Coexistence of atrioventricular accessory pathways and drug-induced type 1 Brugada pattern

Diagnosis of Brugada Syndrome With a Sodium-Channel-Blocker Test: Who Should Be Tested? Who Should Not?

Intravenous infusion of sodium-channel blockers (SCB) with either ajmaline, flecainide, procainamide, or pilsicainide to unmask the ECG of Brugada syndrome is the drug challenge most commonly used for diagnostic purposes when investigating cases possibly related to inherited arrhythmia syndromes. For a patient undergoing an SCB challenge, the impact of a positive result goes well beyond its diagnostic implications. It is, therefore, appropriate to question who should undergo a SCB test to diagnose or exclude Brugada syndrome and, perhaps more importantly, who should not. We present a critical review of the benefits and drawbacks of the SCB challenge when performed in cardiac arrest survivors, patients presenting with syncope, family members of probands with confirmed Brugada syndrome, and asymptomatic patients with suspicious ECG.

Novelties in Brugada Syndrome: Complex Genetics, Risk Stratification, and Catheter Ablation

Brugada syndrome (BrS) is an inherited arrhythmia syndrome with distinctive electrocardiographic abnormalities in the right precordial leads and predisposes to ventricular arrhythmias and sudden cardiac death in otherwise healthy patients. Its complex genetic architecture and pathophysiological mechanism are not yet completely understood, and risk stratification remains challenging, particularly in patients at intermediate risk of arrhythmic events. Further understanding of its complex genetic architecture may help improving future risk stratification, and advances in management may contribute to alternatives to implantable cardioverter-defibrillators. Here, the authors review the latest insights and developments in BrS.

Electrocardiographic variables associated with underlying Brugada syndrome or drug-induced Type 1 Brugada pattern in patients with slow/fast atrioventricular nodal reentrant tachycardia

Background

The coexistence of clinical atrioventricular nodal reentrant tachycardia (AVNRT) and drug-induced type 1 Brugada pattern (DI-Type 1 BrP) has been previously reported. The present study was designed to determine the 12-lead ECG characteristics at baseline and during AVNRT and to identify a subset of 12-lead ECG variables of benefit associated with underlying Brugada syndrome (BrS)/DI-Type 1 BrP among patients with slow/fast AVNRT.

Methods

A total of 40 (11 numerical/29 categorical) 12-lead ECG parameters were analyzed and compared between patients with (n = 69) and without (n = 104) BrS/DI-Type1-BrP matched for age, female gender, body mass index, left ventricular ejection fraction and comorbid conditions. Five distinct types of ECG pattern (Type A/B/C/D/E) in V1-V2 leads during AVNRT were defined.

Results

A total of nine electrocardiographic variables, four at baseline, and five during AVNRT were identified. At baseline, patients with BrS/DI-Type 1 BrP had higher prevalence of interatrial block, leftward shift of frontal plane QRS axis, the absence of normal QRS pattern (the presence of rSr' pattern or type 2/3 Brugada pattern) in V1-V2 and QRS fragmentation in inferior leads compared to patients without BrS/DI-Type 1 BrP. During AVNRT, patients with BrS/DI-Type 1 BrP had higher prevalence of Type A ECG pattern ("coved-type" ST-segment elevation) in V1-V2, Type C ECG pattern (pseudo-r' deflection in V1 and "RBBB-like" pattern in V2), pseudo-r' deflection in V1, QRS fragmentation in inferior leads and "isolated" QRS fragmentation/notching/slurring in aVL compared to patients without BrS/DI-Type 1 BrP.

Conclusions

We identify several electrocardiographic variables that point to an underlying type 1 BrP among patients with slow/fast AVNRT.

NGS in Hereditary Ataxia: When Rare Becomes Frequent

The term hereditary ataxia (HA) refers to a heterogeneous group of neurological disorders with multiple genetic etiologies and a wide spectrum of ataxia-dominated phenotypes. Massive gene analysis in next-generation sequencing has entered the HA scenario, broadening our genetic and clinical knowledge of these conditions. In this study, we employed a targeted resequencing panel (TRP) in a large and highly heterogeneous cohort of 377 patients with a clinical diagnosis of HA, but no molecular diagnosis on routine genetic tests. We obtained a positive result (genetic diagnosis) in 33.2% of the patients, a rate significantly higher than those reported in similar studies employing TRP (average 19.4%), and in line with those performed using exome sequencing (ES, average 34.6%). Moreover, 15.6% of the patients had an uncertain molecular diagnosis. STUB1, PRKCG, and SPG7 were the most common causative genes. A comparison with published literature data showed that our panel would have identified 97% of the positive cases reported in previous TRP-based studies and 92% of those diagnosed by ES. Proper use of multigene panels, when combined with detailed phenotypic data, seems to be even more efficient than ES in clinical practice.

