Long-term prognosis of patients withJ-wave syndrome

Risk stratification for the occurrence of ventricular fibrillation in patients with early repolarization syndrome

BACKGROUND

Several signs of malignant early repolarizations have been proposed in patients with early repolarization syndrome (ERS). However, reports have challenged the efficacy of these signs in predicting future ventricular fibrillation (VF) in patients with ERS.

OBJECTIVE

This study aimed to assess the predictive value of various electrocardiogram (ECG) markers for future VF events in patients with ERS.

METHODS

We retrospectively evaluated the clinical characteristics of 44 patients with ERS to identify risk factors for VF during follow-up.

RESULTS

After the initial event, 16 patients experienced VF (VF group), whereas 28 did not (non-VF group). The VF group had a longer QRS interval, more fragmented QRS (fQRS), and a higher T/R voltage ratio than the non-VF group. Wide J waves were more prevalent in the VF group; however, other J-wave markers did not differ between the groups. Positive late potentials recorded on signal-averaged ECGs were more frequent in the VF group. Whereas none of the patients showed spontaneous Brugada syndrome on ECG, the VF group frequently exhibited pilsicainide-induced ST-segment elevation. These ECG markers were significantly associated with the occurrence of VF during follow-up. Patients with multiple ECG factors, including QRS abnormalities (wide QRS or fQRS), wide J waves, and a high T/R ratio, had a worse prognosis than patients without multiple factors, effectively stratifying patient risk.

CONCLUSION

The occurrence of VF in patients with ERS may be associated with conduction abnormalities such as QRS widening, fQRS, high T/R ratio, positive late potentials, and pilsicainide test results. Therefore, ECG factors could be useful in identifying high-risk patients.

Clinical characteristics of electrical storm in patients with early repolarization syndrome

BACKGROUND

Early repolarization syndrome (ERS) is an idiopathic ventricular fibrillation (VF) associated with inferolateral J waves. While electrical storm (ES) in ERS is not rare, their characteristics and risk factors are not fully understood.

OBJECTIVE

This study aimed to clarify the significance of ES in ERS.

METHODS

We evaluated 44 patients with ERS who experienced VF/sudden cardiac death or arrhythmic syncope. We assessed clinical characteristics to identify the risk factors for ES.

RESULTS

In total, 13 patients (30%) experienced ES (ES group). Of these, 11 patients (85%) experienced ES during the acute phase of initial VF episodes and 2 patients (2%) experienced ES during follow-up. VF associated with ES occurred during therapeutic hypothermia in 6 of 13 patients (46%). The J-wave voltage during therapeutic hypothermia was higher in the ES group than that in the patients without ES. Isoproterenol was used in 5 patients (38%), which decreased J-wave voltage and relieved ES. Among the clinical markers, shorter QT and QTp intervals (the interval from QRS onset to the peak of T wave), pilsicainide-induced ST elevation, and high scores on the Shanghai Score System were associated with ES. Although pilsicainide induced ST elevation in 6 of 34 patients (18%), spontaneous Brugada electrocardiographic patterns did not appear to be associated with VF. Therapeutic hypothermia was also a risk factor for acute phase ES.

CONCLUSION

Patients with ERS in the ES group frequently had short QT and QTp intervals, pilsicainide-induced ST elevations, and high Shanghai Score System scores. Therapeutic hypothermia was also associated with acute phase ES.

Significance of left posterior extension of early repolarization in patients with J-wave syndrome

BACKGROUND

J waves in the inferior or lateral leads are characteristic electrocardiographic (ECG) changes in patients with early repolarization syndrome (ERS). However, the presence of J waves in the left posterior region has not yet been evaluated.

OBJECTIVE

The purpose of this study was to clarify the significance of J waves in the posterior left ventricle using leads V7-V9 and a body surface mapping (BSM) system.

METHODS

Forty patients diagnosed with ERS were included. All patients exhibited J waves in either the contiguous inferior, lateral, or posterior leads. We evaluated the incidence of J waves in the inferolateral and posterior leads using a 15-lead ECG with synthesized V7-V9 and an 87-lead BSM. Additionally, we assessed the arrhythmogenicity of the posterior regions based on the morphology of the premature ventricular complexes (PVCs) associated with ventricular fibrillation (VF).

