Preoperative regional homogeneity predicts postoperative delirium susceptibility after cardiac surgery

Postoperative delirium (POD) is common after cardiac surgery, linked to prolonged hospitalization and adverse outcomes. Despite its clinical impact, objective preoperative neuroimaging markers with robust POD predictive value remain elusive. This study explored whether preoperative regional homogeneity (ReHo) alterations correlate with POD and validated their predictive utility, with a focus on heart-brain interaction implications.

In this prospective observational study, resting-state functional MRI data were collected from patients undergoing valve replacement surgery with cardiopulmonary bypass preoperatively, as well as on postoperative days 7 and 30, alongside data from healthy controls. POD was assessed twice daily over 5 postoperative days using standardized delirium tools. Voxel-wise analyses detected group-level differences and longitudinal ReHo changes, and explored associations between preoperative ReHo alterations, cardiac function, and cognitive performance. Support vector machine (SVM) models incorporating preoperative ReHo features and age were constructed to evaluate their discriminative performance for POD.

Of 43 recruited patients, 35 were included in final analyses, with 7 (20%) developing POD. Compared with non-POD patients, POD patients exhibited significantly reduced preoperative ReHo in the left hippocampus, precuneus, and rolandic operculum. Reduced hippocampal ReHo correlated with cardiac function, while rolandic operculum ReHo linked to episodic memory. SVM models incorporating preoperative ReHo features and age showed discriminative performance for distinguishing patients who developed POD from those who did not.

Preoperative ReHo alterations in specific brain regions reflect latent neural vulnerability to POD. These findings support the potential value of integrating ReHo features with age for preoperative risk stratification, and shed light on heart-brain interactions underlying POD susceptibility after cardiac surgery.