AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the ECG: Part VI: Acute Ischemia/Infarction

Authors, Journal, Affiliations, Type, DOI

• Authors: Galen S. Wagner, Peter Macfarlane, Hein Wellens, Mark Josephson, Anton Gorgels, David M. Mirvis, Olle Pahlm, Borys Surawicz, Paul Kligfield, Rory Childers, Leonard S. Gettes
• Journal: Journal of the American College of Cardiology, Vol. 53, No. 11, 2009:1003–11
• Affiliations: Multi-institutional (Duke, Glasgow, Maastricht, Harvard, Cornell, Chicago, North Carolina et al.)
• Type: Multi-society scientific statement (AHA/ACCF/HRS)
• DOI: https://doi.org/10.1016/j.jacc.2008.12.016

Overview

This is the sixth and final part of the AHA/ACCF/HRS ECG Standardization series, providing consensus recommendations for ECG diagnosis of acute myocardial ischemia and infarction. It establishes sex- and age-adjusted J-point elevation thresholds, recommends the Cabrera anatomically contiguous lead display format, and maps ST-segment spatial vector patterns to specific occluded coronary arteries and occlusion sites. The document formalizes recognition of the Wellens T-wave pattern as a pre-infarction warning for critical proximal LAD stenosis, and summarizes Sgarbossa criteria for ischemia diagnosis in LBBB with updated sensitivity/specificity data from GUSTO-I and HERO-2.

Keywords

Electrocardiography, ischemia, infarction, STEMI, NSTEMI, ST-segment elevation, ST-segment depression, contiguous leads, Cabrera format, Wellens syndrome, Sgarbossa criteria, Selvester QRS score, right ventricular infarction, posterior infarction, coronary artery localization

Key Takeaways

ST-Segment Elevation and Depression — Bioelectric Principles

• All ECG leads are bipolar; leads I, II, III use 2 dedicated electrodes; remaining 9 leads use Wilson's central terminal or averaged limb inputs as the negative electrode
• ST elevation in any lead is associated with reciprocal ST depression in leads whose positive pole is ~180° opposite; if no lead fulfills this geometrically, only STE or STD appears on the routine ECG
• Injury currents cause STE, STD, both, or neither depending on electrode spatial orientation relative to the ischemic zone, voltage magnitude, and confounding abnormalities (LVH, LBBB, pericarditis)
• ST depression in V1–V2 is a common reciprocal manifestation of posterior or lateral ST-elevation infarction; the positive pole of V1/V2 is anterior — opposite to the ischemic posterior/lateral wall
• Subendocardial ischemia causing multi-lead STD is tenable as reciprocal of endocardial STE from injury currents directed toward the ventricular chamber
• Leads should be labeled by standard nomenclature (I, II, III, aVR, aVL, aVF, V1–V6); labels "anterior," "inferior," "lateral" should not be applied to leads — only to the anatomic region of ischemia

Concept of Anatomically Contiguous Leads — Cabrera Format

• Classic ECG display does not show limb leads in anatomically contiguous order; the anatomically contiguous sequence is: aVL, I, −aVR, II, aVF, III (Cabrera format)
• −aVR exists at 30° in the hexaxial frontal plane (midway between I at 0° and II at 60°)
• Cabrera format has been the standard in Sweden for 25 years; recommended by the 2000 ESC/ACC guidelines for universal adoption
• Recommendation: ECG machines should provide switching to display and label limb leads in their anatomically contiguous sequence

Threshold Values for ST-Segment Changes (by sex/age/lead)

• Abnormal J-point elevation:
  • Men ≥40 years: ≥0.2 mV (2 mm) in V2–V3; ≥0.1 mV in all other leads
  • Men <40 years: ≥0.25 mV (2.5 mm) in V2–V3; ≥0.1 mV in all other leads
  • Women: ≥0.15 mV (1.5 mm) in V2–V3; >0.1 mV in all other leads
  • V3R/V4R: ≥0.05 mV (0.5 mm); men <30 years: ≥0.1 mV (1 mm)
  • V7–V9: ≥0.05 mV (0.5 mm) for both sexes
• Abnormal J-point depression: ≤−0.05 mV (−0.5 mm) in V2–V3; ≤−0.1 mV (−1 mm) in all other leads

Coronary Artery Localization — Anterior Wall

• Anterior wall ischemia = LAD occlusion; ST vector directed left and laterally → STE in some or all of V1–V6
• Proximal LAD (above 1st septal and 1st diagonal branches): STE in V1–V4, I, aVL, often aVR + reciprocal STD in II, III, aVF, often V5; more STE in aVL than aVR; more STD in III than II (ST vector directed more to the left)
• Mid-LAD (between 1st septal and 1st diagonal): Basal septum spared → V1 not elevated; ST vector directed toward aVL (elevated) and away from III (depressed)
• Distal LAD (below both 1st septal and 1st diagonal): Basal LV not involved; no STE in V1/aVR/aVL; no STD in II/III/aVF; STE may occur in II/III/aVF; STE more prominent in V3–V6, less prominent in V2

Coronary Artery Localization — Inferior Wall

• Inferior STE in II, III, aVF = RCA or LCx occlusion depending on which provides the posterior descending branch (dominance)
• RCA occlusion: ST vector directed more rightward → greater STE in III vs II; often STD in I and aVL (positive poles oriented left/superiorly)
• Proximal RCA occlusion: Right ventricular involvement → STE in right precordial leads (V3R/V4R) and often V1; RV STE persists for a much shorter period than inferior limb lead STE — V3R/V4R must be recorded rapidly after chest pain onset
• LCx occlusion: ST vector directed more leftward → greater STE in II vs III; isoelectric or elevated in I/aVL
• V3R/V4R not helpful to differentiate RCA vs LCx when accompanied by V1–V3 STD (posterior ischemia pattern)
• Recommendation: V3R and V4R should be recorded in all patients with ECG evidence of acute inferior wall ischemia/infarction

