Abstract
Purpose: Intravenous tissue plasminogen activator (tPA) is indicated prior to mechanical thrombectomy (MT) to treat large vessel occlusion (LVO). However, administration takes time, and rates of clot migration complicating successful retrieval and hemorrhagic transformation may be higher. Given time-to-effectiveness, the benefit of tPA may vary significantly based on whether administration occurs at a thrombectomy-capable center or transferring hospital.Methods: We prospectively evaluated 170 individuals with LVO involving the anterior circulation who underwent MT at our Comprehensive Stroke Center over a 3.5 year period. Two thirds (n = 114) of patients were admitted through our Emergency Department (ED). The other 33% were transferred from outside hospitals (OSH). Patients meeting criteria were bridged with IV tPA; the others were treated with MT alone. Clot migration, recanalization times, TICI scores, and hemorrhage rates were compared for those bridged vs. treated with MT alone, along with modified Rankin scores (mRS) at discharge and 90-day follow-up. Multivariable regression was used to determine the relationship between site of presentation and effect of tPA on outcomes.Results: Patients presenting to an OSH had longer mean discovery to puncture/recanalization times, but were actually more likely to receive IV tPA prior to MT (70 vs. 42%). The rate of clot migration was low (11%) and similar between groups, though slightly higher for those receiving IV tPA. There was no difference in symptomatic ICH rate after tPA. TICI scores were also not significantly different; however, more patients achieved TICI 2b or higher reperfusion (83 vs. 67%, p = 0.027) after tPA, and TICI 0 reperfusion was seen almost exclusively in patients who were not treated with tPA. Those bridged at an OSH required fewer passes before successful recanalization (2.4 vs. 1.6, p = 0.037). Overall, mean mRS scores on discharge and at 90 days were significantly better for those receiving IV tPA (3.9 vs. 4.6, 3.4 vs. 4.4 respectively, p ~ 0.01) and differences persisted when comparing only patients recanalized in under 6 h.Conclusion: Independent of site of presentation, IV tPA before MT appears to lead to better radiographic outcomes, without increased rates of clot migration or higher intracranial hemorrhage risk, and overall better functional outcomes.
Highlights
MATERIALS AND METHODSIn 1995, intravenous tissue plasminogen activator, a thrombolytic designed to recanalize occluded blood vessels, was shown to significantly improve outcomes and became the first FDA approved treatment for acute ischemic stroke [1]
It has been proposed that tissue plasminogen activator (tPA), which works immediately on clot breakdown, may facilitate the use of mechanical thrombectomy (MT) and help to treat distal embolization [7, 8]; a recent study published in Stroke suggested that the use of IV tPA prior to mechanical lysis may complicate the procedure by converting easy to reach clots located at the proximal M1 branch to distal M2 branches [9]
(20) While we did not find major significant differences in radiographic or functional outcomes between patients presenting to the Emergency Department (ED) vs. an outside hospital (OSH), those transferred did tPA Improves Thrombectomy Outcomes require fewer passes to achieve recanalization, which may have been in part due to the fact that there was a longer period of time for tPA to soften the clot
Summary
MATERIALS AND METHODSIn 1995, intravenous tissue plasminogen activator (tPA), a thrombolytic designed to recanalize occluded blood vessels, was shown to significantly improve outcomes and became the first FDA approved treatment for acute ischemic stroke [1]. Subsequent studies have shown that following IV tPA with mechanical thrombectomy (MT) in patients with large vessel occlusion (LVO) [e.g., internal carotid (ICA) terminus or middle cerebral artery (MCA) lesions] can improve outcomes further [2,3,4,5]. This has become the standard practice at most Comprehensive Stroke Centers. In trials demonstrating the efficacy of MT for large vessel occlusion, the majority of eligible patients were bridged with IV tPA prior to intervention [2,3,4,5]. Though not different in the SYNTHESIS trial, it is possible that in some cases IV tPA may increase the rate of other complications such as hemorrhagic transformation that worsen long-term outcomes
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