Impact of the Location of ST-T Abnormalities Accompanying Minor Q-Waves on the Definition of Prior Myocardial Infarction

Abstract

According to the Fourth Universal Definition of myocardial infarction (MI), the likelihood of a previous MI is increased when ST-T abnormalities exist with minor Q-waves in the same leads. Therefore, we examined whether differences in location of ST-T abnormalities in relation to minor Q-waves as part of the old MI definition impact the prevalence and prognostic significance of MI. This analysis included 7,878 participants with available baseline electrocardiogram (ECG) and follow-up data from the third National Health and Nutrition Examination Survey. Two ECG MI definitions were utilized; both were based on the standards of the Minnesota Code (MC) ECG Classification, and both incorporated major Q-waves but differed in whether major ST-T abnormalities and minor Q waves, as part of the definition, were in the same lead group (Standard MC-MI) or not (Fourth Universal MI). All-cause mortality and cardiovascular disease mortality were ascertained during 14 years (median). We found no difference between baseline prevalence of Standard MC-MI (3.48%; n = 274) and Fourth Universal MI (3.27%; n = 258), p = 0.46. Also, Standard MC-MI and Fourth Universal MI were similarly associated with increased risk of all-cause mortality (hazard ratio [95% confidence interval] 1.64 [1.42 to 1.90] and 1.61 [1.38 to 1.87], respectively; p value for differences in associations = 0.86), and cardiovascular disease mortality (hazard ratio [95% confidence interval] 1.99 [1.61 to 2.48] and 1.94 [1.56 to 2.42], respectively; p value for differences in associations = 0.84). In conclusion, the location of ST-T abnormalities accompanying minor Q-waves does not impact the prevalence or prognostic significance of a prior MI which raise doubts about the clinical impact of considering the location of ST-T in relation to minor Q-waves when defining an old MI.