Catecholaminergic Polymorphic Ventricular Tachycardia Patients Research Articles

Insights into adherence to medication and lifestyle recommendations in an international cohort of patients with catecholaminergic polymorphic ventricular tachycardia.

In patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), a rare inherited arrhythmia syndrome, arrhythmic events can be prevented by medication and lifestyle recommendations. In patients who experience breakthrough arrhythmic events, non-adherence plays an essential role. We aimed to investigate the incidence and potential reasons for non-adherence to medication and lifestyle recommendations in a large, international cohort of patients with CPVT. An online multilingual survey was shared with CPVT patients worldwide by their cardiologists, through peer-recruitment, and on social media from November 2022 until July 2023. Self-reported non-adherence was measured using the validated Medication Adherence Rating Scale (MARS) and a newly developed questionnaire about lifestyle. Additionally, validated questionnaires were used to assess potential reasons for medication non-adherence. Two-hundred-and-eighteen patients completed the survey, of whom 200 (92%) were prescribed medication [122 (61%) female; median age 33.5 years (interquartile range: 22-50)]. One-hundred-and-three (52%) were prescribed beta-blocker and flecainide, 85 (43%) beta-blocker, and 11 (6%) flecainide. Thirty-four (17%) patients experienced a syncope, aborted cardiac arrest or appropriate implantable cardioverter defibrillator shock after diagnosis. Nineteen (13.4%) patients were exercising more than recommended. Thirty (15%) patients were non-adherent to medication. Female sex [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.3-12.0, P = 0.019], flecainide monotherapy compared to combination therapy (OR 6.8, 95% CI 1.6-31.0, P = 0.010), and a higher agreement with statements regarding concerns about CPVT medication (OR 1.2, 95% CI 1.1-1.3, P < 0.001) were independently associated with non-adherence. The significant rate of non-adherence associated with concerns regarding CPVT-related medication, emphasizes the potential for improving therapy adherence by targeted patient education.

Clinical and genetic characterization of patients with catecholaminergic polymorphic ventricular tachycardia: a case series

AIM: of the study was to evaluate the clinical and genetic characteristics, including the development of adverse events and outcomes in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT).&#x0D; MATERIALS AND METHODS: The clinical phenotype of eight patients with CPVT, two of whom were relatives of probands, was observed over 4 years. The clinical and instrumental study included ECG-12, 24-hour Holter ECG monitoring, genealogical history collection and family history of sudden cardiac death (SCD), transthoracic echocardiography and cardiac magnetic resonance imaging to detect structural myocardial changes, electrophysiologic study according to indications, and ICD monitoring. High-throughput sequencing (NGS) was utilized to search for mutations in genes linked to the onset of channelopathies and other inherited rhythm disorders.&#x0D; RESULTS: In 8 patients, nucleotide variants of pathogenicity classes III-V were identified according to the ACMG (2015) criteria in the RYR2 gene associated with CPVT. Pathogenic (IV-V class) and likely pathogenic (IV class) mutations in the RYR2 gene were found in 6 (75%) probands, variants with uncertain clinical significance (VUS, class III) were found in 2 patients. At the time of diagnosis, transient QTc interval prolongation of more than 480 ms was detected in 4 (50%) patients; bradycardia less than 54 beats/min — in 2 (25%) patients, sequences of supraventricular tachycardia and ventricular tachyarrhythmia — in 2 (25%) patients. The most severe form of the disease with marked clinical manifestations and an episode of clinical death with subsequent resuscitation, as well as a transient QTc interval prolongation exceeding 500 ms was observed in patients with mutations c.11814C A (p.Ser3938Arg, rs794728704); c.463G A (p.Gly155Arg) and c.14876G A (p.Arg4959Gln, rs794728811) in the RYR2 gene. Three (37.5%) patients underwent ICD implantation; one for primary SCD prevention and two for secondary prevention.&#x0D; CONCLUSION: In this study, the spectrum of clinical manifestations in patients with genetically confirmed CPVT was examined. The findings highlight transient QTc interval extensions, significant sinus bradycardia, and sequences of supraventricular tachyarrhythmias, which can escalate into life-threatening ventricular tachyarrhythmias in CPVT patients.

