The Importance of Reciprocal Changes in aVL

ECG interpretation is one of the most important skills to master as an emergency  physician, and its interpretation can be very complex and frustrating. ECG manifestations can be very subtle, and sometimes the earliest and only ECG change seen will be reciprocal changes alone. To further complicate this, many patients have the atypical symptoms of nausea/vomiting, weakness, or shortness of breath and not chest pain.

What is the anatomic location of aVL to the heart?

  • aVL is the only lead facing the superior part of the left ventricle
  • aVL is the only lead that is opposite the inferior wall of the heart (almost 180 degrees from lead III)

What is the differential diagnosis for reciprocal changes in aVL?

  • Inferior acute myocardial infarction
  • Anterior acute myocardial infarction
  • Left ventricular hypertrophy
  • Left bundle branch block
  • Digitalis Use

How good are reciprocal changes in aVL in diagnosing myocardial infarction (MI)?

  • 53.3% of patients with inferior wall MI had reciprocal changes ≥ ST elevation in inferior leads [1]
  • 70 – 97.2% of patients with inferior wall MI had reciprocal changes in aVL [2] [3]
  • 30% of patients with anterior wall MI had reciprocal changes in aVL [3]

Can lead aVL give prognostic information for acute MI?

ST depression ≥0.1 mV in 2 or more lateral leads (I, aVL, V5, or V6) are more likely to:

  1. Die (14.9% vs 4.1%) [4]
  2. Suffer severe heart failure (14.3% vs 4.1%) [4]
  3. Have angina with ECG changes (20.0% vs 11.6%) [4]

 What is the most likely culprit artery in inferior MI?

  • Right coronary artery (80% of cases): Most likely especially if:
    • ST segment elevation lead III  > lead II and ST segment depression in lead I and aVL (> 1 mm)
    • Sens 90%, Spec 71%, PPV 94%, and NPV 70%) [5]
  • Left circumflex artery (20% of cases)

STEMI and Reciprocal Change in Lead aVL


Reading of the ECG remains a crucial diagnostic and prognostic tool for acute MI, and the earliest finding of an acute MI may be reciprocal changes in lead aVL.


  1. Parale GP et al. Importance of Reciprocal Leads in acute Myocardial Infarction. J Assoc Physicians India 2004. PMID: 15656026
  2. Birnbaum Y et al. ST Segment Depression in aVL: A Sensitive Marker for Acute Inferior Myocardial Infarction. Eur Heart J 1993. PMID: 8432289
  3. Morris F et al. ABC of Clinical Electrocardiography. Acute Myocardial Infarction Part 1. BMJ 2002. PMID: 11934778
  4. Barrabes JA et al. Prognostic Significance of ST Segment Depression in Lateral Leads I, aVL, V5 and V6 on Admission Electrocardiogram in Patients with a First Acute Myocardial Infarction Without ST Segment Elevation. JACC 2000. PMID: 10841229
  5. Use of the Electrocardiogram in Acute Myocardial Infarction. NEJM 2003. PMID: 12621138
Cite this article as: Salim Rezaie, "The Importance of Reciprocal Changes in aVL", REBEL EM blog, November 1, 2013. Available at:
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Salim Rezaie

Emergency Physician at Greater San Antonio Emergency Physicians (GSEP)
Creator & Founder of REBEL EM

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2 thoughts on “The Importance of Reciprocal Changes in aVL”

  1. Interesting subject — about which I have the following comments. I don’t see support for the contention that the earliest (only) finding in acute MI may be reciprocal changes in lead aVL without abnormality in any other lead. It would be interesting to see an actual ECG demonstrating this … On the other hand, It is true that lead aVL (because it is the “highest” lateral lead) may on rare occasion be the only lead that demonstrates ST elevation. In my experience — many interpreters confuse true “reciprocal ST depression” in lead aVL with other ST-T changes such as flattening or T wave inversion that may be seen in this lead. The ECG you post here is a beautiful example of true reciprocal ST depression (in which the ST-T wave seen in lead aVL is the “mirror-image” of what is seen in lead III). That said — the “culprit artery” for this patient isn’t obvious to me because of the inferior changes in association with what we see in the chest leads, which is not what is seen with simple RCA occlusion … Do you have cath confirmation of the “culprit artery” for this ECG? Finally — I submit that I’ve never had to consider a “differential diagnosis” per se for ST depression in aVL — as the other 11 leads almost always provide me with the answer. Thank you for your receptivity to my constructive comments on this interesting topic.

    • Hello Ken,
      It has been awhile…always love your thoughts on ECG interpretation. Don’t have much to add to what you have already so eloquently stated. As for the “culprit artery”…I have de-identified this ECG so well I don’t even remember which patient this was or where the ECG was received from. I do remember though there was a cath performed. I will sift through my records later today and see if I have kept that information. Hope all is well with you. 🙂



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