Occlusion-focused ECG triage finds more blocked arteries early than NSTEMI risk criteria

Design

Substudy of a multicentre cluster-randomised trial

Population

4,398 adults with suspected MI and no diagnostic ST elevation on admission ECG

Primary outcome

Invasive management within 2 hours and adjudicated acute coronary occlusion

Effect

Early invasive management 45.4% vs 13.6%; occlusion found within 2 hours 35.1% vs 16.7%

DIFOCCULT-3 was a multicentre cluster-randomised trial in which consecutive adults whose admission ECG showed no diagnostic ST elevation were managed either under the conventional STEMI/NSTEMI framework or under an occlusion-focused approach, which looks for ECG and clinical signs of acute coronary occlusion (OMI) whether or not ST-elevation criteria are met. This substudy compared that approach with the guideline definition of very-high-risk NSTEMI, which is supposed to trigger an immediate invasive strategy.

Among 4,398 patients, very-high-risk criteria picked out few people and were inconsistently acted on. The occlusion-focused approach sent 45.4% to invasive management within two hours, against 13.6% under the conventional framework, and adjudicated acute coronary occlusion was found within two hours in 35.1% against 16.7%. Angiographic yield did not fall despite the higher referral rate.

This is a process outcome — earlier identification — not a hard-outcome result, and it depended on staff trained in occlusion-pattern ECG reading. It does reinforce that the absence of ST-elevation criteria does not mean the artery is open.

• Do not rule out acute coronary occlusion because the ECG misses ST-elevation thresholds.
• Look for hyperacute T waves, de Winter pattern, posterior involvement and subtle reciprocal depression.
• Treat refractory ischaemic pain, haemodynamic instability or arrhythmia as reasons for immediate angiography.
• Repeat the ECG every 15–30 minutes while symptoms persist.
• Discuss borderline ECGs with the interventional team early rather than waiting for troponin.

Why it matters

The STEMI/NSTEMI split leaves many patients with an occluded artery waiting for angiography they need now.

Don't overread it

Earlier identification of occlusion is a process gain; this substudy does not show fewer deaths or smaller infarcts.

The statistics, in plain English

45.4% versus 13.6% means about three times as many patients went for early angiography under the occlusion approach. Because angiographic yield held up, the extra referrals were not mostly normal arteries.

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