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Energy drinks potentially can trigger life-threatening cardiac arrhythmias. It has been postulated that the highly stimulating and unregulated ingredients alter heart rate, blood pressure, cardiac contractility, and cardiac repolarization in a potentially proarrhythmic manner. The purpose of this study was to describe our experience regarding sudden cardiac arrest (SCA) occurring in proximity to energy drink consumption in patients with underlying genetic heart diseases. The electronic medical records of all SCA survivors with proven arrhythmias referred to the Mayo Clinic Windland Smith Rice Genetic Heart Rhythm Clinic for evaluation were reviewed to identify those who consumed an energy drink before their event. Patient demographics, clinical characteristics, documented energy drink consumption, and temporal relationship of energy drink consumption to SCA were obtained. Among 144 SCA survivors, 7 (5%; 6 female; mean age at SCA 29 ± 8 years) experienced an unexplained SCA associated temporally with energy drink consumption. Of these individuals, 2 had long QT syndrome and 2 had catecholaminergic polymorphic ventricular tachycardia; the remaining 3 were diagnosed with idiopathic ventricular fibrillation. Three patients (43%) consumed energy drinks regularly. Six patients (86%) required a rescue shock, and 1 (14%) was resuscitated manually. All SCA survivors have quit consuming energy drinks and have been event-free since. Overall, 5% of SCA survivors experienced SCA in proximity to consuming an energy drink. Although larger cohort studies are needed to elucidate the incidence/prevalence and quantify its precise risk, it seems prudent to sound an early warning on this potential risk. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sixty-six patients with non-ischaemic sudden cardiac arrest without LV structural disease. • A genetic variant of interest was found in 1/3 of tested patients. • Most patients had no phenotypic clues, but genetic testing was still profitable. • Many had channelopathies and arrhythmogenic RV cardiomyopathy-associated genes. • 1/3 of variants were (likely) pathogenic, so useful for family screening. With the development of advanced sequencing techniques, genetic testing has emerged as a valuable tool for the work-up of non-ischaemic sudden cardiac arrest (SCA). To evaluate the effectiveness of genetic testing in patients with unexplained SCA, according to clinical phenotype. All patients who underwent molecular genetic testing for non-ischaemic SCA with no left ventricular cardiomyopathy between 2012 and 2021 in two French university hospitals were included. Of 66 patients (mean age 36.7 ± 11.9 years, 54.5% men), 21 (31.8%; 95% confidence interval 22.4–45.3%) carried a genetic variant: eight (12.1%) had a pathogenic or likely pathogenic (P/LP) variant and 13 (19.7%) had a variant of uncertain significance (VUS). Among 37 patients (56.1%) with no phenotypic clues, genetic testing identified a P/LP variant in five (13.5%), mainly in RYR2 (n = 3) and SCN5A (n = 2), and a VUS in nine (24.3%). None of the nine patients with phenotypic evidence of channelopathies had P/LP variants, but two had VUS in RYR2 and NKX2.5. Among the 20 patients with suspected arrhythmogenic cardiomyopathy, three P/LP variants (15.0%) and two VUS (10.0%) were found in DSC2 , PKP2 , SCN5A and DSG2 , TRPM4 , respectively. Genetic testing was performed sooner after cardiac arrest (P < 0.001) and results were obtained more rapidly (P = 0.02) after versus before 2016. This study highlights the utility of molecular genetic testing with a genetic variant of interest identified in one-third of patients with unexplained SCA. Genetic testing was beneficial even in patients without phenotypic clues, with one-fourth of patients carrying a P/LP variant that could have direct implications. [ABSTRACT FROM AUTHOR]

Short-coupled ventricular fibrillation (SCVF) is a distinct phenotype among individuals with unexplained cardiac arrest accounting for 7% to 14% of cases of idiopathic ventricular fibrillation (IVF). VF is typically initiated by a trigger premature ventricular contraction with a short-coupling interval of less than 350 milliseconds. In the absence of specific electrocardiographic features or provocative tests, the diagnosis remains challenging and requires documentation of VF onset. Most cases are diagnosed during follow-up at the time of VF recurrence. SCVF is characterized by a high risk of VF recurrence. Insertion of an implantable cardioverter-defibrillator and quinidine are the keystones of SCVF management. [ABSTRACT FROM AUTHOR]

Calcium release deficiency syndrome (CRDS) is a newly described form of inherited arrhythmia caused by damaging loss-of-function variants in the cardiac ryanodine receptor (RyR2). Unlike the prototypical RyR2 gain-of-function channelopathy, known as catecholaminergic polymorphic ventricular tachycardia, patients with CRDS are predisposed to sudden death usually in the absence of any electrical abnormalities at rest or during stress electrocardiography. This makes diagnosis incredibly challenging, however, an invasive electrophysiologic test appears to be effective in unmasking the phenotype, called the long-burst, long-pause, short-coupled ventricular extra-stimulus protocol. Optimal therapies for patients with CRDS remain unestablished, although flecainide appears to be a promising candidate drug. [ABSTRACT FROM AUTHOR]

Unexplained cardiac arrest (UCA) is a working diagnosis that should be replaced by a final diagnosis once evaluation is completed. Complete evaluation of UCA should include high-yield tests like cardiac magnetic resonance imaging, exercise treadmill test, and sodium-channel blocker challenge to identify latent causes of UCA. If no clear etiology is revealed after complete evaluation, idiopathic ventricular fibrillation may be diagnosed, and the strength of its diagnosis can be divided into definitive, probable, and possible based on the number of high-yield tests performed. Care should be provided by a multidisciplinary team with expertise in this area. [ABSTRACT FROM AUTHOR]