Artificial intelligence for a cardiac drug study

Machine learning that is the vital part of modern artificial intelligence was used to classify the potential effects of two drugs on induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM). Peak data were detected from calcium transient signals of cycling iPSC-CMs first at baseline, second exposed to adrenaline and third exposed with one of the drugs either flecainide or carvedilol. Various machine learning classification tests were executed to evaluate whether a drug did or did not affect signal shape after exposing adrenaline or the drugs. According to our classification results, machine learning can be applied to analyze possible effects of drugs on induced pluripotent stem cell-derived cardiomyocytes derived from the catecholaminergic polymorphic ventricular tachycardia patients’ cell samples.

An online international survey study into the incidence and potential reasons of therapy non-adherence in catecholaminergic polymorphic ventricular tachycardia: preliminary results

Abstract Background Since the first description of catecholaminergic polymorphic ventricular tachycardia (CPVT), a rare inherited cardiac arrhythmia, effective medical therapy to prevent the arrhythmic events – syncope, sudden cardiac arrest, sudden cardiac death – have been described. However, a significant proportion of patients experience breakthrough events despite optimal medical therapy, which are regularly associated with therapy non-adherence. Purpose To investigate the incidence of and potential reasons for therapy non-adherence in a large cohort of patients with CPVT. Methods An online survey was created in Dutch, English, and French and shared with CPVT patients at the outpatient clinic, through peer-recruitment, and on social media from November 1, 2022 onwards. Self-reported non-adherence was measured using the validated Medication Adherence Rating Scale (MARS, contains five 5-Point Likert scale questions, non-adherence was defined as a score &amp;lt;22). The Beliefs about Medication Questionnaire (BMQ, eleven 5-Point Likert scale statements regarding concern and necessity of CPVT medication and eight 5-Point Likert scale questions regarding overuse and harm of medication in general) and Illness Perception Questionnaire (IPQ, statements rated with a scale from 0 to 10) were used to explore associations between patient beliefs and non-adherence. Results After three months, 85 patients had completed the survey, of whom 77 (91%) used medication (32 [42%] used a beta-blocker, 5 [6%] flecainide, and 40 [52%] beta-blocker and flecainide dual therapy). Of the patients using medication, current median age was 37 (interquartile range [IQR]: 26-55) years, 56 (73%) were female, and 15 (20%) suffered from syncope, aborted cardiac arrest or appropriate ICD shock after diagnosis. Ten (13%) of the patients were non-adherent. Clinical characteristics of non-adherent patients did not differ from adherent patients (Table). Non-adherent patients reported a significantly higher agreement with statements regarding concern about CPVT-related medication (17.5 [15.2-20.8] vs. 14.0 [12.0-18.0], p=0.039), specifically the statement about unpleasant adverse effects (4.0 [3.2-4.8] vs. 3.0 [2.0-4.0], p=0.008, Figure). The IPQ statements did not differ between non-adherent and adherent patients (Figure). Conclusion Preliminary data of this survey study shows that the rate of self-reported non-adherence is significant and is associated with concern regarding CPVT-related medication. This knowledge could assist in improving patient education aimed at therapy adherence. In addition, this preliminary data show that it is feasible and useful to study non-adherence in a CPVT population using online surveys.TableFigure

Clinical and genetic analysis of five children with Catecholaminergic polymorphic ventricular tachycardia due to variants of RYR2 gene

To explore the clinical and genetic characteristics of five children with Catecholaminergic polymorphic ventricular tachycardia (CPVT). Five children with clinical manifestations consistent with CPVT admitted to the Department of Cardiology of Children's Hospital Affiliated to Zhengzhou University from November 2019 to November 2021 were selected as the study subjects. Their clinical data were collected. Potential variants were detected by whole exome sequencing, and Sanger sequencing was used to verify the candidate variants. All patients were treated with β-blocker propranolol and followed up. All patients had developed the disease during exercise and presented with syncope as the initial clinical manifestation. Electrocardiogram showed sinus bradycardia. The first onset age of the 5 patients were (10.4 ± 2.19) years, and the time of delayed diagnosis was (1.6 ± 2.19) years. All of the children were found to harbor de novo heterozygous missense variants of the RYR2 gene, including c.6916G>A (p.V2306I), c.527G>C (p.R176P), c.12271G>A (p.A4091T), c.506G>T (p.R169L) and c.6817G>A (p.G2273R). Among these, c.527G>C (p.R176P) and c.6817G>A (p.G2273R) were unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.527G>C (p.R176P) was classified as a pathogenic variant (PS2+PM1+PM2_Supporting+PM5+PP3+PP4), and the c.6817G>A (p.G2273R) was classified as a likely pathogenic variant (PS2+PM2_Supporting+PP3+PP4). The symptoms of all children were significantly improved with the propranolol treatment, and none has developed syncope during the follow up. Discovery of the c.527G>C (p.R176P) and c.6817G>A (p.G2273R) variants has expanded the mutational spectrum of the RYR2 gene. Genetic testing of CPVT patients can clarify the cause of the disease and provide a reference for their genetic counseling.

