Study Population and Design

This study is composed of 2 separate cohorts. First, we retrospectively reviewed data of nonvalvular AF patients with cardioembolic stroke between January 2013 and December 2016 from the nationwide stroke registry including 9 institutes in Korea. Of these, consecutive patients with a CHA₂DS₂‐VA score of 0 or 1 at the time of stroke event were enrolled. Second, we defined a control group as subjects who were matched by the nearest‐neighbor method with type of AF and CHA₂DS₂‐VASc score among nonvalvular AF patients without stroke from a consortium AF registry from 3 Korea University Hospitals from 2015 to 2016.14

The CHA₂DS₂‐VA score was calculated by adding 2 points for age ≥75 years old and prior stroke or transient ischemic attack, and 1 point for congestive heart failure (or left ventricular ejection fraction ≤40%), hypertension, age 65 to 74 years, diabetes mellitus, and vascular disease (prior myocardial infarction, peripheral artery disease or aortic plaque) with a maximum 8 points.12, 15

Medical records of all subjects were comprehensively reviewed for demographic data, cardiovascular risk factors, parameters of transthoracic echocardiography, and laboratory data (complete blood counts, red blood cell distribution width, NT‐proBNP [N‐terminal pro B‐type natriuretic peptide], blood urea nitrogen, creatinine, uric acid, and low‐density cholesterol). Left ventricular ejection fraction was calculated using Simpson's biplane method and dimension of the left atrium (LA) was measured using M‐mode of transthoracic echocardiography.

This study was conducted with approval of the Institutional Review Board at each institution. The authors declare that all supporting data are available within the article. The board waived the need for patient consent because of the retrospective, cross‐sectional analysis design of the present study. All procedures performed in the present study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee. This study was registered with ClinicalTrials.gov, unique identifier {"type":"clinical-trial","attrs":{"text":"NCT03147911","term_id":"NCT03147911"}}NCT03147911.