Ventricular fibrillation (VF) can be initiated by ventricular premature depolarizations (VPDs) in the absence of obvious structural abnormalities. The purpose of this study was to determine the prevalence of 12-lead electrocardiographic (ECG) sinus rhythm reduced QRS amplitude, QRS fractionation (QRSf), and early repolarization (ER) pattern, and the outcome of catheter ablation and VPD anatomic distribution in patients with VPDs initiating VF. We compared a cohort with no apparent structural heart disease and VPDs initiating VF (group 1; n = 42) to a reference cohort (group 2; n = 61) of patients with no structural heart disease and symptomatic unifocal VPDs. A reduced QRS amplitude (<0.55 mV) in aVF (59% vs 10%; P <.001), QRSf in ≥2 contiguous leads (50% vs 16%; P <.001), and ER pattern (21.4% vs 1.6%; P =.01) were more common in group 1 than in group 2. At least 1 abnormal ECG finding was present in 34 group 1 patients (81%) vs 17 group 2 patients (28%) (P <.001). VPD origin included right ventricular and left ventricular distal Purkinje system and moderator band/papillary muscles in 83% of group 1 patients vs 18% of group 2 patients (P <.001). VF was eliminated with a single ablation procedure in 77% of group 1 patients with at least 2 years of follow-up. A reduced QRS amplitude (<0.55 mV) in aVF, QRSf in ≥2 contiguous leads, and/or an ER pattern are frequently observed in patients with VPDs initiating VF. VPDs initiating VF typically originate from the distal Purkinje system and papillary muscles and can be successfully eliminated with catheter ablation. [Display omitted] [ABSTRACT FROM AUTHOR]

Deterioration of atrial fibrillation into ventricular fibrillation has frequently been described in patients with pre-excitation of the ventricles. We report two cases of atrial fibrillation without pre-excitation leading to rapid ventricular tachycardias and recurrent implantable cardioverter defibrillator therapy in young idiopathic ventricular fibrillation patients. [ABSTRACT FROM AUTHOR]

Background: Sodium channel blocker (SCB) infusion is used to unmask the electrocardiographic pattern of Brugada syndrome. The test may also induce premature ventricular complexes (PVCs) in individuals without Brugada pattern, the clinical relevance of which is little known.Objective: The purpose of this study was to describe the prevalence of short-coupled (Sc) PVCs induced by ajmaline or flecainide in patients with suspected or documented severe ventricular arrhythmias.Methods: We reviewed the SCB tests performed in 335 patients with suspected ventricular arrhythmias and structurally normal hearts in 9 centers. ScPVCs were defined as frequent and repetitive PVCs with an R-on-T pattern on SCB tests. Repeated SCB tests were performed in 7 patients and electrophysiological mapping of ScPVCs in 9.Results: Sixteen patients (8 men; mean age 36 ± 11 years) showed ScPVCs and were included. ScPVCs appeared 229 ± 118 seconds after the initiation of infusion and displayed coupling intervals of 288 ± 28 ms. ScPVC patterns were monomorphic in 12 patients, originating from the Purkinje system in mapped patients. Repetitive PVCs were induced in 15 patients (94%) including polymorphic ventricular tachycardias in 9 (56%). SCB infusion was repeated 45 (interquartile range 0.6-46) months later and induced identical ScPVC in all. SCB test was the only mean to reveal the malignant arrhythmia in 6 patients. Catheter ablation was performed in 9 patients, resulting in arrhythmia elimination in 8 with a follow-up of 6 (interquartile range 2-9) years.Conclusion: SCB can induce ScPVC, mostly from Purkinje tissue, in a small subset of patients with idiopathic ventricular arrhythmias. Its high reproducibility suggests a distinct individual mechanism. [ABSTRACT FROM AUTHOR]

In some cases with idiopathic ventricular fibrillation, short-coupled premature ventricular contractions (PVCs) initiate fatal arrhythmia, which has recently been proposed as short-coupled ventricular fibrillation (SCVF). In the present case of SCVF, catheter ablation for trigger PVCs originating from the His-Purkinje system in both ventricles caused transient complete atrioventricular block, and a combination of quinidine and verapamil suppressed ventricular tachyarrhythmia. < Learning objective: In some cases with short-coupled ventricular fibrillation, a combination of quinidine and verapamil can suppress fatal ventricular tachyarrhythmia.> [ABSTRACT FROM AUTHOR]

Background: Purkinje ectopics (PurkEs) are major triggers of idiopathic ventricular fibrillation (VF). Identifying clinical factors associated with specific PurkE characteristics could yield insights into the mechanisms of Purkinje-mediated arrhythmogenicity.Objective: The purpose of this study was to examine the associations of clinical, environmental, and genetic factors with PurkE origin in patients with PurkE-initiated idiopathic VF.Methods: Consecutive patients with PurkE-initiated idiopathic VF from 4 arrhythmia referral centers were included. We evaluated demographic characteristics, medical history, clinical circumstances associated with index VF events, and electrophysiological characteristics of PurkEs. An electrophysiology study was performed in most patients to confirm the Purkinje origin.Results: Eighty-three patients were included (mean age 38 ± 14 years; 44 [53%] women), of whom 32 had a history of syncope. Forty-four patients had VF at rest. PurkEs originated from the right ventricle (RV) in 41 patients (49%), from the left ventricle (LV) in 36 (44%), and from both ventricles in 6 (7%). Seasonal and circadian distributions of VF episodes were similar according to PurkE origin. The clinical characteristics of patients with RV vs LV PurkE origins were similar, except for sex. RV PurkEs were more frequent in men than in women (76% vs 24%), whereas LV and biventricular PurkEs were more frequent in women (81% vs 19% and 83% vs 17%, respectively) (P < .0001).Conclusion: PurkEs triggering idiopathic VF originate dominantly from the RV in men and from the LV or both ventricles in women, adding to other sex-related arrhythmias such as Brugada syndrome or long QT syndrome. Sex-based factors influencing Purkinje arrhythmogenicity warrant investigation. [ABSTRACT FROM AUTHOR]

