What is the evidence leading to the AHA recommendation: "In patients with AIS who have salvageable ischemic penumbra detected on automated perfusion imaging and who (a) awake with stroke symptoms within 9 hours from the midpoint of sleep or (b) are 4.5–9 hours from last known well, IV thrombolysis may be reasonable to improve functional outcomes."

Comment by InpharmD Researcher

As noted in the current AHA stroke guidelines regarding extended time windows for IV thrombolysis, patients with AIS who have salvageable ischemic penumbra detected on automated perfusion imaging and who are awake with stroke symptoms within 9 hours from the midpoint of sleep or are 4.5 to 9 hours from last known well state may be administered IV thrombolysis. Based on the evidence provided in the guidelines, this recommendation is primarily supported by advanced imaging-selected late-window thrombolysis trials. These trials are summarized in Tables 1-7. Most of these studies generally indicate improved clinical outcomes in patients treated with IV thrombolysis; however, some results were conflicting, and studies also noted a higher incidence of symptomatic intracranial hemorrhage. Despite the higher incidence of intracranial hemorrhage, mortality rates were comparable between groups.

Background

A 2019 systematic review and meta-analysis investigated the potential of extending the time window for thrombolysis in acute ischemic stroke patients using perfusion imaging to identify salvageable brain tissue. This analysis pooled individual patient data from three trials - EXTEND, ECASS4-EXTEND, and EPITHET - comprising a total of 414 patients who were treated with intravenous alteplase or placebo more than 4.5 hours after stroke onset or upon waking with stroke symptoms. The primary outcome focused on achieving an excellent functional outcome, defined as a modified Rankin Scale (mRS) score of 0-1 at three months. The analysis was adjusted for baseline age and clinical severity, utilizing mixed-effects logistic regression models. The findings revealed that patients administered alteplase presented significantly better functional outcomes, with 36% achieving an mRS score of 0-1 compared to 29% in the placebo group, yielding an adjusted odds ratio of 1.86. Additionally, secondary outcomes, including functional improvement and early neurological improvement, were notably better in the alteplase group. Symptomatic intracerebral hemorrhage occurred more frequently in the alteplase group, yet the increased risk did not outweigh the overall therapeutic benefit. Notably, patients meeting automated perfusion mismatch criteria experienced the most pronounced benefit, enhancing the therapeutic potential of thrombolysis beyond the conventional time window when guided by advanced imaging techniques. The analysis highlighted that while there was a higher incidence of symptomatic hemorrhage, mortality rates remained similar between both groups. [1]

Literature Review

A search of the published medical literature revealed 7 studies investigating the researchable question:

Level of evidence

B - One high-quality study or multiple studies with limitations Read more→

Please see Tables 1-7 for your response.

