All patients with suspected acute stroke or TIA must have an immediate clinical evaluation to establish a diagnosis and to determine eligibility for intravenous thrombolytic therapy or/and endovascular thrombectomy (EVT).

  • intravenous thrombolysis (IVT) is the standard therapy for acute ischemic stroke → fibrinolytic drugs
    • a clear benefit of treatment, NNT to achieve mRS 0-1 varies in different publications
  • start IVT ASAP! – the earlier thrombolysis is started, the higher is the chance of achieving recanalization and the lower the risk of ICH, mortality, and dependency [Emberson, 2014]
    • mortality: <3 h HR 1, 3-4.5 h HR 1.14, >4.5 h HR 1.22   Effect of alteplase on 90-day mortality by treatment delay (Emberson, 2014)
    • mRS 0-1: <3 h OR 1.68, 3-4.5h OR 1.26, >4.5 h HR 1.07   Outcome is dependent on the time window (Emberson, 2014)
    • each 15 min delay in IVT administration reduces the chance of achieving mRS 0-1 by 16%
  • IVT is indicated even in patients scheduled for endovascular treatment
    • results of SWIFT-DIRECT and DIRECT-SAFE trials do not support omitting intravenous alteplase before thrombectomy in eligible patients
    • mechanical thrombectomy should not prevent the initiation of IVT, and IVT should not delay mechanical thrombectomy (do not wait for possible clinical/radiological/neurosonological improvement)
    • IVT can be performed concomitantly with EVT, and there is insufficient evidence for premature termination of IVT before initiation of EVT
    • transport from the stroke center to the comprehensive stroke center should be performed immediately after initiation of IVT
  • wake-up stroke (WUS) within 4.5 hours of symptom recognition after wakeup ⇒  IVT + MT (ESO guidelines 2022)
  • the selection criteria for IVT and MT for patients with wake-up stroke (ESO guidelines 2021)
    • core < 70 ml  (rCBF <30% on CTP or ADC < 620 μm2/s)
    • mismatch ratio (penumbra/core)  > 1.2  – penumbra is defined as Tmax > 6s
    • mismatch volume > 10 ml
  • the thrombolysis eligible patient should be preferably treated in the stroke center or comprehensive stroke center (CSC) and should be admitted to the ICU for at least the first 24 h after the initiation of IVT
  • in the stroke center, the availability of emergent transport to CSC (to perfrom MT) should be secured before starting IVT in patients with LVO


  • alteplase and recently tenecteplase are the only fibrinolytic drugs recommended for intravenous thrombolysis (IVT) in stroke patients  (ESO guidelines 2021)
  • based on the results of the ACT trial, a switch from tPA to TNK can be expected

Alteplase (ACTILYSE)

  • alteplase (ACTILYSE) is a tissue plasminogen activator and has long been the standard treatment of acute ischemic stroke
  • planned mechanical thrombectomy is not a reason for avoiding IVT !!! → more
    • non-randomized studies suggest better outcomes with combination therapy [Mistry, 2017] [Goyal, 2018]
    • on the other hand, if the indication criteria for EVT are met, do not wait for the eventual effect of IVT
  • in 0-4.5h window prefer standard dose (0.9 mg/kg) to reduced dose (ESO guidelines 2021)
Actilyse (alteplase)

Tenecteplase (METALYSE)

  • tenecteplase (METALYSE) is an alternative to alteplase in 4.5h time window
    • genetically modified tPA with enhanced fibrin specificity and longer half-life,  allowing bolus administration
    • according to registry data, TNK is associated with a lower risk of sICH compared to tPA → see here; in the ACT trial, however, the risk of hemorrhage was similar
  • at a dose of 0.25 mg/kg administered as a bolus, TNK is an alternative to tPA:
    • in patients indicated for EVTESO guidelines 2021 prefer TNK in patients scheduled for MT (at dose 0.25 mg/kg)
      • the EXTEND-IA TNK  trial demonstrated a higher incidence of reperfusion and better functional outcome of TNK compared to tPA in patients with large artery occlusion (LVO) followed by MT (complete reperfusion 22% for TNK vs. 10% for alteplase)
      • a meta-analysis of 4 RCTs demonstrated greater efficacy of TNK versus IVT in patients with large artery occlusion (LVO) [Katsanos, 2020]
      • in ExTEND-IA trial part 2, a dose of 0.40 mg/kg compared with 0.25 mg/kg did not significantly improve reperfusion before MT  (Cambell, 2020)
    • standard acute stroke patients eligible for IVT
      • randomized ACT trial (2022) demonstrated non-inferiority of TNK at a dose of 0.25 mg/kg compared to tPA in the standard indication
      • a meta-analysis of 5 trials demonstrated the non-inferiority of TNK versus tPA  [Burgos, 2019]
  •  NOR-TEST 2 trial part A with TNK dose of 0,4 mg/kg was prematurely terminated for safety reasons (TNK did worse than tPA)
Metalyse (tenecteplase)


