ECG criteria for occlusive myocardial infarction in out of hospital cardiac arrest patients: more than STEMI?

Current strategies for patients with acute coronary syndrome (ACS) aim to identify acute coronary occlusion or near occlusion. Current guidelines recommend immediate coronary angiography and intervention in STEMI patients following cardiac arrest. However, some OHCA (Out of hospital cardiac arrest) patients with occlusive myocardial infarction do not fulfil the STEMI criteria.

We aimed to investigate whether ECG patterns beyond STEMI can indicate coronary occlusion in OHCA-patients, as misinterpretation can result in a delay in intervention.

In this retrospective study the first ECG taken after OHCA was analysed, and patients were categorised in two groups (group 1: patients with STEMI; group 2: patients without STEMI but predefined OMI-criteria (including modified Sgarbossa Criteria, de Winter Sign, Wellens Sign (types A and B), left-main equivalent, shark-fin sign, and ST-depression in two contiguous leads without ST-elevation or ST-elevation in just one lead)) and compared with the presence of occlusive myocardial infarction.

An occlusive myocardial infarction was found in 54.6% of OHCA-patients (n=97), of which only 47.2% met the STEMI criteria (group 1) and 39.6% met the OMI-ECG criteria (group 2). However, STEMI ECG pattern alone failed to diagnose occlusive myocardial infarction in 52.8%, while a combination of the ECG criteria of both groups would have predicted an occlusive myocardial infarction in 86.8% of cases (p < 0.001). Patients in group 2 were less likely to undergo immediate coronary angiography (73.1% vs. 96.8%; p = 0.021), with longer delays when performed (94.5 vs. 47.5 minutes; p = 0.009) and had higher 24-hour mortality (p = 0.072), with those not receiving the procedure showing a significantly increased risk of death within 24 hours (p = 0.03). Mean survival time of deceased patients was shorter (5.8 vs. 14.5 days; p = 0.041), and cardiac death occurred more often (30.8% vs. 9.7%; p = 0.01).

We were able to show that a combination of the ECG criteria of both groups can predict an occlusive myocardial infarction better than the STEMI criteria alone. This could lead to faster treatment and possibly better survival of OHCA patients, which needs to be verified in further studies.