Thrombolysis Guided by Perfusion Imaging up to 9 Hours after Onset of Stroke
Design	Multicenter, randomized, placebo-controlled trial (EXTEND) N= 225
Objective	To test the hypothesis that intravenous thrombolysis with alteplase initiated between 4.5 and 9.0 hours after stroke onset or on awakening with stroke symptoms would provide a benefit in patients who had a small core volume of cerebral infarction that was disproportionate to a larger area of hypoperfusion.
Study Groups	Alteplase group (n= 113) Placebo group (n= 112)
Inclusion Criteria	Patients aged ≥18 years with excellent functional status before enrollment (modified Rankin scale score <2), a stroke with NIHSS score of 4 to 26, and hypoperfused but salvageable brain regions detected on automated perfusion imaging.
Exclusion Criteria	Patients considered for endovascular thrombectomy at the time of enrollment.
Methods	Patients were randomly assigned to receive either alteplase (0.9 mg/kg, max 90 mg, administered as a 10% bolus and 90% infusion over 1 hour) or placebo. Randomization was stratified by geographic region and time of intervention. Imaging techniques included CT perfusion imaging or perfusion-diffusion MRI, processed with RAPID software. The authors estimated the volume of irreversibly injured ischemic-core tissue, using a threshold for relative cerebral blood flow of less than 30% of that in normal brain regions. Perfusion lesion-ischemic core mismatch was defined as a ratio greater than 1.2 between the volume of hypoperfusion and the volume of the ischemic core, an absolute difference in volume greater than 10 ml, and an ischemic-core volume of less than 70 ml.
Duration	August 2010 to June 2018
Outcome Measures	Primary: Score of 0 or 1 on the modified Rankin scale at 90 days Secondary: Distribution of scores on the modified Rankin scale at 90 days, functional independence (score of 0 to 2 on the modified Rankin scale), percentages of reperfusion at 24 hours Tertiary: Recanalization at 24 hours, major neurologic improvement at 24 hours, 72 hours, and 90 days
Baseline Characteristics		Alteplase (N=113)	Placebo (N=112)
	Age, years	73.7±11.7	71.0±12.7
	Male sex	59 (52.2%)	66 (58.9%)
	Median NIHSS score (IQR)	12.0 (8.0–17.0)	10.0 (6.0–16.5)
	Clinical history of atrial fibrillation	46 (40.7%)	36 (32.1%)
	Geographic region - Australia, New Zealand, and Finland	90 (79.6%)	88 (78.6%)
	Geographic region - Taiwan	23 (20.4%)	24 (21.4%)
	Time from stroke onset to randomization >4.5 to 6.0 hr	12 (10.6%)	11 (9.8%)
	Time from stroke onset to randomization >6.0 to 9.0 hr	28 (24.8%)	28 (25.0%)
	Awoke with stroke symptoms	73 (64.6%)	73 (65.2%)
	Median time from stroke onset to hospital arrival (IQR) - min	308 (227–362)	293 (230–357)
	Median time from stroke onset to initiation of intravenous therapy (IQR) - min	432 (374–488)	450 (374–500)
	Median time from hospital arrival to initiation of intravenous therapy (IQR) - min	124 (81–179)	127 (87–171)
	Large-vessel occlusion	78 (69.0%)	81 (72.3%)
	Median volume of irreversibly injured ischemic-core tissue at initial imaging (IQR) - ml	4.6 (0–23.2)	2.4 (0–19.5)
	Median perfusion-lesion volume at initial imaging (IQR) - ml	74.3 (40.1–134.0)	78 (47.7–111.8)
Results	Endpoints	Alteplase (N=113)	Placebo (N=112)	Adjusted Effect Size (95% CI)	p-Value
	Primary outcome - Score of 0 to 1 on the modified Rankin scale at 90 days	40/113 (35.4%)	33/112 (29.5%)	1.44 (1.01–2.06)	0.04
	Secondary outcomes - Functional independence	56/113 (49.6%)	48/112 (42.9%)	1.36 (1.06–1.76)	---
	Secondary outcomes - Percentage of reperfusion at 24 hr ≥90%	53/106 (50.0%)	31/109 (28.4%)	1.73 (1.22–2.46)	---
	Secondary outcomes - Percentage of reperfusion at 24 hr ≥50%	76/106 (71.7%)	57/109 (52.3%)	1.35 (1.09–1.67)	---
	Tertiary outcomes - Recanalization at 24 hr	72/107 (67.3%)	43/109 (39.4%)	1.68 (1.29–2.19)	---
	Tertiary outcomes - Major neurologic improvement at 24 hr	32/113 (28.3%)	13/112 (11.6%)	2.52 (1.40–4.56)	---
Adverse Events	Symptomatic intracerebral hemorrhage occurred in 6.2% of patients in the alteplase group compared to 0.9% in the placebo group. Death within 90 days was similar between groups (11.5% vs. 8.9%).
Study Author Conclusions	The use of alteplase in patients with ischemic stroke and salvageable brain tissue between 4.5 and 9 hours after stroke onset resulted in a higher percentage of patients with no or minor neurologic deficits compared to placebo. However, there was a higher incidence of symptomatic cerebral hemorrhage in the alteplase group.
InpharmD Researcher Critique	The study was prematurely terminated, limiting the power of its conclusions. The trial showed a benefit of alteplase in extending the treatment window for ischemic stroke, but the increased risk of hemorrhage is a concern. The lack of significant difference in secondary outcomes and the longer door-to-needle time are limitations. Further trials are needed to confirm these findings.

References:
[1] [1] Ma H, Campbell BCV, Parsons MW, Churilov L, Levi CR, Hsu C, Kleinig TJ, Wijeratne T, Curtze S, Dewey HM, Miteff F, Tsai CH, Lee JT, Phan TG, Mahant N, Sun MC, Krause M, Sturm J, Grimley R, Chen CH, Hu CJ, Wong AA, Field D, Sun Y, Barber PA, Sabet A, Jannes J, Jeng JS, Clissold B, Markus R, Lin CH, Lien LM, Bladin CF, Christensen S, Yassi N, Sharma G, Bivard A, Desmond PM, Yan B, Mitchell PJ, Thijs V, Carey L, Meretoja A, Davis SM, Donnan GA; EXTEND Investigators. Thrombolysis Guided by Perfusion Imaging up to 9 Hours after Onset of Stroke. N Engl J Med. 2019 May 9;380(19):1795-1803. doi:10.1056/NEJMoa1813046. Erratum in: N Engl J Med. 2021 Apr 1;384(13):1278. doi:10.1056/NEJMx200014.

