Ferdinand Miteff

A Randomized Trial of Tenecteplase versus Alteplase for Acute Ischemic Stroke

BACKGROUND Intravenous alteplase is the only approved treatment for acute ischemic stroke. Tenecteplase, a genetically engineered mutant tissue plasminogen activator, is an alternative thrombolytic agent. METHODS In this phase 2B trial, we randomly assigned 75 patients to receive alteplase (0.9 mg per kilogram of body weight) or tenecteplase (0.1 mg per kilogram or 0.25 mg per kilogram) less than 6 hours after the onset of ischemic stroke. To favor the selection of patients most likely to benefit from thrombolytic therapy, the eligibility criteria were a perfusion lesion at least 20% greater than the infarct core on computed tomographic (CT) perfusion imaging at baseline and an associated vessel occlusion on CT angiography. The coprimary end points were the proportion of the perfusion lesion that was reperfused at 24 hours on perfusion-weighted magnetic resonance imaging and the extent of clinical improvement at 24 hours as assessed on the National Institutes of Health Stroke Scale (NIHSS, a 42-point scale on which higher scores indicate more severe neurologic deficits). RESULTS The three treatment groups each comprised 25 patients. The mean (±SD) NIHSS score at baseline for all patients was 14.4±2.6, and the time to treatment was 2.9±0.8 hours. Together, the two tenecteplase groups had greater reperfusion (P=0.004) and clinical improvement (P<0.001) at 24 hours than the alteplase group. There were no significant between-group differences in intracranial bleeding or other serious adverse events. The higher dose of tenecteplase (0.25 mg per kilogram) was superior to the lower dose and to alteplase for all efficacy outcomes, including absence of serious disability at 90 days (in 72% of patients, vs. 40% with alteplase; P=0.02). CONCLUSIONS Tenecteplase was associated with significantly better reperfusion and clinical outcomes than alteplase in patients with stroke who were selected on the basis of CT perfusion imaging. (Funded by the Australian National Health and Medical Research Council; Australia New Zealand Clinical Trials Registry number, ACTRN12608000466347.).

Acute ischemic stroke Imaging-guided tenecteplase treatment in an extended time window

Background: Tenecteplase is a modified tissue plasminogen activator with a longer half-life and higher fibrin specificity than alteplase. Methods: We conducted a prospective, nonrandomized, pilot study of 0.1 mg/kg IV tenecteplase given 3 to 6 hours after ischemic stroke onset. For a control group, we used patients contemporaneously treated with sub–3-hour 0.9 mg/kg IV alteplase following standard selection criteria. All patients underwent pretreatment and 24-hour perfusion/angiographic imaging with CT or MRI. Eligibility criteria for tenecteplase (but not alteplase) treatment included a perfusion lesion at least 20% greater than the infarct core, with an associated vessel occlusion. Primary outcomes, assessed blind to treatment group, were reperfusion (reduction in baseline–24-hour mean transit time lesion) and major vessel recanalization. Results: Fifteen patients received tenecteplase, and 35 patients received alteplase. The tenecteplase group had greater reperfusion (mean 74% vs 44% in the alteplase group, p = 0.01) and major vessel recanalization (10/15 tenecteplase vs 7/29 alteplase, p = 0.01). Despite later time to treatment, more tenecteplase patients (10/15 vs 7/35 alteplase, p = 0.001) had major neurologic improvement at 24 hours (NIH Stroke Scale reduction ≥8). Four of the alteplase patients and none of the tenecteplase patients had parenchymal hematoma at 24 hours. Conclusions: Tenecteplase 0.1 mg/kg, using advanced imaging guidance in an extended time window, may have significant biologic efficacy in acute ischemic stroke. The imaging selection differences between the tenecteplase and alteplase groups prevent a conclusive efficacy comparison. Nonetheless, these results lend support for randomized trials comparing tenecteplase with alteplase, preferably incorporating penumbral/angiographic imaging selection. CBV = cerebral blood volume; CTA = CT angiography; CTP = perfusion CT; DWI = diffusion-weighted echo-planar spin-echo sequence; ICH = intracranial hemorrhage; MNI = major neurologic improvement; MR = magnetic resonance; mRS = modified Rankin Scale; MTT = mean transit time; NCCT = noncontrast CT; NIHSS = NIH Stroke Scale; PH = parenchymal hematoma; TIMI = Thrombolysis in Myocardial Infarction.

