The Investigation of Left Atrial Structure and Stroke Etiology: The I-LASER Study

Background Left atrial (LA) function is important in stroke, but often poorly characterized. We evaluated the association of 2-dimensional speckle tracking echocardiography LA variables with stroke subtype (cardioembolic stroke [CS] or cryptogenic stroke versus other). The hypothesis is worse LA active function is associated with CS, but not cryptogenic strokes. Methods and Results In this prospective cohort (2017-2019), left ventricular/LA structure and function were quantified by 2-dimensional and speckle tracking echocardiography in 151 patients with stroke. Strain/strain rate curves for the 3 components of the LA cycle, ie, (1) Reservoir (global longitudinal strain [Srmax]), (2) Conductive (early LA Sr [Sre]), and (3) Active (late LA strain [Sra]) were evaluated, masked to stroke subtype. Associations of cardiac features with stroke subtype were tested using multivariable logistic regressions. Odds of CS were increased in patients with a larger LA systolic diameter (odds ratio [OR], 2.96, 95% CI, 1.14-7.69) but reduced in patients with a higher Srmax (better reservoir) (OR, 0.80, 95% CI, 0.67-0.97). Lower Sra (worse function) was associated with an increased odds of CS (OR, 1.72, 95% CI, 1.07-2.76) but not independent of atrial fibrillation. Higher active LA emptying fraction (better active phase) was associated with reduced odds of CS (OR, 0.74, 95% CI, 0.57-0.95) or cryptogenic stroke (OR, 0.82, 95% CI, 0.68-0.98) versus other subtypes; other associations between cryptogenic stroke and speckle tracking echocardiography were not found. Conclusions Markers of LA structure and function were associated with CS. Similar associations were not found for cryptogenic stroke, which might suggest different underlying mechanisms, given study limitations. Further understanding could aid stroke diagnosis and secondary stroke prevention research.