MRI-Guided Thrombolysis for Stroke with Unknown Time of Onset
Design	Multicenter, randomized, double-blind, placebo-controlled clinical trial (WAKE-UP) N= 503
Objective	To determine whether patients with stroke with an unknown time of onset and features suggesting recent cerebral infarction on MRI would benefit from thrombolysis with the use of intravenous alteplase.
Study Groups	Alteplase (n= 254) Placebo (n= 249)
Inclusion Criteria	Patients with clinical signs of acute stroke, aged 18 to 80, able to carry out usual activities without support before the stroke, with an unknown time of symptom onset, and MRI showing an ischemic lesion on diffusion-weighted imaging but no parenchymal hyperintensity on fluid-attenuated inversion recovery (FLAIR).
Exclusion Criteria	Patients with planned thrombectomy, severe stroke (NIHSS score >25), intracranial hemorrhage, lesions larger than one third of the middle cerebral artery territory, or contraindications to alteplase (except unknown time of onset).
Methods	Patients were randomized to receive 0.9 mg/kg of alteplase (10% as a bolus, remainder over 60 minutes) or placebo. MRI was used to identify ischemic lesions on diffusion-weighted imaging without parenchymal hyperintensity on FLAIR. Randomization was stratified according to age (≤60 or >60 years) and severity of symptoms as assessed on the NIHSS (score, ≤10 or >10). Clinical assessments were performed at baseline, at 22 to 36 hours after randomization, at 5 to 9 days (or at hospital discharge, if earlier), and at 90 days.
Duration	September 24, 2012, to June 30, 2017
Outcome Measures	Primary: Favorable outcome (modified Rankin scale score of 0 or 1) at 90 days Secondary: Ordinal score on the modified Rankin scale at 90 days, treatment response at 90 days, global outcome score at 90 days, Beck Depression Inventory score at 90 days, EQ-5D scores at 90 days, infarct volume on MRI 22 to 36 hours after randomization
Baseline Characteristics		Alteplase (N=254)	Placebo (N=249)
	Mean age, year	65.3±11.2	65.2±11.9
	Male	165 (65.0%)	160 (64.3%)
	Nighttime sleep — no. (%)	227 (89.4)	222 (89.2)
	Daytime sleep — no. (%)	12 (4.7)	11 (4.4)
	Aphasia, confusion, or other — no. (%)	15 (5.9)	16 (6.4)
	Arterial hypertension — no. (%)	135 (53.1)	131 (52.6)
	Diabetes mellitus — no. (%)	43 (16.9)	39 (15.7)
	Hypercholesterolemia — no. (%)	93 (36.6)	85 (34.1)
	Atrial fibrillation — no. (%)	30 (11.8)	29 (11.6)
	History of ischemic stroke — no. (%)	37 (14.6)	31 (12.4)
	Median NIHSS score (IQR)	6 (4–9)	6 (4–9)
Results	Endpoint	Alteplase (N=254)	Placebo (N=249)	Effect Variable	Adjusted Value (95% CI)	p-Value
	Favorable outcome at 90 days — no./total no. (%)	131/246 (53.3)	102/244 (41.8)	Odds ratio	1.61 (1.09 to 2.36)	0.02
	Median score on modified Rankin scale at 90 days (IQR)	1 (1–3)	2 (1–3)	Common odds ratio	1.62 (1.17 to 2.23)	0.003
	Correlation between treatment response at 90 days and deficit level at baseline — no./total no. (%)	72/246 (29.3)	44/244 (18.0)	Odds ratio	1.88 (1.22 to 2.89)	0.004
	Global Outcome Score at 90 days	---	---	Odds ratio	1.47 (1.07 to 2.04)	0.02
	Median Score on Beck Depression Inventory at 90 days	6.0 (2.0-11.0)	7.0 (2.0-14.0)	Mean difference (log_e)	−0.04 (−0.22 to 0.15)	0.69
	Median infarct volume at 22–36 hr (IQR) — ml	3.0 (0.8–17.7)	3.3 (1.1–16.6)	Mean difference (log_e)	−0.16 (−0.47 to 0.15)	0.32
Adverse Events	Death was reported in 10 patients (4.1%) in the alteplase group and in 3 patients (1.2%) in the placebo group. The rate of symptomatic intracranial hemorrhage was 2.0% in the alteplase group and 0.4% in the placebo group. Parenchymal hemorrhage type 2 occurred more frequently in the alteplase group (4.0%) than in the placebo group (0.4%).
Study Author Conclusions	In patients with acute stroke with an unknown time of onset, intravenous alteplase guided by a mismatch between diffusion-weighted imaging and FLAIR in the region of ischemia resulted in a significantly better functional outcome and numerically more intracranial hemorrhages than placebo at 90 days.
InpharmD Researcher Critique	The study demonstrated a significant improvement in functional outcomes with alteplase in patients with unknown stroke onset time, using MRI criteria. However, the trial was stopped early due to funding issues, which may limit the robustness of the safety data. Additionally, numerically higher number of deaths in alteplase group may have become statistically significant with a larger sample size. The exclusion of patients eligible for thrombectomy and the lack of systematic information on endovascular treatment availability may limit the generalizability of the findings.

References:
[1] [1] Thomalla G, Simonsen CZ, Boutitie F, Andersen G, Berthezene Y, Cheng B, Cheripelli B, Cho TH, Fazekas F, Fiehler J, Ford I, Galinovic I, Gellissen S, Golsari A, Gregori J, Gnther M, Guibernau J, Husler KG, Hennerici M, Kemmling A, Marstrand J, Modrau B, Neeb L, Perez de la Ossa N, Puig J, Ringleb P, Roy P, Scheel E, Schonewille W, Serena J, Sunaert S, Villringer K, Wouters A, Thijs V, Ebinger M, Endres M, Fiebach JB, Lemmens R, Muir KW, Nighoghossian N, Pedraza S, Gerloff C; WAKE-UP Investigators. MRI-Guided Thrombolysis for Stroke with Unknown Time of Onset. N Engl J Med. 2018 Aug 16;379(7):611-622. doi:10.1056/NEJMoa1804355.

