ECG patterns of ischaemia and infarction — structured viva

Abbreviations

Stem

Practice viva (not a real examination). You are the cardiology registrar. The examiner hands you a series of ECG descriptions and asks you to defend your reading: thresholds, supplemental leads, occlusion without classic ST elevation, bundle branch block, high-risk patterns and mimics. Name the body and year for every rule you quote.

Branch A — Thresholds and measurement

Examiner: Where do you measure the ST segment, and what are the cut-points?

Strong answer:

• ESC 2023, ACC/AHA 2025 and the Fifth UDMI (2026) all measure ST elevation at the J-point.^[1][2][12]
• ESC 2023 (in the appropriate clinical context), ACC/AHA 2025 and the Fifth UDMI: new (ACC/AHA: new or presumed new) ST elevation at the J-point in at least two contiguous leads of ≥1 mm in leads other than V2–V3; in V2–V3, ≥2.5 mm in men under 40, ≥2 mm in men 40 or over and ≥1.5 mm in women regardless of age.^[1][2][12]
• The Fifth UDMI requires this in the absence of LVH or LBBB; ESC 2023 adds, after its other-leads cut-point, that it applies in the absence of LV hypertrophy or LBBB; the ACC/AHA Table 3 footnote says ST changes may be observed in other conditions, including LVH and LBBB, that may obscure the diagnosis of STEMI.^[12][1][2]
• Fourth UDMI (2018), not restated in the Fifth (history): it defined the J-point as the junction between QRS termination and ST-segment onset, and recommended QRS onset as the reference point for J-point determination.^[5]

Follow-up: How do the V2–V3 cut-points differ by sex and age, and what did the Fourth UDMI (2018) report about J-point elevation in healthy people?^[12][5]

• The Fifth UDMI (2026) and ESC 2023 set a higher V2–V3 cut-point for men than for women, and for men under 40 than for men 40 or over.^[12][1]
• Fourth UDMI (2018), not restated in the Fifth (history): it noted that, in healthy men under 40, J-point elevation can be as much as 2.5 mm in V2 or V3 but decreases with increasing age.^[5]
• The same Fourth UDMI (2018) text, also not restated in the Fifth, said sex differences require different cut-off points for women, because healthy women have less J-point elevation in V2 and V3 than men.^[5]

Branch B — Supplemental leads

Examiner: The patient has an inferior STEMI. What else do you record, and why?

Strong answer:

• ESC 2023 recommends additional ECG leads (V3R, V4R and V7–V9) in inferior STEMI or if total vessel occlusion is suspected and standard leads are inconclusive (Class I, Level B).^[1]
• ACC/AHA 2025 text says right-sided leads should be obtained when there is concern for inferior STEMI, to evaluate for RV involvement.^[2]
• The Fifth UDMI (2026) says a right ventricular MI is indicated by ST elevation in the right precordial leads (V3R–V6R), especially when accompanied by ST elevation in aVR.^[12]

Follow-up: What do changes in the extra leads mean, and what thresholds have been used?^[1]

• ESC 2023: ST elevation in V3R and V4R is highly suggestive of ongoing RV ischaemia, and ST elevation in V7–V9 is highly suggestive of posterior coronary occlusion, often of the left circumflex artery.^[1]
• The Fifth UDMI (2026) says a posterior MI is suggested by ST depression ≥1 mm in V1, V2 and/or V3, particularly when the R wave is dominant (R-wave amplitude greater than the S wave) in V1 or V2, and is confirmed by ST elevation in the posterior leads V7 to V9.^[12]
• Fourth UDMI (2018), not restated in the Fifth (history): it gave ST elevation ≥0.5 mm in V3R and V4R (≥1 mm in men under 30) as supportive criteria in inferior and suspected RV infarction, and noted that right precordial changes may be transient and that their absence did not exclude RV infarction.^[5]
• Fourth UDMI (2018), not restated in the Fifth (history): for V7–V9 it recommended a 0.5 mm ST elevation cut-off, noted that specificity was increased at ≥1 mm, and said ≥1 mm should be used in men under 40.^[5]

Branch C — Occlusion without classic ST elevation

Examiner: Can an artery be occluded without the classic ST elevation criteria?

Strong answer:

• Yes. ESC 2023 says some cases may warrant immediate reperfusion triage despite the absence of ST elevation, and that other ECG findings can suggest ongoing coronary occlusion (or severe ischaemia).^[1]
• The Fifth UDMI (2026) says previous studies have shown that up to 1 in 4 patients managed as NSTEMI without classical ST elevation on the conventional 12-lead ECG have an acute occlusion of the culprit artery.^[12]
• NHFA/CSANZ 2025 describes ACOMI patterns beyond traditional criteria, including high lateral MI, posterior MI, RV MI, De Winter T waves, modified Sgarbossa criteria and transient STE.^[4]
• People with symptoms and ECG changes consistent with ACOMI require urgent reperfusion, without a clinical decision pathway (NHFA/CSANZ 2025, strong recommendation, very low certainty).^[4]

Follow-up: How does the Fifth UDMI (2026) describe the de Winter pattern, and what has been published on precordial J-point depression with tall T waves?^[12][9]

