As the inter-relationships of objectively-ascertained sleep disordered breathing (SDB), post-cardiac surgery atrial fibrillation (PCSAF) and obesity remain unclear; we aimed to further investigate in a clinic-based cohort.
Patients with polysomnography (PSG) and cardiac surgery (coronary artery bypass surgery and/or valvular surgery) within 3 years, from January 2009 to January 2014 were identified excluding those with pre-existing AF. Logistic models were used to determine the association of SDB (apnea hypopnea index (AHI) per 5 unit increase) and secondary predictors [central sleep apnea (CSA) (central apnea index>5) and oxygen desaturation index (ODI)] with PCSAF. Models were adjusted for age, sex, race, body mass index (BMI) and hypertension. Statistical interaction and stratification by median BMI was performed. Odds ratios and 95% confidence intervals are presented.
190 patients comprised the analytic sample; age: 60.6±11.4 years, 36.1% females, 80% white, BMI:33.3±7.5 kg/m2, 93.2% had AHI >5 and 30% with PCSAF. Unlike unadjusted analyses (OR=1.06, 1.01-1.1), in the adjusted model, increasing AHI was not significantly associated with increased odds of PCSAF: OR=1.04 (0.98, 1.1). Neither CSA nor ODI was associated with PCSAF. A significant interaction with median BMI was noted (p=0.015). Effect modification by median BMI was observed; those with a higher BMI>32 kg/m2 had 15% increased odds of PCSAF: OR=1.15 (1.05, 1.26; P<0.003).
SDB was significantly associated with PCSAF in unadjusted analyses, but not after taking into account obesity; those with both SDB and obesity may represent a vulnerable subgroup to target in order to reduce PCSAF and its associated morbidity.