Mechanical thrombectomy for emergent large vessel occlusion: a critical appraisal of recent randomized controlled clinical trials

Abstract

Background and PurposeAfter numerous attempts to prove efficacy for endovascular treatment of ischemic stroke, a series of recent randomized controlled clinical trials (RCTs) established fast mechanical thrombectomy (MT) as a safe and effective novel treatment for emergent large vessel occlusion (ELVO) in the anterior cerebral circulation.MethodsWe reviewed five recent RCTs that evaluated the safety and efficacy of MT in ELVO patients and captured available information on recanalization/reperfusion, symptomatic intracranial hemorrhage (sICH), clinical outcome, and mortality. MT was performed with stent retrievers, aspiration techniques, or a combination of these endovascular approaches. We applied meta‐analytical methodology to evaluate the pooled effect of MT on recanalization/reperfusion, sICH, functional independence (modified Rankin scale score of 0–2) and 3‐month mortality rates in comparison to best medical therapy (BMT).Results MT was associated with increased likelihood of complete recanalization/reperfusion (RR: 2.22; 95%CI: 1.89–2.62; P < 0.00001) and 3‐month functional independence (RR: 1.72; 95%CI: 1.48–1.99; P < 0.00001) without any heterogeneity across trials (I 2 = 0%). The absolute benefit increase in MT for complete recanalization/reperfusion and functional independence was 44 (NNT = 2) and 16 (NNT = 6), respectively. MT was not associated with increased risk of 3‐month mortality (15% with MT vs. 19% with BMT) and sICH (4.6% with MT vs. 4.3% with BMT), while small heterogeneity was detected across the included trials (I 2 < 25%).Conclusions MT is a safe and highly effective treatment for patients with ELVO in the anterior circulation. For every six ELVO patients treated with MT three more will achieve complete recanalization at 24 h following symptom onset and one more will be functionally independent at 3 months in comparison to BMT.

Mechanical Thrombectomy Improves Functional Outcomes Independent of Pretreatment With Intravenous Thrombolysis

“…However, it should be noted that in two trials the method of endovascular treatment was left to the discretion of the local interventionist, 3,4 while in another trial the neurointerventionists used not a sole, but every available thrombectomy device to achieve reperfusion. 1 Even though there is a theoretical risk of introducing unmeasured biases both within subgroup and across subgroups in these trials, we considered that the aforementioned approaches were dictated by technical issues and thus were unlikely to introduce systematic biases. Even though all 6 RCTs had open-label treatment with blinded end-point evaluation (PROBE design), [1][2][3][4][5][6] we considered that the outcome measure was likely not influenced by the lack of double blinding.…”

“…1 Even though there is a theoretical risk of introducing unmeasured biases both within subgroup and across subgroups in these trials, we considered that the aforementioned approaches were dictated by technical issues and thus were unlikely to introduce systematic biases. Even though all 6 RCTs had open-label treatment with blinded end-point evaluation (PROBE design), [1][2][3][4][5][6] we considered that the outcome measure was likely not influenced by the lack of double blinding. Industry financial support was reported in 4 of the 6 trials, 1,2,5,6 and mainly public funding in the remaining two.…”

“…1 The question of whether pretreatment with intravenous thrombolysis (IVT) has a significant impact on the functional outcome (FO) of patients with ELVO still remains unanswered.…”

Response to Letter Regarding Article, “Mechanical Thrombectomy Improves Functional Outcomes Independent of Pretreatment With Intravenous Thrombolysis”

“…2 This finding drew our attention, as no such interaction was detected in the individual randomized controlled clinical trials including patients with and without IVT pretreatment. 3 Even though our systematic review and meta-analysis provide additional evidence that ET is effective for patients with acute ischemic stroke (AIS) with anterior circulation ELVO independent of IVT pretreatment, 1 we disagree with the notion that at present ET can be considered as an independent and initial treatment option for all patients with AIS. Current American Heart Association/American Stroke Association guidelines 4 advocate that patients with AIS are eligible for ET with stent retrievers only if they have received previous treatment with IVT within the therapeutic window of 4.5 hours (class I, level of evidence A).…”

Quality improvement in neurology

“…However, systems of care to implement this technology are heterogeneous and often poorly organized. [9][10][11] Data from the Get With The Guidelines-Stroke registry indicate that only 23.4% of hospitals provide ET. 12 When performed, multiple in-hospital care processes affect the overall treatment effect of ET, including a reduction in absolute risk difference for good outcome by 6% for every hour of delay.…”