.
Patients included in the study all had a body mass index of 35 kg/m2; those with OSA had slightly higher BMIs that did not differ significantly from those without OSA.
That CPAP seems to have additive blood pressure–lowering effect when used concomitantly with losartan “favors the idea that it contributes to a further down-regulation of RAAS [renin-angiotensin-aldosterone system] activity in new-onset hypertension and OSA,” the authors wrote.
RAAS activity is often changed in hypertension, and in animal studies it has been shown to be up-regulated by intermittent hypoxia. Angiotensin II receptor antagonists are thus viewed as a good choice in the treatment of patients with OSA and new-onset hypertension, they wrote.