Introduction: Baseline elevated Factor VIII (FVIII) level is a significant independent predictor of stroke occurrence and severity. We conducted a prospective serial laboratory cohort study to assess the correlation of FVIII levels in response to thrombolysis in patients with large vessel occlusion (LVO) and acute ischemic stroke (AIS).
Methods: AIS patients with anterior circulation LVO were enrolled within 4.5 hours from last seen normal. Baseline and serial FVIII levels were obtained to determine whether FVIII serves as a surrogate marker of clot burden and if FVIII levels or changes predict (1) recanalization with intravenous tissue plasminogen activator (IV tPA) or (2) symptomatic intracranial hemorrhage (sICH) following tPA. Linear and logistic regression analyses were used to determine significant predictors.
Results: Patients (n=29) had a mean age of 71years, median NIHSS of 15, 62% were of black race and 48% were female. Baseline pre -tPA FVIII was not significantly correlated with clot burden score (-0.15, p=0.45) or vessel recanalization (-0.13, p=0.50). Median FVIII decreased significantly from baseline to 6hrs post-tPA (282% to 161%, p=0.0024), but delta in FVIII level did not correlate with vessel recanalization (0.01, p=0.95). No patient had sICH. There was no difference between median FVIII level at baseline and 90 days post AIS.
Interpretation: FVIII level decreased significantly after tPA, but baseline FVIII level and early change in FVIII level were not significant predictors of clot burden, vessel recanalization after treatment with IV tPA, or symptomatic hemorrhage. This trial provided no evidence to support the value of acute FVIII level as a biomarker in AIS due to LVO. The physiology behind the decrease in FVIII level after tPA remains unknown.