Background: Idiopathic ventricular fibrillation (IVF) is diagnosed in patients with sudden onset of ventricular fibrillation of unidentified origin. New diagnostic tools that can detect subtle abnormalities are needed to diagnose and treat patients with an underlying substrate.Objective: The purpose of this study was to explore echocardiographic deformation characteristics in IVF patients.Methods: Echocardiograms were analyzed with deformation imaging by 2-dimensional speckle tracking. Global and regional measurements of the left ventricle (LV) and right ventricle (RV) were performed. Regional LV deformation patterns were evaluated for the presence of postsystolic shortening. Regional RV deformation patterns were classified as type I (normal) or type II/III (abnormal).Results: In total, 47 IVF patients (mean age 45 years; left ventricular ejection fraction [LVEF] 56%) and 47 healthy controls (mean age 41 years; LVEF 60%) were included. IVF patients showed more global deformation abnormalities as indicated by lower LV global longitudinal strain (18.5% ± 2.6% vs 21.6% ± 1.8%; P <.001) and higher LV mechanical dispersion (41 ± 12 ms vs 26 ± 6 ms; P <.001). In addition, IVF patients showed more regional LV postsystolic shortening compared to healthy controls (50% vs 11%; P <.001). Abnormal RV deformation patterns were observed in 16% of IVF patients and in none of the control subjects (P <.001).Conclusion: We were able to show both regional and global echocardiographic deformation abnormalities in IVF patients. This study provides evidence that localized myocardial disease is present in a subset of IVF patients. [ABSTRACT FROM AUTHOR]

QT interval prolongation is a marker of increased risk for life-threatening arrhythmias, and needs to be promptly recognized. Many effective drugs, however, prolong QTc (QT interval corrected for heart rate) in genetically predisposed subjects. The possibility of remote monitoring and QTc measurement for up to 2 weeks, continuously providing physicians with real time data, allows life-saving interventions or changes in drug therapy. This applies especially to patients with the long QT syndrome and to those taking drugs blocking the IKr current and prolonging the QT interval. Patch monitors recording ECG traces continuously are available and contribute to effective arrhythmic prevention. [ABSTRACT FROM AUTHOR]

Background: Unexplained cardiac arrest (UCA) is rare in children. Despite investigations, the etiology in up to one-half of patients remains unknown.Objective: The purpose of this study was to assess the management and outcomes of pediatric UCA survivors through the Canadian Pediatric Heart Rhythm Network.Methods: A retrospective case series of children (age 1-19 years) who presented with UCA between January 1, 2004, and November 1, 2017, was conducted. Patients with known heart disease pre-UCA were excluded. UCA details, investigations, genetic test results, treatment, implantable cardioverter-defibrillator (ICD) data, subsequent diagnoses, and family screening data were collected.Results: Forty-six patients (61% male) were survivors of sudden unexpected death and met inclusion criteria at 8 participating sites. Median age at UCA was 13.8 years (interquartile range [IQR] 9-16 years). Baseline retrievable investigations included electrocardiogram (96%), echocardiogram (85%), exercise stress test (73%), and cardiac magnetic resonance imaging (57%). The presumed etiology for the UCA was identified in 24 (52%), mainly long QT syndrome or catecholaminergic polymorphic ventricular tachycardia. Genetic testing was performed in 33 of 46 (72%), with pathogenic/likely pathogenic variants identified in 13 of 33 (39%) and variants of uncertain significance in 8 of 33 (24%). ICDs were implanted in 35 of 46 (76%). Over median follow-up of 36 months (IQR 17-57 months), 8 of 35 had arrhythmia events captured on device interrogation. Families of 26 of 46 patients(57%) underwent screening, leading to a cardiac diagnosis in 6 of 26 families.Conclusion: A cause for UCA was not identified in nearly 50% of patients despite extensive investigations, including cascade screening. A large proportion (75%) of ICD shocks occurred in patients without a diagnosis. [ABSTRACT FROM AUTHOR]

Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is characterized by adrenergically induced ventricular tachycardia, syncope, and sudden cardiac arrest (SCA). In the absence of structural disease, exercise-provoked premature ventricular contractions in bigeminy or couplets and nonsustained ventricular tachycardia are highly predictive of CPVT.Objective: The purpose of this study was to determine the number of missed or delayed CPVT diagnoses attributable to exercise testing oversights in a cohort of young SCA survivors.Methods: A retrospective review of 101 young SCA survivors (younger than 35 years at the time of SCA) with otherwise structurally normal hearts was used to identify those with a missed or delayed CPVT diagnosis because of overlooked evidence or lack of an exercise stress test (EST) or catecholamine provocation test (CPT) post-SCA.Results: Of the 101 young SCA survivors, 41 (41%) had exertion/emotion-associated SCA (EEA-SCA). After primary post-SCA investigations, a probable root cause was established in 20 of 41 EEA-SCA survivors (49%; CPVT in 8) and in 30 of 60 non-EEA-SCA survivors (50%; CPVT in 2) (P = 1). Only 14 of 21 unexplained EEA-SCA survivors (67%) had an EST/CPT performed before their referral evaluation. Secondary review of these prior ESTs/CPTs provided evidence of CPVT in 3 of 14 (21%). Of the 7 remaining unexplained cases of EAA-SCA who had never undergone an EST/CPT, 2 (29%) underwent their first EST at our institution that led to CPVT diagnosis.Conclusion: Of the 15 SCA survivors diagnosed ultimately with CPVT, one-third had a delay in diagnosis because an EST was either never performed or performed but misinterpreted. EST/CPT must become the standard of care after SCA in the young, especially if the SCA occurred during either exertion or emotion. [ABSTRACT FROM AUTHOR]

Background: Idiopathic ventricular fibrillation (IVF) is a rare primary cardiac arrhythmia syndrome that is diagnosed in a resuscitated cardiac arrest victim, with documented ventricular fibrillation, in whom no underlying cause is identified after comprehensive clinical evaluation. In some patients, causative genetic mutations are detected that facilitate patient treatment and follow-up. The feasibility of next-generation sequencing (NGS) has increased with its greater availability and decreasing costs.Objective: The aim of this study was to assess the diagnostic yield of NGS in patients with IVF.Methods: A total of 33 patients initially diagnosed with IVF were included (mean age 53 ± 15 years; 14(42%) men). In all included patients, NGS of 33 genes and the DPP6 haplotype revealed no pathogenic mutations. Genetic screening comprised NGS of a panel of 179 additional genes. Variants with a minor allele frequency of <0.05% were assessed for pathogenicity by using existing mutation databases and in silico predictive algorithms.Results: In 1 of 33 patients, a likely pathogenic mutation was detected. The added yield of genetic testing with NGS of 179 additional genes is 3% in patients with IVF. In 15% of patients, 1 or multiple variants of uncertain clinical significance were detected.Conclusion: The added yield of genetic screening of extended NGS panels in patients initially diagnosed with IVF is minimal. Routine analysis of large diagnostic NGS panels is therefore not recommended. [ABSTRACT FROM AUTHOR]