&lt;i&gt;CASQ2&lt;/i&gt;: clinical and genetic insights into catecholaminergic polymorphic ventricular tachycardia across three families

Catecholaminergic polymorphic ventricular tachycardia is a primary channelopathy with a high mortality rate if left untreated. In 3 to 5% of catecholaminergic polymorphic ventricular tachycardia patients, mutations in the CASQ2 gene, either in a homozygous or compound heterozygous form, have been identified. In this article, we present a clinical case series of patients from three unrelated families with mutations in the CASQ2 gene, including three novel mutations (p.Leu167Pro, p.Asp325GlyfsTer7, and p.Glu259Ter). All our patients with homozygous or compound heterozygous CASQ2 gene mutations experienced a severe disease course, with early manifestations and resistance to specific anti-arrhythmic treatment, including beta-blockers. They exhibited a wide range of heart rhythm abnormalities, both ventricular and supraventricular, and had a high risk of sudden cardiac death. In all cases, ventricular heart arrhythmias persisted despite regular treatment with specific anti-arrhythmic agents, unless selective left-sided sympathectomy had been performed. The management of this patient group emphasized an individualized approach, combining medical and surgical treatment methods tailored to each patient's unique needs and condition.

Generation of two induced pluripotent stem cell lines from catecholaminergic polymorphic ventricular tachycardia patients carrying RYR2 mutations

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a congenital arrhythmic syndrome caused by the RYR2 gene encoded ryanodine receptor. Mutations on RYR2 are commonly associated with ventricular tachycardia after adrenergic stimulation, leading to lethal arrhythmias and sudden cardiac death. We generated two human induced pluripotent stem cell (iPSC) lines from CPVT affected patients carrying single missense heterozygote RYR2 mutations, c.1082 G > A and c.100 A > C. Pluripotency and differentiation capability into derivatives of three germ layers were evaluated along with karyotype stability in the report. The generated patient-specific iPSC lines provide a reliable tool to investigate the CPVT phenotype and understand underlaying mechanisms.

PE-452787-1 THE RELATIONSHIP BETWEEN VENTILATORY ANAEROBIC THRESHOLD AND ARRHYTHMIA ONSET IN PATIENTS WITH CATECHOLAMINERGIC VENTRICULAR TACHYCARDIA

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a genetic disease associated with malignant ventricular arrhythmias, typically developing at high heart rate (HR) and catecholamine states. Patients are often restricted from exercise. Cardiopulmonary exercise testing (CPET) is used to diagnose and monitor patients to ensure HR-associated arrhythmias are adequately blunted on beta blockers (BB). In addition to peak HR, CPET can also determine the ventilatory anaerobic threshold (VAT), the point at which the body shifts from aerobic to anaerobic metabolism generating lactic acid as a byproduct. VAT is commonly used in prescribing exercise intensity in those with and without heart disease but has not been evaluated in CPVT patients. This transition point could be useful clinically in determining more precise exercise limits in patients with CPVT. To assess if there is an association between VAT and the development of arrhythmia during exercise in those diagnosed with CPVT. This is a retrospective cohort study on all patients with CPVT completing exercise testing at our institution from July 2017 through September 2022. VAT was calculated utilizing the V-slope method. Simple ectopy was defined as single, uniform premature ventricular complexes (PVCs) and complex ectopy defined as polymorphic PVCs or ventricular tachycardia. The HR at the time ventricular ectopy first developed was noted. There were 44 CPETs completed by 10 patients (19.8±10.4 years-old at first test; 50% male) with genetically-confirmed CPVT. Most tests occurred while the patient was on BB therapy (39/44). Patients had simple ectopy in 34 tests and complex ectopy in 25. No patients developed complex ectopy before VAT during any test (Figure 1). Average HR at VAT (101.4±14.7 bpm) was below both the HR at which simple (122.1±14.3 bpm) and complex (136.8±18.4 bpm) ectopy developed. Average HR at each point in exercise was lower in the group on BB than those not on a BB. These HR and arrhythmia trends were similar on the initial CPET at diagnosis and on their subsequent tests. Patients with CPVT seem to reach VAT prior to the onset of ventricular ectopy. Anaerobic metabolism may play a role in the arrhythmogenicity of these patients, possibly due to lactic acid production. If confirmed in larger studies, activity restrictions could be liberalized to allow low-intensity exercise below the VAT with precise HR goals in patients with CPVT.

