Letter by Millar and Makanjee Regarding Article, “Masking Inferior Infarction by Anterior Myocardial Injury”
To the Editor:
Drs Deng and Das1 have provided ECGs showing the apparent disappearance and reappearance of signs of old inferior myocardial infarction during transient ischemia of the anterolateral left ventricle. They ascribe this to electrical forces in 1 zone reciprocally changing the QRS vector in the opposite myocardial zone. We believe there is an alternative explanation.
Figures 1 and 3 of the original article both show pathological Q waves in leads II, III, and aVF, whereas these are absent in Figure 2, which shows transient Q waves in leads I and aVL. It is unusual for pathological Q waves to come and go in this manner, particularly in the absence of biochemical evidence for infarction. One possible mechanism for loss of inferior Q waves is left anterior fascicular block, but this does not seem to have occurred in this case.
An alternative explanation is that the ECG in Figure 2 was recorded with the left-arm and left-leg electrodes transposed. In this situation, lead I becomes lead II, lead III is inverted, and aVF becomes aVL. aVR does not change significantly. The pattern recorded in the second ECG is compatible with this phenomenon.