Background: Ventricular fibrillation may be caused by premature ventricular contractions (PVCs) whose coupling intervals are <300 ms, a characteristic of the short-coupled variant of torsades de pointes (scTdP).Objective: The purpose of this study was to analyze the underlying cardiac ryanodine receptor (RyR2) variants in patients with scTdP.Methods: Seven patients with scTdP (mean age 34 ± 12 years; 4 men and 3 women) were enrolled in this study. The RyR2 gene was screened by targeted gene sequencing methods; variant minor allele frequency was confirmed in 3 databases; and the pathogenicity was investigated in silico analysis using multiple tools. The activity of wild-type and mutant RyR2 channels was evaluated by monitoring Ca2+ signals of HEK293 cells with a [3H]ryanodine binding assay.Results: The mean coupling interval of PVCs was 282 ± 13 ms. The 12-lead electrocardiogram had no specific findings except PVCs with an extremely short-coupling interval. Genetic analysis revealed 3 novel RyR2 variants and 1 polymorphism, all located in the cytoplasmic region. p.Ser4938Phe was not detected in 3 databases, and in silico analysis indicated its pathogenicity. In functional analysis, p.Ser4938Phe demonstrated loss of function and impaired RyR2 channel Ca2+ release, while 2 other variants, p.Val1024Ile and p.Ala2673Val, had mild gain-of-function effects but were similar to the polymorphism p.Asn1551Ser.Conclusion: We identified an RyR2 variant associated with reduced Ca2+ release and short-coupled torsades de pointes ventricular arrhythmia. The mechanisms of arrhythmogenesis remain unclear. [ABSTRACT FROM AUTHOR]

A 21-year-old man developed ventricular fibrillation (VF) while drinking alcohol and was admitted to our hospital. An electrocardiogram (ECG) on admission revealed remarkably prominent slurs on the terminal part of QRS complexes in the left precordial leads and a coved type ST elevation at higher intercostal spaces. After hypothermia therapy, he underwent implantation of an implantable cardioverter-defibrillator (ICD). Standard twelve-lead follow-up ECGs revealed early repolarization pattern and an intermittent coved type ST elevation. When the coved type ST elevation appeared, the early repolarization pattern in the inferior and left precordial leads was attenuated. Prominent early repolarization pattern was the most likely trigger of the VF storm in this Brugada patient. [ABSTRACT FROM AUTHOR]

Background: Familial idiopathic ventricular fibrillation (IVF) is a severe disease entity and is notoriously difficult to manage because there are no clinical risk indicators for premature cardiac arrest. Previously, we identified a link between familial IVF and a risk haplotype on chromosome 7q36 (involving the arrhythmia gene DPP6). Objective: The purpose of this study was to expand our knowledge of familial IVF and to discuss its (extended) clinical characteristics. Methods: We studied 601 family members and probands: 286 DPP6 risk-haplotype positive (haplotype-positive) and 315 DPP6 risk-haplotype negative (haplotype-negative) individuals. Clinical parameters, a combination of all-cause mortality and (aborted) cardiac arrest and differences between haplotype-positives and haplotype-negatives, were evaluated. Results: There were no differences in electrocardiographic indices between haplotype-positives and haplotype-negatives, or between haplotype-positives with or without events. Cardiac magnetic resonance documented slightly larger ventricular volumes in haplotype-positives compared to controls (P <.05), but these were not clinically useful. Mortality and/or cardiac arrest occurred in 85 haplotype-positives (30%) and 18 haplotype-negatives (6%). Twenty-four haplotype-positives (8% male) were resuscitated from ventricular fibrillation (VF). Documented VF was always elicited by monomorphic short-coupled extrasystoles from the right ventricular apex/lower free wall. Median survival in risk-haplotype haplotype-positives was 70 vs. 93 years for haplotype-negatives (P < .01), with a worse phenotype in males (median survival 63 vs. 83 years in females, P < .01). Implantable cardioverter-defibrillators were implanted in 99 patients (76 [77%] for primary prevention). Two arrhythmic events occurred in the primary prevention group during follow-up (5 ± 3 years). Conclusion: Despite our extensive analysis, the complexity in identifying asymptomatic IVF family members at risk for future arrhythmias based on clinical parameters is once more demonstrated. [ABSTRACT FROM AUTHOR]

Background The moderator band (MB) can be a source of premature ventricular contractions (PVCs), monomorphic ventricular tachycardia (VT), and idiopathic ventricular fibrillation (IVF). Objective The purpose of this study was to define the electrocardiographic (ECG) characteristics and procedural techniques to successfully identify and ablate MB PVCs/VT. Methods In 10 patients with left bundle branch block morphology PVCs/VT, electroanatomic mapping in conjunction with intracardiac echocardiography (ICE) localized the site of origin of the PVCs to the MB. Clinical characteristics of the patients, ECG features, and procedural data were collected and analyzed. Results Seven patients presented with IVF and 3 presented with monomorphic VT. In all patients, the ventricular arrhythmias (VAs) had a left bundle branch block QRS with a late precordial transition (>V 4 ), a rapid downstroke of the QRS in the precordial leads, and a left superior frontal plane axis. Mean QRS duration was 152.7 ± 15.2 ms. Six patients required a repeat procedure. After mean follow-up of 21.5 ± 11.6 months, all patients were free of sustained VAs, with only 1 patient requiring antiarrhythmic drug therapy and 1 patient having isolated PVCs no longer inducing VF. There were no procedural complications. Conclusion VAs originating from the MB have a distinctive morphology and often are associated with PVC-induced ventricular fibrillation. Catheter ablation can be safely performed and is facilitated by ICE imaging. [ABSTRACT FROM AUTHOR]

