Early cardiovascular abnormalities in newly diagnosed obstructive sleep apnea

Abstract

Obstructive sleep apnea (OSA) is associated with high cardiovascular morbidity and mortality. Recent studies have shown that it is associated with atherosclerosis and left ventricular dysfunction markers. The aim of this study was to assess the cardiovascular effects of OSA depending on its severity, in patients without clinically diagnosed cardiovascular disease. One hundred thirty newly diagnosed, nondiabetic OSA patients (mean age 49 +/- 10 years), without vasoactive treatment were included. They underwent clinical and ambulatory blood pressure measurements, echocardiography, carotid ultrasound examination, and a carotid-femoral pulse wave velocity (PWV) measurement. Seventy-five percent of the subjects were hypertensive according to the clinical or ambulatory measurement. More patients with the most severe forms (respiratory disturbance index >37/hour) had a nondipper profile (52% vs 34%; P = 0.025) and their left ventricular mass was higher (40 +/- 7 vs 36 +/- 8 g/m, p = 0.014). This last parameter was independently and inversely associated with mean nocturnal oxygen saturation (P = 0.004). PWV and carotid intima-media thickness did not differ between one OSA severity group to another, but the prevalence of carotid hypertrophy was higher when mean SaO(2) was below 93.5% (29.5 vs 16%; P = 0.05). Our study shows that in OSA patients without clinically diagnosed cardiovascular disease, there is a significant left ventricular and arterial effect, which is even more marked when OSA is severe.

Trial registration: ClinicalTrials.gov NCT00764218.

Keywords: arterial stiffness; hypertension; intima-media thickness; left ventricular hypertrophy; obstructive sleep apnea.

Figure 1

Relationship between carotid IMT and mean nocturnal SaO₂ (r = −0.21, P = 0.017). Abbreviations: IMT, intima-media thickness; SaO₂, oxygen saturation.

Figure 2

LVMI-height^2.7 according to the mean nocturnal SaO₂ group (median) (P = 0.003 between groups 1 and 2). Notes: Group 1: mean nocturnal SaO₂ < 93.5%; Group 2: mean nocturnal SaO₂ ≥ 93.5%. Abbreviations: LVMI, left ventricular mass index; SaO₂, oxygen saturation.