Tenecteplase for Ischemic Stroke at 4.5 to 24 Hours without Thrombectomy
Design	Phase 3, multicenter, prospective, open-label, randomized, blinded-outcome-assessment trial (TRACE-III) N= 516
Objective	To investigate the efficacy and safety of tenecteplase administered 4.5 to 24 hours after stroke onset in patients with ischemic stroke due to large-vessel occlusion who do not have access to endovascular thrombectomy
Study Groups	Tenecteplase (n= 264) Standard medical treatment (n= 252)
Inclusion Criteria	Patients aged 18 or older with ischemic stroke, including stroke on awakening and unwitnessed stroke, recruited within 4.5 to 24 hours after last known well. Eligible patients had a prestroke modified Rankin scale score of 0 or 1, NIHSS score of 6 to 25, evidence of large-vessel occlusion, and salvageable brain tissue on perfusion imaging
Exclusion Criteria	Patients with planned endovascular thrombectomy at randomization or guideline-based contraindications to thrombolytic agents
Methods	Patients were randomly assigned to receive tenecteplase (0.25 mg/kg, max 25 mg) or standard medical treatment. Tenecteplase was administered intravenously as a bolus over 5 to 10 seconds. Standard treatment included antiplatelet therapy at the discretion of investigators. Rescue thrombectomy was allowed if the patient's condition deteriorated.
Duration	January 2022 through November 2023
Outcome Measures	Primary: Absence of disability (modified Rankin scale score of 0 or 1) at 90 days Secondary: Ordinal distribution of modified Rankin scale scores at 90 days, functional independence (modified Rankin scale score ≤2) at 90 days, major neurologic improvement at 72 hours, reperfusion at 24 hours, change in NIHSS score at 7 days
Baseline Characteristics		Tenecteplase (N= 264)	Standard Medical Treatment (N= 252)
	Median age (IQR), years	67 (58–75)	68 (59–76)
	Male sex	183 (69.3%)	167 (66.3%)
	Hypertension	177 (67.0%)	180 (71.4%)
	Diabetes mellitus	69 (26.1%)	71 (28.2%)
	Atrial fibrillation	49 (18.6%)	48 (19.0%)
	Modified Rankin scale score before stroke	0: 230 (87.1%)	0: 216 (85.7%)
	Median NIHSS score at randomization (IQR)	11 (7–15)	10 (7–14)
	Known onset time of stroke	143 (54.2%)	149 (59.1%)
	Median volume of irreversibly injured ischemic core at initial imaging (IQR), mL	16.4 (5.7–28.4)	14.9 (6.0–29.3)
	Median volume of perfusion lesion at initial imaging (IQR), mL	119.1 (79.8–177.2)	123.2 (74.6–180.1)
Results		Tenecteplase (N= 264)	Standard Medical Treatment (N= 252)	Effect Size (95% CI)
	Score of 0 or 1 on the modified Rankin scale at 90 days	87 (33.0%)	61 (24.2%)	1.37 (1.04 to 1.81)
	Ordinal distribution of scores on modified Rankin scale at 90 days 0 1 2 3 4 5 6	26 (9.8%) 61 (23.1%) 28 (10.6%) 46 (17.4%) 57 (21.6%) 11 (4.2%) 35 (13.3%)	17 (6.7%) 44 (17.5%) 23 (9.1%) 59 (23.4%) 57 (22.6%) 19 (7.5%) 33 (13.1%)	1.33 (0.98 to 1.81)
	Major neurologic improvement at 72 hr	40/250 (16.0%)	15/249 (6.0%)	2.66 (1.51 to 4.69)
	Reperfusion at 24 hr	48/239 (20.1%)	27/229 (11.8%)	1.70 (1.10 to 2.64)
	Change in the NIHSS score at 7 days (IQR)	−4 (−6 to −1)	−2 (−5 to 0)	−1.47 (−2.30 to −0.64)
	Symptomatic intracranial hemorrhage within 36 hr after randomization	8 (3.0%)	2 (0.8%)	3.82 (0.82 to 17.87)
	Death within 90 days	35 (13.3%)	33 (13.1%)	1.01 (0.65 to 1.58)
Adverse Events	Symptomatic intracranial hemorrhage was higher in the tenecteplase group (3.0%) compared to the standard-treatment group (0.8%; effect size 3.82; 95% CI 0.82 to 17.87). Moderate or severe systemic bleeding occurred in 1.9% of the tenecteplase group and 0.8% of the standard-treatment group (effect size 2.36; 95% CI 0.46 to 12.09) Any adverse event: 50.8% in tenecteplase group vs. 51.2 in standard-treatment group (effect size 0.99; 95% CI 0.84 to 1.17) Any serious adverse event: 20.1% in tenecteplase group vs. 17.1% in standard-treatment group (effect size 1.18; 95% CI 0.82 to 1.69)
Study Author Conclusions	In patients with ischemic stroke due to large-vessel occlusion who do not have access to endovascular thrombectomy, tenecteplase administered 4.5 to 24 hours after stroke onset resulted in less disability and similar survival compared to standard medical treatment, although with a higher incidence of symptomatic intracranial hemorrhage.
Critique	The study's strengths include its large sample size and rigorous design with blinded outcome assessment. However, the open-label nature and the exclusion of patients with access to thrombectomy may limit generalizability. The trial was conducted in China, which may affect applicability to other populations due to differences in stroke etiology. The higher incidence of symptomatic intracranial hemorrhage in the tenecteplase group warrants careful consideration.

