Author + information
- Brendan P Phibbs, MDa
We appreciate Dr. Sgarbossa’s kind comments about our review entitled “Q wave vs. non–Q wave myocardial infarction: a meaningless distinction.” She points out, appropriately, the need to include “Q wave equivalent” deflections in any comparative study, but we would also like to reemphasize the overriding importance of comparing first myocardial infarctions (MIs) onlyin this type of study, because subsequent MIs have a much higher morbidity and mortality and usually do not generate Q waves. The main thrust of our review was that there is no basis for the notion that the non–Q wave MI is somehow “unstable,” with an increased risk of post-MI acute events, and with this we are sure Dr. Sgarbossa agrees. In fact, we quoted a study from Sgarbossa’s group (1)supporting this point of view in our review.
She quotes her own study of T wave polarity after MI, in combination with the presence or absence of Q waves, as a prognostic index in both the Q wave and non–Q wave categories. Because this report has appeared only in abstract so far, it is impossible to comment on the details of the protocol.
Were only first MIs included in the study? An outcome study based on two variables can be very tricky, as any statistician will attest, but the results may well be significant.
Dr. Sgarbossa comments on several other studies addressing the value of ST segment depression and T wave inversion as prognostic indexes. This element was not included in our review, because we were concerned only with the presence or absence of depolarization abnormality as a clinical marker. The studies cited by Sgarbossa, suggesting that the type of S-T-T deformity may contribute important prognostic information, are all based on assessment of only non–Q-wave MIs, which dates from a period when the non–Q wave MI was assumed to be a valid subset with unique characteristics. It is to be hoped that this misconception has been permanently put to rest and, further, that investigations of outcome after MI will avoid the egregious error of combining random mixtures of first and subsequent infarcts.
- American College of Cardiology