Differential responses of J waves to heart rate changes in idiopathic ventricular fibrillation and the general population in Japan.

Previous case studies have reported bradycardia-dependent augmentation of J waves in patients with idiopathic ventricular fibrillation (VF). However, the response patterns of J waves to changing heart rates have rarely been evaluated in the general population. In this review, the response patterns of J waves to varying RR intervals were analyzed in the general population during premature beats or pacing and compared with the patterns observed in idiopathic VFs. Furthermore, the mechanism and clinical importance of the J waves are discussed. J waves associated with idiopathic VFs showed bradycardia-dependent augmentation and tachycardia-dependent attenuation, whereas those unrelated to idiopathic VFs exhibited tachycardia-dependent augmentation and less obvious bradycardia-dependent attenuation. These different response patterns suggest the presence of different mechanisms-repolarization- and depolarization-dependent mechanisms-and can be used for risk stratification and selection of therapeutic options.