Introduction:
Ischemic stroke accounts for 87% of all strokes1, and
cryptogenic stroke constitutes approximately 30-40% of all ischemic
strokes2, 3{Perera, 2022 #584}. Embolic Stroke of
Undetermined Source (ESUS) is a subtype of cryptogenic stroke in which
there is embolic-appearing infarction on CT and/or MRI without an
identifiable etiology despite standard diagnostic
evaluation4. It is associated with a high
recurrence5, 6; thus, in addition to risk factor
modification, identifying and targeting the primary causal mechanisms
may improve secondary prevention strategies7. Better
characterization of left atrial (LA) structure and function may
elucidate a mechanistic pathway in the development of cryptogenic
stroke. Previous studies have shown an association of left atrial
enlargement (LAE)8, 9 and left atrial volume index
(LAVI)10 with ESUS stroke subtype as compared to
non-cardioembolic (NCE) stroke subtype. However, LA chamber remodeling
and biomechanical dysfunction precede volumetric changes in LA
chamber11. Speckle tracking echocardiography (STE) and
strain analysis have been shown to detect these early signals prior to
structural changes found on traditional imaging
methods12-14. Atrial cardiopathy has been
characterized as a time-dependent adaptive structural remodeling with
electrical and mechanical dysfunction causing stasis of blood. It may
provide a potential substrate for the development of thrombus even in
the absence of atrial enlargement or fibrillation13,
15. Atrial fibrosis, an early sign of atrial remodeling, correlates
inversely with LA strain16, 17 and is reported more
frequently in ESUS compared NCE subtype18. A recent
single-center study showed the association of LA strain and stroke
subtypes including cryptogenic stroke19.
The goal of our study is to investigate the relationship between LA
strain and stroke, specifically ESUS and NCE stroke subtypes, in a
geographically distinct population using a comprehensive stroke
database. Additionally, we aim to examine the relationship between LA
strain and future atrial fibrillation (AF) events in ESUS patients.