References:
[1] [1] Xiong Y, Campbell BCV, Schwamm LH, Meng X, Jin A, Parsons MW, Fisher M, Jiang Y, Che F, Wang L, Zhou L, Dai H, Liu X, Pan Y, Duan C, Xu Y, Xu A, Zong L, Tan Z, Ye W, Wang H, Wang Z, Hao M, Cao Z, Wang L, Wu S, Li H, Li Z, Zhao X, Wang Y; TRACE-III Investigators. Tenecteplase for Ischemic Stroke at 4.5 to 24 Hours without Thrombectomy. N Engl J Med. 2024 Jul 18;391(3):203-212. doi:10.1056/NEJMoa2402980.

Thrombolysis With Alteplase at 0.6 mg/kg for Stroke With Unknown Time of Onset: A Randomized Controlled Trial
Design	Investigator-initiated, multicenter, randomized, open-label, blinded-end point trial (THAWS) N= 131
Objective	To assess whether lower-dose alteplase at 0.6 mg/kg is efficacious and safe for acute fluid-attenuated inversion recovery-negative stroke with unknown time of onset
Study Groups	Alteplase group (n= 70) Control group (n= 61)
Inclusion Criteria	Patients with stroke symptoms on awaking or with unknown time of onset, presented >4.5 hours since last-known-well and within 4.5 hours after symptom recognition, age 20 years or older, premorbid modified Rankin Scale (mRS)
Exclusion Criteria	Mild stroke with NIHSS <5 or severe stroke with NIHSS >25, contraindications for MRI, planned surgery or endovascular reperfusion, pregnant or lactating, life expectancy of 6 months or less, intracranial hemorrhage or large infarct with ASPECTS of 4 or less
Methods	Patients were randomized to receive either intravenous alteplase at 0.6 mg/kg or standard treatment. Alteplase was administered with 10% bolus and 90% by 60-minute infusion. Standard treatment included 1 to 3 antithrombotic drugs.
Duration	May 1, 2014 to July 10, 2018
Outcome Measures	Primary: Favorable outcome (90-day modified Rankin Scale score of 0–1) Secondary: mRS score 0 to 2 at 90 days, category shift in NIHSS score at 24 hours and 7 days, recanalization of the culprit artery, infarct volume and growth on FLAIR
Baseline Characteristics		Alteplase Group (n=70)	Control Group (n=61)
	Age, years	73.2 ± 12.4	75.8 ± 11.9
	Female	25 (36%)	30 (49%)
	Hypertension	49 (70%)	41 (67%)
	Diabetes mellitus	14 (20%)	12 (20%)
	Dyslipidemia	23 (33%)	23 (38%)
	Atrial fibrillation	27 (39%)	21 (34%)
	History of ischemic stroke/TIA	8 (11%)	14 (23%)
Results		Alteplase Group (n=70)	Control Group (n=61)	Effect Variable	Value (95% CI)	P-Value
	Favorable outcome at 90 days	32/68 (47.1)	28/58 (48.3)	Relative risk	0.97 (0.68–1.41)	0.89
	mRS score at 90 days	2 (1-3)	2 (0-3)	Common odds ratio	0.88 (0.47-1.63)	0.67
	mRS score 0–2 at 90 days	40/68 (58.8)	35/58 (60.3)	Relative risk	0.97 (0.73–1.30)	0.86
	Categorical shift in NIHSS score after initiation of treatment from baseline At 24 hours At 7 days	-2.6 ± 4.2 (70) -3.3 ± 7.4 (68)	-2.8 ± 3.9 (61) -4.3 ± 4.2 (60)	Estimated difference	0.1 (-1.2 to 1.5) 0.8 (-1.2 to 2.7)	0.85 0.44
	Recanalization of culprit artery on MRA at 22–36 hours	14/19 (73.7)	9/22 (40.9)	Relative risk	1.80 (1.02–3.64)	0.04
Adverse Events	Symptomatic intracranial hemorrhage occurred in 1.4% of the alteplase group and 0% of the control group. No major extracranial bleeding was reported in either group. Death at 90 days was 2.8% in the alteplase group and 3.3% in the control group
Study Author Conclusions	No difference in favorable outcome was seen between alteplase and control groups among patients with ischemic stroke with unknown time of onset. The safety of alteplase at 0.6 mg/kg was comparable to that of standard treatment. Early study termination precludes any definitive conclusions
Critique	The study was limited by its premature termination, resulting in a smaller sample size than planned. The open treatment design may have influenced the treatment process, and the exclusion of mechanical thrombectomy could have introduced selection bias. The use of a lower dose of alteplase compared to other trials may complicate comparisons

References:
[1] [1] Koga M, Toyoda K, Kimura K, Yamamoto H, Sasaki M, Hamasaki T, Kitazono T, Aoki J, Seki K, Homma K, Sato S, Minematsu K; THAWS investigators. THrombolysis for Acute Wake-up and unclear-onset Strokes with alteplase at 0.6mg/kg (THAWS) Trial. Int J Stroke. 2014 Dec;9(8):1117-24. doi:10.1111/ijs.12360.

