Stent-Retriever Thrombectomy after Intravenous t-PA vs. t-PA Alone in Stroke

Mohammed Naveed Aijaz, Mercer University College of Pharmacy Class of 2016

A stroke is a medical condition when the blood supply to the brain is impeded or reduced, resulting in a lack of oxygen and nutrients and leading to cell death. Stroke, a medical emergency, requires immediate medical attention according to the Mayo Clinic.1 There are two types of stroke: acute ischemic and hemorrhagic. Acute ischemic stroke, considered to be more common, has been more thoroughly studied.2 According to Harrison’s Principles of Internal Medicine, this type of stroke may be caused by the occlusion of an intracranial artery by an embolus from distant site, thrombosis of an intracranial vessel, or hypoperfusion.3 Chronic use antiplatelet agents are the drugs of choice for secondary prevention of noncardioembolic ischemic stroke. Tissue plasminogen activators (t-PA) are beneficial for acute treatment, but must be administered less than 4.5 hours after onset of stroke. According to experts, use of these agents has been connected to reduction in disability as a result of ischemic stroke.2 Finally, an additional option for reperfusion therapy following a stroke is neurovascular thrombectomy using mechanical treatments to remove clots.4

Title: Stent-Retriever Thrombectomy after Intravenous t-PA vs. t-PA Alone in Stroke5
Design Prospective, randomized trial; N = 196
Objective To compare intravenous t-PA followed by neurovascular thrombectomy with the use of a stent retriever with intravenous t-PA alone in patients with acute ischemic stroke
Study Groups Two study groups: patients receiving (1) intravenous t-PA plus stent retriever (n = 98) or (2) intravenous t-PA alone (n = 93)
Methods Assessments were performed at baseline, 27 hours after randomization, then seven to 10 days (depending on discharge date), 30 days, and 90 days. Analysis of functional disability was done using modified Rankin scale with scores ranging from zero (no symptoms) to six (death).
Duration Ninety days
Primary Outcome Measure Severity of global disability at 90 days
Baseline Characteristics The average patient age was 65.5 years old; the majority of patients were white (89%) and had hypertension.
Results In the intravenous t-PA plus stent retriever group, 60% of patients scored zero, one, or two (considered independent in daily function) on the Rankin scale for functional disability versus 36% of patients in the intravenous t-PA alone group (P < 0.001).
Adverse Events Common Adverse Events: none reported
Serious Adverse Events: symptomatic intracranial hemorrhage at 27 hours 0% in t-PA plus stent retriever group versus 3% in t-PA alone group; total occurrence all other events at 90 days 36% in t-PA plus stent retriever group versus 31% in t-PA alone group; individual events: nervous system disorders 15.3% and 18.6%, respiratory disorders 6.1% and 8.2%, cardiac disorders 8.2% and 5.2%, vascular disorders 5.1% and 7.2%, infections 5.1% and 6.2%, renal and urinary disorders 4.1% and 4.1%, injury or poisoning or procedural complications 3.1% and 3.1%, blood and lymphatic system disorders 3.1% and 0%, neoplasms 0% and 2.1%, psychiatric disorders 1% and 1%
Percentage that Discontinued due to Adverse Events: none reported
Study Author Conclusions Our study showed that in patients with acute ischemic stroke with confirmed large-vessel occlusions of the anterior circulation who were treated with intravenous t-PA, treatment with the stent retriever within six hours after symptom onset improved functional outcomes at 90 days. For every 2.6 patients who were treated, one additional patient had an improved disability outcome; for every four patients who were treated, one additional patient was functionally independent at 90-day follow-up.

This study suggests that stroke patients may have a better outcome if treated with an intravenous t-PA agent combined with a stent retriever device versus treatment with a t-PA agent alone. This study is different than comparable previous studies because it utilized a mechanical thrombectomy device called the Solitaire™, which the author considered to be superior to the early generation devices used in prior studies. The results of this study were found to be statistically significant, however the study was limited in the demographics of its patient population and more information is needed before this treatment can be considered efficacious for a more general population of patients.

References:

1) Mayo Clinic Staff. Stroke. The Mayo Clinic. http://www.mayoclinic.org/diseases-conditions/stroke/home/ovc-20117264. Revised May 15, 2015. Accessed June 17, 2015.

2) Fagan SC, Hess DC. Chapter 10. Stroke. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey L. eds. Pharmacotherapy: A Pathophysiologic Approach, 9e. New York, NY: McGraw-Hill; 2014. http://accesspharmacy.mhmedical.com/content.aspx?bookid=689&Sectionid=45310472. Accessed June 17, 2015.

3) Longo DL, Fauci AS, Kasper DL, et al. Harrison’s Principals and Practice of Internal Medicine, 18th ed. New York: McGraw-Hill, 2012.

4) Ciccone A, Valvassori L, Nichelatti M, et al. Endovascular treatment for acute ischemic stroke. N Engl J Med 2013;368:904-913

5) Saver JL, Goyal M, Bonafe A, et al. Stent-Retriever Thrombectomy after Intravenous t-PA vs. t-PA Alone in Stroke. N Engl J Med. 2015; Doi: 10.1056/NEJMoa1415061

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