Background The circadian pattern of ventricular fibrillation (VF) episodes in patients with idiopathic ventricular fibrillation (IVF) is poorly understood. Objective The purpose of this study was to assess the circadian pattern of VF occurrence in patients with IVF. Methods Excluding Brugada syndrome and other primary electrical diseases, the circadian pattern of VF occurrence was determined in 64 patients with IVF. The clinical and electrocardiographic characteristics were compared among patients with nocturnal (midnight to 6:00 AM) VF and nonnocturnal VF in relation to J waves. A J wave was defined as either notching or a slur at the QRS terminal >0.1 mV above the isoelectric line in contiguous leads. Results The overall distribution pattern of VF occurrence showed 2 peaks at approximately 6:00 AM and around 8:00 PM. Nocturnal VF was observed in 20 patients (31.3%), and J waves were present in 14 of these 20 individuals (70.0%), whereas J waves were less frequent in the 44 nonnocturnal patients with VF: 16 (36.4%) ( P = .0117). Among patients with J waves, nocturnal VF was observed in 46.7% with a peak at approximately 4:00 AM. Nocturnal VF was less common in patients without J waves, occurring in only 17.6% ( P = .0124). Both the type and location of J waves and the pattern of the ST segment were similar between the nocturnal and nonnocturnal VF groups. J waves were associated with a VF storm and long-term arrhythmia recurrence. Conclusion In IVF, the presence of J waves may characterize a higher nocturnal incidence of VF and a higher acute and chronic risk of recurrence. [ABSTRACT FROM AUTHOR]

Abstract: We describe a 38-year-old male who experienced several episodes of syncope after having ventricular fibrillation. The electrocardiographic monitoring after his hospitalization revealed repetitive polymorphic ventricular tachycardias. All polymorphic ventricular tachycardias were consistently initiated by a short-coupled monomorphic ventricular premature contraction (VPC). This VPC was suggested to originate from the inferoposterior region of the right ventricle (RV). Radiofrequency catheter ablation targeting the VPC was successfully performed, and the CARTO merge system (Biosense Webster Inc., Diamond Bar, CA, USA) revealed that the culprit region was the root of the posterior papillary muscle of the RV. A subsequent follow-up of 15 months has been uneventful. [Copyright &y& Elsevier]

Abstract: An early repolarization (ER) pattern in the ECG, consisting of J point elevation, distinct J wave with or without ST segment elevation or slurring of the terminal part of the QRS, was long considered a benign electrocardiographic manifestation. Experimental studies a dozen years ago suggested that an ER is not always benign, but may be associated with malignant arrhythmias. Validation of this hypothesis derives from recent case–control and population-based studies showing that an ER pattern in inferior or infero-lateral leads is associated with increased risk for life-threatening arrhythmias, termed early repolarization syndrome (ERS). Because accentuated J waves characterize both Brugada syndrome (BrS) and ERS, these syndromes have been grouped under the heading of J wave syndromes. BrS and ERS appear to share common ECG characteristics, clinical outcomes, risk factors as well as a common arrhythmic platform related to amplification of Ito-mediated J waves. However, they differ with respect to the magnitude and lead location of abnormal J waves and can be considered to represent a continuous spectrum of phenotypic expression. Recent studies support the hypothesis that BrS and ERS are caused by a preferential accentuation of the AP notch in right or left ventricular epicardium, respectively, and that this repolarization defect is accentuated by cholinergic agonists. Quinidine, cilostazol and isoproterenol exert ameliorative effects by reversing these repolarization abnormalities. Identifying subjects truly at risk is the challenge ahead. Our goal here is to review the clinical and genetic aspects as well as the cellular and molecular mechanisms underlying the J wave syndromes. [Copyright &y& Elsevier]

Background: J‐point elevation has been demonstrated to be associated with ventricular fibrillation (VF) and has been proposed as a cause of the J‐wave syndrome (JWS). A mutation of KCNJ8, S422L, was reported as a culprit gene. This study aimed to determine the prevalence of KCNJ8 mutations in a Japanese population with JWS or idiopathic VF (IVF). Methods: A total of 230 probands with JWS and IVF underwent genetic screening of KCNJ8. To analyze and compare clinical and electrocardiographic characteristics, the probands were divided into 4 groups: Brugada (Br) pattern only, early repolarization (ER) pattern only, Br and ER patterns, and true IVF. Results: The results of the genetic analysis revealed no S422L or other KCNJ8 mutations and indicated no significant difference between the groups. Conclusion: The KCNJ8 mutation showed no association with JWS or IVF among our Japanese patients. [ABSTRACT FROM AUTHOR]

Background: Little is known about the clinical and prognostic impact of early repolarization (ER) on patients with Brugada syndrome (BrS), especially those with documented ventricular fibrillation (VF).Objective: To investigate the prevalence and prognostic significance of ER in inferolateral leads in patients with BrS and documented VF.Methods: We investigated 10 different 12-lead electrocardiograms (ECGs) recorded on different days to identify the presence of ER, which was defined as J-point elevation ≥0.1 mV in inferior (II, III, aVF) or lateral leads (I, aVL, V₄-V₆), in 49 individuals (46 men; age 46 ± 13 years) with a type 1 ECG of BrS and previous history of VF.Results: ER was observed persistently (in all ECGs) in 15 patients (31%; P group), intermittently (in at least one but not in all ECGs) in 16 patients (33%; I group), and not observed in 18 patients (37%; N group), yielding an overall ER incidence of 63% (31/49). During the follow-up period (7.7 years), recurrence of VF was documented in all 15 patients (100%) in the P group, and less in 12 patients (75%) in the I group and in 8 patients (44%) in the N group. The P group showed a worse prognosis than N group (P = .0001) by Kaplan-Meier analysis. Either persistent or intermittent ER in an inferolateral lead was an independent predictor of fatal arrhythmic events (hazard ratio 4.88, 95% confidence interval 2.02-12.7, P = .0004; and hazard ratio 2.50, 95% confidence interval 1.03-6.43, P = .043, respectively).Conclusion: The prevalence of ER in inferolateral leads was high and an especially persistent form of ER was associated with a worse outcome in BrS patients with documented VF. [ABSTRACT FROM AUTHOR]