Frequency of Irritable Bowel Syndrome in Patients with Brugada Syndrome and Drug-Induced Type 1 Brugada Pattern

Irritable bowel syndrome (IBS) is one of the most widely recognized functional bowel disorders (FBDs) with a genetic component. SCN5A gene and SCN1B loci have been identified in population-based IBS cohorts and proposed to have a mechanistic role in the pathophysiology of IBS. These same genes have been associated with Brugada syndrome (BrS). The present study examines the hypothesis that these two inherited syndromes are linked. Prevalence of FBDs over a 12 months period were compared between probands with BrS/drug-induced type 1 Brugada pattern (DI-Type 1 BrP) (n = 148) and a control group (n = 124) matched for age, female sex, presence of arrhythmia and co-morbid conditions. SCN5A/SCN1B genes were screened in 88 patients. Prevalence of IBS was 25% in patients with BrS/DI-Type 1 BrP and 8.1% in the control group (p = 2.34 × 10^-4). On stepwise logistic regression analysis, presence of current and/or history of migraine (OR of 2.75; 95% CI: 1.08 to 6.98; p = 0.033) was a predictor of underlying BrS/DI-Type 1 BrP among patients with FBDs. We identified 8 putative SCN5A/SCN1B variants in 7 (12.3%) patients with BrS/DI-Type 1 BrP and 1 (3.2%) patient in control group. Five out of 8 (62.5%) patients with SCN5A/SCN1B variants had FBDs. In conclusion, IBS is a common co-morbidity in patients with BrS/DI-Type 1 BrP. Presence of current and/or history of migraine are a predictor of underlying BrS/DI-Type 1 BrP among patients with FBDs. Frequent co-existence of IBS and BrS/DI-Type 1 BrP necessitates cautious use of certain drugs among the therapeutic options for IBS that are known to exacerbate the Brugada phenotype.

Assessment of atrial functional remodeling in patients with atrioventricular nodal reentrant tachycardia with and without drug-induced type 1 Brugada pattern: A case-control study

PURPOSE

The time interval between the onset of the P-wave on electrocardiogram (ECG) and peak A' velocity of the lateral left atrial wall assessed by tissue Doppler imaging (PA-TDI interval) determine total atrial conduction time (TACT) which reflects atrial remodeling and arrhythmic substrate. In this retrospective study, we aimed to assess TACT in patients with atrioventricular nodal reentrant tachycardia (AVNRT) with and without drug-induced type 1 Brugada electrocardiogram ECG pattern (DI-Type 1 BrP) and control subjects.

METHODS

Study population consisted of 62 consecutive patients (46 women; mean age 44 ± 12 years) undergoing electrophysiological study and ablation for symptomatic, drug-resistant AVNRT, and 42 age-matched and sex-matched control subjects. All patients and control subjects underwent ajmaline challenge test and tissue Doppler imaging.

RESULTS

A DI-Type 1 BrP was uncovered in 24 of 62 patients with AVNRT (38.7%). PA-TDI interval was similar among AVNRT patients with and without DI-Type 1 BrP (124 ± 12 ms vs 119 ± 14 ms, respectively, P = .32), but significantly longer in patients with AVNRT with as well as without DI-Type 1 BrP than in control subjects (124 ± 12 ms and 119 ± 14 ms vs 105 ± 11 ms, respectively, P < .001).

CONCLUSION

The TACT assessed by PA-TDI interval is longer in patients with AVNRT with and without DI-Type 1 BrP than in age-matched and sex-matched healthy control subjects.

2020 APHRS/HRS expert consensus statement on the investigation of decedents with sudden unexplained death and patients with sudden cardiac arrest, and of their families

This international multidisciplinary document intends to provide clinicians with evidence-based practical patient-centered recommendations for evaluating patients and decedents with (aborted) sudden cardiac arrest and their families. The document includes a framework for the investigation of the family allowing steps to be taken, should an inherited condition be found, to minimize further events in affected relatives. Integral to the process is counseling of the patients and families, not only because of the emotionally charged subject, but because finding (or not finding) the cause of the arrest may influence management of family members. The formation of multidisciplinary teams is essential to provide a complete service to the patients and their families, and the varied expertise of the writing committee was formulated to reflect this need. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by Class of Recommendation and Level of Evidence. The recommendations were opened for public comment and reviewed by the relevant scientific and clinical document committees of the Asia Pacific Heart Rhythm Society (APHRS) and the Heart Rhythm Society (HRS); the document underwent external review and endorsement by the partner and collaborating societies. While the recommendations are for optimal care, it is recognized that not all resources will be available to all clinicians. Nevertheless, this document articulates the evaluation that the clinician should aspire to provide for patients with sudden cardiac arrest, decedents with sudden unexplained death, and their families.

