Paediatric/young versus adult patients with congenital long QT syndrome or catecholaminergic polymorphic ventricular tachycardia

Introduction

Congenital long QT syndrome (LQTS) and catecholaminergic ventricular tachycardia (CPVT) are less prevalent cardiac ion channelopathies than Brugada syndrome in Asia. The present study compared paediatric/young and adult patients with these conditions.

Method

This was a territory-wide retrospective cohort study of consecutive patients diagnosed with congenital LQTS and CPVT attending public hospitals in Hong Kong. The primary outcome was spontaneous ventricular tachycardia/ventricular fibrillation (VT/VF).

Results

A total of 142 congenital LQTS (mean onset age= 27±23 years old) and 16 CPVT (mean presentation age=11±4 years old) patients were included. For congenital LQTS, arrhythmias other than VT/VF (HR=4.67, 95% confidence interval = [1.53–14.3], p=0.007), initial VT/VF (HR=3.25 [1.29–8.16], p=0.012) and Schwartz score (HR=1.90 [1.11–3.26], p=0.020) were predictive of the primary outcome for the overall cohort, whilst arrhythmias other than VT/VF (HR=5.41 [1.36–21.4], p=0.016) and Schwartz score (HR=4.67 [1.48–14.7], p=0.009) were predictive for the adult subgroup (>25 years old; n=58). All CPVT patients presented before the age of 25 but no significant predictors of VT/VF were identified. A random survival forest model identified initial VT/VF, Schwartz score, initial QTc interval, family history of LQTS, initially asymptomatic, and arrhythmias other than VT/VF as the most important variables for risk prediction in LQTS, and initial VT/VF/sudden cardiac death, palpitations, QTc, initially symptomatic and heart rate in CPVT.

Conclusion

Clinical and ECG presentation vary between the pediatric/young and adult congenital LQTS population. All CPVT patients presented before the age of 25. Machine learning models achieved more accurate VT/VF prediction.

Funding Acknowledgement

Type of funding sources: None. Kaplan-Meier survival curve for LQTSKaplan-Meier survival curve for CPVT

Brugada syndrome in Hong Kong: long term outcome prediction through machine learning

Funding Acknowledgements

Type of funding sources: None.

Introduction

 Brugada syndrome (BrS) is an ion channelopathy that predisposes affected patients to spontaneous ventricular tachycardia/fibrillation (VT/VF) and sudden cardiac death (SCD). Despite its greater prevalence in Asia and epidemiological heterogeneity in disease manifestation, the majority of the conducted cohort studies available in current literature are based in Western countries. 

Purpose

The aim of this study is to examine the clinical and electrocardiographic predictive factors of spontaneous VT/VF for Asian BrS patients.

Methods

This was a territory-wide retrospective cohort study of patients diagnosed with BrS between 1997 and 2019. The primary outcome was spontaneous VT/VF detected either during hospital admission or by implantable-cardioverter defibrillator (ICD) data. Cox regression was used to identify significant clinical and electrocardiographic risk predictors. Non-linear interactions between variables (latent patterns) were extracted using non-negative matrix factorization (NMF) and used as inputs into the random survival forest (RSF) model.

Results

This study included 516 consecutive BrS patients (mean age of initial presentation= 50 ± 16 years, male= 92%) with a median follow-up of 86 (interquartile range: 45-118) months. The cohort was divided into subgroups based on initial disease manifestation: asymptomatic (n = 314), syncope (n = 159) or VT/VF (n = 41). Annualized event rates per person-year were 1.70%, 0.05% and 0.01% for the VT/VF, syncope and asymptomatic subgroups, respectively. Multivariate Cox regression analysis revealed initial presentation of VT/VF (HR = 24.0, 95% CI = [1.21, 479] , P= 0.037) and standard deviation of P-wave duration (HR = 1.07, 95% CI = [1.00, 1.13], P = 0.044) were significant predictors. The NMF-RSF showed the best predictive performance compared to RSF and Cox regression models (precision: 0.87 v.s. 0.83 v.s. 0.76, recall: 0.89 v.s. 0.85 v.s. 0.73, F1-score: 0.88 v.s. 0.84 v.s. 0.74).

