We have read with interest the article by Rai et al., which provides valuable information on the electrocardiographic manifestations of left main occlusion/subocclusion. However, we would like to make some clarifications:
The “STE-type” example in Figure 1B is not the most typical example of total left main occlusion. The figure legend states: “STE in leads V2-V5” (however, it is minimally elevated in V1 and not in V5) “and lateral leads I (however, it is not elevated) and aVL, together with reciprocal STD in leads II, III, aVF and concomitant bifascicular block, eg, RBBB +LAFB (however, it does not meet LAFB criteria), with or without STE in aVR (in our experience, lead aVR is not relevant for total left main occlusion, only for subocclusion). In our opinion, this example is more typical of proximal LAD occlusion, since the ischemic vector is directed anteriorly and upwards, and somewhat to the right. The projection of this vector in the positive and negative hemifieds of different leads explains the ST-segment elevation from V1 to V4 and in aVR. The ischemic vector due to total left main occlusion, resulting from an proximal LAD and LCX occlusion is directed forward and somewhat to the left.
On the other hand, in our opinion, the literature gives excessive importance to the elevated ST in lead aVR in isolation, as the authors also suggest. ST elevation in aVR is an expression of the vector sum of circumferential subendocardial ischemia in cases of left main subocclusion or 3-vessel disease, but also in cases of very proximal LAD occlusion. A similar pattern of diffuse ST-segment elevation in lead aVR is often seen in patients with left ventricular hypertrophy, cardiomyopathy, or critical aortic stenosis. In Figure 3, the authors highlight ST elevation in aVR in 50% of cases of LM culprit patients, probably due to left main subocclusion.
At a practical level, the most important consideration is the suspicion of total left main occlusion unprotected, which should be treated with emergent mechanical reperfusion at a referral hospital. Circumferential subendocardial ischemia with ST elevation in aVR > V1 is suggestive of left main subocclusion or 3-vessel disease, and the indication for emergent coronary angiography will depend on the degree of ventricular dysfunction.
Conflict of interest
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