Evaluation of left atrial function by two-dimensional speckle tracking echocardiography in patients with cryptogenic stroke
Authors: Setouhi Amr , Ali Ahmed M , Rahman Tarek A , A. Wahab Mohamed A Kader 
Published: September 2023

Abstract
Cryptogenic cerebro-vascular stroke is defined as ischemic stroke without definite etiology in spite of complete work up. It differs from embolic stroke of undetermined source (ESUS) which is a subgroup including the cardio-embolic sources.We aimed to evaluate the left atrial function using two-dimensional speckle tracking echocardiography (2D-STE) as a possible cause for cryptogenic stroke or a predictor for subclinical AF.TEE has an important role in the work up of cryptogenic stroke and ESUS searching for a possible cardio-embolic source including PFO, left atrial appendage thrombi and atheromatous plaques in aortic arch.

Patients and methods
Our retrospective cohort study included 62 patients of both sexes with unexplained cerebro-vascular stroke or TIA in stroke unit of Minia University.After performing TEE, 22 patients were excluded as they were proven to have a possible source for cardio-embolism.So, Participants were divided into two groups, group I which included 40 patients with cryptogenic stroke and group II which included 40 healthy participants with no medical history of significance as a control group.Two-dimensional trans-thoracic echocardiography and speckle tracking echocardiography were performed in both groups. We used LA diameter in PLAX, LA volume index (LAVI), LA ejection fraction (LAEF), LA strain rate during reservoir phase (LASr) and LV diastolic dysfunction as parameters of LA dysfunction.48 hours ECG rhythm monitoring during hospitalization was used in participants of group I for detection of more than 30 s episodes of subclinical or paroxysmal atrial fibrillation.Bilateral carotid duplex ultrasonography was also performed for exclusion of significant carotid artery stenosis as a possible cause for stroke.

Results
The parameters of LA dysfunction were significantly affected in group I than group II with P-value &lt; 0.0001 for LV diastolic dysfunction, LAVI, LAEF and LASr, and 0.001 for LA diameter in PLAX.
Episodes of AF were noticed in 14 patients of group I (group Ia, 35%) and the other 26 patients were called (group Ib, 65%).We compared LA dysfunction parameters in Group Ib and group II (healthy controls). There was significant affection of LV diastolic dysfunction in group Ib than group II with P-value &lt; 0.011. LAVI, LAEF and LASr were significantly affected in group Ib than group II with P-value &lt; 0.0001. While, there is no significant difference in LA diameter between both groups with P-value = 0.053.We found that left atrial strain rate during reservoir phase (LASr) is the most sensitive and specific parameter of left atrial cardiopathy in prediction of AF with cut-off point ≤24.5 % and P-value &lt; 0.0001, then LAEF with cut-off point ≤40.5 % and P-value = 0.011. The LAVI is the least sensitive and specific parameter with cut-off point ≥38.5 ml/m2 and P-value = 0.003.

Conclusion
2D-STE has an important role in the evaluation of LA dysfunction as a possible cause for cryptogenic stroke after performing of TEE and exclusion of possible sources for cardio-embolism.LA strain during reservoir phase (LASr) is a strong parameter for LA cardiopathy even before the occurrence of AF.Also, LASr is an independent risk factor for AF. LAEF and LAVI are important as parameters for LA dysfunction and predictors for AF as well but with less sensitivity and specificity than LASr.