Conclusions

This is one of the largest territory-wide cohort studies on BrS and the largest study in Asia published to date, with an extensive median follow-up duration of 7 years. Clinical history, electrocardiographic markers and investigation results provide important information for risk stratification. Machine learning techniques using NMF and RSF significantly improves overall risk stratification performance.

Sudden arrhythmia death syndrome in young victims: a five-year retrospective review and two-year prospective molecular autopsy study by next-generation sequencing and clinical evaluation of their first-degree relatives

OBJECTIVE

Sudden arrhythmia death syndrome (SADS) accounts for about 30% of causes of sudden cardiac death (SCD) in young people. In Hong Kong, there are scarce data on SADS and a lack of experience in molecular autopsy. We aimed to investigate the value of molecular autopsy techniques for detecting SADS in an East Asian population.

METHODS

This was a two-part study. First, we conducted a retrospective 5-year review of autopsies performed in public mortuaries on young SCD victims. Second, we conducted a prospective 2-year study combining conventional autopsy investigations, molecular autopsy, and cardiac evaluation of the first-degree relatives of SCD victims. A panel of 35 genes implicated in SADS was analysed by next-generation sequencing.

RESULTS

There were 289 SCD victims included in the 5-year review. Coronary artery disease was the major cause of death (35%); 40% were structural heart diseases and 25% were unexplained. These unexplained cases could include SADS-related conditions. In the 2-year prospective study, 21 SCD victims were examined: 10% had arrhythmogenic right ventricular cardiomyopathy, 5% had hypertrophic cardiomyopathy, and 85% had negative autopsy. Genetic analysis showed 29% with positive heterozygous genetic variants; six variants were novel. One third of victims had history of syncope, and 14% had family history of SCD. More than half of the 11 first-degree relatives who underwent genetic testing carried related genetic variants, and 10% had SADS-related clinical features.

CONCLUSION

This pilot feasibility study shows the value of incorporating cardiac evaluation of surviving relatives and next-generation sequencing molecular autopsy into conventional forensic investigations in diagnosing young SCD victims in East Asian populations. The interpretation of genetic variants in the context of SCD is complicated and we recommend its analysis and reporting by qualified pathologists.

Genetic basis of channelopathies and cardiomyopathies in Hong Kong Chinese patients: a 10-year regional laboratory experience

INTRODUCTION

Hereditary channelopathies and cardiomyopathies are potentially lethal and are clinically and genetically heterogeneous, involving at least 90 genes. Genetic testing can provide an accurate diagnosis, guide treatment, and enable cascade screening. The genetic basis among the Hong Kong Chinese population is largely unknown. We aimed to report on 28 unrelated patients with positive genetic findings detected from January 2006 to December 2015.

METHODS

Sanger sequencing was performed for 28 unrelated patients with a clinical diagnosis of channelopathies or cardiomyopathies, testing for the following genes: KCNQ1,KCNH2,KCNE1,KCNE2, and SCN5A, for long QT syndrome; SCN5A for Brugada syndrome; RYR2 for catecholaminergic polymorphic ventricular tachycardia; MYH7 and MYBPC3 for hypertrophic cardiomyopathy; LMNA for dilated cardiomyopathy; and PKP2 and DSP for arrhythmogenic right ventricular dysplasia/cardiomyopathy.

RESULTS

There were 17 males and 11 females; their mean age at diagnosis was 39 years (range, 1-80 years). The major clinical presentations included syncope, palpitations, and abnormal electrocardiography findings. A family history was present in 13 (46%) patients. There were 26 different heterozygous mutations detected, of which six were novel-two in SCN5A (NM_198056.2:c.429del and c.2024-11T>A), two in MYBPC3 (NM_000256.3:c.906-22G>A and c.2105_2106del), and two in LMNA (NM_170707.3:c.73C>A and c.1209_1213dup).