Effects of alteplase beyond 3 h after stroke in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET): a placebo-controlled randomised trial
Design	Phase II, prospective, randomized, double-blind, placebo-controlled, multinational study across 15 centers in Australia, New Zealand, and the United Kingdom (EPITHET) N=101 enrolled (80 included in primary analysis due to mismatch)
Objective	To test whether alteplase given 3–6 h after stroke onset promotes reperfusion and attenuates infarct growth in patients who have a mismatch in perfusion-weighted MRI (PWI) and diffusion-weighted MRI (DWI)
Study Groups	Alteplase 0.9 mg/kg total (max 90 mg), with 10% given as bolus over 1 min and the remainder as an intravenous infusion over 1 h (n=52, 37 included in primary analysis) Placebo (n=49, 43 included in primary analysis)
Inclusion Criteria	Adult patients ≥18 years old with acute hemispheric ischemic stroke presenting within 3–6 h after symptom onset, National Institutes of Health stroke scale score (NIHSS) ≥4, premorbid modified Rankin score (mRS) ≤2
Exclusion Criteria	Acute intracranial hemorrhage (ICH) on baseline screening non-contrast head computed tomography (CT), major early ischemic change (defined as ischemia >1/3 of the territory of the middle cerebral artery) on baseline head CT, inability to undergo magnetic resonance imagine (MRI), standard contraindications to alteplase, confounding neurological diseases (e.g., dementia or life-threatening illness)
Methods	Patients were randomized to receive either alteplase or placebo following initial clinical evaluation. Patients were imaged with 1.5-Tesla echoplanar-equipped MRI scanners before treatment. Standardized DWI, PWI, and magnetic resonance angiography (MRA) sequences were obtained before treatment and repeated at day 3–5. An isotropic diffusion trace image was created from DWI images equivalent to a T2-weighted image and 1000 s/mm². Perfusion images were derived from the concentration–time curves obtained after administration of intravenous gadolinium at 0.2 mmol/kg, injected at 5 mL/s with gradient-echo images acquired on average every 1.4–2.5 s, over 10–24 axial slices (5–7 mm thickness). MRA (time of flight or phase contrast) was done at baseline and day 3–5. At day 90, T2-weighted images were obtained to measure final infarct volume. For patients who died or could not be studied at day 90, the last results at day 3–5 were carried forward as a measure of imaging outcome.
Duration	April 2001 though January 2007
Outcome Measures	Primary: Infarct growth attenuation in mismatch patients MRI mismatch defined as PWI÷DWI volume >1.2, and PWI–DWI volume ≥10 mL Infarct growth defined as the expansion between baseline DWI and day-90 T2-weighted lesion size Secondary: Difference in mismatch patients in reperfusion, good neurological outcome, and good functional outcomes
Baseline Characteristics (for patients with mismatch)		Alteplase (n=37)	Placebo (n=43)
	Mean age, years	71.3±12.8	72.2±13.1
	Male sex, n (%)	16 (43)	22 (51)
	Hypertension, n (%)	29 (78)	27 (63)
	Diabetes mellitus, n (%)	10 (27)	9 (21)
	Hyperlipidemia, n (%)	16 (43)	14 (33)
	Atrial fibrillation, n (%)	17 (46)	17 (40)
	Median NIHSS at presentation	14 (4 to 23)	11 (5 to 25)
	Mean time to treatment, min	293±45	291±51
	Median baseline DWI volume, mL	18 (3 to 173)	20 (0 to 180)
	Median baseline PWI volume, mL	157 (40 to 558)	200 (40 to 428)
	Median baseline mismatch volume, mL	135 (22 to 452)	153 (37 to 420)

Results (for patients with mismatch at day 90)	Endpoint	Alteplase (n=37)	Placebo (n=43)	Difference or ratio (95% CI), p-Value
	Geometric mean infarct growth	1.24	1.78	0.69 (0.38 to 1.28), p=0.239
	Reperfusion ≥90%, n (%)	19/34 (56)	11/43 (26)	30 (9 to 51), p=0.010
	Good neuroloical outcome, n (%)	21/42 (50)	16/43 (37)	13 (-8 to 34), p=0.278
	Good clinical outcome, n (%) mRS 0 to 2 mRS 0 to 1	19/42 (45) 15/42 (36)	17/43 (40) 9/43 (21)	5 (-15 to 27), p=0.278 15 (-4 to 34)< p=0.153

Adverse Events	Incidence of symptomatic ICH was 7·7% (4/52, 95% CI 2.1 to 18.5) with alteplase vs 0% with placebo Of the patients with symptomatic ICH, 3 had mismatch Median baseline DWI volumes did not differ significantly between patients with symptomatic ICH (median 32.2 mL, IQR 21.3 to 47.4) and those without (median 19.6, IQR 8.2 to 447)
Study Author Conclusions	Alteplase was non-significantly associated with lower infarct growth and significantly associated with increased reperfusion in patients who had mismatch. Because reperfusion was associated with improved clinical outcomes, phase III trials beyond 3 h after treatment are warranted.
Critique	This study was robustly designed to examine the impact of alteplase on clinical outcomes in patients presenting beyond the standard 3-4.5 h window from last known normal time given the incorporation of MRI mismatch analysis. Blinding of investigators who interpreted MRI scans helped to reduce interindividual bias. Despite meeting its initial intended sample size, the study was likely underpowered to detect a true difference in infarct growth and large sample sizes per group would be needed to confirm this.

