The Role of Left Atrial Strain in Differentiating Embolic Stroke of Undetermined Source From Other Acute Ischemic Stroke Subtypes Related to Large‐Vessel Occlusion

INTRODUCTION: To evaluate left atrial (LA) function in patients with embolic stroke of undetermined source (ESUS) and other subtypes of acute ischemic stroke (AIS) related to large-vessel occlusion (LVO). METHODS: Consecutive patients with LVO-related AIS were prospectively enrolled from July 2019 to August 2022. To compare LA function with ESUS patients, a control group without prior stroke was sex- and age-matched with ESUS patients in a 1:1 ratio. LA strain was measured within 3 days after stroke. Multivariable logistic regression analysis was performed to assess associations between LA function and stroke subtypes. RESULTS: This study included 126 patients (mean age 67.7 ± 12.3 year, 39.7% women). Of these, 28 patients met the diagnostic criteria for ESUS, while the remaining were classified as large artery atherosclerosis (n = 49) and non-valvular AF-related cardioembolic stroke (n = 49). Patients with ESUS had lower left atrial reservoir strain (LASr) and left atrial conduit strain (LAScd) compared to those with large artery atherosclerosis (27.8 ± 7.1% vs. 32.0 ± 5.3%, p = 0.004, and 14.3 ± 3.8% vs. 17.3 ± 4.6%, p = 0.005, respectively) and the control group (27.8 ± 7.1% vs. 37.6 ± 7.2%, p < 0.001 and 14.3 ± 3.8% vs. 21.5 ± 7.9%, p < 0.001, respectively). A 5% reduction in LASr and LAScd was associated with a 1.92- and 2.45-fold increase, respectively, in the likelihood of having ESUS compared to large artery atherosclerosis. Lower LASr and LAScd in ESUS patients were prone to be associated with a higher likelihood of cardiovascular events during follow-up. CONCLUSIONS: LA strain is associated with ESUS in stroke patients with LVO. Further studies are needed to explore its utility in identifying specific stroke etiologies.