CONCLUSIONS

We have characterised the genetic heterogeneity in channelopathies and cardiomyopathies among Hong Kong Chinese patients in a 10-year case series. Correct interpretation of genetic findings is difficult and requires expertise and experience. Caution regarding issues of non-penetrance, variable expressivity, phenotype-genotype correlation, susceptibility risk, and digenic inheritance is necessary for genetic counselling and cascade screening.

Initial experience of cryoballoon catheter ablation for atrial fibrillation in Hong Kong

OBJECTIVE. To report the initial experience in using cryoballoon catheter ablation in the treatment of atrial fibrillation in Hong Kong. DESIGN. Single-centre, prospective case series. SETTING. Regional hospital, Hong Kong. PATIENTS. Sixteen patients (mean age, 55 years; standard deviation, 14 years; 11 males) with paroxysmal (n=12) or persistent (n=4) atrial fibrillation. INTERVENTIONS. Pulmonary vein isolation by ablation with a 28-mm cryoballoon catheter. MAIN OUTCOME MEASURES. Safety, effectiveness, and learning curve of this procedure. RESULTS. Of 67 pulmonary veins, 61 (91%) could be successfully isolated with the cryoballoon alone. The remaining pulmonary veins were isolated with additional ablation using an 8-mm tip cryocatheter. One phrenic nerve palsy developed during right middle pulmonary vein ablation, which resolved. Another patient endured a minor guidewire dissection of the right inferior pulmonary vein. The mean (standard deviation) procedural and fluoroscopic times were 231 (32) and 62 (18) minutes, respectively. On comparing the first nine and last seven procedures, there was a significant improvement in procedural time (mean [standard deviation], 244 [32] vs 213 [24] minutes; P=0.04) and in the fluoroscopic time (70 [21] vs 51 [7] minutes; P=0.038). With a median follow-up of 21 months, nine (75%) of the 12 patients with paroxysmal atrial fibrillation and one (25%) of those four with persistent atrial fibrillation had no recurrence, without the use of anti-arrhythmic drugs. CONCLUSIONS. Pulmonary vein isolation by cryoballoon catheter ablation is safe and effective in treating patients with paroxysmal, but not for patients with persistent atrial fibrillation. A relatively short learning curve of around 10 cases was deemed appropriate.

Clopidogrel-induced hepatotoxicity after percutaneous coronary stenting

Clopidogrel, an adenosine diphosphate receptor blocker, is widely used as an adjunctive antiplatelet therapy in acute coronary syndrome and percutaneous coronary stenting. The occurrence of hepatotoxicity is rare. We describe the occurrence of symptomatic liver disease in a 74-year-old man 5 weeks following commencement of therapy with clopidogrel. The reported cases of clopidogrel-induced hepatotoxicity are reviewed and the clinical significance of this event are discussed.

Clinical profile and genetic basis of Brugada syndrome in the Chinese population

OBJECTIVE

To study the clinical profile and genetic basis of Brugada syndrome in Chinese patients.

DESIGN

Prospective observational study.

SETTING

Seven regional public hospitals, Hong Kong.

MAIN OUTCOME MEASURES

The clinical and follow-up data of 50 patients (47 men, 3 women; mean age, 53 years) were collected, and genetic data of 36 probands and eight family members of three genotyped probands were analysed.

RESULTS

Eight patients survived sudden cardiac death (group A), 12 had syncope of unknown origin but no sudden death (group B), and 30 were asymptomatic before recognition of Brugada syndrome (group C). Programmed electrical stimulation induced sustained ventricular arrhythmias in 88% (7/8), 82% (9/11), and 27% (3/11) of patients in group A, group B, and group C, respectively. New arrhythmic events occurred in 50% (4/8) of patients in group A and 17% (2/12) of patients in group B after a mean follow-up period of 30 (standard deviation, 13) months and 25 (7) months, respectively. All group C patients remained asymptomatic during a mean follow-up period of 25 (standard deviation, 11) months. Five of 36 probands and three of eight family members who underwent genetic testing were found to have a mutation in their SCN5A gene.