Assessment of leptomeningeal collaterals using dynamic CT angiography in patients with acute ischemic stroke

Whole-brain dynamic time-resolved computed tomography angiography (CTA) is a technique developed on the new 320-detector row CT scanner capable of generating time-resolved cerebral angiograms from skull base to vertex. Unlike a conventional cerebral angiogram, this technique visualizes pial arterial filling in all vascular territories, thereby providing additional hemodynamic information. Ours was a retrospective study of consecutive patients with ischemic stroke and M1 middle cerebral artery +/– intracranial internal carotid artery occlusions presenting to our center from June 2010 and undergoing dynamic time-resolved CTA and perfusion CT within 6 hours of symptom onset. Leptomeningeal collateral status was assessed by determining relative prominence of pial arteries in the ischemic region, rate and extent of retrograde flow, and various topographical patterns of pial arterial filling. Twenty-five patients were included in the study. We demonstrate the existence of the following novel properties of leptomeningeal collaterals in humans: (a) posterior (posterior cerebral artery (PCA)–MCA) dominant collateralization, (b) intra-territorial ‘within MCA region’ leptomeningeal collaterals, and (c) significant variability in size, extent, and retrograde filling time in pial arteries. We also describe a simple and reliable collateral grading template that, for the first time on dynamic CTA, incorporates back-filling time as well as size and extent of collateral filling.

A multicenter, randomized, controlled study to investigate EXtending the time for Thrombolysis in Emergency Neurological Deficits with Intra-Arterial therapy (EXTEND-IA)

Background and Hypothesis Thrombolysis with tissue plasminogen activator is proven to reduce disability when given within 4.5 h of ischemic stroke onset. However, tissue plasminogen activator only succeeds in recanalizing large vessel arterial occlusion in a minority of patients. We hypothesized that anterior circulation ischemic stroke patients, selected with ‘dual target’ vessel occlusion and evidence of salvageable brain using computed tomography or magnetic resonance imaging ‘mismatch’ within 4.5 h of onset, would have improved reperfusion and early neurological improvement when treated with intra-arterial clot retrieval after intravenous tissue plasminogen activator compared with intravenous tissue plasminogen activator alone. Study Design EXTEND-IA is an investigator-initiated, phase II, multicenter prospective, randomized, open-label, blinded-endpoint study. Ischemic stroke patients receiving standard 0.9 mg/kg intravenous tissue plasminogen activator within 4.5 h of stroke onset who have good prestroke functional status (modified Rankin Scale <2, no upper age limit) will undergo multimodal computed tomography or magnetic resonance imaging. Patients who also meet dual target imaging criteria: vessel occlusion (internal carotid or middle cerebral artery) and mismatch (perfusion lesion: ischemic core mismatch ratio >1.2, absolute mismatch >10 ml, ischemic core volume <70 ml) will be randomized to either clot retrieval with the Solitaire FR device after full dose intravenous tissue plasminogen activator, or tissue plasminogen activator alone. Study Outcomes The coprimary outcome measure will be reperfusion at 24 h and favorable clinical response (reduction in National Institutes of Health Stroke Scale by ≥8 points or reaching 0–1) at day 3. Secondary outcomes include modified Rankin Scale at day 90, death, and symptomatic intracranial hemorrhage.

