Lower serum calcium levels are associated with increased hemorrhagic transformation volume following endovascular treatment in acute ischemic stroke

Abstract Background Hemorrhagic transformation (HT) is a frequent and serious complication after endovascular treatment (EVT) for acute ischemic stroke and is strongly associated with poor clinical outcomes. While several predictors of HT have been identified, factors in fluencing the severity of HT, particularly hemorrhage volume, remain in sufficiently explored. Objective To evaluate the association between serum calcium levels and both the occurrence and volume of HT following EVT in patients with acute ischemic stroke. Methods We retrospectively analyzed consecutive patients who underwent EVT for acute ischemic stroke at a tertiary care center between December 2022 and December 2025. HT was assessed on non-contrast computed tomography (CT) performed 24 ± 12 h after EVT. Admission serum calcium levels were recorded. Logistic regression was used to identify predictors of HT occurrence, and linear regression analysis was performed to evaluate factors associated with HT volume. Results A total of 139 patients (mean age 70.8 years; 55% female) were included. HT occurred in 43 patients (31%). Serum calcium levels were lower in patients with HT, although this difference did not reach statistical significance. In multivariable logistic regression analysis, higher National Institutes of Health Stroke Scale (NIHSS) scores and admission glucose levels were independently associated with HT occurrence, whereas serum calcium was not. Among patients with HT, serum calcium levels showed a significant inverse correlation with HT volume (ρ = −0.64, p < 0.001). In linear regression analysis, lower serum calcium levels were independently associated with larger HT volumes (B = − 4.263, p = 0.046). HT volume was positively correlated with mortality (ρ = 0.68, p < 0.001). Conclusions Lower serum calcium levels were independently associated with larger HT volumes following EVT for acute ischemic stroke, although no significant association was observed with HT occurrence. These exploratory findings indicate an association between lower serum calcium levels and greater HT volume among patients who developed HT. Given the retrospective design and the limited number of patients with HT, these findings require confirmation in larger prospective studies.