An occlusion-focused approach identified acute coronary occlusion within two hours twice as often

Design

Substudy of a multicentre cluster-randomised trial

Population

4,398 consecutive adults with suspected ACS and no diagnostic ST elevation

Primary outcome

Immediate invasive management and adjudicated acute coronary occlusion within 2 hours

Effect

Invasive <2 h 45.4% vs 13.6%; occlusion identified <2 h 35.1% vs 16.7%

DIFOCCULT-3 was a multicentre, cluster-randomised trial in which sites managed consecutive patients without diagnostic ST elevation using either the conventional STEMI/NSTEMI framework or an occlusion-focused OMI/NOMI approach, which reads the ECG and clinical picture for signs of acute coronary occlusion beyond millimetre criteria. This substudy compared that approach with guideline very-high-risk NSTEMI criteria, which are meant to trigger immediate angiography.

Among 4,398 patients, very-high-risk NSTEMI criteria flagged few patients and were inconsistently acted on. The OMI/NOMI approach sent 45.4% for invasive management within two hours against 13.6% under the conventional framework, and found adjudicated acute coronary occlusion within two hours in 35.1% against 16.7%. Angiographic yield did not fall, so the extra procedures were not simply more negative angiograms.

This substudy reports process outcomes — speed and yield — rather than infarct size or mortality, and the OMI approach depends on ECG expertise that varies between sites. Guidelines have not changed. But the finding supports what many emergency physicians already suspect: waiting for millimetres of ST elevation delays reperfusion for a substantial group of patients with occluded arteries.

• In chest pain without ST elevation, actively look for occlusion patterns rather than relying on millimetre criteria.
• Apply the very-high-risk NSTEMI criteria consistently: haemodynamic instability, refractory pain, arrhythmia or heart failure mean immediate angiography.
• Discuss suspected occlusion with the interventional team early, sharing serial ECGs.
• Build ECG review skills in the department; the approach depends on interpretation.
• Track time to angiography for NSTEMI patients who turn out to have occluded arteries.

Why it matters

The conventional framework identified fewer than half as many occlusions within two hours.

Don't overread it

The substudy reports timing and yield, not whether faster angiography improved survival or heart function.

The statistics, in plain English

The figures compare proportions treated and diagnosed within two hours, so they measure speed of recognition, not clinical benefit. Cluster randomisation by site helps, but sites using the new approach may also have had more ECG expertise.

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