Curriculum in Cardiology
Electrocardiographic diagnosis of acute myocardial infarction: Current concepts for the clinician

https://doi.org/10.1067/mhj.2001.113571Get rights and content

Abstract

Background Over the past 2 decades, the 12-lead electrocardiogram has attained special significance for the diagnosis and triage of patients with chest pain because timely detection of myocardial injury and a rapid assessment of myocardium at risk proved pivotal to implementing effective reperfusion therapies during acute myocardial infarction. However, this wealth of information could still be underutilized by clinicians who may restrict their diagnostic quest in patients with chest pain to the more classic electrocardiographic signs. Methods The medical literature on electrocardiographic manifestations of acute myocardial infarction was extensively reviewed. Results The widespread utilization of both coronary angiography and methods to determine myocardial function and metabolism in patients with acute myocardial infarction over the last 10 years has provided the means for rigorous comparisons with electrocardiographic information. We summarize these electrocardiographic signs and patterns in terms of their relevance to the clinician to help reduce the incidence of “nondiagnostic electrocardiograms” and improve timely decision-making. Conclusions The electrocardiogram continues to be an invaluable tool in the initial evaluation of patients with chest pain. The plethora of data currently available on electrocardiographic changes correlating with myocardial injury allows clinicians to make faster and better decisions than ever before. (Am Heart J 2001;141:507-17.)

Section snippets

Normal anatomic references

Several anatomic caveats are pertinent to the assessment of new fascicular blocks or axis changes and to the assessment of infarct location.

The heart lies horizontally with the atria at its base and the ventricles at its apex.4 Because the heart is rotated over its long axis, the right atrium and ventricle are more anterior than the left chambers, and the right and left sides of the heart are not aligned with the same sides of the body. Thus the interventricular septum is almost parallel with

Value of ST-segment elevation

The electrocardiograms that give us the most concern in emergency departments are those with a large amount of ST-segment deviation. The initial ST-segment sum is the main variable influencing “door to thrombolysis” time; the largest ST deviations result in the shortest times to treatment.11 Although this is usually justified, many factors such as myocardial mass, distance between the electrodes and the ischemic zone, and reciprocal “cancellation” changes may affect the magnitude of ST

Electrocardiographic-angiographic correlations revisited

The most frequent infarct-related artery among patients admitted with chest pain or discharged from the hospital after AMI is the LAD (44% to 56% of cases), followed by the RCA (27% to 39%) and the LCX (17%).13

Anterior plus inferior injury

The combination of anterior and inferior ST elevation in the electrocardiogram may give the impression of a critical mass of myocardial injury. However, it often results from distal occlusion of a long LAD, which “wraps around” the cardiac apex and results in wall motion abnormalities circumscribed to the cardiac apex.37 When injury in leads II, III, and aVF is accompanied by ST elevation in V1 but ST depression in V2, right ventricular—rather than apical—infarction is likely.38

Septal infarction

The ST elevation

ST-segment depression

Many patients with acute chest pain have “reciprocal” ST-segment depression, that is, ST-segment depression concomitant with ST-segment elevation in a lead group different than the one showing ST elevation. The mechanism underlying this ST depression is usually mirroring, a phenomenon of electrical reflection of the transmural injury onto the opposite ventricular wall. The ST depression is captured by a lead placed at 180 degrees of the lead recording the ST elevation, although the terms

Bundle branch block/ventricular pacing

Inclusion criteria for patients with chest pain in many clinical studies and registries require grouping patients with either RBBB or LBBB into a common category of “difficult” or “impossible” early diagnoses.57 However, the diagnosis of AMI in patients with RBBB is rarely obscured by the conduction defect. Myocardial injury should not be missed more often in these patients than in those with normal conduction because ST-segment elevation in both anterior and inferior injury (as well as

Pseudoinfarction patterns

Several conditions mimic AMI and may pose a diagnostic challenge.