  • NINDS effect of tPA was demonstrated within 3h after stroke onset – mRS 0-1/3months: 39% vs 26% (placebo)
  • ECASS 3 – tPA effect demonstrated within 4.5h window after stroke onset
  • SITS-MOST  – effect of tPA within 4.5h window
    • analysis of SITS online registry data
    • comparable results from routine clinical practice with results of randomized trials
  • EXTEND (2018)
    • time window 4.5-9h, CTP mismatch ratio >1.2 + mismatch ≥ 10 ml
    • mRS 0-1 /3m RR 1.44 (35.4% vs 29.5%)
  • the efficacy and safety of IVT indicated by CTP were also demonstrated in a meta-analysis of the EXTEND, ECASS-4/EXTEND a EPITHET (mRS 0-1, OR 1.86) [Campbell, 2020].
    • MR DWI/FLAIR mismatch   DWI-FLAIR mismatch
    • OR 1.61 (mRS 0-1 53.3 vs 41.8)
    • effect present also in lacunar infarcts


  • NOR-TEST  (bolus 0.4 mg/kg, maximum 40mg vs. tPA 0.9 mg/kg)
    • n=1100, time window 4.5 h, median NIHSS 4
    • similar results compared to tPA
    • TNK 0.25 mg/kg vs tPA within 4.5 h
    • large artery occlusion (LVO), administration before subsequent mechanical thrombectomy
    • better results than tPA
  • meta-analysis of 4 RCTs in patients with LVO [Katsanos, 2020]
    • TNK vs tPA – mRS 0-2 OR 2.06, recanalization 3.05
  • NOR-TEST 2 part A  (Norwegian Tenecteplase Stroke Trial 2)
    • pre-maturely terminated trial
    • TNK 0.4 mg/kg vs TPA in moderate/severe ischemic stroke
    • tenecteplase yielded worse safety- and functional outcomes than alteplase did
  • ongoing studies comparing effect of tPA and TNK:
    • TASTE (Tenecteplase Versus Alteplase for Stroke Thrombolysis Evaluation)
    • TEMPO-2 (Multicentre, Prospective Randomized Open Label, Blinded-End Point (PROBE)
    • ACT (Alteplase Compared to Tenecteplase in Patients With Acute Ischemic Stroke: QuICR & OPTIMISE Registry Based Pragmatic Randomized Controlled Trial],
    • TWIST (Tenecteplase in Wake-up Ischaemic Stroke Trial)

Advantages and disadvantages of IVT

  • no special equipment required
  • quick initiation of therapy
  • low price
  • narrow therapeutic window
  • low efficacy in larger thrombosis (Clot Burden Score)
    • larger artery occlusion = lower efficacy
    • complete recanalization in terminal occlusion ICA ~10%, M1~20-30%   Complete recanalization odds after IVT according to the thrombus localization
    • recanalization (TIBI 2b/3) in medium-sized artery occlusion (MeVO – mostly M2 segment) in approx. 42% [Ospel, 2020]
    • according to the INTERRSECT study, recanalization in intracranial ICA and MCA occlusion is achieved in 27% of patients [Ohara, 2020]
  • risk of bleeding (IC, but also systemic bleeding)
    • different definitions of symptomatic IC bleeding. ~ 6-7% according to NINDS definition
    • risk is lower in posterior circulation   [Keselman, 2020]
  • numerous contraindications (many of which have become relative over time)  [Tsivgoulis, 2021]

Indications for intravenous thrombolysis

Time from onset of stroke (AHA/ASA 2018 a ESO guidelines 2021)

< 4.5 h

  • age ≥ 16 years
    • risk/benefit of treatment of individuals < 16 years is unknown
    • since 2019, Actilyse has been approved in patients aged 16-17 years based on SITS-ISTR registry data
  • the upper limit of 80 years was removed (ESO guidelines 2021)

