Reply

Dear Editor,

We read with great interest the comment of Dr. Hayiroglu to our recently published paper assessing the significance of ST elevation in aVL during anterior myocardial infarction (MI; Allencherril et al., 2018).

Details on the angiographic findings were not collected in this MITOCARE study dataset. Therefore, we cannot comment. While the exact distribution of the infarct‐related epicardial coronary arteries, the presence of additional coronary lesions in the no culprit coronary arteries, as well as the previously infarcted territories all have major effects on the electrocardiogram, these issues have been previously reported. We expect that variations in the coronary anatomy would affect the distribution of the ischemic area at risk, manifested by cardiac MRI as myocardium at risk (MaR). Thus, the cardiac MRI (CMR) data should reflect the actual distribution of the ischemia (as opposed to speculation based on the coronary anatomy).

If the LAD wraps around the apex, we would expect more apical and infero‐apical distribution of MaR. As suggested by Dr. Hayiroglu, Sasaki, Yotsukura, Sakata, Yoshino, and Ishikawa (2001) described that proximal occlusion of a wrapping left anterior descending artery (LAD) and distal occlusion of a short LAD can result in anterior STEMI without ST elevation in aVL. Distal occlusion of a wrapping LAD is expected to cause concomitant ST elevation in the inferior leads and ST depression in aVL. Based on a small number of patients (CMR studies are small in size due to limited availability and the high cost of the procedure), we observed less basal anterior involvement and less apical inferior involvement in the patients with ST elevation in aVL, suggesting that in the 13 patients with ST elevation in aVL, the distribution of ischemia was more basal (compatible with proximal occlusion of a short LAD). The size of the group without ST elevation in aVL (n = 19) is too small for meaningful subgroup analysis. Nevertheless, we found no significant difference in the size of MaR between the group of anterior STEMI without or with ST elevation in aVL.

An ongoing issue is whether CMR can identify myocardial segments with subendocardial ischemia. In contrast to transmural ischemia resulting in edema after reperfusion, it is unclear whether subendocardial ischemia causes edema that can be detected by the CMR. Currently, we have no imaging tool to assess this besides the ECG and speculation based on the coronary anatomy.

More studies with larger numbers of patients are needed to verify what proportion of patients with anterior STEMI without ST elevation in aVL demonstrate distal occlusion of a nonwrapping LAD vs. proximal occlusion of a wrapping LAD.