Objective Recent studies have suggested an emerging link between sleep apnoea and atrial fibrillation (AF). It has also been reported that an inflammatory process is involved in the development of atrial fibrillation. In this study we hypothesised that premature atrial contractions (PAC) might be the precursor of atrial fibrillation. We assessed the impact of severity of OSAS on the atrial size and CRP level in patients who were found to have atrial premature complexes.

Methods 277 patients diagnosed with obstructive sleep apnoea after overnight polysomnography underwent a 24-h Holter electrocardiography and ambulatory blood pressure monitoring. 137 patients (49%) were found to have premature atrial complexes (PAC). These patients were classified into 3 groups according to the apnoea-hypopnoea index (AHI) as mild (5≥AHI<15), moderate (15≥AHI<30) and severe (AHI≥30). Their C-reactive protein level was assessed by a high-sensitive radio-immunoassay. Of the 137 patients with PAC, 77 underwent transthoracic Doppler echocardiography (TTE) and their left atrial diameter (LAD), interventricular septal thickness (IVSD), left ventricle posterior wall thickness (LVPW), left ventricle mass weight (LVMW), peak diastolic early (E) and late (A) transmitral flow were recorded and their respective E/A ratio and left ventricular ejection fraction (LVEF) calculated CRP and echocardiographic parameters were compared between the different severity of OSAS patients having premature atrial complexes.

Results There is a high prevalence of premature atrial contraction in OSAS patients’-reactive protein and left atrial diameter was significantly increased with severity of OSAS irrespective of systolic and disastolic function. CRP was higher in severe OSAS (5.01±4.68) mg/L as compared to moderate (3.03±1.94) mg/L and mild OSAS (2.98±1.82) mg/L, [mild v/s severe OSAS (p=0.040); moderate v/s severe (p=0.033)]; left atrial diameter was more increased in severe OSAS (40.1±7.9) mm as compared to moderate (37.9±5.5) mm and mild OSAS (33.7±3.8) mm, [mild v/s moderate (p=0.025), mild v/s severe OSAS (p=0.002)].

Conclusion The prevalence of premature atrial contraction (PAC) in OSAS patients is in line with the prevalence of AF in OSAS patients. Severity of OSAS was associated with increase in left atrial size and CRP level in patients with premature atrial complexes. Inflammation associated with OSAS might contribute to atrial structural and electrical remodelling in OSAS patients with premature atrial contraction.