Left Atrial Strain and Cryptogenic Stroke

Cryptogenic stroke accounts for nearly one-third of ischemic strokes, yet its underlying mechanism often remains unidentified, leaving patients without targeted therapy. Atrial fibrillation (AF) is detected up to one third of cryptogenic strokes, but its detection frequently requires prolonged monitoring due to subclinical paroxysmal episodes. Increasing evidence suggests that structural and functional abnormalities of the left atrium (LA) precede AF and contribute to thromboembolic risk independently of rhythm disturbances.

This multicenter retrospective study aims to determine whether impaired LA strain, a sensitive echocardiographic measure of atrial function, is associated with cryptogenic stroke and can predict recurrent events. Echocardiographic images of the patients who were referred to the echocardiography laboratory as part of stroke work up will be analyzed offline, using standardized speckle-tracking software. De-identified clinical and imaging data will be collected in the central core laboratory at the University of Pittsburgh for uniform analysis and validation.

By establishing LA strain as a biomarker of atrial cardiopathy and cryptogenic stroke risk, this study seeks to bridge the current gap between stroke classification and management. Demonstrating the independent association between LA dysfunction and cryptogenic stroke and the recurrence of cryptogenic stroke independently of AF could support the use of LA strain as a risk marker to for monitoring patient and developing preventive strategies such as anticoagulation without documented AF. Hence, our findings may improve preventive care and reduce the burden of disabilities due to cryptogenic stroke.

Inclusion criteria

• Adult patients (age > 18 years and < 80 years) who had a complete transthoracic echocardiography (TTE) exam at the University of Pittsburgh Medical Center (UPMC) Presbyterian Echocardiography Lab with a referral diagnosis of suspected stroke.

2- Patients with an established diagnosis of stroke by stroke neurologists.

3- Patients in sinus rhythm documented at the time of referral.

4- Availability of adequate echocardiographic images for strain quantification.

5- Clinical follow-up data available for evaluation of study endpoints, including stroke recurrence, atrial fibrillation development, and mortality.

6- Patients from collaborating centers will be included with de-identified echocardiographic images and clinical data meeting the above criteria.

Exclusion criteria

Incomplete or technically difficult transthoracic echocardiography (TTE) studies and studies from subjects younger than 18 years of age will be excluded. Additional exclusion criteria include:

1- Pre-existing atrial fibrillation (AF): Patients with a documented history AF prior to the index echocardiography study will be excluded because it is well established that AF justifies cryptogenic stroke requiring anticoagulation.

2 -Structural heart disease: Patients with significant structural abnormalities, such as moderate or severe mitral stenosis, moderate or severe mitral regurgitation, prosthetic heart valves, devices in the left atrium, atrial septal defect or patent foramen ovale will be excluded as these conditions are known causes of stroke and abnormal left atrial function.

3- Coagulopathy: Patient having disease leading to hypercoagulable (thrombus formation) state will be excluded (presence of cancer, antiphospholipid antibodies, hematological diseases).

4- Inadequate clinical follow-up: Patients with insufficient follow-up data or missing medical records that preclude evaluation of study endpoints (e.g., stroke recurrence, AF development) will be excluded unless death is documented.

5- Poor image quality for strain analysis: Patients having echo exams with inadequate image quality that prevent reliable strain quantification will be excluded.

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