    • according to metanalysis, IVT at the age of > 80 y is safe  [Bluhmki, 2020]
    • age alone should not be a limiting factor for IVT (even in wake-up stroke, an ischemic stroke of 4.5–9 h duration with CT or MRI mismatch, minor stroke with disabling symptoms, etc.)
  • ESO guidelines from 2021 recommend ACTILYSE 0.9 mg/kg in patients without subsequent EVT and METALYSE 0.25 mg/kg in case of scheduled EVT
    • it is not recommended to reduce the tPA dose
  • initial non-contrast brain CT is normal or shows early ischemic changes of small or moderate extent (<1/3 MCA territory or ASPECTS ≥7)
    • even with more extensive early ischemic changes, IVT can be given after careful risk-benefit consideration, but a worse outcome and higher bleeding risk should be expected (ESO Guidelines 2021)
    • in the presence of extensive pronounced hypodensities, do not administer IVT

> 4.5 h non-selected

  • IVT is accepted for basilar artery occlusion (BAO) outside the 4.5h window without the use of advanced imaging (perfusion, DWI/FLAIR mismatch)
  • the absence of completed brainstem ischemia is required

4.5-9 h

  • advanced brain imaging should be used to select patients for treatment with alteplase if they present between 4.5 and 9 h after the start of symptoms or if a stroke is noticed at waking from sleep (ESO guidelines 2021)
  • CT/MRI perfusion mismatchEXTEND (2018)  criteria   (SO guidelines 2021)
    • ≥ 18 years, premorbid mRS < 2, NIHSS 4-26
    • time:
      • 4.5-9 h from onset (if the time of onset is known)
      • stroke present on awakening – IVT initiated within 9h of mid-sleep interval
    • radiological parameters:
      • mismatch >1.2 , absolute >10 ml (Tmax >6 s on perfusion)
      • core < 70 ml – rCBF < 30% (CTP) or ADC < 620 mm2/s (DWI)
    • results: mRS 0-1 /3m RR 1.44 (35.4% vs 29.5%)
    • efficacy and safety were also demonstrated by meta-analysis of the EXTEND, ECASS-4/EXTEND, and EPITHET trials (mRS 0-1, OR 1.86) [Campbell, 2020]
  • MR DWI/FLAIR mismatch (according to WAKE-UP trial criteria)
  • for patients with no CT or MRI core/perfusion mismatch, ESO 2021 guidelines suggest against IVT with alteplase
  • if the patient is a candidate for both IVT and MT in the 4.5-9 h window (according to the above criteria), then:
    • initiate IVT before transport from stroke center to CSC (ESO guidelines 2021)
    • if the patient is in a comprehensive stroke center, there is no consensus on whether to start IVT before MT (ESO guidelines 2021)

Wake Up Stroke (WUS) / Stroke of Unknown Time of Onset

  • according to a meta-analysis of the WAKE-UP, EXTEND, THAWS, and ECASS-4  studies, IVT in patients with persisting salvageable brain tissue (according to advanced CT/MR  techniques) is safe and effective [Thomalla, 2020]
    • therapy with tPA led to a higher percentage of patients with no or minor neurologic deficit than the use of placebo
  • MR DWI/FLAIR mismatch – DWI lesion without a correlate in FLAIR, with a DWI lesion < 1/3 of the MCA territory  (AHA/ASA 2019 IIa/B-R) (ESO guidelines 2021)
    • in the absence of changes on FLAIR, the predicted stroke duration is < 4.5h – see positive results of the WAKE-UP  trial
  • CT/MR perfusion (perfusion mismatch on CT or MR – see EXTEND study criteria above) (ESO guidelines 2021)

    • IVT administered within 9 hours of mid-sleep interval
  • if the patient is a candidate for both IVT and EVT, then IVT is likely to be administered before EVT (ESO Guidelines 2021, expert consensus)
  • IVT indication based on ASPECTS score on NCCT –  ESO guidelines 2021 recommend advanced imaging in the time window of > 4.5h or WUS

    • however, it seems safe to thrombolyse patients with wake-up strokes and a normal NCCT; similar outcomes in patients with witnessed-onset and wake-up strokes and normal CT were reported (Armon, 2019)
    • patients with WUS < 4.5h from awakening or patients with an unclear stroke onset time
    • NCCT: normal findings or early ischemic changes in < 1/3 of the MCA territory and/or ASPECTS > 7
    • non-randomized TRUST-CT trial showed benefit in patients with ASPECTS ≥ 7 (OR 1.94 ) – RCTs are needed