Nondiagnostic electrocardiograms

Fifteen percent to 18% of patients with AMI do not show changes in the initial electrocardiogram, and an additional 25% show nonspecific changes.2 Although nondiagnostic electrocardiograms in patients with chest pain are often associated with lesions in branch vessels, the probability of detecting AMI does increase by recording serial electrocardiograms.76 However, because reperfusion therapies are more effective when administered early, it is ideal to maximize the information provided by the

Conclusions and recommendations

Relative to other diagnostic methods in cardiology, electrocardiographic technology has lagged behind. Experts in electrocardiography have called for a concerted effort to incorporate modern features to the bedside diagnosis such as high-resolution, additional leads and 3D vectrocardiography imaging.78 These additions would improve our ability to diagnose AMI.

In the meantime, however, the plethora of data currently available on electrocardiographic changes accompanying chest pain should allow

References (78)

  • DJ Engelen et al.

    Value of the electrocardiogram in localizing the occlusion site in the left anterior descending coronary artery in acute myocardial infarction

    J Am Coll Cardiol

    (1999)
  • RH Selvester et al.

    Ventricular excitation during percutaneous transluminal angioplasty of the left anterior descending coronary artery

    Am J Cardiol

    (1988)
  • T Ben-Gal et al.

    Importance of the conal branch of the right coronary artery in patients with acute anterior wall myocardial infarction: electrocardiographic and angiographic correlation

    J Am Coll Cardiol

    (1997)
  • IL Geft et al.

    ST elevations in leads V1 to V5 may be caused by right coronary artery occlusion and acute right ventricular infarction

    Am J Cardiol

    (1984)
  • S Sclarovsky et al.

    Isolated midanterior myocardial infarction: a special electrocardiographic sub-type of acute myocardial infarction consisting of ST-elevation in nonconsecutive leads and two different morphologic types of ST-depression

    Int J Cardiol

    (1994)
  • Y Birnbaum et al.

    Acute myocardial infarction entailing ST segment elevation in lead aVL: electrocardiographic differentiation among occlusion of the left anterior descending, first diagonal, and first obtuse marginal coronary arteries

    Am Heart J

    (1996)
  • SH Braat et al.

    Value of lead V4R for recognition of the infarct coronary in acute inferior myocardial infarction

    Am J Cardiol

    (1984)
  • I Herz et al.

    New electrocardiographic criteria for predicting either the right or left circumflex artery as the culprit coronary artery in inferior wall acute myocardial infarction

    Am J Cardiol

    (1997)
  • PJ Zimetbaum et al.

    Usefulness of ST-segment elevation in lead III exceeding that of lead II for identifying the location of the totally occluded coronary artery in inferior wall myocardial infarction

    Am J Cardiol

    (1998)
  • AR Assali et al.

    Comparison of patients with inferior wall acute myocardial infarction with versus without ST-segment elevation in leads V5 and V6

    Am J Cardiol

    (1998)
  • M Kosuge et al.

    New electrocardiographic criteria for predicting the site of coronary artery occlusion in inferior wall acute myocardial infarction

    Am J Cardiol

    (1998)
  • S Matetzky et al.

    Significance of ST segment elevations in posterior chest leads (V7 to V9) in patients with acute inferior myocardial infarction: application for thrombolytic therapy

    J Am Coll Cardiol

    (1998)
  • BL Huey et al.

    A comprehensive analysis of myocardial infarction due to left circumflex artery occlusion: comparison with infarction due to right coronary artery and left posterior descending artery occlusion

    J Am Coll Cardiol

    (1988)
  • WE Boden et al.

    . Electrocardiographic evolution of posterior myocardial infarction: importance of early precordial ST-depression

    Am J Cardiol

    (1987)
  • PM Sapin et al.

    Implications of inferior ST-segment elevation accompanying anterior wall acute myocardial infarction for the angiographic morphology of the left anterior de-scending coronary artery morphology and site of occlusion

    Am J Cardiol

    (1992)
  • KH Mak et al.

    Simultaneous ST-segment elevation in lead V1 and depression in lead V2: a discordant ECG pattern indicating right ventricular infarction

    J Electrocardiol

    (1994)
  • Y Shalev et al.

    Does the electrocardiographic pattern of “anteroseptal” myocardial infarction correlate with the anatomic location of myocardial injury?

    Am J Cardiol

    (1995)
  • WE Boden et al.

    Inferoseptal myocardial infarction: another cause of precordial ST-segment depression in transmural inferior wall myocardial infarction?

