Stent-retriever thrombectomy shrank infarcts in heavy-thrombus STEMI, without moving ejection fraction

Design

Open-label, multicentre, randomised superiority trial

Population

156 patients with STEMI and TIMI thrombus grade ≥3, treated within 8 hours of symptom onset

Primary outcome

Infarct size by CK-MB area under the curve

Effect

3,965 IU/L·h (IQR 2,480–5,092) vs 5,250 (IQR 3,506–7,449); difference −1,359 (95% CI −2,231 to −522), P = 0.001

NATURE randomised 156 patients with ST-elevation myocardial infarction and TIMI thrombus grade of 3 or more in the infarct-related artery to stent-retriever thrombectomy before conventional PCI, or conventional PCI alone, all within eight hours of symptom onset. Infarct size measured as CK-MB area under the curve was lower with thrombectomy: 3,965 IU/L·h (IQR 2,480–5,092) versus 5,250 (IQR 3,506–7,449), difference −1,359 (95% CI −2,231 to −522, P = 0.001).

Exploratory cardiac magnetic resonance in 123 of them agreed: infarct occupied 17% of the left ventricle (IQR 11–28) versus 28% (IQR 18–33), difference −7.0 percentage points (95% CI −12 to −2.0). Left ventricular volumes and ejection fraction did not differ. Adverse cardiovascular events were few in both arms — one at 30 days with thrombectomy, three without.

The context every interventionalist will bring to this is aspiration thrombectomy, which reduced surrogate markers and then failed on hard outcomes with a stroke signal in the large trials. This is a different device in a narrowly selected group, the trial was open-label, and 156 patients cannot speak to stroke or mortality. It is a reason to run a larger trial, not to add a step to the cath lab workflow.

• Do not add routine stent-retriever thrombectomy to primary PCI on this evidence.
• Where thrombus burden is high, the established levers remain: adequate anticoagulation, glycoprotein IIb/IIIa inhibitors in selected cases, and deferred stenting where flow is restored.
• Record TIMI thrombus grade explicitly — it is the entry criterion any future trial will use.
• Note the eight-hour window: this says nothing about late presenters, who are a large share of Indian STEMI.

Why it matters

Aspiration thrombectomy looked this good on surrogates too, and then did not survive an outcome trial.

Don't overread it

Smaller infarcts on imaging are not the same as fewer deaths; this trial was neither powered nor designed to show that.

The statistics, in plain English

CK-MB area under the curve and cardiac MRI infarct size are surrogate endpoints: they measure damage, not what happens to the patient. Ejection fraction and ventricular volumes — the surrogates closest to clinical outcome — did not differ, which weakens the chain of inference. With 156 patients the trial had no power to detect a difference in death or stroke either way.

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