Predictive value of free fatty acid levels in embolic stroke of undetermined source: A retrospective observational study

The present study aimed to investigate the predictive value of free fatty acid (FFA) in embolic stroke of undetermined source (ESUS) according to the presence of potential embolic sources (PES) after extensive etiologic evaluation. This was a retrospective observational study based on a single-center registry from January 2011 to July 2017. Stroke subtypes were determined through laboratory findings, brain, and angiographic imaging, carotid ultrasonography, transthoracic echocardiography, and 24-hour Holter monitoring. If ESUS was suspected, transesophageal echocardiography was additionally performed. Patients were classified into ESUS with PES and ESUS without PES. PES included mitral annular calcification, mitral valve prolapse, patent foramen ovale, atrial septal aneurysm, spontaneous echo contrast, ventricular aneurysm, and high-risk plaques of aortic arch, or carotid bulb. We compared clinical and laboratory findings between the two groups. Of a total of 110 ESUS patients, 61 patients (55.5%) had no PES. Patients with ESUS without PES had higher levels of serum FFA, systolic blood pressure, diastolic blood pressure (DBP), and left atrial (LA) enlargement compared with those of ESUS with PES. Multivariable analysis demonstrated that the FFA level, DBP, and LA volume index were associated with ESUS without PES [odds ratio (OR) 1.038, 95% confidence interval (CI) 1.019–1.058 for FFA/10 μEq/L, OR 1.414, 95% CI 1.037–1.928 for DBP/10 mm Hg, and OR 1.073, 95% CI 1.009–1.141 for LA volume index]. Higher levels of FFA, DBP, and LA volume index are associated with ESUS without PES, highlighting the need to identify the role of these markers in ESUS through further large-scale, multi-center and prospective studies.