Tenecteplase versus Alteplase before Thrombectomy for Ischemic Stroke

BACKGROUND Intravenous infusion of alteplase is used for thrombolysis before endovascular thrombectomy for ischemic stroke. Tenecteplase, which is more fibrin‐specific and has longer activity than alteplase, is given as a bolus and may increase the incidence of vascular reperfusion. METHODS We randomly assigned patients with ischemic stroke who had occlusion of the internal carotid, basilar, or middle cerebral artery and who were eligible to undergo thrombectomy to receive tenecteplase (at a dose of 0.25 mg per kilogram of body weight; maximum dose, 25 mg) or alteplase (at a dose of 0.9 mg per kilogram; maximum dose, 90 mg) within 4.5 hours after symptom onset. The primary outcome was reperfusion of greater than 50% of the involved ischemic territory or an absence of retrievable thrombus at the time of the initial angiographic assessment. Noninferiority of tenecteplase was tested, followed by superiority. Secondary outcomes included the modified Rankin scale score (on a scale from 0 [no neurologic deficit] to 6 [death]) at 90 days. Safety outcomes were death and symptomatic intracerebral hemorrhage. RESULTS Of 202 patients enrolled, 101 were assigned to receive tenecteplase and 101 to receive alteplase. The primary outcome occurred in 22% of the patients treated with tenecteplase versus 10% of those treated with alteplase (incidence difference, 12 percentage points; 95% confidence interval [CI], 2 to 21; incidence ratio, 2.2; 95% CI, 1.1 to 4.4; P=0.002 for noninferiority; P=0.03 for superiority). Tenecteplase resulted in a better 90‐day functional outcome than alteplase (median modified Rankin scale score, 2 vs. 3; common odds ratio, 1.7; 95% CI, 1.0 to 2.8; P=0.04). Symptomatic intracerebral hemorrhage occurred in 1% of the patients in each group. CONCLUSIONS Tenecteplase before thrombectomy was associated with a higher incidence of reperfusion and better functional outcome than alteplase among patients with ischemic stroke treated within 4.5 hours after symptom onset. (Funded by the National Health and Medical Research Council of Australia and others; EXTEND‐IA TNK ClinicalTrials.gov number, NCT02388061.)

Relationship Between Collateral Status, Contrast Transit, and Contrast Density in Acute Ischemic Stroke

Background and Purpose— Collateral circulation is recognized to influence the life expectancy of the ischemic penumbra in acute ischemic stroke. The best method to quantify collateral status on acute imaging is uncertain. We aimed to determine the relationship between visual collateral status, quantitative collateral assessments, baseline computed tomographic perfusion measures, and tissue outcomes on follow-up imaging. Methods— Sixty-six consecutive patients with acute ischemic stroke clinically eligible for recanalization therapy and with M1 or M2 middle cerebral artery occlusion were evaluated. We compared the visual collateral scoring with measures of contrast peak time delay and contrast peak density. We also compared these measures for their ability to predict perfusion lesion and infarct core volumes, final infarct, and infarct growth. Results— Shorter contrast peak time delay (P=0.041) and higher contrast peak density (P=0.002) were associated with good collateral status. Shorter contrast peak time delay correlated with higher contrast peak density (&bgr;=−4.413; P=0.037). In logistic regression analysis after adjustment for age, sex, onset–computed tomographic time, and occlusion site, higher contrast peak density was independently associated with good collateral status (P=0.009). Multiple regression analysis showed that higher contrast peak density was an independent predictor of smaller perfusion lesion volume (P=0.029), smaller ischemic core volume (P=0.044), smaller follow-up infarct volume (P=0.005), and smaller infarct growth volume (P=0.010). Conclusions— Visual collateral status, contrast peak density, and contrast peak time delay were inter-related, and good collateral status was strongly associated with contrast peak density. Contrast peak density in collateral vessel may be an important factor in tissue fate in acute ischemic stroke.

The Influence of Anterior Cerebral Artery Flow Diversion Measured by Transcranial Doppler on Acute Infarct Volume and Clinical Outcome in Anterior Circulation Stroke

Introduction Anterior cerebral artery flow diversion, measured by transcranial Doppler ultrasound, is correlated with leptomeningeal collateral flow on digital subtraction angiography in the setting of middle cerebral artery occlusion. We aimed to assess the influence of flow diversion as a marker of leptomeningeal collateralization on infarct size and penumbral volume. Methods We assessed consecutive patients presenting within six-hours of ischaemic stroke. Anterior cerebral artery flow diversion, defined as ipsilateral mean velocity of at least 30% greater than the contralateral artery, was used as the Doppler index of leptomeningeal collateralization. Multivariable regression analysis was performed to assess the impact of anterior cerebral artery flow diversion, controlling for other important clinical variables. Leptomeningeal collateralization was also graded on computed tomography angiography. Infarct core and penumbral volumes were defined using computed tomography perfusion thresholds of cerebral blood volume and mean transit time. Infarct volume, reperfusion, and vessel status were measured at 24 h using magnetic resonance techniques. Results Fifty-three patients qualified for analysis. Anterior cerebral artery flow diversion was associated with good collateral flow on computed tomography angiography (P < 0·001) and was an independent predictor of admission infarct core volume (P < 0·001), and 24 h infarct volume (P < 0·001). The likelihood of a favourable outcome (modified Rankin Score 0–2) was higher (odds ratio = 27·5, P < 0·001) in those with flow diversion. Conclusions Anterior cerebral artery flow diversion indicates effective leptomeningeal collateralization as measured by computed tomography angiography, and independently predicts acute infarct size and 90-day clinical outcome. Flow diversion appears to provide penumbral perfusion, offering some protection against infarct expansion. Acute bedside transcranial Doppler assessment of flow diversion aids prognostication and therapeutic decision making in anterior circulation stroke.

