Background Post-stroke inflammation contributes to poor outcomes, but its impact on patients with stroke receiving endovascular thrombectomy (EVT) remains unknown.

Methods We enrolled adult patients with stroke who received EVT, with blood sampling immediately before (T1) and after EVT (T2), and at 24 hours after EVT (T3). Non-stroke controls and patients with non-EVT stroke were also enrolled. The medical information, image findings and levels of serum amyloid A (SAA) and C-reactive protein (CRP) were analyzed to clarify the association with poor functional outcome (modified Rankin Scale 4–6) at 3 months after stroke.

Results A total of 93 patients with stroke receiving EVT, 51 non-stroke controls, and 64 with non-EVT stroke were enrolled in this study. The SAA and CRP levels at T1 to T3 in patients with stroke receiving EVT were higher compared with those in controls (all p<0.001), and their levels at T3 were significantly higher than those at T1 (both p<0.0001) while similar to those in patients with non-EVT stroke. The SAA levels at the three time points were significantly associated with poor functional outcome (p=0.003 to 0.009). Furthermore, adding SAA level at T3 significantly improved the basic prediction model for 3-month poor functional outcome by receiver operating characteristic (ROC) analysis (areas under ROC curves from 0.803 to 0.878, p=0.03).

Conclusions Our findings demonstrate that plasma levels of SAA at an early stage are significant predictors for poor functional outcomes at 3 months in patients with stroke receiving EVT, indicating the substantial role of systemic inflammation in shaping stroke outcomes following EVT.