RESULTS

J waves were observed in the lateral, inferior, and posterior leads of 26 (65%), 31 (78%), and 39 (97%) patients, respectively. J waves were found only in the posterior leads of 5 patients. BSM was evaluated in 9 patients, all of whom exhibited a positive area on the posterior region. PVCs associated with VF were recorded in 5 patients. Among patients with inferolateral and posterior J waves, all except 1 patient who displayed left bundle branch block morphology showed PVCs originating from the posterior left ventricular region.

CONCLUSION

Posterior J waves are common in ERS patients. This abnormality can be detected using leads V7-V9 and the BSM system and may be associated with arrhythmogenesis.

Functional identification of hot-spot mutations in cardiac calcium channel genes associated with the J wave syndromes

J wave syndrome (JWS) is an inherited cardiac channelopathy associated with malignant ventricular arrhythmias and sudden cardiac death (SCD), which comprises early repolarization syndrome and Brugada syndrome. Here, we explore the association between variants in the L-type calcium channel gene subunits, α1C (CACNA1C) and β2b (CACNB2b), and the JWS phenotype. Using next-generation genetic sequencing of 402 JWS probands and their family members, we identified a CACNA1C-G37R (p.Gly37Arg) mutation in five individuals in four families, two of which had a family history of SCD as well as a CACNB2b-S143F (p.Ser143Phe) mutation in seven individuals in three families, two of which had a family history of SCD. The variants were located in exon 2 in CACNA1C and exon 5 in CACNB2b; both were in highly conserved amino acid residues. Whole-cell patch-clamp results showed that compared with the wild-type group, calcium current density of CACNB2b-S143F and CACNA1C-G37R were significantly lower displaying a dominant-negative effect. Our findings provide further support for the hypothesis that variants in CACNA1C and CACNB2b are associated with JWS. The results suggest that mutations in these two genes lead to loss-of-function of the cardiac calcium channel current warranting their inclusion in genetic screening protocols. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.

Predictive effect of J waves on cardiac compression and clinical prognosis of esophageal tumors: a retrospective study

Background

The J wave syndromes (JWS) could be observed in patients with mediastinal tumors, though few studies have verified the statistical correlation between J waves and cardiac compression by tumors. This study aimed to investigate the relationship between J waves and cardiac compression by esophageal tumor and to compare the prediction of J waves on clinical prognosis with that of cardiac compression by esophageal tumor.

Methods

We enrolled 273 patients (228 males, 45 females; mean 63.8±7.5 years) with esophageal tumors admitted to Shanghai Chest Hospital between August 2016 and November 2020. The J wave was defined as a J-point elevation of ≥0.1 mV in a 12-lead electrocardiogram (ECG) and classified into multiple types. Chest computed tomography (CT) was reviewed to clarify the anatomical relationship between the heart and the esophageal tumor. The prognosis of severe cardiac events and survival status were followed up through medical history, examination records and telephone records.

Results

J waves were present in 141 patients among all 273 cases. The sensitivity and specificity of cardiac compression by the tumor for J waves were 78.1% and 67.3%, respectively. The odds ratio (OR) of cardiac compression by the tumor to J waves was 7.33 [95% confidence interval (CI): 4.21-12.74; P<0.001]. The Kappa coefficient between J waves and cardiac compression was 0.44±0.05. The significance association between J waves and cardiac compression was independent from other clinical variables (P<0.001). Decreased J wave amplitude was correlated with the disappearance of cardiac compression during follow-up (P=0.03). Patients with J waves had a higher risk of severe cardiac events than those without J waves (OR =2.84, 95% CI: 1.22-6.63; P=0.01). During the follow-up period, we found that the presence of J waves [hazard ratio (HR) =2.28; 95% CI: 1.35-3.84; P=0.002] and cardiac compression by the tumor (HR =2.51; 95% CI: 1.51-4.17; P<0.001) were both negatively correlated with the survival time of patients.

Conclusions

The presence of J waves could be used as an effective mean to predict the mechanical impact of esophageal tumor on the heart, and played an important role in predicting the survival of patients.