Tenecteplase versus alteplase before endovascular thrombectomy (EXTEND-IA TNK): A multicenter, randomized, controlled study

Background and hypothesis Intravenous thrombolysis with alteplase remains standard care prior to thrombectomy for eligible patients within 4.5 h of ischemic stroke onset. However, alteplase only succeeds in reperfusing large vessel arterial occlusion prior to thrombectomy in a minority of patients. We hypothesized that tenecteplase is non-inferior to alteplase in achieving reperfusion at initial angiogram, when administered within 4.5 h of ischemic stroke onset, in patients planned to undergo endovascular therapy. Study design EXTEND-IA TNK is an investigator-initiated, phase II, multicenter, prospective, randomized, open-label, blinded-endpoint non-inferiority study. Eligibility requires a diagnosis of ischemic stroke within 4.5 h of stroke onset, pre-stroke modified Rankin Scale≤3 (no upper age limit), large vessel occlusion (internal carotid, basilar, or middle cerebral artery) on multimodal computed tomography and absence of contraindications to intravenous thrombolysis. Patients are randomized to either IV alteplase (0.9 mg/kg, max 90 mg) or tenecteplase (0.25 mg/kg, max 25 mg) prior to thrombectomy. Study outcomes The primary outcome measure is reperfusion on the initial catheter angiogram, assessed as modified treatment in cerebral infarction 2 b/3 or the absence of retrievable thrombus. Secondary outcomes include modified Rankin Scale at day 90 and favorable clinical response (reduction in National Institutes of Health Stroke Scale by ≥8 points or reaching 0–1) at day 3. Safety outcomes are death and symptomatic intracerebral hemorrhage. Trial registration ClinicalTrials.gov NCT02388061

Endovascular thrombectomy for ischemic stroke increases disability-free survival, quality of life, and life expectancy and reduces cost

Background Endovascular thrombectomy improves functional outcome in large vessel occlusion ischemic stroke. We examined disability, quality of life, survival and acute care costs in the EXTEND-IA trial, which used CT-perfusion imaging selection. Methods Large vessel ischemic stroke patients with favorable CT-perfusion were randomized to endovascular thrombectomy after alteplase versus alteplase-only. Clinical outcome was prospectively measured using 90-day modified Rankin scale (mRS). Individual patient expected survival and net difference in Disability/Quality-adjusted life years (DALY/QALY) up to 15 years from stroke were modeled using age, sex, 90-day mRS, and utility scores. Level of care within the first 90 days was prospectively measured and used to estimate procedure and inpatient care costs (US

Ischemic core thresholds change with time to reperfusion: A case control study

reference year 2014). Results There were 70 patients, 35 in each arm, mean age 69, median NIHSS 15 (IQR 12–19). The median (IQR) disability-weighted utility score at 90 days was 0.65 (0.00–0.91) in the alteplase-only versus 0.91 (0.65–1.00) in the endovascular group (p = 0.005). Modeled life expectancy was greater in the endovascular versus alteplase-only group (median 15.6 versus 11.2 years, p = 0.02). The endovascular thrombectomy group had fewer simulated DALYs lost over 15 years [median (IQR) 5.5 (3.2–8.7) versus 8.9 (4.7–13.8), p = 0.02] and more QALY gained [median (IQR) 9.3 (4.2–13.1) versus 4.9 (0.3–8.5), p = 0.03]. Endovascular patients spent less time in hospital [median (IQR) 5 (3–11) days versus 8 (5–14) days, p = 0.04] and rehabilitation [median (IQR) 0 (0–28) versus 27 (0–65) days, p = 0.03]. The estimated inpatient costs in the first 90 days were less in the thrombectomy group (average US