Embolic Stroke of Undetermined Source Linked to Atrial Fibrosis Without Afib

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Patients with embolic stroke of undetermined source (ESUS) exhibit similar atrial fibrosis as patients with atrial fibrillation and more fibrosis than healthy controls, according to a study published in Neurology. Even after controlling for stroke risk factors, fibrosis is still associated with ESUS, indicating that patients with advanced fibrosis but no atrial fibrillation may benefit from oral anticoagulation for stroke prevention.

Researchers used late-gadolinium-enhancement MRI to compare the atrial fibrosis burden in individuals with ESUS, individuals with atrial fibrillation, and healthy controls (no stroke, no atrial fibrillation). Each cohort comprised 10 participants, mean age was 51±15 years, and 43% were female.

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Atrial fibrosis was more prevalent among individuals in the ESUS cohort compared to the control cohort (16.8±5.7% vs 10.6±5.7%; P =.019); comparable fibrosis was seen in the atrial fibrillation cohort (17.8±4.8%,P =.65). The odds ratios of ESUS per quartile of fibrosis were 3.22 (95% CI, 1.11–9.32; P =.031) and 3.17 after adjusting for the CHA2DS2-VASc Score for Stroke Risk Assessment in Atrial Fibrillation (95% CI, 1.05–9.52; P =.041). Participants with more than 12% fibrosis had a higher percentage of ESUS (77.8% vs 27.3%, P =.02), and 4 in 5 participants with >20% fibrosis had ESUS. Among ESUS participants, increasing CHA2DS2-VASc Score correlated with degree of atrial fibrosis (3.87% fibrosis per point, P =.03).

The primary limitations of this study included its small sample size and case-control design.

The study investigators concluded, “Atrial fibrosis may be the common etiology of ESUS and [atrial fibrillation]; further studies are required to validate this hypothesis.” They go on to state that “Patients with advanced atrial fibrosis without [atrial fibrillation] may benefit from oral anticoagulation for primary and secondary prevention of stroke.”


Tandon K, Tirschwell D, Longstreth WT, Smith B, Akoum N. Embolic stroke of undetermined source correlates to atrial fibrosis without atrial fibrillation [published online June 25, 2019]. Neurology. doi: 10.1212/WNL.0000000000007827