• The Fifth UDMI (2026) Table 5 describes de Winter T waves as tall, prominent, symmetrical T waves with upsloping ST segment depression in the precordial leads.^[12]
• Its text lists the de Winter pattern (upsloping ST depression with tall, symmetric T waves in V2–V5) among further ECG patterns that suggest acute coronary occlusion, citing de Winter and colleagues (2008), "A new ECG sign of proximal LAD occlusion".^[12]
• In a single-centre observational study of acute anterior wall MI referred for primary PCI between 1998 and 2008, 35 of 1890 patients (2%) having primary PCI of the LAD had a static, distinct ECG pattern without ST elevation and an occlusion of the proximal LAD at urgent coronary angiography before PCI; the ECG showed precordial J-point depression of at least 1 mm with upsloping ST segments continuing into tall, symmetrical T waves, and the authors concluded that, in patients presenting with chest pain, this pattern signifies proximal LAD occlusion.^[9]

Branch D — LBBB and paced rhythm

Examiner: A patient with LBBB has ongoing chest pain. How do you read the ECG?

Strong answer:

• ESC 2023: with high clinical suspicion of ongoing ischaemia, LBBB, RBBB or a paced rhythm precludes accurate assessment of ST elevation, and such patients with highly suspicious signs or symptoms should be managed like those with clear ST elevation, whether or not the block is previously known.^[1]
• ACC/AHA 2025: new or presumably new LBBB should not be considered diagnostic of AMI in isolation; clinical correlation is required.^[2]
• NHFA/CSANZ 2025 counts LBBB with modified Sgarbossa criteria among the ECG changes indicative of ACOMI to which its STEMI/ACOMI management rows apply.^[4]
• The Fifth UDMI (2026): among patients with pre-existing LBBB or ventricular pacing, ST elevation ≥1 mm concordant with (in the same direction as) the QRS complex, ST depression ≥1 mm in V1, V2 or V3, and ST elevation ≥5 mm not concordant with (in the opposite direction to) the QRS complex suggest acute coronary occlusion (Sgarbossa criteria).^[12]

Follow-up: Where did the modified Sgarbossa rule come from?^[7]

• The original Sgarbossa criteria (NEJM 1996) came from baseline ECGs of GUSTO-1 patients with LBBB and enzyme-confirmed acute MI, compared blindly with controls who had chronic coronary disease and LBBB; the third criterion was discordant ST elevation of 5 mm or more.^[6][7][12]
• The modified rule replaced it with an ST/S ratio of -0.25 or less, with angiographically documented coronary occlusion as the reference standard, and is unweighted, requiring just 1 of 3 criteria.^[7]
• The cut point (the most negative ST/S ratio with at least 90% specificity) was set, and the rules compared, on admission ECGs of all patients with an acutely occluded coronary artery and LBBB at 3 institutions (33 ECGs), against ED patients with chest pain or dyspnoea and LBBB but no coronary occlusion (129 ECGs).^[7]
• Sensitivity was 91% against 52% and 67% for the weighted and unweighted original rules, and specificity was 90% against 98% and 90%.^[7]
• The Fifth UDMI (2026) says the modified Sgarbossa criteria may improve the detection of acute coronary occlusion with LBBB or ventricular pacing by replacing the absolute discordant ST elevation threshold with a proportional rule.^[12]

Branch E — High-risk patterns and mimics

Examiner: The ECG shows ST depression of 1 mm or more in seven leads with ST elevation in aVR. What does that mean?

Strong answer:

• ESC 2023: ST depression ≥1 mm in ≥6 surface leads with ST elevation in aVR and/or V1 suggests multivessel ischaemia or left main obstruction, particularly if the patient presents with haemodynamic compromise.^[1]
• The Fifth UDMI (2026) says global ischaemic changes (diffuse ST depression along with ST elevation in aVR) may reflect left main stem or balanced three-vessel coronary artery disease, and that these ECG findings are not specific to MI and can be observed in other cardiac and non-cardiac conditions.^[12]
• NHFA/CSANZ 2025 lists diffuse ST depression in multiple leads with ST elevation in aVR among high-risk patterns associated with potential progression to ACOMI; recognition should prompt urgent, continuous cardiac monitoring and consideration for coronary angiography.^[4]

Follow-up: Name conditions other than an acute coronary pathology in which ST changes may be observed, and say how the Fifth UDMI contrasts ST elevation with an acute coronary pathology with ST elevation in other conditions.^[2][12]

• ACC/AHA 2025: ST changes may be observed in other conditions, including acute pericarditis, LVH, LBBB, Brugada syndrome, right ventricular pacing, Takotsubo syndrome and early repolarisation, that may obscure the diagnosis of STEMI.^[2]
• The Fifth UDMI (2026): ST elevation is not specific to MI and can also be found in early repolarisation or other cardiac conditions (e.g. myocarditis, pericarditis, Brugada syndrome, and Takotsubo syndrome or cardiomyopathies) and non-cardiac conditions (e.g. pulmonary embolism, hyperkalaemia, hypothermia, elevated intracranial pressure).^[12]
• Contrast (Fifth UDMI): with an acute coronary pathology, ST elevation is typically regional and often accompanied by reciprocal ST depression.^[12]
• In contrast, in pericarditis or early repolarisation it is often diffuse or global, not confined to a single coronary territory, and occurs without reciprocal changes.^[12]