Abstract Body (Do not enter title and authors here): Introduction:
Acute ischemic stroke (AIS) represents a significant long-term complication following cardiac surgery, often linked with unfavorable outcomes. Left atrial (LA) mechanics, notably LA strain, have been identified as predictors for both stroke and atrial fibrillation in various populations. However, conflicting evidence exists regarding the clinical relevance of postoperative atrial fibrillation (POAF), and its contribution to the relationship between LA mechanics and ischemic stroke remains uncertain.

Objective
Our study examined the significance of left atrial strain parameters as autonomous predictors of acute ischemic stroke (AIS) among patients undergoing coronary artery bypass grafting (CABG). Additionally, we investigated the association between AIS and postoperative atrial fibrillation (POAF) in CABG patients.

Methods and Materials:
For a retrospective cohort analysis, we enrolled patients undergoing isolated coronary artery bypass grafting between 2021 and 2023. Transthoracic echocardiography was conducted preoperatively. The main outcome assessed was ischemic stroke. We explored the relationship between left atrial (LA) reservoir strain and ischemic stroke using uni- and multivariable Cox proportional hazards regression models, with adjustments for postoperative atrial fibrillation.

Results:
We analyzed a cohort comprising 410 patients, among whom 78 (19%) developed postoperative atrial fibrillation (POAF). Over a median follow-up period of 1.4 years, 19 patients (4.6%) experienced ischemic stroke. In univariable analysis, a significant association was observed between left atrial (LA) reservoir strain and ischemic stroke (hazard ratio [HR] 1.34, 95% confidence interval [CI] 0.97–1.23, p < 0.005) per 1% absolute decrease. Even after adjusting for factors including LA volume index (LAVi) and prior stroke, LA reservoir strain remained a significant predictor of ischemic stroke (HR 1.07, 95% CI 1.01–1.21, p < 0.005 per 1% absolute decrease; HR 3.6, 95% CI 1.23–11.04, p < 0.005 for < vs. >median). The inclusion of POAF as a covariate did not affect the significance of LA reservoir strain in the model.

Conclusion:
Our study concluded that among patients who underwent CABG, LA reservoir strain independently predicted ischemic stroke over the long term.