Background: A substantial number of patients with idiopathic ventricular fibrillation (IVF) present with no specific electrocardiographic (ECG) findings. Objective: To evaluate complete right bundle branch block (RBBB) in patients with IVF. Methods: Patients with IVF showing complete RBBB were included in the present study. Structural and primary electrical diseases were excluded, and provocation tests were performed to exclude the presence of spastic angina or Brugada syndrome (BrS). The prevalence of complete RBBB and the clinical and ECG parameters were compared either in patients with IVF who did not show RBBB or in the general population and age and sex comparable controls with RBBB. Results: Of 96 patients with IVF, 9 patients were excluded for the presence of BrS. Of 87 patients studied, 10 (11.5%) patients showed complete RBBB. None had structural heart diseases, BrS, or coronary spasms. The mean age was 44 ± 15 years, and 8 of 10 patients were men. Among the ECG parameters, only the QRS duration was different from that of the other patients with IVF who did not show complete RBBB. Ventricular fibrillation recurred in 3:2 in the form of storms, which were well suppressed by isoproterenol. Complete RBBB was found less often in control subjects (1.37%; P < .0001), and the QRS duration was more prolonged in patients with IVF: 139 ± 10ms vs 150 ± 14ms (P = .0061). Conclusions: Complete RBBB exists more often in patients with IVF than in controls. A prolonged QRS complex suggests a conduction abnormality. Our findings warrant further investigation of the role of RBBB in the development of arrhythmias in patients with IVF. [Copyright &y& Elsevier]

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Background: Early repolarization (ER) in the inferior electrocardiogram leads is associated with idiopathic ventricular fibrillation, but the majority of subjects with ER have a benign prognosis. At present, there are no risk stratifiers for asymptomatic ER. Objective: To examine the response to ajmaline provocation and exercise in potentially high-risk subjects with ER and without a definitive cardiac diagnosis. Methods: Electrocardiographic data were reviewed for ER at baseline and during ajmaline and exercise testing in 229 potentially high-risk patients (mean age 37.7±14.9 years; 55.9% men). ER was defined as J-point elevation in≥2 consecutive leads and stratified by type, territory, J-point height, and ST-segment morphology. Results: Baseline ER was present in 26 (11.4%; 19 men) patients. During ajmaline provocation and exercise, there were no new ER changes. ER with rapidly ascending ST-segment and lateral ER consistently diminished. There were 7 patients with persistent ER during ajmaline and/or exercise. They were all men with inferior or inferolateral ER and horizontal/descending ST segment. Those with persistent ER during exercise were more likely to have a history of unexplained syncope than those in whom ER changes diminished (P<.01). Subtle nondiagnostic structural abnormalities were demonstrated in 3 of these patients. Conclusions: ER with horizontal/descending ST-segment morphology in the inferior or inferolateral leads that persists during exercise is more common in patients with prior unexplained syncope and may identify patients at higher risk of arrhythmic events. ER that persists during ajmaline provocation and/or exercise may reflect underlying subtle structural abnormalities and should prompt further investigation. [ABSTRACT FROM AUTHOR]

Background: Means for distinguishing the very common “benign early repolarization” from the very rare but malignant form are needed. Recently, the presence of early repolarization with “horizontal ST segment” was found to predict arrhythmic death during long-term follow-up in a large population study. We therefore speculated that the combination of “J waves with horizontal ST segment” would correlate with a history of idiopathic ventricular fibrillation (VF) better than the mere presence of J waves. Objectives: To determine whether the morphology of the ST segment adds diagnostic value to the mere presence of J waves in a case–control series of idiopathic VF. Methods: We reanalyzed our case–control study showing that the presence of J waves strongly correlates with a history of idiopathic VF among 45 patients with this disorder, 124 controls matched for age and gender (“matched-control” group), and 121 young athletes. This time we focused only on those patients with J waves and graded their ST-segment morphology as either “horizontal” or “ascending” according to predefined criteria. Results: The presence of J waves was associated with a history of idiopathic VF with an odds ratio of 4.0 (95% confidence intervals = 2.0–7.9), but having both J waves and horizontal ST segment yielded an odds ratio of 13.8 (95% confidence intervals = 5.1–37.2) for having idiopathic VF. Conclusions: We report, for the first time, that the combination of J waves with horizontal/descending ST segment improved our ability to distinguish patients with idiopathic VF from controls matched by gender and age. [ABSTRACT FROM AUTHOR]

Background: A high incidence of early repolarization (ER) pattern in the inferolateral leads has been reported in patients with idiopathic ventricular fibrillation (IVF). Brugada syndrome (BS) is characterized by J-point or ST-segment elevation in the right precordial leads and ventricular fibrillation, and some patients with BS also have ER in the inferolateral leads. Objective: To compare the clinical characteristics and effects of sodium-channel blockade on ER between IVF patients with ER (early repolarization syndrome [ERS]) and BS patients with or without ER. Methods: Fourteen patients with ERS and 21 patients with BS were included in this study. ER was defined as an elevation of at least 0.1 mV from baseline in the QRS–T junction in the inferorolateral leads. Provocative tests with sodium-channel blockers were conducted in all patients with ERS to distinguish ERS from BS. Results: In the ERS group, all patients were male and most patients experienced ventricular fibrillation during sleep or low activity (79%). ER was attenuated by sodium-channel blockers in most patients with ERS (13/14, 93%) and BS (5/5, 100%), whereas ST-segment elevation was augmented in the right precordial leads in the BS group. The rates of positive late potentials were significantly higher in the BS group (60%) than in the ERS group (7%) (P <.01). Conclusions: Some similarities were observed between ERS and BS, including gender, arrhythmia triggers, and response of ER to sodium-channel blockers. Unlike the ST segment in the right precordial leads in BS, ER was attenuated in patients with both ERS and BS, suggesting a differential mechanism between ER in the inferolateral leads and ST elevation in the right precordial leads. [ABSTRACT FROM AUTHOR]

