Heightened stroke risk for patients with sleep apnea and atrial fibrillation

By Lucy Piper, Senior medwireNews Reporter

Atrial fibrillation (AF) may play an intermediary role in the relationship between obstructive sleep apnea (OSA) and stroke, research findings suggest.

Sean Caples, from Mayo Clinic College of Medicine in Rochester, Minnesota, USA, and colleagues found that patients with OSA who had a stroke had significantly higher rates of atrial fibrillation, even after accounting for potential confounders, than their peers without stroke.

"This could potentially indicate that patients with OSA and AF need aggressive treatment to mitigate the risk of future stroke," the researchers say, although they caution that as theirs was a case-control study, a causal relationship between AF and stroke could not be established.

The researchers identified 2980 patients from a clinical database of Olmsted County residents who were newly diagnosed with OSA based on polysomnography between 2005 and 2010. Of these patients, 34 suffered a stroke during the same time period and 74 patients without stroke were chosen from the database as controls.

AF was significantly more common in the patients with stroke than in the control group, at 50.0% versus 10.8%.

Even after taking into account age, body mass index, coronary artery disease, hypertension, diabetes, hyperlipidemia, and smoking status, patients who had suffered a stroke were a significant 5.4 times more likely to have AF.

The researchers suggest in Sleep Medicine that "OSA may predispose to the development of AF by causing recurrent swings in intrathoracic pressure during airway narrowing, which in turn may result in the enlargement of the relatively thin walled atria of the heart."

Another possible underlying mechanism for the association may include changes in intrathoracic pressure, which the researchers explain is involved in remodeling of the pulmonary vein ostia from which electrical discharges are thought to spread in patients with AF.

The fact that OSA may play an additive causative role in the relationship between AF and stroke, if proven, "heightens the urgency for further prospective studies to help answer important management questions, such as whether OSA should be considered in risk assessments for stroke or prophylactic anticoagulation," Caples et al conclude.

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