Although J-wave elevation (JWE) in the inferior or lateral leads is characteristic of subtype of idiopathic ventricular fibrillation (IVF), difference between malignant and benign JWE remains to be elucidated. So, we assessed the hypothesis that the rate dependent changes in JWE could be different between patients with IVF and control subjects. Six male patients with IVF and 18 age matched male controls with JWE (>2 mm) in the lateral leads were studied. CM-5 lead digital Holter ECG was recorded and J wave amplitude was automatically measured. J/RR relationships were evaluated by means of J/RR linear regression lines for 24 hours, and according to four 6-hour periods. From J-RR linear regression lines, J-RR slope (mm/sec), J wave amplitude (mm) at RR intervals of both 0.6 sec and 1.2 sec (J
(0.6)
and J
(1.2)
) were determined. In all 6 patients with IVF, the time of spontaneous episodes of VF were investigated from the implantable cardioverter defibrillator (ICD) stored data. For 24 hours, J-RR slope was greater in IVF patients than in controls (3.5±0.7 vs 2.4±0.8, p<0.01). (J
(0.6)
) wasn’t different between 2 groups; however, J
(1.2)
was greater in IVF patients than in controls (2.8±0.9 vs 2.0±0.6, p<0.05). In IVF patients, ST/RR slope was highest during 18:00–24:00; however, these circadian changes were blunted in controls. J(1.2) was greater during 18:00 – 6:00 in IVF patients than in controls. Seven (59%) of total 9 episodes of spontaneous VF of IVF patients occurred during 18:00 – 6:00. In patients with subtype of IVF, JWE augmented during bradycardia especially at night. This could relate to nighttime occurrence of IVF.
A female patient with hypokalaemia-induced J wave syndrome
