Effect of Nocturnal Intermittent Hypoxia on Left Atrial Appendage Flow Velocity in Atrial Fibrillation

Abstract Background The mechanism underlying the associations of sleep-disordered breathing (SDB) with stroke and atrial fibrillation (AF) is not well established. We explored the relationship between nocturnal intermittent hypoxia, a marker of SDB, and left atrial (LA)/LA appendage (LAA) function among AF patients. Methods We evaluated 134 consecutive AF candidates for catheter ablation (age, 59.6 ± 9.4 years; body mass index [BMI], 24.8 ± 3.2; C ongestive Heart Failure, H ypertension, A ge (≥75 years), D iabetes, S troke/Transient Ischemic Attack, V ascular Disease, A ge (65-74 years), S ex (Female) (CHA2 DS2 -VASc) score, 1.2 ± 1.1, paroxysmal AF, n = 83) using nocturnal pulse oximetry, a noninvasive screening method for nocturnal intermittent hypoxia. Based on 3% oxygen desaturation index (3% ODI), patients were divided into nocturnal intermittent hypoxia (3% ODI > 15; n = 32) and control groups (3% ODI ≤ 15; n = 102). Results The nocturnal intermittent hypoxia group demonstrated significantly higher weight, BMI, C ongestive Heart Failure, H ypertension, A ge, D iabetes, S troke/Transient Ischemic Attack (CHADS2 ) and CHA2 DS2 -VASc scores, serum hemoglobin A1c and plasma brain natriuretic peptide levels, LA size, and prevalence of hypertension, vascular disease, and sick sinus syndrome. Echocardiographically, nocturnal intermittent hypoxia was associated with a higher grade of spontaneous echo contrast and low LAA flow velocity. Multiple regression analysis adjusted for type of AF, CHA2 DS2 -VASc score, BMI, plasma brain natriuretic peptide level, LA size, and rhythm on echocardiography revealed that 3% ODI was a factor independently associated with LAA flow velocity (β = −0.184; 95% confidence interval, −0.818 to −0.006). Conclusions Nocturnal intermittent hypoxia was an independent determinant for low LAA flow velocity in patients with AF, suggesting that the connection between SDB and LAA function might underlie the association of AF with stroke.