OSA linked to arrhythmias during sleep in IHD patients

A significant association between obstructive sleep apnoea (OSA) and nocturnal atrial fibrillation (AF)/flutter has been observed in patients with ischaemic heart disease (IHD), reveals a Singapore study. 

“This underscores the need to evaluate for OSA in patients with IHD, as it may have important implications on clinical outcomes,” suggest the researchers. 

Some 103 consecutive patients with IHD who underwent an overnight polysomnography were included in this analysis. Exposed patients were defined as those who had an apnoea–hypopnoea index (AHI) ≥30/h (severe OSA), while nonexposed patients were those who had an AHI <30/h (nonsevere OSA). 

Electrocardiogram (ECG) results were interpreted by the Somte ECG analysis software and validated by a physician who was blinded to the presence or absence of exposure. 

In addition, the researchers categorized arrhythmias as supraventricular and ventricular. They also analysed arrhythmia subtypes (eg, ventricular, atrial, and conduction delay) as dichotomous outcomes using multiple logistic regression models. 

The severe OSA group was more likely to experience AF and flutter (odds ratio, 13.5, 95 percent confidence interval, 1.66–109.83; p=0.003) during sleep than the nonsevere OSA group. Such association persisted even after adjusting for potential confounders. [Singapore Med J 2025;66:190-194] 

On the other hand, no significant between-group difference was observed in the prevalence of ventricular and conduction delay arrhythmias. 

“Our finding lends further support to previous literature that suggests an association between OSA and nocturnal arrhythmias,” the researchers said. 

Previous studies 

In the Sleep Heart Health Study, individuals with severe sleep-disordered breathing were two to four times more likely to have complex arrhythmias, specifically AF, than those without sleep-disordered breathing. [Am J Respir Crit Care Med 2006;173:910-916] 

A retrospective cohort study of 3,542 adults also found a robust association between OSA and the incidence of AF within 5 years of its diagnosis. It also noted the independent association of the degree of oxygen desaturation with the risk of AF, which was similar to the finding of another study. [J Am Coll Cardiol 2007;49:565-571; Circulation 1998;98:946-952] 

Additionally, a study by Dhakal and colleagues found a 10.44-percent prevalence of AF in OSA patients, regardless of severity. [J Nepal Med Assoc 2020;58:80-83] 

"In our study, we found that among IHD patients, those with severe OSA had [an] increased risk of having AF during sleep,” the researchers of the current study said. 

Mechanisms 

Potential mechanisms may explain the association between AF and OSA, such as the effect of negative intrathoracic pressure and impaired autonomic nervous control. 

“Repetitive forced inspiration against an obstructed upper airway generates very substantial negative pressures in the chest cavity,” the researchers said. “This pressure is transmitted to the atrial walls and thought to contribute to atrial enlargement, which is a risk factor for AF.” [Chest 2007;132:1863-1870] 

Other plausible explanations could be the alterations in sympathetic and parasympathetic nervous system activity because of hypoxia in OSA. [Circulation 1999;99:1183-1189] 

"It is possible that the effects of these pathophysiologic mechanisms are further exaggerated in patients who have already had ischaemic injury to their myocardium,” the researchers said.