Elevated serum S100B levels indicate a higher risk of haemorrhagic transformation after thrombolytic therapy in acute stroke

Background and purpose: Intracerebral haemorrhage constitutes an often fatal sequela of thrombolytic therapy in patients with ischaemic stroke. Early blood brain barrier (BBB) disruption may play an important role, and the astroglial protein S100B is known to indicate BBB dysfunction. We investigated whether elevated pretreatment serum S100B levels predict haemorrhagic transformation (HT) in thrombolysed stroke patients.

Methods: We retrospectively included 275 ischaemic stroke patients (mean age of 69±13 years; 46% female) who had received thrombolytic therapy within six hours of symptom onset. S100B levels were determined from pretreatment blood samples. Follow-up brain scans were obtained 24 hours after admission, and HT was classified as either haemorrhagic infarction (HI-1, HI-2) or parenchymal haemorrhage (PH-1, PH-2).

Results: HT occurred in 80 patients (29%; 45 HI, 35 PH). Median S100B values were significantly higher in patients with HT (0.14 vs. 0.11µg/l; p=0.017). An S100B value in the highest quintile corresponded to an odds ratio (OR) for any HT of 2.87 (95% CI 1.55–5.32; p=0.001) in univariate analysis and of 2.74 (1.37–5.47; p=0.004) after adjustment for age, sex, symptom severity, time span from symptom onset to hospital admission and vascular risk factors. A pretreatment S100B value above 0.23µg/l had only a moderate sensitivity (0.46) and specificity (0.82) for predicting severe parenchymal bleeding (PH-2).

Conclusions: Elevated S100B serum levels before thrombolytic therapy constitute an independent risk factor for HT in acute stroke patients. Unfortunately, the diagnostic accuracy of S100B is too low for it to function in this context as a reliable biomarker in clinical practice.