References:
[1] Davis SM, Donnan GA, Parsons MW, et al; EPITHET investigators. Effects of alteplase beyond 3 h after stroke in the Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET): a placebo-controlled randomised trial. Lancet Neurol. 2008 Apr;7(4):299-309. doi:10.1016/S1474-4422(08)70044-9.

Thrombolysis with Alteplase 3 to 4.5 Hours after Acute Ischemic Stroke
Design	Randomized, placebo-controlled, phase 3 trial (ECASS) N= 821
Objective	To test the efficacy and safety of alteplase administered between 3 and 4.5 hours after the onset of a stroke
Study Groups	Alteplase group (n= 418) Placebo group (n= 403)
Inclusion Criteria	Acute ischemic stroke; age 18 to 80 years; onset of stroke symptoms 3 to 4.5 hours before initiation of study-drug administration; stroke symptoms present for at least 30 minutes with no significant improvement before treatment
Exclusion Criteria	Intracranial hemorrhage; time of symptom onset unknown; symptoms rapidly improving or only minor before start of infusion; severe stroke as assessed clinically (e.g., NIHSS score >25) or by appropriate imaging techniques; seizure at the onset of stroke; stroke or serious head trauma within the previous 3 months; combination of previous stroke and diabetes mellitus; administration of heparin within the 48 hours preceding the onset of stroke, with an activated partial-thromboplastin time at presentation exceeding the upper limit of the normal range; platelet count of less than 100,000 per cubic millimeter; systolic pressure greater than 185 mm Hg or diastolic pressure greater than 110 mm Hg, or aggressive treatment (intravenous medication) necessary to reduce blood pressure to these limits; blood glucose less than 50 mg per deciliter or greater than 400 mg per deciliter; symptoms suggestive of subarachnoid hemorrhage, even if CT scan was normal; oral anticoagulant treatment; major surgery or severe trauma within the previous 3 months; other major disorders associated with an increased risk of bleeding
Methods	Patients were randomly assigned to receive 0.9 mg of alteplase per kilogram, administered intravenously (with an upper limit of 90 mg), or placebo. 10% of the total dose was administered as a bolus, and the remainder was given by continuous intravenous infusion over a period of 60 minutes. CT or MRI was performed before treatment and 22 to 36 hours after treatment. Safety end points included death, symptomatic intracranial hemorrhage, and other serious adverse events
Duration	July 29, 2003, to November 13, 2007
Outcome Measures	Primary: Disability at 90 days (modified Rankin scale score of 0 or 1) Secondary: Global outcome analysis of four neurologic and disability scores combined
Baseline Characteristics		Alteplase (n= 418)	Placebo (n= 403)
	Age, year	64.9±12.2	65.6±11.0
	Male sex (%)	63.2	57.3
	Weight, kg	78.5±15	78.0±16
	NIHSS score	10.7±5.6	11.6±5.9
	Systolic pressure (mm Hg)	152.6±19.2	153.3±22.1
	Diastolic pressure (mm Hg)	84.4±13.5	83.9±13.6
	Diabetes (%)	14.8	16.6
	Previous use of aspirin or antiplatelet drugs (%)	31.1	32.5
	Hypertension (%)	62.4	62.8
	Atrial flutter or fibrillation (%)	12.7	13.6
	History of stroke (%)	7.7	14.1
	Smoking status Never smoked Ex-smoker Current smoker	48.6 20.6 30.6	46.2% 24.6% 28.8%
Results		Alteplase (n= 418)	Placebo (n= 403)	Odds ratio (95% CI)	p-value
	Favorable outcome (mRS score of 0 or 1)*	52.4%	45.2%	Unadjusted: 1.34 (1.02-1.76) Adjusted: 1.42 (1.02-1.98)	0.04 0.04
	Global outcome nRS score 0 or 1 Barthel index score ≥ 95% National Institutes of Health Stroke Scale score of 0 or 1 Glasgow Outcome Scale score of 1	219 (52.4%) 265 (63.4%) 210 (50.2%) 213 (51.0%)	182 (45.2%) 236 (58.6%) 174 (43.2%) 183 (45.4%)	1.28 (1.00-1.65) 1.34 (1.02-1.76) 1.23 (0.93-1.62) 1.33 (1.01-1.75) 1.25 (0.95-1.64)	< 0.05 0.04 0.16 0.04 0.11
	Any intracranial hemorrhage	27.0%	17.6%	-	0.001
	Symptomatic intracranial hemorrhage	2.4%	0.2%	-	0.008
	Mortality	7.7%	8.4%	-	0.68
	*Intention to treat population
Adverse Events	There was no significant difference in the rate of other serious adverse events.
Study Author Conclusions	As compared with placebo, intravenous alteplase administered between 3 and 4.5 hours after the onset of symptoms significantly improved clinical outcomes in patients with acute ischemic stroke; alteplase was more frequently associated with symptomatic intracranial hemorrhage.
Critique	The study demonstrated a significant improvement in clinical outcomes with alteplase administered between 3 and 4.5 hours after stroke onset, which is a notable finding. However, the increased risk of symptomatic intracranial hemorrhage is a concern. The study's strengths include its randomized, placebo-controlled design and large sample size. Limitations include the potential for selection bias due to the exclusion of patients with severe strokes and the fact that the study was conducted in a European population, which may limit generalizability to other populations.

