We read with interest the article published by Fernández-Sánchez et al.1 in which they described the South African flag sign. This is one of many signs already described to help identify particular electrocardiogram patterns associated with acute coronary syndrome, such as the shark fin sign, the triangular wave, and the lambda-like wave. Nonetheless, in our opinion, the South African flag sign is an ill-suited teaching tool,2 as one must first be familiar with the flag. The sign also demands a certain degree of imagination and only applies to 3×4 display formats. In addition, the ST depression mirror image is also observed in II and aVF, meaning it is positioned outside the flag. This is, however, not the main point we wish to make in reference to the article by Fernández-Sánchez et al.

The pattern described by the authors is a characteristic finding in first diagonal or intermediate branch occlusion. Although this pattern has traditionally been considered to depict high lateral ischemia due to circumflex artery occlusion, when not associated with ST depression in V1-V2,3 it is a manifestation of occlusion of the first diagonal or intermediate branch, which both supply blood to the mid-low anterolateral wall, not the high lateral wall.4 Strictly speaking, thus, the pattern represents mid-anterior myocardial infarction, which in its subacute or chronic phase can be confirmed by delayed enhancement cardiac magnetic resonance imaging.5

We agree with the authors that it is a grave error to expect ST elevation in 2 contiguous leads when assessing a potential case of acute coronary syndrome. In this particular case, however, the I and aVL leads displaying ST elevation in the frontal plane can be considered contiguous.