February 6, 2020

Background Information: The administration of alteplase (tPA) in acute ischemic stroke (AIS) continues to remain a highly debated topic. As hospital systems continue to undergo major changes to facilitate this controversial drug’s administration, more studies are coming out focusing on neuroimaging and how it plays a role in the time window of AIS. The WAKE-UP trial was one of the first studies to identify MRI patterns suggestive of a stroke in patient whose onset time was unknown.1,2 Over the past 10+ years, other studies have also attempted to identify the role of advanced neuroimaging guiding tPA administration for improved functional outcomes. The authors conducted a meta-analysis to test the hypothesis that tPA improves functional outcomes compared with placebo 4.5 - 9 hours after onset in AIS patients who received advanced neuroimaging. Before getting into the study, we need to better understand the terminology and different types of neuroimaging modalities available and how they play a role in strokes.

October 30, 2019

Background: Currently, alteplase is the mainstay of treatment of acute ischemic stroke.  Advocates of alteplase suggest that the benefit of alteplase is greatest when given early and declines with increasing time from stroke symptom onset (i.e. time is brain).  Therefore, the AHA/ASA guidelines recommend intravenous alteplase within 4.5 hours after stroke onset, which is based on very weak evidence (i.e. NINDS & ECASS III). Due to weak evidence in support of it’s use and significant patient risks associated with alteplase, it’s use in acute ischemic stroke remains controversial.  One of the big issues is that by decreasing the time for evaluation and treatment, there is an increased risk of administrating alteplase to patients presenting with noncerebrovascular conditions that can resemble an acute ischemic stroke (i.e. stroke mimics).  This puts patients with no chance of improvement with alteplase at risk for increased mortality and symptomatic ICH.  There is some limited data on the safety of alteplase in stroke mimics and this study adds to that knowledge.

April 1, 2019

Background: No matter which side of the debate you sit on in regard to systemic thrombolysis in acute ischemic stroke (AIS), there is one truth: systems have undergone major changes to ensure tPA is offered to patients in the ≤4.5-hour window.  The debate surrounding tPA in AIS lies in the equipoise surrounding benefits while there are very real harms.  Advocates of tPA in AIS hang on to two trials that have never been replicated (i.e. NINDS and ECASS-III), and both have major methodological issues. Skeptics of tPA in AIS appropriately argue that there are 11 other randomized clinical trials which have shown almost no benefit, but come at the cost of early increased early mortality and symptomatic intracranial hemorrhage (sICH) (Nice breakdown of individual trials of thrombolysis in stroke can be found at First10EM).  Now there is a push to extend the window of tPA out to 9 hours in AIS with newer imaging modalities such as MRI diffusion-weighted studies in patients with unknown onset of symptoms. The push for this stems from the fact that patients with a visible ischemic lesion on diffusion-weighted imaging, combined with the absence of a clearly visible hyperintense signal in the same region on fluid-attenuated inversion recovery (FLAIR) is predictive of symptom onset within 4.5 hours before imaging.

September 6, 2018

Background: Despite serious concerns about the role of alteplase in the management of acute ischemic stroke including, but not limited to, significant conflicts of interest, unbalanced baseline patient characteristics, systematic devaluation of contrary data, lack of reproduced benefit and low fragility index, it remains standard care for patients presenting with symptoms of acute ischemic stroke within 3 (or 4.5 depending on system) hours of onset of symptoms. Though the NINDS studies only showed benefit in a specific subgroup of patients, subsequent work has endeavored to expand the target group in a classic example of indication creep. Patients with minor CVA (NIHSS < 5 without disabling features or, essentially mRS 0-1) represent one such subgroup in which alteplase is often not employed due mainly in part to the perception of minimal benefit with continued potential for harm (i.e. anaphylaxis, intracranial hemorrhage). Alteplase supporters argue that minor stroke patients should still get the drug as it not only may reduce symptoms but can also prevent deterioration. The evidence for this viewpoint is both extremely limited and of poor methodologic quality.

June 4, 2018

Background: Alteplase is a tissue plasminogen activator that is approved for use prior to thrombectomy in ischemic strokes with the goal of reperfusion to ischemic areas of the brain. Tenecteplase is a recombinant enzyme derived from alteplase that is more specific to fibrin and more resistant to inactivation by alteplase inhibitors. Tenecteplase is less expensive, can be administered at a faster rate than alteplase and has a longer half-life allowing for bolus dosing. Prior studies have shown similar to better outcomes with use of tenecteplase versus alteplase in patients with ischemic stroke.

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