To the Editor:
May I express my thanks to Dr Alarcón-Duque and his co-authors.
I would like to make it clear that the electrocardiographic criteria for Q wave myocardial infarction refer to patients with STEACS who, in the chronic phase, present tall Q or R waves in V1. Thanks to the correlation with magnetic resonance, our study shows that in these patients the presence of Q waves of necrosis or equivalent images (R in V1 with R/S >1, and/or R 340 ms in duration) enables us to locate the infarction. In Alarcón-Duque et al's example, R duration is <4 ms and the R/S relation is around 0.5. I seem to recall that an R/S relation 31 is the value which has 100% specificity for lateral infarction.
What we want to illustrate is that in a patient with myocardial infarction following STEACS, a tall R in V1—above all if the R/S relation is ≥1 and R duration ≥40 ms—necrosis must be lateral and not posterior. It cannot be posterior because: a) the posterior wall (now segment 4 of the Cerqueira classification: inferobasal) often does not exist because segment 4 does not curve upwards; b) even if it existed, necrosis would not give a tall R in V1, the mirror-image of the Q-wave of the leads on the back, because it is depolarized after 30-40 ms when the normal R wave has begun to register, meaning there cannot be Q on the back; and c) because, in any case, even if the necrosis vector existed, it would be directed towards V3-V4 not V1-V2 due to the oblique position of the heart in the chest.
Naturally, with a tall R wave in V1, we need to rule out Wolf-Parkinson-White syndrome, right bundle branch block, and right ventricular growth. In their absence, never in normal individuals, duration of R is ≥40 ms and the R/S relation is >1. The ECG presented by Alarcón-Duque et al presents neither R ≥40 ms nor R/S ≥1.
I thank Alarcón-Duque et al for stating the need always to correlate the ECG with the symptoms. Furthermore, I would like to add that more information on these data can be found in some of our other studies,1-4 in addition to those they quote.