Left atrial diameter is independently associated with arterial stiffness in patients with obstructive sleep apnea: potential implications for atrial fibrillation.

BACKGROUND: Obstructive sleep apnea (OSA) is associated with increased risk for the occurrence and recurrence of atrial fibrillation. However, the mechanisms involved are poorly understood.
METHODS: We studied 73 middle-aged subjects divided in two groups: with moderate-to-severe OSA (apnea-hypopnea index [AHI] ≥ 15 events/h) or without OSA (AHI ≤5 events/h) by polysomnography. The groups were matched for age, sex, body mass index and hypertension diagnosis. Carotid-femoral pulse wave velocity (a non invasive measurement of arterial stiffness of the aorta) and transthoracic echocardiography were performed in all participants.
RESULTS: As expected, patients with OSA presented higher AHI than patients without OSA (49.6 ± 21.5 vs. 3.3 ± 1.4 events/h; P<0.001). Compared with subjects without OSA, pulse wave velocity (9.6 ± 1.5 vs. 10.7 ± 1.8 m/s; P<0.001) and left atrial diameter (34.7 ± 3.2 vs. 37.6 ± 3.3 mm; P<0.001) were significantly increased in patients with OSA. Pulse wave velocity significantly correlated with left atrial diameter (r=0.45; P<0.001). Multivariate regression analysis showed that AHI and systolic blood pressure were the only independent determinants of pulse wave velocity (F=30.5; r(2)=0.48; P<0.01). The only independent variable associated with left atrial diameter was pulse wave velocity.
CONCLUSIONS: Left atrial diameter is significantly increased and independently associated with arterial stiffness in patients with OSA. This potential mechanism of atrial remodeling may contribute to explain the increase risk of atrial fibrillation in these patients.