The Spectrum of Idiopathic Ventricular Fibrillation and J-Wave Syndromes: Novel Mapping Insights.

Idiopathic ventricular fibrillation and J-wave syndromes are causes of sudden cardiac death (SCD) without any identified structural cardiac disease after extensive investigations. Recent data show that high-density electrophysiological mapping may ultimately offer diagnoses of subclinical diseases in most patients including those termed "unexplained" SCD. Three major conditions can underlie the occurrence of SCD: (1) localized depolarization abnormalities (due to microstructural myocardial alteration), (2) Purkinje abnormalities manifesting as triggering ectopy and inducible reentry; or (3) repolarization heterogeneities. Each condition may result from a spectrum of pathophysiologic processes with implications for individual therapy.

Depolarization versus repolarization abnormality underlying inferolateral J-wave syndromes: New concepts in sudden cardiac death with apparently normal hearts.

Early repolarization indicates a distinct electrocardiographic phenotype affecting the junction between the QRS complex and the ST segment in inferolateral leads (inferolateral J-wave syndromes). It has been considered a benign electrocardiographic variant for decades, but recent clinical studies have demonstrated its arrhythmogenicity in a small subset, supported by experimental studies showing transmural dispersion of repolarization. Here we review the current knowledge and the issues of risk stratification that limit clinical management. In addition, we report on new mapping data of patients refractory to pharmacologic treatment using high-density electrogram mapping at the time of inscription of J wave. These data demonstrate that distinct substrates, delayed depolarization, and abnormal early repolarization underlie inferolateral J-wave syndromes, with significant implications. Finally, based on these data, we propose a new simplified mechanistic classification of sudden cardiac deaths without apparent structural heart disease.

Early repolarization is involved in ventricular fibrillation in patients with variant angina.

BACKGROUND: Variant angina (VA) is caused by reversible coronary artery spasm, which is characterized by chest pain with ST segment elevations on a standard 12-lead electrocardiogram (ECG) at rest. VA attack often causes lethal ventricular arrhythmia. The early repolarization (ER) pattern is associated with ventricular fibrillation (VF). However, whether the ER pattern is involved in VF in patients with VA is not known. We investigated the association between the ER pattern and VF in patients with VA. METHODS: Fifty patients underwent induction of ST elevation on 12-lead ECGs with total or nearly total occlusion by provocation test (VA patients). Twelve of these patients underwent induction of VF or had documented VF before hospital admission (VF occurrence group). The J-wave morphology was characterized as exhibiting notching or slurring. The amplitude of each J wave was measured manually with amplified waveforms. RESULTS: ER patterns were observed significantly more often in the VF occurrence group than in the non-VF occurrence group (P = 0.007). The J-wave amplitude was significantly higher in the VF occurrence group compared with the non-VF occurrence group (P = 0.02). Univariate analyses suggested that age, smoking, and ER patterns were associated with VF. Upon multivariate analyses, age (odds ratio [OR] = 0.880; 95% confidence interval [CI]: 0.794-0.975; P = 0.014) and ER patterns (OR = 8.937; 95% CI:1.661-48.06; P = 0.011) predicted VF independently. CONCLUSIONS: These data suggest that an ER pattern in VA patients is a risk factor for VF. The ER pattern may be one of the useful factors for adaptation of implantation of implantable cardioverter-defibrillator in patients with coronary spasm-induced VF.

Characteristics of early repolarization parameters and prognostic implications in the general ambulatory Korean population.

BACKGROUND: We tested a hypothesis that the 2 fundamental components of early repolarization (ER), J wave and ST elevation (STE) might have different prevalence and prognostic implications. METHODS: The study population comprised 26,345 general ambulatory Korean subjects (mean 48.0±10.2years old, 53.2% male) who underwent medical checkups from January 2002 to December 2002. ER was found in 2950 subjects (11.2%), who were divided into 3 groups (J [J wave only, n=1874, 7.1%], JST [both J wave and STE, n=489, 1.8%], and ST [STE only, n=587, 2.3%]). RESULTS: The prevalence of STE decreased with age, whereas J waves remained at a constant level in all age groups. The most common pattern of ER was the J pattern, with a horizontal/descending ST segment in the inferior leads; in lateral precordial leads, ST or JST patterns with ascending ST segments were more common. During the mean follow-up of 126.0±11.1months, a total of 710 subjects died (2.7%). Subjects in the J group were at higher risk (Hazard ratio 1.60, 95% confidence interval 1.27-2.01, p<0.001), while those in the JST and ST groups showed similar survival outcomes compared to controls without J waves or STE. CONCLUSIONS: J waves and STE showed different age and lead distributions and prognostic implications. The presence of the J wave itself was associated with a higher relative risk of mortality. However, due to the low event rate, its clinical significance appears to be limited.