Abstract: The J wave, a deflection that follows the QRS complex of the surface electrocardiogram, is usually partially buried in the R wave in humans, appearing as a J-point elevation. An early repolarization (ER) pattern characterized by J-point elevation, slurring of the terminal part of the QRS, and ST-segment elevation has long been recognized and considered to be totally benign. Recent studies have presented evidence demonstrating that an ER pattern in inferior leads or inferolateral leads is associated with increased risk for life-threatening arrhythmias, named early repolarization syndrome. Early repolarization syndrome and Brugada syndrome share similar electrocardiographic characteristics, clinical outcomes, risk factors, as well as a common arrhythmic platform related to amplification of Ito-mediated J waves. Although Brugada syndrome and early repolarization syndrome differ with respect to the magnitude and lead location of abnormal J wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression, termed J-wave syndromes. Early repolarization syndrome has been proposed to be divided into 3 subtypes: type 1, displaying an ER pattern predominantly in the lateral precordial leads, is prevalent among healthy male athletes and rarely seen in ventricular fibrillation survivors; type 2, displaying an ER pattern predominantly in the inferior or inferolateral leads, is associated with a higher level of risk; whereas type 3, displaying an ER pattern globally in the inferior, lateral, and right precordial leads, is associated with the highest level of risk for development of malignant arrhythmias and is often associated with ventricular fibrillation storms. [Copyright &y& Elsevier]

The presence of J waves and ST-segment elevation on the electrocardiogram (ECG), jointly termed “the early repolarization pattern,” has traditionally been considered a marker of “good health.” However, recent case control series and long-term population studies have established a statistically significant association between this ECG pattern and an increased risk for arrhythmic death. This finding has raised concern among physicians, who now are asked to estimate the “arrhythmic risk” following the incidental discovery of J waves on routine ECG. Therefore, we review the literature linking early repolarization with arrhythmic risk to place this “fear of J waves” in the right perspective. We found five case control studies (involving 331 patients with idiopathic ventricular fibrillation [VF] and 8,649 controls). All of these studies showed that J waves, particularly of large amplitude and recorded in multiple leads, are more prevalent among patients with idiopathic VF. We also found three large population studies (involving >17,000 individuals) looking at the prognostic value of early repolarization. Two of these studies showed that the presence of J waves >2 mm in amplitude in asymptomatic adults is associated with a threefold increased of arrhythmic death during very long-term follow-up. Individuals with J waves do have some degree of increased dispersion of repolarization that places them at increased risk for arrhythmic death, but only in the presence of additional proarrhythmic factors or triggers. A sensible approach for the asymptomatic patient with J waves is proposed. [ABSTRACT FROM AUTHOR]

The article discusses research on the role of gene modulatory protein KCNE5 mutation in Brugada syndrome (BrS) and other idiopathic ventricular fibrillation (IVF). BrS is described to be associated with death caused by IVF. Details concerning patient selection, genomic DNA isolation, and recording of whole-cell membrane currents are presented. It is concluded that KCNE5 mutation screening is necessary to detect risks for sudden cardiac death.

Background: J-wave syndromes have emerged conceptually to encompass the pleiotropic expression of J-point abnormalities including Brugada syndrome (BrS) and early repolarization syndrome (ERS). KCNJ8, which encodes the cardiac KATP Kir6.1 channel, recently has been implicated in ERS following identification of the functionally uncharacterized missense mutation S422L. Objective: The purpose of this study was to further explore KCNJ8 as a novel susceptibility gene for J-wave syndromes. Methods: Using polymerase chain reaction, denaturing highperformance liquid chromatography, and direct DNA sequencing, comprehensive open reading frame/splice site mutational analysis of KCNJ8 was performed in 101 unrelated patients with J-wave syndromes, including 87 with BrS and 14 with ERS. Six hundred healthy individuals were examined to assess the allelic frequency for all variants detected. KCNJ8 mutation(s) was engineered by site-directed mutagenesis and coexpressed heterologously with SUR2A in COS-1 cells. Ion currents were recorded using whole-cell configuration of the patch-clamp technique. Results: One BrS case and one ERS case hosted the identical missense mutation S422L, which was reported previously. KCNJ8-S422L involves a highly conserved residue and was absent in 1,200 reference alleles. Both cases were negative for mutations in all known BrS and ERS susceptibility genes. KATP current of the Kir6.1-S422L mutation was increased significantly over the voltage range from 0 to 40 mV compared to Kir6.1-WT channels (n = 16–21; P <.05). Conclusion: These findings further implicate KCNJ8 as a novel J-wave syndrome susceptibility gene and a marked gain of function in the cardiac KATP Kir6.1 channel secondary to KCNJ8-S422L as a novel pathogenic mechanism for the phenotypic expression of both BrS and ERS. [ABSTRACT FROM AUTHOR]

Background: The presence of J waves on ECGs is related to idiopathic ventricular fibrillation (VF). Objective: The purpose of this study was to investigate the pathophysiology of J waves by assessing risk markers that reflect electrophysiologic abnormalities. Methods: The study enrolled 22 idiopathic VF patients (17 men and 5 women; mean age 36 ± 13 years). Patients were divided into two groups according to the presence or absence of J waves. The following risk stratifiers were assessed: late potentials (LPs; depolarization abnormality marker) for 24 hours using a newly developed signal-averaging system, and T-wave alternans and QT dispersion (repolarization abnormality markers). Frequency-domain heart rate variability (HRV), which reflects autonomic modulation, also was assessed. The results were compared to those of 30 control subjects with J waves and 30 with no J wave, matched for age and gender to the idiopathic VF patients. Results: J waves were present in 7 (32%) idiopathic VF patients. The incidence of LP in the idiopathic VF J-wave group was higher than in the idiopathic VF non–J-wave group (86% vs 27%, P = .02). In contrast, repolarization abnormality markers did not differ between the two groups. In the idiopathic VF J-wave group, dynamic changes in LP parameters (fQRS, RMS40, LAS40) were observed and were pronounced at nighttime; this was not the case in the idiopathic VF non–J-wave group and the control J-wave group. High-frequency components (vagal tone index) on frequency-domain HRV analysis were associated with J waves in idiopathic VF patients (P < .05). Conclusion: Idiopathic VF patients with J waves had a high incidence of LP showing circadian variation with night ascendancy. J waves may be more closely associated with depolarization abnormality and autonomic modulation than with repolarization abnormality. [Copyright &y& Elsevier]

