br Introduction The early repolarization ER pattern has been
Introduction The early repolarization (ER) pattern has been considered a benign electrocardiographic phenomenon affecting 2–5% of the general population and is most commonly seen in healthy young men and athletes [1–3]. Recent studies have challenged the view of this electrocardiogram (ECG) variant being benign, and instead implicate it as an important marker of vulnerability for ventricular fibrillation (VF) and sudden cardiac death (SCD). Haïssaguerre et al. were the first to document a high incidence of ER in the inferolateral leads in patients with idiopathic VF . Similarly, Rosso et al. showed that J-point elevation is more common among patients with idiopathic VF than among healthy individuals . Recent studies have provided evidence supporting an association between the ER pattern and life-threatening arrhythmias, such as ER syndrome (ERS) or Brugada syndrome, depending on the region of the LY2874455 responsible for the arrhythmogenic substrate. Although Brugada syndrome and ERS differ with respect to the magnitude and location of the leads in the abnormal ECG J waves, the 2 disorders are thought to represent a continuous spectrum of phenotypes, termed J wave syndromes by Antzelevitch and Yan . There is growing evidence that amplifications of the spatial and transmural dispersion of repolarization underlies the development of life-threatening ventricular arrhythmias associated with inherited ion channelopathies, such as the long-QT, short-QT, and Brugada syndromes, as well as catecholaminergic polymorphic ventricular tachycardia .
Material and methods
Results Clinical, electrocardiographic, and electrophysiological characteristics of the study patients are shown in Table 1. Two ERS patients had a family history of SCD (P=0.22). Six ERS patients had a type 1 ER ECG and two had a type 3 ER ECG. One ER pattern patient had a type 1 ER ECG, 1 had a type 2 ER ECG, and 3 had a type 3 ER ECG. Late ventricular potentials were positive in 7 of the 8 (87.5%) ERS patients and in 3 of the 5 (60.0%) ER pattern patients (P=0.25). Electrophysiological studies were performed in all 8 ERS patients, and VF was induced in 6 of the 8 (75.0%) patients. Electrophysiological studies were not performed in the ER pattern patients. An implantable cardioverter-defibrillator (ICD) was implanted in all 8 ERS patients, and appropriate ICD discharge occurred in 2 of these patients during the follow-up period of 47.4±28.9 months. No arrhythmic event was noted in ER pattern patients during the follow-up period of 30.0±20.2 months. Average RTc and average RTend-c were significantly shorter in ERS patients than in ER pattern patients (201.7±18.8ms vs. 234.0±25.5ms, P=0.0404; 287.1±10.3ms vs. 325.8ms±42.8ms, P=0.0481). The average T(p-e)-c did not differ between ERS and ER pattern patients (41.0±9.9ms vs. 42.4±8.2ms, P=0.883). The average spatial and transmural repolarization times (average RTc, average RTend-c, and average T(p-e)-c) obtained from the 187-ch SAVP-ECG per group are shown in Table 2. There was no significant difference in the RTc dispersion (71.9±14.3ms vs. 84.2±11.9ms, P=0.223), or T(p-e)-c dispersion RTend-c dispersion (52.7±14.3ms vs. 52.6±11.3ms, P=0.807) between the ERS and ER pattern patients, (Figs. 3a and b, 4a and b, Table 2). The fQRS, RMS40, and LAS40 values (Table 2), as well as the prevalence of late potentials did not differ between ERS and ER pattern patients (7/8 vs. 3/5, P=0.254). No statistically significant differences were observed in the parameters on the spatial and transmural dispersion of repolarization between ERS and ER pattern patients.
Conflicts of interest
Introduction Although the techniques of catheter ablation for treating persistent atrial fibrillation (AF) have improved, the success rate of persistent sinus rhythm after multiple procedures is only 50–85%.  Several factors, including AF duration and left atrial dimension, [2–4] have shown to predict successful persistent sinus rhythm after ablation. These factors are associated with atrial remodeling characterized by shortening of the refractory period  and by the development of fibrosis,  which are important for initiating and maintaining reentry. The local AF cycle length correlates with atrial refractoriness [7,8]. Recently, the f-wave cycle length, estimated by manually measuring a surface electrocardiogram (ECG), was found to correlate with intracardiac signal cycle lengths and to predict whether sinus rhythm is restored during radiofrequency (RF) ablation for persistent AF [2,9]. However, manual measurement is limited to sites with a clearly identifiable signal peak, such as that in lead V1. In contrast, a frequency analysis can estimate the activation frequency of any signal. Fast Fourier transform (FFT) has been applied to intracardiac and surface ECGs [10–13] to determine the site of RF applications  and to monitor the effects of antiarrhythmic drugs . It is unclear whether the frequency characteristics of a surface ECG can predict successful outcome of catheter ablation for persistent AF. Further, the characteristics underlying intracardiac structures most affected by the frequency characteristics of each surface signal have not been determined.