Clinical and Functional Genetic Characterization of the Role of Cardiac Calcium Channel Variants in the Early Repolarization Syndrome

Background: Early repolarization syndrome (ERS) is an inherited sudden cardiac death (SCD) syndrome. The present study investigates the role of genetic variants in cardiac calcium-channel genes in the pathogenesis of ERS and probes the underlying mechanisms. Methods: Polymerase chain reaction-based next-generation sequencing was carried out using a targeted gene approach. Unrelated ERS probands carrying calcium-channel variants were evaluated clinically and compared with matched healthy controls. Wild-type (WT) and mutant CACNA1C genes were coexpressed with CACNB2b and CACNA2D1 in HEK293 cells and studied using whole-cell patch-clamp techniques and confocal fluorescence microscope. Results: Among 104 ERS probands, 16 carried pathogenic variants in calcium-channel genes (32.2 ± 14.6 years old, 87.5% male). The symptoms at diagnosis included syncope (56.3%), ventricular tachycardia/fibrillation (62.5%), and SCD (56.3%). Three cases (18.8%) had a family history of SCD or syncope. Eight patients (50.0%) had a single calcium gene rare variant. The other half carried rare variants in other ERS-susceptible genes. Compared with controls, the heart rate was slower (72.7 ± 8.9 vs. 65.6 ± 16.1 beats/min, * p < 0.05), QTc interval was shorter (408.2 ± 21.4 vs. 386.8 ± 16.9 ms, ** p < 0.01), and Tp-e/QT was longer (0.22 ± 0.05 vs. 0.28 ± 0.04, *** p < 0.001) in single calcium mutation carriers. Electrophysiological analysis of one mutation, CACNA1C-P817S (c.2449C>T), revealed that the density of whole-cell calcium current (I Ca) was reduced by ~84.61% compared to WT (-3.17 ± 2.53 vs. -20.59 ± 3.60 pA/pF, n = 11 and 15, respectively, ** p < 0.01). Heterozygous expression of mutant channels was associated with a 51.35% reduction of I Ca. Steady-state inactivation was shifted to more negative potentials and significantly accelerated as well. Confocal microscopy revealed trafficking impairment of CACNA1C-P817S (peripheral/central intensity: 0.94 ± 0.10 in WT vs. 0.33 ± 0.12 in P817S, n = 10 and 9, respectively, ** p < 0.01). Conclusions: ERS associated with loss-of-function (LOF) genetic defects in genes encoding the cardiac calcium channel represents a unique clinical entity characterized by decreased heart rate and QTc, as well as increased transmural dispersion of repolarization. In the case of CACNA1C-P817S, impaired trafficking of the channel to the membrane contributes to the LOF.

Long-term prognosis in patients with non-type 1 Brugada electrocardiogram: Results from a large Japanese cohort of idiopathic ventricular fibrillation

Background

Brugada syndrome (BrS) is diagnosed in patients with ST‐segment elevation with spontaneous, drug‐induced, or fever‐induced type 1 morphology. Prognosis in type 2 or 3 Brugada electrocardiogram (Br‐ECG) patients remains unknown. The purpose of this study is to evaluate long‐term prognosis in non‐type 1 Br‐ECG patients in a large Japanese cohort of idiopathic ventricular fibrillation (The Japan Idiopathic Ventricular Fibrillation Study [J‐IVFS]).

Methods

From 567 patients with Br‐ECG in J‐IVFS, a total of 28 consecutive non‐type 1 patients who underwent programmed electrical stimulation (PES) (median age: 58 years, all male, previous sustained ventricular tachyarrhythmias [VTs] 1, syncope 11, asymptomatic 16) were enrolled. Cardiac events (CEs: sudden cardiac death or sustained VT/ventricular fibrillation) during the follow‐up period were examined.

Results

During a median follow‐up of 136 months, four patients (14%) had CEs. None of patients with PES‐ have experienced CEs. There was no statistically significant clinical risk factor for the development of CEs. Using the Kaplan–Meier method, the event‐free rate significantly decreased in a group with all 3 risk factors (symptom, wide QRS complex in lead V₂, and positive PES) (p = .01).

Conclusions

Our study revealed long‐term prognosis in patients with non‐type 1 Br‐ECG. The combination analysis of these risk factors may be useful for the risk stratification of CEs in non‐type 1 Br‐ECG patients. The present study suggests that the patients with all these parameters showed high risk for CEs and need to be carefully followed.