Characteristics of IVF patients with J point elevation in the 3rd intercostal space
There is a strong male dominance in IVF, early repolarization syndrome, and BrS.15, 16 Similar to these diseases characterized by risk of VF unassociated with structural heart diseases, majority of patients with J point elevation in the 3rd ICS were men (93%). In this study, VF occurred less frequently during exercise in IVF patients with J point elevation in the 3rd ICS than those without J point elevation in right ICS, suggesting that increased vagal tone is associated with risk of VF in patients with J point elevation in the 3rd ICS. In BrS, VF is associated increased vagal tone and often develops at rest and during sleep.17, 18 The characteristic J point and ST-segment elevation is often pronounced in the 3rd and 2nd ICS in BrS. Although Type I Brugada ECG was not observed in patients with J point elevation in the 3rd ICS at rest and during sodium channel blocker test, IVF with J point elevation in the 3rd ICS and BrS share clinical and electrophysiological characteristics, suggesting the presence of common arrhythmogenic substrate between two disorders.
Kamakura et al.16 reported that the frequency of VF recurrences is higher in ERS patients with J point elevation in standard and/or high right ICS (58%) than those without J point elevation in right ICS (11%). In this study, the frequency of VF recurrences was also higher in IVF patients with J point elevation in high right ICS (36%) than those without J point elevation in right ICS (11%). Taken together, J point elevation in 3rd ICS may be an electrographic risk factor for VF recurrence in patients with VF unassociated with structural heart diseases.