Thrombectomy in mild large-vessel stroke: excellent outcome 69% versus 50%

Design

Multicentre, open-label randomised trial (MILD-MT)

Population

300 patients with NIHSS under 6, anterior large-vessel occlusion and large perfusion mismatch within 24 hours

Primary outcome

Modified Rankin 0–1 at 90 days

Effect

69.4% vs 50.0%; OR 2.32 (95% CI 1.41–3.81); serious procedural complications 13.2%

MILD-MT was a multicentre, open-label trial in China. It randomised 304 patients with anterior-circulation large-vessel occlusion and mild deficits (NIHSS under 6), with a small infarct core and a large perfusion mismatch, within 24 hours of onset, to thrombectomy plus medical management or medical management alone. 300 were analysed.

At 90 days, an excellent outcome (modified Rankin 0 or 1) was reached by 69.4% after thrombectomy against 50.0% (odds ratio 2.32, 95% CI 1.41 to 3.81). Symptomatic haemorrhage was three patients in each group. But serious procedural complications occurred in 13.2%, and there was one death, after thrombectomy.

Whether to take a mildly affected patient to thrombectomy has been one of stroke care's open questions, and earlier trials were not clearly positive. Selection here was strict: perfusion imaging had to show substantial tissue at risk. The result is likely to push more mild large-vessel strokes towards discussion with a stroke centre, but it is one open-label, single-country trial, and guidelines have not yet changed.

• Do not dismiss a mild stroke as low priority; ask whether there is a large-vessel occlusion.
• Selection required perfusion imaging showing a large mismatch and small core.
• Discuss eligible patients urgently with a stroke centre within 24 hours of last known well.
• Explain the procedural risk: serious complications in about one in eight treated patients.
• Guidelines have not changed; treat this as one strong trial awaiting confirmation.

Why it matters

It challenges the habit of managing mild deficits medically even when a major artery is blocked.

Don't overread it

One open-label trial from one country with strict imaging selection does not extend thrombectomy to all mild strokes.

The statistics, in plain English

An absolute gain of about 19 percentage points in excellent outcome means roughly one extra patient free of disability for every five treated. The interval (1.41 to 3.81) excludes 1, but open-label assessment of a functional score can bias results somewhat.

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