Author + information
- Hideki Hayashi, MD, PhD∗ (, )
- Yoshitaka Murakami, PhD and
- Minoru Horie, MD, PhD
- ↵∗Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Tsukiwa-machi, Seta, Otsu, Shiga 520-2192, Japan
We read with much interest the paper published by Wu et al. (1). The paper summarized previous papers dealing with early repolarization pattern (ERP). In their meta-analysis, epidemiological studies regarding ERP were selected to examine whether ERP was associated with cardiac mortality in the general population. Although they selected suitable studies, several questions arise in their data analyses and interpretations.
First, we are concerned that the authors overestimated the results of “death from cardiac cause” in their meta-analysis. We have carefully reviewed the risk ratios and corresponding person-years and events of each study in Figure 2 of their paper (1). Although it is noted that “total” represents person-years in the annotation, the numbers in the “total” column did not present the values of person-years in “death from cardiac cause.” Indeed, the numbers in this “total” column correspond exactly to the numbers of subjects with ERP or subjects without ERP in each study cited. Because of these errors, the risk ratios that the authors calculated were much lower than hazard ratios reported in some studies. For example, the risk ratio for “death from cardiac cause” is unrealistically low compared with that in the study of Haruta et al. (2). We were concerned that the procedure used to analyze “death from cardiac cause” was apparently different from those used for “death from all causes” and “death from arrhythmia.”
Second, we are concerned about the different clinical outcomes used to analyze “death from arrhythmia.” Haruta et al. (2) studied an association between ERP and “unexplained death,” and Olson et al. (3) set sudden cardiac death as an endpoint. In these studies, whether or not arrhythmic death occurred was not clarified. Therefore, including the results of these two studies in the part of “death from arrhythmia” may cause overestimation of the risk ratios for arrhythmic death.
Third, the definition of ERP was not consistent among the studies. ERP was identified when J-point elevation was present in at least two leads in most studies, whereas J-point elevation in any lead was used to identify ERP in the study by Olson et al. (3). Thus, comparing the risk ratios of these studies does not yield an accurate conclusion. In addition, Haruta et al. (2) included Brugada-type electrocardiographic findings in ERP, which may increase the incidence of unexplained death. Therefore, caution is required in interpreting ERP as a potential phenotype as is stated by Wu et al. (1).
- American College of Cardiology Foundation
- Wu S.H.,
- Lin X.X.,
- Cheng Y.J.,
- Qiang C.C.,
- Zhang J.
- Haruta D.,
- Matsuo K.,
- Tsuneto A.,
- et al.