A new study showed atrial fibrillation was associated with a more than two-fold risk of silent strokes.
Past studies have consistently shown an increased risk of silent cerebral infarctions (SCIs) in patients with Afib, but variations in the definition of SCI and image modalities have resulted in confusion about how high this risk really is, Medpage Today reported.
To make their findings the researchers looked at five studies that used MRIs and four that employed computed tomography (CT) to screen for lesions indicating SCI. All nine of these studies reported adjusted risk estimates.
"MRI is by far the most sensitive imaging we have to look for silent cerebral infarctions, but even within the MRI studies there were variations," said researcher Jeremy N. Ruskin, MD, of Massachusetts General Hospital.
Patients with Afib have a between four and five-fold increased risk for clinically evident stroke and some even experience larger brain infarctions. A recent meta-analysis also found Afib to be associated with a 40 percent increased risk of cognitive impairment. The correlations was independent from other factors such as stroke history, hypertension, and heart failure, MedPageToday reported.
"These findings highlight the elusiveness of the mechanisms underlying this association and suggest pathways other than symptomatic stroke and shared risk factors listed previously as the underlying cause of this association," Ruskin and colleagues wrote. "One such mechanism may be silent cerebral infarctions."
The researchers noted that pinpointing the prevalence of SCIs in patients suffering from Afib is important because it could be an indicator of clinical symptomatic stroke and death. The researchers have not yet extensively looked at how risk is influenced by SCI lesion site.
"Although the determinants of SCI versus symptomatic stroke are not well-defined, smaller lesions in deep white matter are more likely to remain silent, and larger cortical lesions are more likely to become symptomatic," the researchers wrote.
The findings were published in a recent edition of Annals of Internal Medicine.