CONCLUSIONS

Chinese patients with Brugada syndrome who are symptomatic have a high likelihood of arrhythmia recurrence, whereas asymptomatic patients enjoy a good short-term prognosis. The prevalence of SCN5A mutation among probands is 14%. Thus, Chinese patients with Brugada syndrome share with their western counterparts similar clinical and genetic heterogeneity.

Prolonged jaundice following percutaneous coronary intervention and ticlopidine therapy

Ticlopidine, an adenosine diphosphate receptor blocker, is widely used to prevent subacute stent thrombosis after percutaneous coronary intervention. Along with neutropenia and thrombotic thrombocytopenic purpura, cholestatic hepatitis is one of the most serious potential side-effects of ticlopidine therapy. Four patients with prolonged jaundice after ticlopidine therapy, including one fatal case, are presented. Alternative antithrombotic therapy for subsequent percutaneous coronary intervention is also described. Clopidogrel therapy was found to be safe and effective in two patients with a history of ticlopidine-related cholestatic hepatitis.

Left main coronary artery aneurysm: sealing by stent graft and long-term follow-up

We describe the implantation of a stent graft to seal off the left main coronary artery aneurysm of a 64-year-old man with guidance by intravascular ultrasound. The aneurysm was successfully sealed off. At 6-month and 1-year follow-up, a small residual aneurysm reappeared, which was treated conservatively. The technical issues in closing this aneurysm and the management of the residual aneurysm are discussed.

Multiple coronary-pulmonary fistulae involving all three coronary arteries: a case report

Coronary pulmonary fistulae are rare cardiac anomalies. We present the case of a 46-year-old woman with multiple coronary-pulmonary fistulae involving all three coronary arteries. She presented with atypical chest pain and had no obstructive coronary lesion. SPECT thallium study demonstrated no perfusion defect. The fistulae were multiple but small with only a small left to right shunt (Qp:Qs = 1.2). The patient has remained well without intervention.

New artefacts for old: an alterative method of preparing hard and soft tissue interfaces of developing enamel

Serial sections (each from 150 to 200 μm thick) of porcine molar tooth germs within their bony crypts, rodent incisor teeth (in situ), and human extracted teeth were cut with a thin rotating diamond-impregnated disc, without prior embedding. Some specimens were cut unfixed, at room temperature (21°C) or frozen (-70°C), some in fixative, and others cut after fixation. A variety of routine fixatives has been tried, and in general the preservation of hard/soft tissue interfaces is best achieved when fixation precedes cutting. Several histological and histochemical methods have also been tried successfully. The damaged surface layers of the specimens brought about by the cutting disc can be removed after staining, if the section is embedded in a thin sheet of Epon and then thinned by being polished. The method provides a novel way of studying hard/soft tissue junctions.

Metric rigidity theorems on Hermitian locally symmetric spaces

Let X = Omega/Gamma be a compact quotient of an irreducible bounded symmetric domain Omega of rank >/=2 by a discrete group omega of automorphisms without fixed points. It is well known that the Kähler-Einstein metric g on X carries seminegative curvature (in the sense of Griffiths). I show that any Hermitian metric h on X carrying seminegative curvature must be a constant multiple of g. This can be applied to prove rigidity theorems of holomorphic maps from X into Hermitian manifolds (Y, k) carrying seminegative curvature. These results are also generalized to the case of quotients of finite volume. On the other hand, let (X(c), g(c)) be an irreducible compact Hermitian symmetric manifold of rank >/=2. Then g(c) is Kähler and carries semipositive holomorphic bisectional curvature. I prove that any Kähler h on X(c) carrying semipositive holomorphic bisectional curvature must be equal to g(c) up to a constant multiple and up to a biholomorphic transformation of X(c).