    Am J Cardiol

    (1984)
  • APM Gorgels et al.

    Value of the electrocardiogram in diagnosing the number of severely narrowed coronary arteries in rest angina pectoris

    Am J Cardiol

    (1993)
  • SH Braat et al.

    Right ventricular involvement with acute inferior wall myocardial infarction identifies high risk of developing atrioventricular nodal conduction disturbances

    Am Heart J

    (1984)
  • J López-Sendon et al.

    Electrocardiographic findings in acute right ventricular infarction: sensitivity and specificity of electrocardiographic alterations in right precordial leads V4R, V3R, Vl, V2, and V3

    J Am Coll Cardiol

    (1985)
  • HA Kopelman et al.

    Right ventricular myocardial infarction in patients with chronic lung disease: possible role of right ventricular hypertrophy

    J Am Coll Cardiol

    (1985)
  • EJN Camara et al.

    Reciprocal ST change in acute myocardial infarction: assessment by electrocardiography and echocardiography

    J Am Coll Cardiol

    (1983)
  • RA Tabbalat et al.

    Are reciprocal changes a consequence of “ischemia at a distance” or merely a benign electric phenomenon? A PTCA study

    Am Heart J

    (1993)
  • HS Lee et al.

    Patients with suspected myocardial infarction who present with ST depression

    Lancet

    (1993)
  • Y Birnbaum et al.

    Correlation of angiographic findings and right (V1 to V3) versus left (V4 to V6) precordial ST-segment depression in inferior wall acute myocardial infarction

    Am J Cardiol

    (1999)
  • JH O’Keefe et al.

    Do patients with left circumflex coronary artery-related acute myocardial infarction without ST-segment elevation benefit from reperfusion therapy?

    Am J Cardiol

    (1995)
  • A Shah et al.

    Electrocardiographic differentiation of the ST-segment depression of acute myocardial injury due to the left circumflex artery occlusion from that of myocardial ischemia of nonocclusive etiologies

    Am J Cardiol

    (1997)
  • A Langer et al.

    Late assessment of thrombolytic efficacy (LATE) study: prognosis in patients with non-Q wave myocardial infarction

    J Am Coll Cardiol

    (1996)
  • Cited by (50)

    • Deep learning model to detect significant aortic regurgitation using electrocardiography

      2022, Journal of Cardiology
      Citation Excerpt :

      Raw data from each ECG examination record were represented as a 5,000 × 12 matrix of ECG voltages, in which the first dimension was the temporal dimension (each row represented a specific time point) and the second dimension was the spatial dimension (each column represented one lead) [14]. Therefore, to emphasize the spatial information, we rearranged the leads as follows: II, III, aVF, I, aVL, V6, aVR, V1, V2, V3, V4, and V5 [15]. Before training models, the training and validation datasets were augmented.

    • Trends in myocardial infarction rates and case fatality by anatomical location in four united states communities, 1987 to 2008 (from the atherosclerosis risk in communities study)

      2013, American Journal of Cardiology
      Citation Excerpt :

      Anterior STEMI was defined as an ST-segment elevation of ≥2.0 mm in any of the leads V1 to V4 or an ST-segment elevation of ≥1.0 mm in V5; inferior STEMI as an ST-segment elevation of ≥1.0 mm in any of the leads II, III, or aVF; and lateral STEMI as an ST-segment elevation of ≥1.0 mm in any of the leads I, aVL, and V6 alone or in the presence of anterior ST-segment elevations.16 ST elevations in the anterior and lateral electrocardiographic lead groups were combined to increase sensitivity to detect lateral STEMI, as ischemia of the lateral wall may be poorly represented by the lateral leads (I, aVL, and V6) alone.17,18 Finally, to represent ischemia in multiple anatomic locations, a multilocation STEMI was defined as ST-segment elevations in ≥2 of anterior, inferior, or lateral locations.

    View all citing articles on Scopus

    Reprint requests: Elena B. Sgarbossa, MD, Cardiology, Rush Presbyterian-St Luke’s Medical Center, 1750 W Harrison St, Chicago, IL 60612. E-mail: [email protected]

    View full text