Differences in the onset mode of ventricular tachyarrhythmia between patients with J wave in anterior leads and those with J wave in inferolateral leads.

BACKGROUND: The pathophysiological mechanism of J wave in anterior leads (A-leads) and inferolateral leads (L-leads) remains unclear. OBJECTIVE: We investigated the onset mode and circadian distribution of ventricular tachyarrhythmia (VTA) episodes between patients with early repolarization syndrome (ERS) and Brugada syndrome (BrS). METHODS: The study enrolled 35 patients with ERS and 52 patients with type 1 BrS with spontaneous ventricular fibrillation who were divided into 4 groups: ERS(A+L) (n = 15), patients with ERS who had a non-type 1 Brugada pattern electrocardiogram in any A-leads (second to fourth intercostal spaces) in control and/or after drug provocation tests; ERS(L) (n = 20), patients with ERS with J wave only in L-leads; BrS(A) (n = 24), patients with BrS without J wave in L-leads; and BrS(A+L) (n = 28), patients with BrS with J wave in L-leads. The onset mode of 206 VTAs obtained from electrocardiograms or implantable cardioverter-defibrillators and the circadian distribution of 352 VTAs were investigated in the 4 groups. RESULTS: Three groups with J wave in A-leads, ERS(A+L), BrS(A), and BrS(A+L), had higher incidences of nocturnal (63%, 43%, and 47%, respectively) and sudden onset VTAs (67%, 97%, and 86%, respectively) with longer coupling intervals of premature ventricular contractions (388.8, 397.3, and 385.6 ms, respectively) than the ERS(L) group with J wave only in L-leads (25%, P = .0019; 19%, P < .0001; and 330.6 ms, P = .0004, respectively), the last of which mainly displayed VTAs with a short-long-short sequence. CONCLUSION: The onset mode of VTAs was different between patients with J wave in A-leads and patients with J wave in only L-leads. The underlying mechanism of J wave may differ between A-leads and L-leads.

Síndromes de la onda J / J wave syndromes

Se realizó una revisión sobre los aspectos más novedosos y polémicos de los síndromes de la onda J, que incluyó el síndrome de repolarización precoz, la fibrilación ventricular idiopática y la muerte súbita nocturna inexplicable. Se enfatiza en las características electrocardiográficas de estos síndromes donde se destaca la presencia de un supradesnivel del ST tipo cóncavo con melladuras o empastamiento del mismo. Se profundiza en las bases genéticas, a veces común a todos ellos, en particular la mutación SCN5A asociada con el supradesnivel del ST y más recientemente la mutación S422L-KCNJ8 como causa de alteración de los canales I K-ATP, lo cual se asocia con mortalidad arrítmica cardíaca. Se concluye que aunque no todos los pacientes con este síndrome estén en riesgo de eventos arrítmicos o de muerte súbita cardíaca, existe un grupo de ellos no despreciable que sí lo están, por lo que el gran desafío de la comunidad médica es desarrollar mejores estrategias de estratificación de riesgo y desarrollar tratamientos más seguros y eficaces para estos

A review was conducted of the newest and most controversial aspects of J wave syndromes, including early repolarization syndrome, idiopathic ventricular fibrillation and sudden unexplained nocturnal death. Emphasis is made on the ECG features of these syndromes, among them the presence of an upwardly concave ST irregularity with notching or slurring. A detailed analysis is made of genetic bases, which are sometimes common to all syndromes, particularly the SCN5A mutation, associated with the ST upwardly irregularity, and more recently the S422L-KCNJ8 mutation causing the alteration in the lK-ATP channels, associated with arrhythmic cardiac mortality. It is concluded that not all patients with this syndrome are at risk of arrhythmic events or sudden cardiac death, but a significant number of them are. Therefore, a great challenge for the medical community is to develop better risk stratification strategies as well as safer and more effective treatments