Posterior/Lateral Wall Terminology

• STD in V1–V2–V3 with inferior wall infarction = traditionally termed "posterior" or "posterolateral" ischemia (Perloff/Horan nomenclature based on ex vivo anatomy)
• In vivo MRI studies demonstrate the region is lateral (not posterior); Bayés de Luna et al. proposed replacing "posterior" with "lateral," "inferolateral," or "basal-lateral"
• AHA 2009 committee position: retain "posterior" terminology for the time being, pending further multicenter MRI studies

Multi-Lead STD — Left Main / Multivessel Disease Pattern

• Diffuse STD in multiple leads at rest = injury currents directed toward the ventricular chamber (nontransmural ischemia); leads aVR and V1 may show STE (right/superior/anterior orientation)
• ≥8 body-surface leads with STD >0.1 mV + STE in aVR and/or V1 at rest → 75% predictive accuracy for 3-vessel or left main stenosis (Gorgels et al.)
• At rest with angina: pattern implies multivessel or left main stenosis; with exercise: cannot identify the obstructed artery
• Recommendation: automated ECG algorithms should suggest multivessel or left main obstruction when this resting pattern is present

Postischemic T-Wave Changes — Wellens Syndrome

• After ischemia/infarction, T waves invert in leads with prior STE; duration varies from days to permanent
• Critical pattern: deeply inverted T waves (>0.5 mV) in V2–V3–V4 (occasionally V5) + significant QT prolongation after chest pain, without further ECG evidence of evolving infarction — no diagnostic STE, no new Q waves
• This pattern indicates severe stenosis of the proximal LAD with collateral circulation (de Zwaan/Bär/Wellens series); identical pattern also follows intracranial hemorrhage ("CVA pattern")
• If unrecognized, high proportion of patients proceed to acute anterior STEMI with the associated risks of proximal LAD occlusion
• Recommendation: this ECG pattern should be interpreted as consistent with severe proximal LAD stenosis or recent intracranial hemorrhage

Ischemia/Infarction in LBBB — Sgarbossa Criteria

• Fascicular blocks and RBBB do not affect standard ST-segment elevation criteria; LBBB does (due to pronounced secondary ST-T changes)
• Sgarbossa criteria (derived retrospectively from GUSTO-I):
  1. Concordant ST elevation ≥0.1 mV in leads with a positive QRS complex — high specificity, low sensitivity
  2. Concordant ST depression ≥0.1 mV in V1–V3 (leads with dominant S wave) — high specificity, low sensitivity
  3. Discordant ST elevation ≥0.5 mV in leads with negative QRS complex — very low specificity and sensitivity (HERO-2 data)
• Concordant ST changes in LBBB are associated with higher 30-day mortality than LBBB with enzyme rise but without concordant changes
• Recommendation: automated ECG algorithms should flag possible MI in LBBB patients meeting these criteria

Quantitative QRS Changes — Selvester QRS Score

• Minnesota Code: developed for infarction diagnosis, not size quantification; correlates poorly with anatomically measured infarct size
• Selvester QRS scoring system: 54 weighted criteria from 10 leads (I, II, aVL, aVF, V1–V6); 32 total QRS points; each point ≈ 3% of LV wall
• Specificity established in normal subjects; correlates with anatomically determined infarct size; most useful for single infarcts
• Recommendation: automated Selvester scoring algorithms should be developed and made available for tracings meeting prior infarction criteria

Limitations of the Document

• Published 2009; predates OMI/NOMI paradigm, high-sensitivity troponin era, and AI-based ECG interpretation
• Cabrera format recommendation has not been universally adopted despite 2000 ESC/ACC endorsement
• Posterior/lateral wall nomenclature remains unresolved; the committee's recommendation to retain "posterior" is contested by subsequent MRI data
• Sgarbossa discordant STE criterion (≥5 mm) shown to have very low specificity and sensitivity (HERO-2); modified Sgarbossa criteria (STE:S ratio ≥0.25) not addressed in this document
• Wellens data based primarily on de Zwaan/Bär/Wellens series without large multicenter prospective validation

Key Concepts Mentioned

• concepts/ST-T-Changes — ischemia ECG changes; thresholds; coronary localization patterns
• concepts/Wellens-Syndrome — deep T-wave inversion pattern for proximal LAD stenosis
• concepts/Sgarbossa-Criteria — LBBB + acute MI ECG diagnosis criteria
• concepts/OMI-NOMI-Paradigm — the historical STEMI/NSTEMI framework this document codifies

Key Entities Mentioned

• entities/Acute-Coronary-Syndrome — clinical context for ischemia/infarction ECG

Wiki Pages Updated

• wiki/sources/ecg-ischemia-aha-2009.md — created
• wiki/concepts/ST-T-Changes.md — updated: coronary localization, right-sided leads, Wellens, full Sgarbossa, Selvester; source count 4→5
• wiki/concepts/Wellens-Syndrome.md — created
• wiki/concepts/Sgarbossa-Criteria.md — created
• wiki/sourceindex.md — new entry added
• wiki/wikiindex.md — two new concept entries; ST-T-Changes description updated