A neurological deficit

Mild deficit → see comments on IVT contraindications

  • mild disabling deficit (mild stroke – NIHSS 0-5, e.g., homonymous hemianopsia, mild aphasia or dysarthria in an actor, mild paresis in a pianist, etc.) ⇒ IVT is recommended (ESO guidelines 2021) (AHA/ASA 2019 I/B-R)
  • mild non-disabling deficit: IVT is not recommended (ESO guidelines 2021) (AHA/ASA 2019 III/B-R)
  • mild non-disabling deficit + LVO ⇒ IVT is suggested, but an individual approach is required (ESO 2021 – expert consensus)
    • neurological deficits may fluctuate; many patients with acute arterial occlusion will eventually progress  if recanalization is not achieved (END – Early Neurological Deterioration)
    • CT perfusion with the RAPID system is a valuable tool for detecting peripheral occlusions
  • rapidly improving but still disabling deficit ⇒ IVT is suggested  (ESO 2021 – expert consensus)
  • thrombolysis in central retinal artery occlusion (CRAO) → see separate chapter here

A severe stroke

  • the benefit of IVT in patients with NIHSS > 25 is unclear; IVT can be considered a life-saving procedure (ESO guidelines 2021)
  • the extent of early ischemic changes that could be considered futile for thrombolytic therapy is not clear
    • however, ASPECTS < 7 has been shown to increase the risk of sICH [Singer, 2009]
    • according to ESO guidelines 2021 (expert consensus), patients with NIHSS > 25 and/or ASPECTS < 7 should  probably be treated with IVT
    • selection criteria might include results of advanced imaging (notably core/perfusion mismatch), the extent of white matter lesions, other contraindications for IVT, and pre-stroke disability
  • direct mechanical thrombectomy (dMT) is suggested


Administration of thrombolytic therapy

Start thrombolysis as soon as possible after the patient’s arrival at the hospital. None of the investigations should delay its initiation.
The so-called Door-To-Needle Time (DTN) should be less than 45-60 min; in uncomplicated patients, the bolus can usually be initiated within 10-15 min.
Urgently consult with a stroke specialist within the institution or through telestroke services if needed.

Initial patient examination and monitoring

  • focus on ultra-fast administration of IVT bolus (in an uncomplicated patient in less than 10-15 minutes !)
    • the procedure requires logistical arrangements within the stroke center
    • many centers no longer insert a urinary catheter, second i.v. cannula or perform an ECG before IVT administration
    • it is a good idea to check contraindications by phone or in the documentation before the patient arrives
    • pre-hospital mobile stroke units are also being tested to speed up treatment. The cost-benefit is still uncertain; one analysis showed no better mRS 0 and 1 compared to standard care; however, there was no higher incidence of hematomas [Kunz, 2016]
  • perform rapid clinical examination including assessment of NIHSS, vital signs, verify the time of onset, and contraindications →  initial examination of a stroke patient 
  • quickly perform non-contrast CT (NCCT) of the brain (sufficient for IVT indication)
    • there is no known threshold for the extent of early CT signs of ischemia that should lead to withholding IVT unless there is a known contraindication
    • hyperdense media sign is not a contraindication for IVT (AHA/ASA 2019 IIa/B-NR)
    • routine use of MRI to exclude microbleeds is not recommended (AHA/ASA 2019 I/B-NR)
  • always consider the risk-benefit of IVT (AHA/ASA 2019 I/C-EO)
  • minimize the risk of stroke mimics (especially exclude hypoglycemia), imaging is helpful (especially CTA/CTP)
  • don´t wait for coagulation test results unless:
  • if no contraindication is detected, administer tPA/TNK bolus
  • continue with CTA/CTP and consider MT

