Early repolarization on ECG: when guidelines confuse ECG criteria

Early repolarization pattern: confused J points, notches and slurs

I once had the privilige of attending a lecture given by professor Salim Yusuf of McMaster University.  Professor Yusuf is the most cited researcher in cardiovascular medicine, a real giant. During his lecture professor Yusuf said that he was not too impressed with current guidelines. He said that guidelines tend to be too complicated and too verbose. Those of us who have read guidelines may agree with those viewpoints. Going through some guidelines the other day I realized that they are indeed becoming thicker and thicker. Guidelines issued by AHA, ACC and ESC could actually serve as textbooks. In fact, going to AHA/ACC/ESC websites, you can make yourself a textbook by downloading all their guidelines.

Nevertheless, I recently read Recommendations for interpretation of 12-lead electrocardiogram in the athlete, which is a great paper written by a dozen of merited scholars. In this paper the authors discuss normal variants and abnormalities which athletes may exhibit on the 12-lead ECG. However, the second ECG in the paper is wrongly interpreted by the authors. They intend to present an ECG with early repolarization (which is associated with 5 times as great a risk of ventricular fibrillation and sudden cardiac death), but instead they display an ECG with male/female pattern. The ECG from the article follows.

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As evident, the figure legend states that the ECGs show two patterns of early repolarization. They assert that the early repolarization in ECG (A) is characterized by upward concavity of the ST segment and positive T-waves. In ECG (B) they state something similar. Unfortunately, these ECGs do not show any sign of early repolarization. Note that this paper has been cited almost 500 times since publication. It should also be noted that this ECG actually shows male/female pattern, which is by far the most common cause of ST segment elevation in any population (up to 90% of males aged 40 years or younger display this). Hence, the authors have confused a completely benign condition (male/female pattern) with a condition which is associated with 5 times as great a risk of sudden cardiac death.

For readers interested in recognizing early repolarization, I recommend a recent consensus document written by MacFarlane et al. Reading this you will realize that early repolarization is actually reocgnized in the J point (where the QRS complex fuses with the ST segment). Early repolarization is defined by a notch or slur in the J point (where the QRS fuses with the ST segment). This is often referred to as “end-QRS slur” or “end-QRS notch”. Se figure below.

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ECG criteria for early repolarization

According to MacFarlane et al (JACC, 2015).

Early repolarization is present if all of the following criteria are met (illustrated above):

  • 1. There is an end-QRS notch or slur on the downslope of a prominent R-wave. If there is a notch, it should lie entirely above the baseline. The onset of a slur must also be above the baseline.
  • 2. Jp is ≥0.1 mV in 2 or more contiguous leads of the 12-lead ECG, excluding leads V1 to V3.
  • 3. QRS duration is <120 ms.

 

 

Panel B in Figure 5 below shows another example of early repolarization.

Figure 5. Early repolarization (after MacFarlane et al, 2016, Eur Hear J).
Figure 5. Early repolarization (after MacFarlane et al, 2016, Eur Hear J).

 

Readers interested in ST segment elevation differential diagnoses may read our own article.

Take home message: Inspect the J point!

 

 

Posted by Dr Dan Olsson.

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