Aims: Measures of left atrial (LA) function are known to predict both ischaemic stroke and atrial fibrillation in specific patient groups. The aim of this study was to investigate the value of LA reservoir strain for predicting ischaemic stroke in patients undergoing coronary artery bypass grafting (CABG) and investigate whether the presence of postoperative atrial fibrillation (POAF) modified this relationship. Methods and results: Patients undergoing isolated CABG were included. The primary endpoint was ischaemic stroke. The association between LA reservoir strain and ischaemic stroke was investigated in uni- and multivariable Cox proportional hazards regression models including adjustment for POAF. We included 542 patients (mean age 67.3±8.9 years, 16.4% female). During a median follow-up period of 3.9 years, 21 patients (3.9%) experienced an ischaemic stroke. In total, 96 patients (17.7%) developed POAF during the index hospitalization. In a multivariable-adjusted Cox proportional hazards regression model, LA reservoir strain was significantly associated with the development of ischaemic stroke [HR (hazard ratio) 1.09 (95% CI 1.02-1.17) per 1% decrease, P = 0.011]. The presence of POAF did not modify this association (p for interaction = 0.07). The predictive value of the LA reservoir strain persisted in multiple sensitivity analyses including restricting the analysis to patients with normal left atrial volumes (LAV<34 ml/m2), patients without POAF, patients without prior stroke, and when excluding patients who developed atrial fibrillation at any time during follow-up. Conclusion LA reservoir strain was independently associated with ischaemic stroke in CABG patients. The predictive value of LA reservoir strain was unaffected by the presence of POAF. Prospective studies are warranted to validate the potential usefulness of LA reservoir strain to predict postoperative ischaemic stroke in the setting of CABG.