Hemostasis & Anticoagulant Reversal in ICH

Hematoma expansion (HE) — occurring in roughly one-third of ICH patients — is the most potent modifiable predictor of poor outcome. Two distinct therapeutic strategies target HE: hemostatic therapies (tranexamic acid, factor VIIa) for spontaneous ICH, and specific reversal agents for anticoagulant-associated ICH (which accounts for an increasing proportion of cases with the widespread use of DOACs). Despite strong biological rationale, hemostatic therapies have consistently failed to improve functional outcomes, while anticoagulant reversal has shown clearer benefits on hematoma control — though at a cost of thrombotic complications.

1. Hematoma Expansion as a Therapeutic Target

HE is typically defined as ≥33% relative increase or ≥6 mL absolute increase in hematoma volume on follow-up CT. Risk factors for HE include early presentation (<3 hours), large initial volume, CTA spot sign, anticoagulant use, and low GCS. The CTA spot sign — active contrast extravasation within or at the margin of the hematoma — has a positive predictive value of approximately 60–70% for clinically significant HE.

The majority of HE occurs within the first 3 hours, with 73% complete by 6 hours. This ultra-early time window represents the critical therapeutic opportunity. However, despite biological plausibility, translating HE reduction into improved functional outcomes has proven remarkably difficult — a disconnect that likely reflects the multifactorial nature of ICH injury (including edema, inflammation, and blood product toxicity beyond the hematoma itself).

2. Tranexamic Acid Trials

Tranexamic acid (TXA), an antifibrinolytic agent, was a logical candidate for ICH given its success in traumatic bleeding and its ability to stabilize clot formation. Four major trials have tested TXA in ICH with remarkably consistent results: HE reduction does not translate to functional benefit.

TICH-2

TICH-2 was the largest TXA trial in ICH, enrolling 2,325 patients within 8 hours of onset across 124 hospitals in 12 countries. Patients received TXA 1g IV bolus followed by 1g over 8 hours, or placebo. TXA significantly reduced HE at 24 hours (adjusted difference −1.37 mL, p=0.03) but had no effect on the primary endpoint of functional status (mRS) at 90 days (adjusted OR 0.88; 95% CI 0.76–1.03; p=0.11). There was no increase in thromboembolic events. A pre-specified analysis suggested potential benefit when administered within 3 hours.

ULTRA

ULTRA tested ultra-early TXA (within 4.5 hours) in 955 patients across 33 hospitals. Like TICH-2, TXA reduced HE but the primary endpoint of HE (≥33% or ≥6 mL) was not significantly different (19% TXA vs. 22% placebo; adjusted OR 0.82; p=0.23). There was no functional outcome benefit and no safety concerns.

STOP-AUST

STOP-AUST was a smaller phase 2 trial (100 patients) testing TXA in spot-sign-positive patients — those at highest risk of HE. Despite enriching for the highest-risk population, TXA did not significantly reduce HE (adjusted OR 0.53; 95% CI 0.22–1.28). The trial demonstrated feasibility but was underpowered.

STOP-MSU (2024)

STOP-MSU was the most ambitious TXA trial, testing ultra-early administration within 2 hours of onset — delivered via mobile stroke units and hospital settings across Australia, Finland, New Zealand, Taiwan, and Vietnam. Among 201 randomized patients, HE occurred in 43% of the TXA group vs. 38% of placebo (adjusted OR 1.31; 95% CI 0.72–2.40; p=0.37). Even within the fastest treatment window ever achieved, TXA did not reduce HE or improve outcomes. Mortality trended numerically higher with TXA (18% vs. 15% at 90 days), though this was not significant.

3. Recombinant Factor VIIa

Recombinant activated factor VIIa (rFVIIa) was tested in the FAST trial (2008), which enrolled 841 patients within 4 hours of ICH onset. rFVIIa (20 μg/kg and 80 μg/kg doses) significantly reduced HE compared to placebo. However, functional outcomes were not improved (mRS 5–6 at 90 days: 24% rFVIIa 80 μg/kg vs. 24% placebo; p=0.97), and the 80 μg/kg dose was associated with increased arterial thromboembolic events (9% vs. 4%).

