Relation of elastic properties of pulmonary artery with left ventricular abnormalities and aortic stiffness in patients with moderate to severe obstructive sleep apnea: A cross-sectional echocardiographic study

OBJECTIVE
In this study, the associations between pulmonary artery stiffness (PAS) and aortic stiffness, left ventricular diastolic parameters, and left ventricular mass (LVM) index in moderate to severe obstructive sleep apnea syndrome (OSAS) patients without coexisting disorders were investigated.

METHODS
A total of 66 non-diabetic, non-hypertensive, and non-smoking volunteers were enrolled. Participants were categorized by apnea-hypopnea index (AHI; event/hour). The control group was defined as no OSAS: AHI<5 (n=35), and OSAS group had moderate to severe OSAS: AHI>15 (n=31). Echocardiographic and biochemical tests, including measurement of C-reactive protein (CRP), were performed. PAS (kHz/s) was calculated by dividing the maximal frequency shift of the pulmonary flow by the acceleration time.

RESULTS
PAS (kHz/s), obtained by echocardiography, was statistically significantly higher in the OSAS group than the control group (28±5 vs 18±4, p<0.001), and was positively correlated with AHI, CRP, aortic stiffness index, E/E’, and LVM index (p=0.034, p=0.039, p<0.001, p=0.040, and p<0.001, respectively), and negatively correlated with aortic strain (AS), aortic distensibility (AD), E/A, E’/A’, and E’ (p<0.001). Regression analyses indicated that CRP and PAS are independent predictors of aortic stiffness (p<0.05). E/A and LVM index were independent predictors of PAS (p=0.002 and p=0.001, respectively).

CONCLUSION
Increased PAS is associated with aortic stiffness, left ventricular diastolic function, and increased LVM index. PAS may be a more effective indicator of aortic stiffness in OSAS patients than CRP.