Clinical Perspectives
Inferolateral early repolarization has a high prevalence but is also associated with ventricular fibrillation. Risk stratification remains
The electrocardiographic (ECG) pattern of inferolateral early repolarization (ER) is common, with a particularly high prevalence reported among athletes and adolescents.1 An association between inferolateral ER with sudden cardiac arrest has been established by a number of different groups.2 Population-based studies have also reported an increased mortality among patients with inferolateral ER compared to controls.1, 3, 4 Despite the reports linking ER with sudden death, only a small minority of patients with this pattern on the ECG will have sudden cardiac arrest, while the majority remain asymptomatic. The identification of this minority of patients represents a significant challenge. Currently, the identification of the malignant variant of the ER pattern is reliant on parameters such as the J-wave distribution, J-wave amplitude, and ST-segment morphology.5, 6 However, the sensitivity and specificity of these parameters remain limited. Additionally, assessment of ST-segment morphology is difficult. The T wave may provide similar information as the ST-segment morphology measured at 100 ms after the J point, and others have advocated analysis of repolarization markers independently of J-wave amplitude for risk stratification in inferolateral ER.7 Furthermore, the concomitant presence of inferolateral ER and long QT syndrome seems to increase arrhythmic risk.8, 9 In this study, we sought to determine the potential role of T-wave parameters to differentiate malignant and benign forms of inferolateral ER.
Cases with ER and aborted sudden death were included from the International Registry of Idiopathic Ventricular Fibrillation, which has enrolled ventricular fibrillation (VF) patients from various tertiary care arrhythmia centers since January 2007.2 The diagnosis of idiopathic VF for patients included in the registry is based on the absence of identifiable structural heart disease (normal echocardiography) and detectable coronary artery disease (normal exercise testing or normal coronary
Patients in the VF group were significantly younger than controls (37.1 ± 13.1 years vs 50.4 ± 10.9 years, P <.001). In both groups, the majority were men (75% VF group vs 77% controls; P = .71). Heart rate was significantly higher and QTc interval longer in the VF group compared to controls (Table 1). Of note, although the QTc interval was normally distributed in controls (P = .20 according to the Kolmogorov–Smirnov test), this was not the case in the VF group (P = .007; Figure 2).
Patients with malignant inferolateral ER have longer QTc intervals, a higher prevalence of low-amplitude T waves, and lower T/R ratios in leads II and V5 than controls with benign inferolateral ER. These T-wave parameters have superior performance in differentiating malignant from benign inferolateral ER than conventional ECG risk markers such as J-wave distribution, maximal J-wave amplitude, and ST-segment morphology.
Multiple studies have reported that the presence of inferior or a combination
Patients with malignant ER have a higher prevalence of low-amplitude T waves, lower T/R ratio (lead II or V5), and longer QTc interval, which lacks a typical gaussian distribution. Combining these parameters with maximal J-wave amplitude and presence of J waves in the inferior leads may allow for improved identification of malignant ER. Inferolateral early repolarization has a high prevalence but is also associated with ventricular fibrillation. Risk stratification remainsClinical Perspectives
The following physicians kindly contributed to data collection: Gabriel Laurent (Dijon), Pascal Defaye (Grenoble), Dominique Lacroix (Lille), Maurice Pornin (Paris), Frederic Anselme (Rouen), Patrice Scanu (Caen), Paul Bru (La Rochelle), Nicolas Delarche (Pau), Jean Vidal (Niort), Pascal Chavernac (Castres), Julien Laborderie (Bayonne), Robert Frank (Paris), Dominique Babuty (Tours), Jean-Luc Pasquié (Montpellier), Christian de Chillou (Nancy), Elisabeth Somody (Montauban), Philippe Jarnier
The ST segment was regarded horizontal or descending if the amplitude of the ST segment 100 ms after the J point was less than or equal to the amplitude at the J-point end, and ascending if the amplitude was greater than the amplitude at the J-point end.18 An ECG was classified to have a low-amplitude T wave if any T wave in leads I, II, or V4–V6 was inverted, biphasic, or had an amplitude ≤0.1 mV and ≤10% of the R-wave amplitude in the same lead.11 We excluded subjects (n = 248) with missing or unreadable ECGs and subjects (n = 331) with second/third-degree atrioventricular block, ventricular pre-excitation, complete or incomplete bundle branch block, left anterior or posterior fascicular block, QRS duration >110 ms, pacemaker rhythm, or rare ECG findings not representing the general population.
ST slope was also determined, and ECGs were classified as ER with an ascending, horizontal, or descending ST segment according to the consensus definitions.13 J-wave amplitude, R amplitude, and T-wave amplitude were automatically measured in a per lead basis, and T/R ratio in leads II and V5 were calculated as previously suggested.17 In addition to ER pattern, standard ECG measures, including heart rate, PR interval, and QRS duration, were calculated.
In an important study which assessed benign versus malignant inferolateral ERP, Roten et al.14 studied 92 patients with history of aborted SCD due to VF and baseline ERP ECG versus another 247 subjects with asymptomatic ERP. They concluded that QRS duration and PR interval were comparable in both groups, while QTc duration was significantly longer in the ERP and VF group than in the asymptomatic ERP group.14 Our study showed that Holter ECG didn’t reveal significant difference between both groups.
This work was supported by special grants from the Direction Générale de l’Offre de Soins (PHRC No. 20-12) and through the Investment of the Future Grant ANR-10-IAHU-04 from the government of France through the Agence National de la Recherche.