Atrial fibrillation (AFib) and obstructive sleep apnea (OSA) have been independently linked to an elevated risk of ischemic stroke in prior research.1,2 The relationship between OSA and AFib is complex. OSA is associated with a higher incidence and severity of AFib, and AFib outcomes seem to improve in patients with treated OSA.3 However, it remains unclear whether OSA changes the relationship between AFib and stroke.
We analyzed the incidence of ischemic stroke in a cohort of 3.9 million AFib patients, comparing rates between patients with and without OSA. We observed a 27.4% higher rate of ischemic stroke within one year of initial AFib diagnosis in patients with OSA, as illustrated in Figure 1.
In clinical practice, the CHA₂DS₂-VASc tool is widely used to assess the risk of adverse cardiovascular events, including stroke, in AFib patients. The tool assigns a risk score based on patient age, sex, and the presence of various health conditions. A higher score indicates a greater likelihood of adverse cardiovascular outcomes. Some researchers have proposed adding OSA to the CHA₂DS₂-VASc tool as an additional risk factor.4
However, stratifying patients by OSA diagnosis at each risk score did not change the relationship between CHA₂DS₂-VASc score and stroke risk. As expected, stroke rates increased as the risk score rose, but there was no statistically significant difference in stroke rates for patients with and without OSA at each risk score level, as shown in Figure 2.
To evaluate the value of incorporating OSA as a risk factor for stroke, we added one point to a patient’s CHA₂DS₂-VASc score when OSA was present. This is in line with currently proposed methods.5 Doing so, however, did not increase the model’s accuracy. This suggests that while ischemic stroke is more common among AFib patients with OSA compared to those without OSA, the existing CHA₂DS₂-VASc score components adequately capture this risk.
