Hemostatic Proteins and Their Association With Hematoma Growth in Patients With Acute Intracerebral Hemorrhage
Background and Purpose—We tested the hypothesis that proteins of hemostasia could be associated with hematoma growth (HG) in patients with acute intracerebral hemorrhage.
Methods—We prospectively studied patients with spontaneous supratentorial intracerebral hemorrhage within the first 6 hours after the onset of symptoms. HG was defined as an increase >33% in the volume of hematoma on CT obtained 24 to 72 hours after the onset of symptoms in comparison with the CT obtained at admission. We collected admission and follow-up blood samples. We measured fibrinogen, factor XIII, thrombin activatable fibrinolysis inhibitor, plasminogen activator inhibitor, plasminogen, α2-antiplasmin, tissue plasminogen activator, d-dimer, thrombomodulin, thrombin–antithrombin complex, and plasmin–antiplasmin complex.
Results—We included 90 patients with a mean age of 71±10.8 years; 61% were men. HG was observed in 35 (39%) of the patients. Mean baseline and follow-up protein measurements showed no difference between the groups with and without HG. The analysis of variance showed that factor XIII activity decreased in the non-HG group in the 24 to 72 hours sample, whereas it increased in the HG group (P=0.001).
Conclusion—Factor XIII was the only measured protein related to HG. The levels at the follow-up sample decreased in the non-HG group and increased in the HG group. Further studies are needed to confirm this association.
Among those patients with intracerebral hemorrhage (ICH) diagnosed within the first 3 hours after the onset of symptoms, 38% exhibit an increase >33% in the hematoma volume when a follow-up CT scan is performed 20 hours later.1 Hematoma growth (HG) is associated with poor outcome and mortality2 and therefore is a therapeutic target during the acute stage of ICH.
Although the pathophysiology of HG is unclear, it is hypothesized that a local coagulopathy develops around the hematoma.3 Our hypothesis was that an increase in the levels of fibrinolytic proteins and/or a decrease in the level of coagulation proteins could be associated with HG. We analyzed sequential blood samples of patients with acute ICH.
Patients and Methods
We prospectively studied patients with ICH at two centers. We performed a provisional analysis after recruiting the first 48 patients, and then we focused our search on those proteins that showed a trend toward significance when comparing patients with and without HG, increased the sample number, and added samples from another center to generalize our findings.
We included patients with a spontaneous supratentorial ICH diagnosed within the first 6 hours after the onset of symptoms. A follow-up CT was obtained within 24 to 72 hours after the onset of symptoms. We excluded patients treated with an emergent surgical evacuation, those who died before a follow-up CT, ICH attributable to anticoagulants, other bleeding diathesis, tumor, and arterio-venous malformation. Patients or their legal representatives gave written consent to participate.
In addition to the admission CT, a follow-up CT was obtained within 24 to 72 hours after the onset of symptoms. Hematoma volume was calculated according to the ABC/2 method.1 The absolute HG value and the percentages of HG were obtained.
We also collected blood samples at admission and at follow-up in one-tenth of 0.129 mol/L sodium citrate. Plasma was obtained by centrifugation at 3000g for 20 minutes at room temperature. We measured fibrinogen, factor XIII activity, functional thrombin activatable fibrinolysis inhibitor, plasminogen activator inhibitor activity, plasminogen, α2-antiplasmin, plasminogen activator, d-dimer, soluble thrombomodulin, thrombin–antithrombin complex, and plasmin–antiplasmin complex.
For each patient we recorded age, gender, intraventricular hemorrhage (yes/no), time to admission CT, volume of admission and follow-up CT, and absolute and percentage of HG.
Mean and SD of continuous variables were compared between the 2 groups (HG vs non-HG) by a nonparametric test (Mann-Whitney U test). Categorical variables were compared using the χ2 test. The time course of values for each protein was evaluated by a 2-way repeated-measures analysis of variance (time [admission or follow-up] and HG group [HG or non-HG]).
During the study period, our center attended to 450 patients. After excluding 379, 90 patients were included in our study. Insufficient volume of blood samples resulted in an incomplete analysis of the hemostatic proteins in some patients.
The mean age in our sample was 71±10.8 years; 61% were men. HG was observed in 35 (39%) of the patients. The HG group and the non-HG group were comparable for demographic data, frequency of intraventricular hemorrhage, and volume of the hematoma at baseline. However, we found a shorter time to first CT (P=0.0003) in the HG group. The follow-up CT showed a significant increase in volume in the HG group (mean absolute increase, 27.5 mL; relative increase, 213.7%).
As shown in Table 1, no differences between both groups were observed in the levels of the hemostatic proteins, although we observed a trend to higher values of factor XIII at admission (P=0.11) and lower values at follow-up (P=0.08) in the non-HG group.
The results of the 2-way analysis of variance analysis (Table 2) indicated that some proteins changed from baseline level to follow-up. Fibrinogen increased, whereas thrombin–antithrombin, plasminogen, plasmin–antiplasmin complex, and functional thrombin activatable fibrinolysis inhibitor decreased. However, the change was observed for all these factors in patients from the HG and non-HG groups. Notably, factor XIII showed a different time course depending on the group (P=0.001), ie, it decreased with time in non-HG patients and increased in patients with HG (Figure).
In this prospective and observational study of patients with acute spontaneous ICH, we did not observe significant differences between groups (with or without HG) in the levels of the hemostatic proteins when measured at admission or at follow-up. It remains possible that a larger study would have demonstrated that a low initial factor XIII is associated with HG. The time course of these levels indicates a systemic activation of hemostasia, but these changes were not associated with HG, except for factor XIII activity.
Some previous prospective studies reported the effect of certain variables on the risk of HG.4 Few studies have examined whether systemic activation of hemostasia occurs in patients with acute ICH3,5 and, specifically, what influence this activation has on the risk of HG.3,6 Ours is the first study to our knowledge that focuses on the relationship between hemostatic factors and HG in sequential samples, and it is the first study to our knowledge to analyze the activity of factor XIII. One study3 suggested that in patients with hypertensive ICH, the hematoma became larger when the thrombin generated after bleeding was insufficient. Fujii et al6 also reported that HG was more likely in patients with coagulation abnormalities. Our study confirms that there is a systemic activation of hemostasia after acute ICH. However, most of the changes in hemostatic protein levels that we observed were common to patients with or without HG, and only the activity of factor XIII differed between the 2 groups. Our hypothesis is that patients with higher factor XIII activity are able to have faster and/or better-stabilized clots with enhanced resistance to endogenous lysis. Because of this increased utilization of factor XIII, its activity in peripheral blood decreases with time, whereas it is stable or increases in HG patients.
The main limitations of our study are the small number of patients, our findings do not imply a causal relationship between factor XIII activity and HG, and the changes that occur at a local level may not be detected in our samples. The results of our study show that the baseline measurement of any of the hemostatic proteins is not useful to predict which patient will experience HG. However, our finding that the time course of factor XIII is associated with HG adds to the knowledge of its pathophysiology and may be a useful means to monitor it. Further studies are needed to confirm this association and to clarify why HG occurs in some but not all patients with ICH.
The authors are grateful to Professor William Stone for his helpful comments.
Sources of Funding
This work was supported by grants from the Fondo de Investigaciones Sanitarias (grant PI030670) and the Spanish Stroke Research Network RETICS (RENEVAS), the Spanish Ministry of Health (Instituto de Salud Carlos III).
- Received July 8, 2010.
- Accepted August 20, 2010.
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