Brugada syndrome and reduced right ventricular outflow tract conduction reserve: a final common pathway?

Brugada syndrome (BrS) was first described as a primary electrical disorder predisposing to the risk of sudden cardiac death and characterized by right precordial lead ST elevation. Early description of right ventricular structural abnormalities and of right ventricular outflow tract (RVOT) conduction delay in BrS patients set the stage for the current controversy over the pathophysiology underlying the syndrome: channelopathy or cardiomyopathy; repolarization or depolarization. This review examines the current understanding of the BrS substrate, its genetic and non-genetic basis, theories of pathophysiology, and the clinical implications thereof. We propose that the final common pathway for BrS could be viewed as a disease of 'reduced RVOT conduction reserve'.

2020 APHRS/HRS expert consensus statement on the investigation of decedents with sudden unexplained death and patients with sudden cardiac arrest, and of their families

This international multidisciplinary document intends to provide clinicians with evidence-based practical patient-centered recommendations for evaluating patients and decedents with (aborted) sudden cardiac arrest and their families. The document includes a framework for the investigation of the family allowing steps to be taken, should an inherited condition be found, to minimize further events in affected relatives. Integral to the process is counseling of the patients and families, not only because of the emotionally charged subject, but because finding (or not finding) the cause of the arrest may influence management of family members. The formation of multidisciplinary teams is essential to provide a complete service to the patients and their families, and the varied expertise of the writing committee was formulated to reflect this need. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by Class of Recommendation and Level of Evidence. The recommendations were opened for public comment and reviewed by the relevant scientific and clinical document committees of the Asia Pacific Heart Rhythm Society (APHRS) and the Heart Rhythm Society (HRS); the document underwent external review and endorsement by the partner and collaborating societies. While the recommendations are for optimal care, it is recognized that not all resources will be available to all clinicians. Nevertheless, this document articulates the evaluation that the clinician should aspire to provide for patients with sudden cardiac arrest, decedents with sudden unexplained death, and their families.

Recognition and clinical implications of high prevalence of migraine in patients with Brugada syndrome and drug-induced type 1 Brugada pattern

INTRODUCTION

We have previously reported high 1-year prevalence of migraine in patients with atrial arrhythmias associated with DI-type 1 BrP. The present study was designed to determine the lifetime prevalence of migraine in patients with Brugada syndrome (BrS) or drug-induced type 1 Brugada pattern (DI-type 1 BrP) and control group, to investigate the demographic and clinical characteristics, and to identify clinical variables to predict underlying BrS/DI-type 1 BrP among migraineurs.

METHODS AND RESULTS

Lifetime prevalence of migraine and migraine characteristics were compared between probands with BrS/DI-type 1 BrP (n = 257) and control group (n = 370). Lifetime prevalence of migraine was 60.7% in patients with BrS/DI-type 1 BrP and 30.3% in control group (p = 3.6 × 10^-14 ). On stepwise regression analysis, familial migraine (odds ratio [OR] of 4.4; 95% confidence interval [CI]: 2.0-9.8; p = 1.3 × 10^-4 ), vestibular migraine (OR of 5.4; 95% CI: 1.4-21.0); p = .013), migraine with visual aura (OR of 1.8; 95% CI: 1.0-3.4); p = .04) and younger age-at-onset of migraine (OR of 0.95; 95% CI: 0.93-0.98); p = .004) were predictors of underlying BrS/DI-type 1 BrP among migraineurs. Use of anti-migraine drugs classified as "to be avoided" or "preferably avoided" in patients with BrS and several other anti-migraine drugs with potential cardiac I_Na /I_Ca channel blocking properties was present in 25.6% and 26.9% of migraineurs with BrS/DI-type 1 BrP, respectively.

CONCLUSION

Migraine comorbidity is common in patients with BrS/DI-type 1 BrP. We identify several clinical variables that point to an underlying type-1 BrP among migraineurs, necessitating cautious use of certain anti-migraine drugs.