References:
[1] [1] Hacke W, Kaste M, Bluhmki E, Brozman M, Dvalos A, Guidetti D, Larrue V, Lees KR, Medeghri Z, Machnig T, Schneider D, von Kummer R, Wahlgren N, Toni D; ECASS Investigators. Thrombolysis with alteplase 3 to 4.5 hours after acute ischemic stroke. N Engl J Med. 2008 Sep 25;359(13):1317-29. doi:10.1056/NEJMoa0804656.

Tenecteplase for Stroke at 4.5 to 24 Hours with Perfusion-Imaging Selection
Design	Multicenter, double-blind, randomized, placebo-controlled trial (TIMELESS) N= 458
Objective	To test the hypothesis that intravenous tenecteplase, initiated 4.5 to 24 hours after stroke onset, would provide a benefit in patients with a large-vessel occlusion of the internal carotid artery or the first (M1) or second (M2) segments of the middle cerebral artery and had evidence of salvageable ischemic brain tissue identified on CT perfusion or MRI perfusion–diffusion studies
Study Groups	Tenecteplase (n= 228) Placebo (n= 230)
Inclusion Criteria	Patients at least 18 years of age with independent function before the stroke (baseline prestroke modified Rankin scale score, 0 to 2) who had an ischemic stroke and could receive tenecteplase or placebo 4.5 to 24 hours after the time they were last known to be well. Patients had to have a National Institutes of Health Stroke Scale (NIHSS) score of at least 5, attributed to occlusion of the internal carotid artery or the M1 or M2 segment of the middle cerebral artery, and evidence of salvageable brain tissue as determined by specific imaging criteria
Exclusion Criteria	Not explicitly stated in the provided text
Methods	Patients were randomly assigned to receive either tenecteplase (0.25 mg per kilogram of body weight, up to 25 mg) or placebo, administered as an intravenous bolus over 5 seconds. Randomization was stratified by age, occlusion site, baseline NIHSS score, and center capability for endovascular treatment. Endovascular thrombectomy was performed according to standard care at each site
Duration	March 2019 through December 2022
Outcome Measures	Primary: Ordinal score on the modified Rankin scale at day 90 Secondary: Functional independence at day 90, recanalization at 24 hours, angiographic reperfusion at 24 hours and at the completion of endovascular thrombectomy
Baseline Characteristics		Tenecteplase (N=228)	Placebo (N=230)
	Median age, years (IQR)	72 (62–79)	73 (63–82)
	Female	122 (53.5)	123 (53.5)
	White	169 (74.1)	170 (73.9)
	Median NIHSS score (IQR)	12 (8–17)	12 (8–18)
	Occlusion site Internal carotid artery M1 segment M2 segment Other	20 (8.8%) 110 (48.2%) 89 (39.0% 9 (3.9%)	17 (7.4%) 117 (50.9%) 84 (36.5%) 12 (5.2%)
	Endovascular thrombectomy performed	176 (77.2%)	178 (77.4%)
Results		Tenecteplase (N=228)	Placebo (N=230)	Adjusted Odds Ratio (95% CI)	p-Value
	Modified Rankin scale score at 90 days (IQR)	3 (1–5)	3 (1–4)	1.13 (0.82–1.57)	0.45
	Functional independence at 90 days	104/226 (46.0%)	97/229 (42.4%)	1.18 (0.80–1.74)	-
	Recanalization at 24 hours	148/193 (76.7%)	124/194 (63.9%)	1.89 (1.21–2.95)	-
	Reperfusion at 24 hours	99/174 (56.9%)	105/182 (57.5%)	1.04 (0.69-1.57)	-
	Death Within 30 days Within 90 days	32/218 (14.7%) 43/218 (19.7%)	32/214 (15.0%) 39/214 (18.2%)	- -	- -
	Symptomatic intracranial hemorrhage within 36 hours	7/218 (3.2%)	5/214 (2.3%)	-	-
Adverse Events	See above
Study Author Conclusions	Tenecteplase therapy initiated 4.5 to 24 hours after stroke onset in patients with occlusions of the middle cerebral artery or internal carotid artery did not result in better clinical outcomes than placebo. The incidence of symptomatic intracerebral hemorrhage was similar in the two groups.
Critique	The study was well-designed as a multicenter, double-blind, randomized, placebo-controlled trial, which strengthens the validity of the findings. However, the lack of significant improvement in functional outcomes with tenecteplase compared to placebo suggests that the extended time window may not be beneficial. The study's reliance on imaging criteria for patient selection is a strength, but the high proportion of patients undergoing endovascular thrombectomy may have influenced the outcomes. Additionally, the study did not enroll enough patients at centers not capable of providing endovascular treatment to assess the effect of tenecteplase in this population.

References:
[1] [1] Albers GW, Jumaa M, Purdon B, Zaidi SF, Streib C, Shuaib A, Sangha N, Kim M, Froehler MT, Schwartz NE, Clark WM, Kircher CE, Yang M, Massaro L, Lu XY, Rippon GA, Broderick JP, Butcher K, Lansberg MG, Liebeskind DS, Nouh A, Schwamm LH, Campbell BCV; TIMELESS Investigators. Tenecteplase for Stroke at 4.5 to 24 Hours with Perfusion-Imaging Selection. N Engl J Med. 2024 Feb 22;390(8):701-711. doi:10.1056/NEJMoa2310392.