HAT (Haemorrhage After Thrombolysis) Score for Post-tPA Haemorrhage Risk
Predicts risk of symptomatic intracerebral haemorrhage (sICH) after IV tPA (alteplase) thrombolysis in acute ischaemic stroke. Calculated at admission, before tPA administration.
Score interpretation
HAT 0-1 -- low risk of symptomatic intracerebral haemorrhage after tPA
→ Proceed with tPA if no contraindications; alteplase 0.9 mg/kg (max 90 mg): 10% as IV bolus, 90% as IV infusion over 60 minutes; BP target: < 180/105 mmHg before tPA, < 180/105 during and for 24 hours after; no antiplatelet or anticoagulant for 24 hours post-tPA; monitor neurological status and BP every 15 minutes during infusion, every 30 minutes for 6 hours, then hourly; if deterioration: CT head immediately (exclude sICH); post-tPA care in stroke unit.
HAT 2-3 -- moderately elevated haemorrhagic transformation risk; inform patient and proceed if appropriate
→ Discuss elevated haemorrhagic risk with patient and family as part of consent; reinforce BP control (labetalol 10 mg IV or nicardipine infusion if BP > 185/110); ensure neurosurgical cover available; NIHSS and GCS monitoring every 15 minutes during tPA infusion; thrombectomy assessment if LVO present -- mechanical thrombectomy with or without tPA; stroke unit admission; if planned thrombectomy: HAT risk does not preclude tPA bridge; repeat CT at 24 hours or earlier if neurological deterioration; have fresh frozen plasma, cryoprecipitate, and platelet concentrates available in case of sICH.
HAT 4 -- very high haemorrhagic risk; tPA benefit may not outweigh risk
→ Urgent multidisciplinary decision: senior stroke neurologist and/or neurosurgeon review; consider direct mechanical thrombectomy if LVO (without preceding tPA) -- thrombectomy benefit maintained and avoids tPA-related haemorrhage; if tPA only option (no thrombectomy centre): explicit informed consent documenting 44% sICH risk; CT perfusion or MR DWI-FLAIR mismatch to confirm viable penumbra; BP strictly < 180/105 mmHg; if decision to thrombolyse: neurosurgical team on standby; post-tPA intensive monitoring; if sICH occurs: stop tPA, CT immediately, neurosurgery referral, reverse coagulopathy with cryoprecipitate (fibrinogen target > 1.5 g/L) and FFP.
Interpretation bands for the HAT Score. Apply clinical judgement and local guidance.
References
- Lou M et al. The HAT score: a simple grading scale for predicting hemorrhage after thrombolysis. Neurology. 2008;71(18):1417-1423.
- NICE NG128. Stroke and transient ischaemic attack in over 16s: diagnosis and initial management. NICE. 2019 (updated 2023).
Related
Curated clinical cross-links plus same-class fallbacks.
- Alteplase (STEMI Thrombolysis) · Thrombolytic / STEMI
- Alteplase (tPA) · Thrombolytic — Ischaemic Stroke / Massive PE
- Tenecteplase (Stroke) · Stroke Thrombolysis
- Alteplase (Peripheral Arterial / DVT Use) · Thrombolytic — Catheter-Directed Thrombolysis / Peripheral Arterial Occlusion
- Lisinopril (HFrEF / Post-MI) · ACE Inhibitor / HFrEF
- Colchicine (Pericarditis / Post-MI Inflammation) · Pericarditis / Coronary Inflammation
- Acute Heart Failure · ESC 2021 Heart Failure Guidelines; NICE NG106
- NSTEMI / Unstable Angina · ESC 2020 NSTEMI Guidelines; NICE NG185
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
- Ventricular Tachycardia / Fibrillation · Resuscitation Council UK ACLS; ESC 2022 Ventricular Arrhythmia Guidelines
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.