Infusion preparation, dose

Actilyse (alteplase) Actilyse
  • vials with alteplase (10mg, 20mg, or 50mg) are diluted with the included solution (there is a vacuum in the t-PA vial, so a cannula is first injected into the water vial)
  • infusion dilution: 1mg/1ml
  • do not further dilute this solution and do not administer it with other drugs (use separate i.v. cannula)
  • ACTILYSE 0.9 mg/kg
    • 10% as an initial intravenous bolus over 2 min
    • the rest (90%) is given as an intravenous infusion over 60 min
    • max dose for stroke indication is 90 mg
  • If lab results show INR > 1.7, aPTT values above the Upper Limit of Normal (ULN), or platelet count < 100,000/μl, IVT must be stopped immediately
Metalyse (tenecteplase) Metalyse
  • the vial of tenecteplase (10 000 units/50 mg) is diluted with the supplied solution (10 ml), and the solvent is added to the powder
  • infusion dilution: 1ml/1000 IU/5mg  → more
  • do not further dilute the solution or administer it with other drugs (use a separate cannula)
  • if INR > 1.7, aPTT above the ULN or platelet count < 100 000/μl is detected in the blood sample, IVT must be discontinued immediately
  • dosage
    • thrombolysis alone (according to the NOR-TEST study) – bolus 0.4 mg/kg (0.08 ml/kg), maximum 40mg
    • thrombolysis preceding MT (according to the EXTEND-IA TNK study) – bolus 0.25 mg/kg (0.05 ml/kg)
TCCD monitoring during intravenous thrombolysis - complete recanalization of occluded MCA was achieved
Basilar artery occlusion on NCCT (dense artery sign)

Care during thrombolysis

  • monitor for vital signs
  • blood pressure (BP) should be lowered and sustained below 180/105 mmHg before, during, and 24h after IVT administration  (BP > 185/110 mmHg is a contraindication to thrombolytic treatment)  (AHA/ASA 2022)
    • check BP every 15 min in the first 2h, then every 30 min in the next 22h
    • in case of decompensated hypertension and parenteral antihypertensive therapy, measure more frequently (every 3-5 min) → protocol for BP correction during IV
    • aggressive BP correction in the first 72 h (BPs < 130140 mmHg) leads to a reduction in ICH risk (14.8% vs. 18.7%) according to the ENCHANTED study, but therapy did not affect the outcome (mRS/3m). Patients with mild and moderate deficits were included in the study [Anderson, 2019])
    • avoid precipitous falls in blood pressure because this might worsen or induce ischemia, particularly in the setting of intracranial or extracranial arterial occlusion/stenosis
  • monitor bleeding complications (injection sites, oral cavity, GIT, urogenital tract, site of injury) and allergic reactions, including angioedema (→ more here)
  • monitor NIHSS / GCS
    • in case of an increase in NIHSS ≥ 4 points (which can not be attributed to, e.g., TCCD-demonstrated reocclusion) and in case of new-onset severe headache, consider stopping IVT and order repeated CT scan
  • TCD/TCCD monitoring
    • repeated quick examinations with TIBI assessment only; continuous monitoring (sonothrombolysis) is not recommended beyond clinical trials
  • In patients with large artery occlusion (LVO), arrange endovascular intervention at the start of IVT and do not await IVT to be completed (the chance of LVO recanalization is low with IVT alone; <10% for terminal ICA occlusion)
    • transport the patient to the center performing EVT immediately after the initiation of IVT
  • criteria of probable persistent occlusion:
    • no clinical improvement (<40% reduction in NIHSS)
    • TCD/TCCD TIBI ≤ 3

Post-thrombolysis monitoring

  • blood samples
    • CBC and coagulation (aPTT, INR, fibrinogen) at 6 and 24 h after IVT
    • basic biochemistry at 12-24 h
  • follow-up NCCT of the brain after 22-36 h
  • continue with precise BP compensation in the first 24h (< 180/105 mm Hg)
  • insert urinary catheter either before thrombolysis or > 60 minutes after completion of IVT
  • do not insert a nasogastric tube, a central venous catheter (CVC), or do not perform arterial puncture in the first 24 hrs
    • in case of emergency, wait at least 30 minutes after infusion; APTT and INR must be normal
    • prefer puncture of the femoral vein to the subclavian vein
  • avoid IM injections during thrombolysis and 60 minutes after finishing IVT
  • avoid anticoagulation therapy in the first 24h after IVT
    • even LMWH in prophylactic doses should be postponed for 24 hrs ⇒ use mechanical DVT prevention (IPC) instead
  • antiplatelet therapy in the first 24 hours:
    • do not administer intravenous aspirin within 90 minutes after starting IVT (ARTIS study) (AHA/ASA 2019 III/B-R)
    • do not administer abciximab concomitantly with IVT
    • standard antiplatelet therapy should be deployed after 24 h if follow-up CT has ruled out a hemorrhagic complication
    • antiplatelet therapy may be given within 24h after IVT if there is a demonstrable benefit in comorbidities (e.g., in a patient after acute stenting, with concomitant acute MI, etc.) (AHA/ASA 2019 IIb/B-NR)


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