Relationship of left atrial size to obstructive sleep apnea severity in end-stage renal disease

Increased left atrial (LA) size is linked to elevated mortality in end-stage renal disease (ESRD). In addition, the degree of overnight rostral fluid shift from the legs is associated with severity of obstructive sleep apnea (OSA). As rostral fluid shift might distend the left atrium and increase fluid accumulation in the neck, we postulated that LA size would be related to the degree of overnight rostral fluid shift and OSA severity in ESRD patients.

Patients with ESRD underwent echocardiography and polysomnography. Leg fluid volume (LFV) was measured by bioelectrical impedance before and after the overnight sleep study in a subset of 21 patients.

Forty patients (22 men), with a mean apnea-hypopnea index (AHI) of 25.1 ± 23.4/h of sleep, had echocardiography and polysomnography performed. In men, there was a correlation between the AHI and LA size indexed for body surface area (r = 0.743, p < 0.001) that was not observed in women. Strong relationships were seen, again in men only, between LA size indexed to body surface area and the overnight change in leg fluid volume (ΔLFV) (r = -0.739, p = 0.02) and between AHI and ΔLFV (r = -0.863, p = 0.003).

In ESRD patients, there are relationships between ΔLFV and both LA size and OSA severity. These findings suggest that the relationship between LA size and mortality in ESRD may be related to ΔLFV and severity of OSA.