Mechanical Thrombectomy for Ischemic Stroke

Elgendy IY, Kumbhani DJ, Mahmoud A, Bhatt DL, Bavry AA.
Mechanical Thrombectomy for Acute Ischemic Stroke: A Meta-Analysis of Randomized Trials. J Am Coll Cardiol 2015;66:2498-2505.

Recently, a number of trials were published showing improved outcomes for acute stroke patients treated with mechanical thrombectomy. Elgendy and colleagues pooled trials of mechanical thrombectomy in acute ischemic stroke for a meta-analysis. The following are nine key points to remember from their study:

  1. Ischemic stroke is associated with a high morbidity and mortality.
  2. Intravenous (IV) thrombolysis with tissue plasminogen activator (tPA) is effective when given soon after stroke onset, but not all patients with large vessel occlusion are recanalized after IV tPA administration. Lack of recanalization is associated with worse outcomes.
  3. Intra-arterial therapy was first described in the 1980s. First-generation devices showed limited recanalization potential; however, contemporary mechanical thrombectomy devices have been shown to have robust recanalization rates. Until recent studies were published, these higher recanalization rates were not associated with improved clinical outcomes.
  4. The authors analyzed trials that randomized acute ischemic stroke patients to usual care (including IV tPA) versus usual care plus mechanical thrombectomy. The primary outcome of this analysis was a good function at 90 days, defined by 0-2 on the modified Rankin scale (a measure of disability). Mortality and safety outcomes were also evaluated.
  5. Nine trials encompassing 2,410 patients were included in the analyses. Two of the studies were not published at the time of the analyses.
  6. Mechanical thrombectomy was associated with a higher incidence of achieving a good functional outcome (43.7% vs. 30.9%; relative risk [RR], 1.45; 95% confidence interval [CI], 1.22-1.72). There was a trend toward reduced mortality in the mechanical thrombectomy group (15.9% vs. 17.9%; RR, 0.86; 95% CI, 0.72-1.02). Mechanical thrombectomy was associated with improved vessel recanalization (66.6% vs. 39.2%; RR, 1.57; 95% CI, 1.11-2.23) when compared with usual care.
  7. The risk of in-hospital symptomatic intracerebral hemorrhage was similar between the groups (5.1% vs. 5.0%; RR, 1.06; 95% CI, 0.73-1.55).
  8. When compared with usual care, mechanical thrombectomy was associated with a 45% higher relative likelihood and 13% absolute likelihood of having a good functional outcome. This corresponds to a number needed to treat of 8.
  9. While IV tPA (for eligible patients) remains the standard of care for acute ischemic stroke, mechanical thrombectomy should be offered to patients with an anterior circulation stroke due to large vessel occlusion who present within 6 hours of symptom onset.

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