Hypertension and obstructive sleep apnoea syndrome: current perspectives

Effects of olmesartan on blood pressure and insulin resistance in hypertensive patients with sleep-disordered breathing

The increased risk of cardiovascular morbidity and mortality among patients with sleep-disordered breathing (SDB) has been linked to arterial hypertension and insulin resistance. However, an effective antihypertensive agent for patients with SDB has not been identified. We investigated the effect of the angiotensin II subtype 1 receptor blocker olmesartan in hypertensive patients with SDB. This prospective, one-arm pilot study included 25 male patients with untreated SDB (mean age, 52.7 ± 11.4 years). We measured blood pressure, oxygen desaturation index (ODI), cardiac function using echocardiography, and insulin resistance using the homeostasis model assessment (HOMA) before and after 12 weeks of olmesartan therapy (mean dose, 17.6 ± 4.4 mg/day). Olmesartan significantly decreased systolic blood pressure (151.4 ± 8.0 vs. 134.0 ± 7.4 mmHg; P < 0.001), diastolic blood pressure (93.4 ± 7.1 vs. 83.9 ± 6.3 mmHg; P < 0.001), and HOMA index (3.7 ± 2.9 vs. 2.8 ± 1.9; P = 0.012). Furthermore, left ventricular ejection fraction significantly increased at 12 weeks (68.1 ± 5.1 vs. 71.6 ± 5.4%; P = 0.009). However, body mass index (BMI) and degree of SDB did not change (BMI, 26.6 ± 4.0 vs. 26.6 ± 4.2 kg/m2, P = 0.129; 3% ODI, 29.5 ± 23.1 vs. 28.2 ± 21.0 events/h, P = 0.394). Olmesartan significantly reduced blood pressure and insulin resistance in hypertensive patients with SDB without changing BMI or SDB severity.

Comparison of continuous positive airway pressure and valsartan in hypertensive patients with sleep apnea

RATIONALE

Randomized controlled trials (RCTs) have shown that continuous positive airway pressure (CPAP) treatment of obstructive sleep apnea (OSA) reduces blood pressure (BP). CPAP treatment has never been compared with antihypertensive medications in an RCT.

OBJECTIVES

To assess the respective efficacy of CPAP and valsartan in reducing BP in hypertensive patients with OSA never treated for either condition.

METHODS

In this 8-week randomized controlled crossover trial, 23 hypertensive patients (office systolic BP/diastolic BP: 155 ± 14/102 ± 11 mm Hg) with OSA (age, 57 ± 8 yr; body mass index, 28 ± 5 kg/m(2); apnea-hypopnea index, 29 ± 18/h) were randomized first to either CPAP or valsartan (160 mg). The second 8-week period consisted of the alternative treatment (crossover) after a 4-week washout period.

MEASUREMENTS AND MAIN RESULTS

Office BP and 24-hour BP were measured before and at the end of the two active treatment periods. Twenty-four-hour mean BP was the primary outcome variable. There was an overall significant difference in 24-hour mean BP between treatments: the change in 24-hour mean BP was -2.1 ± 4.9 mm Hg (P < 0.01) with CPAP, and -9.1 ± 7.2 mm Hg with valsartan (P < 0.001), with a difference of -7.0 mm Hg (95% confidence interval, -10.9 to -3.1 mm Hg; P < 0.001). The difference was significant not only during daytime but also during nighttime: the change in nighttime mean BP with CPAP was -1.3 ± 4.6 mm Hg (not significant), and -7.4 ± 8.4 mm Hg with valsartan (P < 0.001), with a difference of -6.1 mm Hg (P < 0.05) (95% confidence interval, -10.8 to -1.4 mm Hg).

CONCLUSIONS

In an RCT, although the BP decrease was significant with CPAP treatment, valsartan induced a fourfold higher decrease in mean 24-hour BP than CPAP in untreated hypertensive patients with OSA. Clinical trial registered with www.clinicaltrials.gov (NCT00409487).