Severe OSA in IHD patients ups AF risk during sleep

Severe obstructive sleep apnoea (OSA) in patients with ischaemic heart disease (IHD) is associated with an increased risk of atrial fibrillation (AF) during sleep, according to a Singapore study.

“Previous studies have shown an increased prevalence of OSA in patients with IHD, and there is a growing body of evidence that suggests an association between OSA and cardiac arrhythmias, in particular, AF and ventricular arrhythmias,” said the researchers.

“Locally, the reported prevalence of moderate-to-severe OSA is 30.5 percent … and the severity of OSA is associated with an increased prevalence of AF [in another study],” they noted.

The researchers conducted a retrospective, observational study involving 90 IHD patients (mean age 65 years, 71.1 percent male) referred for overnight polysomnography at the Sleep Laboratory, National University Hospital in Singapore.

At baseline, 46 participants had a severe OSA (apnoea-hypopnoea index (AHI) of ≥30/hour), while the remaining had a nonsevere OSA (AHI <30/hour). The mean AHI was 57.48 in the severe OSA group and 13.66 in the nonsevere OSA group.

Initial results showed a significantly higher prevalence of AF or flutter in the severe OSA group compared with the nonsevere OSA group (odds ratio [OR], 13.51, 95 percent confidence interval [CI], 1.66–109.83; p=0.003). [Singapore Med J 2024;doi:10.4103/singaporemedj.SMJ-2021-293]

After adjusting for potential confounders, including demographics, BMI, cardiovascular (CV) risk factors, CV disease manifestations, and medications causing arrhythmias, the association remained significant, showing that AF or flutter during sleep was more likely to occur among patients with IHD and severe OSA compared with those with nonsevere OSA (adjusted OR, 98.5, 95 percent CI, 2.2–4,332.9; p=0.017).

However, the prevalence of ventricular arrhythmias did not significantly differ between the severe and nonsevere OSA groups, the researchers noted. This result was contrary to a previous study, the Heart Health Study, which showed that ventricular arrhythmia was significantly associated with sleep-disordered breathing vs those without this disorder (35.1 percent vs 21.3 percent; p=0.0003). [Am J Respir Crit Care Med 2006;173:910-916]

The researchers acknowledged that this contradiction could be due to their study population being small and different.

“[However,] our study is one of the first to find an association between OSA and AF in patients with stable IHD,” according to the researchers. “This suggests that IHD patients with severe OSA may have a higher risk of developing clinically important AF if OSA was not diagnosed and treated early.”

“As AF is a risk factor for increased mortality in patients with IHD, timely diagnosis and treatment of OSA in this group of patients may lead to improved clinical outcomes,” noted the researchers.

“However, further work is needed to elucidate the complex triangular relationships among OSA, AF, and IHD,” they suggested.