Occlusion-focused triage sent more patients without ST elevation for urgent angiography

Design

Substudy of a multicentre cluster-randomised trial

Population

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

Primary outcome

Immediate invasive management and adjudicated acute coronary occlusion within 2 hours

Effect

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

DIFOCCULT-3 was a multicentre cluster-randomised trial in which hospitals managed chest pain patients either with the standard STEMI/NSTEMI framework or with the occlusion MI (OMI/NOMI) approach, which looks for ECG and clinical signs of an occluded artery whether or not ST elevation criteria are met. This substudy took 4,398 patients without diagnostic ST elevation on arrival.

Guideline very-high-risk NSTEMI criteria, which already call for immediate angiography, identified few patients and were inconsistently acted on. The occlusion-focused approach sent 45.4% for invasive management within two hours, against 13.6% with the standard framework. Adjudicated acute coronary occlusion was found within two hours in 35.1% against 16.7%, and the proportion of angiograms that found a culprit did not fall.

The substudy reports process measures, not mortality or infarct size, and the OMI approach depends on ECG skills that take training. But it shows that many occlusions sit inside the NSTEMI label, and that the current pathway leaves them waiting. Guidelines have not adopted OMI criteria, so the immediate step is to apply the very-high-risk NSTEMI criteria that already exist, and to learn the occlusion ECG patterns.

• Apply very-high-risk NSTEMI criteria strictly: refractory pain, haemodynamic instability, arrhythmia or acute heart failure means immediate angiography
• Learn occlusion ECG patterns such as hyperacute T waves, de Winter pattern and posterior MI
• Discuss patients with ongoing ischaemic pain and a suspicious ECG with cardiology even without STEMI criteria
• Repeat ECGs and use bedside echo for regional wall motion in ongoing chest pain
• Audit your own NSTEMI patients for time to angiography in those with occlusion

Why it matters

About twice as many occlusions were found within two hours when clinicians looked for occlusion rather than ST elevation.

Don't overread it

The outcomes are process measures; the substudy does not show lower mortality, and guidelines have not changed.

The statistics, in plain English

These are proportions in a cluster-randomised comparison, where whole hospitals rather than patients were assigned. That reduces contamination between approaches but means differences between hospitals can also play a part.

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