The FASTEST trial (NCT03496883) is an ongoing phase 3, double-blind, placebo-controlled trial testing rFVIIa in the ultra-early window (<120 minutes from onset). FASTEST was designed to address the hypothesis that rFVIIa administered before most HE has occurred could overcome the limitations of earlier trials. Results are anticipated and could reshape the hemostatic therapy landscape if positive.

4. Anticoagulant-Associated ICH: Reversal Strategies

Anticoagulant-associated ICH accounts for approximately 12–20% of all ICH cases and is increasing in frequency with expanding DOAC use. These hemorrhages are larger, more likely to expand, and carry higher mortality (~50% at 30 days for VKA-ICH). Immediate reversal is a Class 1 recommendation for all anticoagulant-associated ICH.

4.1 VKA-Associated ICH

4.2 DOAC-Associated ICH

5. ANNEXA-I: Andexanet for FXa-Inhibitor ICH

ANNEXA-I (2024) was the pivotal RCT for andexanet alfa in factor Xa inhibitor-associated ICH. This open-label, blinded endpoint trial enrolled 530 patients with ICH on apixaban or rivaroxaban, randomizing to andexanet alfa or usual care (>85% of the usual care group received PCC).

The primary endpoint — hemostatic efficacy at 12 hours (defined as HE <35%, NIHSS increase <7, and no rescue therapy) — was met in 67.0% of the andexanet group vs. 53.1% of usual care (p=0.003). This benefit was driven almost entirely by reduced hematoma expansion. However, the functional outcome (mRS) at 90 days was not significantly different between groups.

6. Antiplatelet-Associated ICH

The PATCH trial (2016) tested platelet transfusion in patients with ICH on antiplatelet therapy. In 190 patients, platelet transfusion was associated with worse outcomes: the odds of death or dependence were significantly higher (adjusted cOR 2.05; 95% CI 1.18–3.56; p=0.01). Mortality at 3 months was also higher (25% vs. 18%).

The mechanism of harm is uncertain but may involve platelet-mediated inflammation and microvascular thrombosis. Current guidelines recommend against platelet transfusion in antiplatelet-associated ICH unless the patient requires neurosurgical intervention (AHA Class 3: Harm).

7. Ongoing & Future Trials

8. Trial Comparison Table

References

1. Sprigg N, et al. Tranexamic acid for hyperacute primary intracerebral haemorrhage (TICH-2). Lancet. 2018;391(10135):2107–2115.
2. Meretoja A, et al. Tranexamic acid in patients with intracerebral haemorrhage (STOP-AUST). Lancet Neurol. 2020;19(12):980–987.
3. Broderick JP, et al. Tranexamic acid in ultra-early intracerebral hemorrhage (ULTRA). Stroke. 2023;54(4):1154–1163.
4. Yassi N, et al. Tranexamic acid versus placebo in individuals with intracerebral haemorrhage within 2h of symptom onset (STOP-MSU). Lancet Neurol. 2024;23(6):577–587.
5. Mayer SA, et al. Efficacy and safety of recombinant activated factor VII for acute intracerebral hemorrhage. N Engl J Med. 2008;358(20):2127–2137.
6. Connolly SJ, et al. Andexanet for factor Xa inhibitor-associated acute intracerebral hemorrhage (ANNEXA-I). N Engl J Med. 2024;390(19):1745–1755.
7. Baharoglu MI, et al. Platelet transfusion versus standard care after acute stroke due to spontaneous cerebral haemorrhage associated with antiplatelet therapy (PATCH). Lancet. 2016;387(10038):2605–2613.
8. Steiner T, et al. Fresh frozen plasma versus prothrombin complex concentrate in patients with ICH related to vitamin K antagonists (INCH). Lancet Neurol. 2016;15(6):566–573.
9. Greenberg SM, et al. 2022 Guideline for the Management of Patients With Spontaneous ICH. Stroke. 2022;53(7):e282–e361.