The J wave, also referred to as an Osborn wave, is a deflection immediately following the QRS complex of the surface ECG. When partially buried in the R wave, the J wave appears as J-point elevation or ST-segment elevation. Several lines of evidence have suggested that arrhythmias associated with an early repolarization pattern in the inferior or mid to lateral precordial leads, Brugada syndrome, or arrhythmias associated with hypothermia and the acute phase of ST-segment elevation myocardial infarction are mechanistically linked to abnormalities in the manifestation of the transient outward current (Ito)-mediated J wave. Although Brugada syndrome and early repolarization syndrome differ with respect to the magnitude and lead location of abnormal J-wave manifestation, they can be considered to represent a continuous spectrum of phenotypic expression that we propose be termed J-wave syndromes. This review summarizes our current state of knowledge concerning J-wave syndromes, bridging basic and clinical aspects. We propose to divide early repolarization syndrome into three subtypes: type 1, which displays an early repolarization pattern predominantly in the lateral precordial leads, is prevalent among healthy male athletes and is rarely seen in ventricular fibrillation survivors; type 2, which displays an early repolarization pattern predominantly in the inferior or inferolateral leads, is associated with a higher level of risk; and type 3, which displays an early repolarization pattern globally in the inferior, lateral, and right precordial leads, is associated with the highest level of risk for development of malignant arrhythmias and is often associated with ventricular fibrillation storms. [Copyright &y& Elsevier]

Although a plethora of earlier studies focused on the histology and action potential characteristics of Purkinje fibers, only recently has the His-Purkinje system been found to play a major role in the genesis of cardiac arrhythmias. The anatomic complexity of the left ventricular conduction system appears to favor reentrant arrhythmias in both diseased and healthy hearts. Macroreentrant circuits between the right and left bundles as well as between the left ventricular fascicles are amenable to cure by ablative techniques. Similarly, fascicular tachycardias occurring in individuals without structural cardiac disease appear to involve macroreentrant circuits between fascicles and associated strands (false tendons?). Exciting newer discoveries strongly implicate the Purkinje system as the cause of ventricular arrhythmias in patients with short-coupled premature ventricular complexes and in those with catecholaminergic polymorphous ventricular tachycardia. The role of the His-Purkinje system in the genesis and maintenance of ventricular fibrillation is yet another frontier for fertile investigation. A rich variety of cardiac arrhythmias appears to involve the ventricular specialized conduction system and may be amenable to ablative therapy. [Copyright &y& Elsevier]

Copyright of Archives of Cardiovascular Diseases is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: We report a patient with a concealed type of Brugada syndrome. The electrocardiogram in the emergency department revealed atrial fibrillation with an almost normal ST segment. Slight electrocardiogram abnormalities of the J wave and mild ST-segment elevation appeared in the inferolateral leads a few days later. Although the ST segment in the right precordial leads, including that recorded from the high intercostal space recording sites, was completely normal, a drug challenge test using pilsicainide revealed a coved-type ST-segment elevation only in a modified V2 lead placed 1 or 2 intercostal spaces higher. [Copyright &y& Elsevier]

Abstract: Aim: We sought to determine whether survivors of sudden death without structural heart disease have beat-to-beat electrocardiographic (ECG) characteristics at the microvolt and at the millisecond level that differ from normal subjects. Methods: We studied patients at our implantable cardioverter defibrillator clinic who had been resuscitated from ventricular fibrillation with no evidence of underlying structural heart disease. Continuous 10-minute high-resolution unfiltered digital surface ECGs at 1000-Hz sampling rate were acquired in these subjects and in a group of healthy volunteers. We then analyzed different parameters of beat-to-beat variations in duration, amplitudes and vectors of the QRS complex, and the T wave using a locally developed program (Comparative Analysis of ECGs, Vectocardiograms, and their Interpretation with Auto-Reference to the patient) and compared them between the 2 groups. Results: Thirteen patients (7 men; age, 46 ± 16 years) were studied. Standard ECGs were unremarkable in 7 patients and suggestive of Brugada syndrome in the 6 others. The control group consisted of 23 age- and sex-matched subjects (13 men; age, 41 ± 10 years). Although the QRS parameters showed only few differences between the 2 groups, there were several differences in parameters evaluating repolarization. Conclusion: High-resolution ECGs show distinct beat-to-beat variations in parameters of repolarization in survivors of sudden death without structural heart disease, as compared with normal subjects. These findings may reflect increased electrical instability and should be evaluated for stratifying arrhythmic risk in asymptomatic individuals. [Copyright &y& Elsevier]

Abstract: ST-segment elevation in a structurally normal heart is associated with an electrocardiographic (ECG) J wave, which can be observed in the early repolarization syndrome (ERS), idiopathic ventricular fibrillation (VF), and the Brugada syndrome. Animal studies have demonstrated that the J wave is the consequence of a transmural voltage gradient resulting from an Ito-mediated action potential notch (spike and dome) in epicardium but not endocardium. Ito-mediated spike and dome morphology predisposes loss or depression of the dome in epicardium, leading to ST-segment elevation. Despite the fact that 3 clinical syndromes share many common ECG features, their clinical consequences are remarkably different. The ERS is a benign ECG finding characterized by a distinct J wave and ST segment in left precordial leads V4 through V6. In contrast, idiopathic VF and the Brugada syndrome, characterized by a J wave and ST-segment elevation in the inferior and right precordial leads, respectively, are the leading causes for sudden cardiac death in young Southeast Asian males. The underlying mechanism for such a difference in clinical consequences among these syndromes is due to a difference in Ito density and Ito-mediated epicardial spike and dome. When Ito is prominent, complete loss of the dome may occur due to either a decrease in inward currents or an increase in outward currents, leading to phase 2 reentry capable of initiating VF as in idiopathic VF and the Brugada syndrome. When Ito is relatively small as in the ERS, partial depression of the dome occurs without the development of phase 2 reentry. [Copyright &y& Elsevier]

This case report describes the rare phenomenon of malignant conversion of benign right ventricular outflow tract ventricular tachycardia into idiopathic ventricular fibrillation 18 years after successful ablation, in the absence of any type of heart disease. We review the current literature looking at predictors for this event, with the conclusion that there are no reliable risk predictors available. Until clear guidelines exist, we suggest patients be informed and monitored for the possibility of “malignant conversion” following ablation for benign idiopathic outflow tract ventricular tachycardia. [ABSTRACT FROM AUTHOR]