Frequency of J point elevation in high intercostal spaces
There have been several reports on ECGs in high right precordial leads in healthy individuals. In a study from South Korea including 225 healthy men, J point elevation > 0.2mV was observed in the 4th ICS in 0% of subjects, and was observed in the 3rd ICS in 1.3%.11 In a report from Turkey including 504 healthy men, J point elevation ≥ 0.2 mV were observed in the 4th ICS in 3% of subjects, whereas the prevalence increased to 5% in the 3rd ICS12. In a report from Japan including 206 men, the prevalence of J point elevation ≥ 0.2 mV increased from 1.5% in the 4th ICS to 5.8% in the 3rd ICS13. In this study, the prevalence of J point elevation ≥ 0.2 mV in healthy control group (1.9% of in the 4th ICS and 2.9% in the 3rd ICS) was similar to those in the previous studies.
The frequency of J point elevation in the 3rd ICS ≥ 0.1 mV was higher in patients with IVF than healthy controls, and the difference became more pronounced when limited to J point elevation ≥ 0.2mV. There have been few previous studies investigating ECGs in the high intercostal space in IVF patients. In a study by Kamakura et al.14including 32 patients with early repolarization syndrome, J point elevation ≥ 0.1mV was observed in the 4th ICS in 8 patients (25%) and was observed in the high ICS in 13 patients (41%). The frequency of J point elevation in right precordial leads seems similar between the previous study and this study, although there was only 17% of patients with early repolarization syndrome in this study.