Thrombectomy after large ischemic strokes: worth the risk?

Weighing improved outcomes against intracranial hemorrhage incidence

Endovascular thrombectomy became standard care for ischemic strokes resulting from large vessel occlusion (LVO) in the anterior cerebral circulation after randomized trials published in the mid-2010s showed improved outcomes with the intervention.

Patients with large strokes (as assessed on imaging) were excluded from those trials establishing thrombectomy's benefits, owing to hypothetical risks (such as bleeding or edema) after reperfusion of large areas of dead or damaged brain tissue. Subgroup analysis from those trials suggested that patients with larger strokes may have benefited (or at least were not harmed), though.

Multiple randomized trials have been performed testing thrombectomy for large ischemic strokes. But they used different imaging modalities to enroll patients, and so their conclusions are not necessarily compatible with each other. Nor are they necessarily applicable to “all comers” with large ischemic strokes.

Nevertheless, some broad conclusions can be drawn from the literature on thrombectomy for large strokes.

Choice of Imaging Influences Apparent Size of Strokes, and Candidacy for Thrombectomy

The benefits of thrombectomy depend on the presence of an injured but salvageable penumbra of brain around the infarcted core.

CT perfusion and MRI are better than noncontrast CT at identifying and quantifying the size of a stroke’s infarct core and potentially viable penumbra. However, these modalities aren’t as widely available as noncontrast CT.

Early thrombectomy trials in large strokes were identified using CT perfusion or MRI, so it’s unclear if their findings of benefit (see below) can be generalized to the wider world where acute ischemic strokes are most often diagnosed with noncontrast CT using the ASPECTS score.

Randomized Trials Testing Thrombectomy for Large Strokes

At least six randomized trials have tested thrombectomy for large ischemic strokes, usually within 24 hours of stroke onset (except in LASTE within 6.5 hours and TENSION within 11 hours).

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The signal seems clear: in clinical trials, thrombectomy performed up to 24 hours after stroke onset improves outcomes from large ischemic strokes, even when factoring in the negative outcomes from more intracranial hemorrhages.