PO-03-157 ACTIVITY RESTRICTION IN PEDIATRIC CATECHOLAMINERGIC POLYMORPHIC VENTRICULAR TACHYCARDIA: DOES IT MATTER WHAT THE DOCTOR SAYS?

Catecholaminergic polymorphic Ventricular Tachycardia (CPVT) is a rare inherited arrhythmia disorder characterized by adrenergic-induced polymorphic ventricular tachycardia (VT). Physical activity (PA) restriction was once a mainstay of therapy. Although an individualized, shared decision approach to PA is recommended, the amount activity considered safe remains unknown. To describe 1) the association between PA levels and ventricular arrhythmia scores and 2) the PA levels in relation to Canadian PA guidelines and physician PA recommendations. Patients 8-18 years with CPVT were prospectively recruited from the International Pediatric CPVT Registry. PA levels were assessed via an Actigraph accelerometer (GT3X) worn for ≥ 10-hours a day for 7-days. Ventricular arrhythmia score was ascertained from treadmill tests (to volitional fatigue) by an established scale (1=no ectopy or premature ventricular complexes (PVCs), 2=bigeminy, 3=couplets, 4=non-sustained VT). The association between ventricular arrhythmia and PA metrics were controlled for medication doses. A total of 26 pediatric CPVT patients (median age 14 (IQR 11-17) years; 46% females) were included. Nine (35%) patients were on BB monotherapy, 15 (58%) BB and flecainide and 2 (8%) were on no medication. Of those on medication, 3 (12%) underwent left cardiac sympathetic denervation. Median ventricular arrhythmia score among all patients was 2 (IQR 1-2); 11 (42%) had no ectopy or isolated PVCs on treadmill. Moderate-to-vigorous PA (odds ratio: 0.98, 95% CI: 0.95-1.0, p=0.31) was not associated with ventricular arrhythmia scores after adjusting for medication. Median moderate-to-vigorous PA was 44 (IQR 29-59) min/day and only 5 (19%) patients met PA guidelines (≥60 min/day in healthy children). Adolescents were less active than younger children (rho=-0.44, p=0.03), and moderate-to-vigorous PA did not differ based on sex (p=0.18). Physician PA recommendation ranged from no restrictions in 14 (54%) to partial PA restrictions (no competitive, team sport and/or endurance PA) in 12 (46%) patients. Ventricular arrhythmia scores (Figure 1; p=0.42) and moderate-to-vigorous PA (p=0.41) did not differ based on physician PA restrictions. There was no association between amount of PA and clinical ventricular arrhythmia scores in this cohort of predominantly treated CPVT children. Only a fifth of patients met PA guidelines irrespective of physician recommendations, and a large proportion continue to be restricted from PA.

Successful pregnancy in a high-risk catecholaminergic polymorphic ventricular tachycardia patient

Objective: To report the case of a successful pregnancy outcome in a severely symptomatic woman affected by catecholaminergic polymorphic ventricular tachycardia (CPVT) carrier of a novel variant in ryanodine receptor 2 (RYR2) followed by a review of the current literature. Case(s): A 27-year-old primigravida affected by CPVT was referred to our tertiary care hospital after an implantable cardioverter defibrillator (ICD) shock. The patient also received medical treatment with metoprolol and flecainide. A healthy baby was born by Cesarean section at 31 weeks after the onset of preterm labor and premature rupture of membranes. CPVT is a rare inherited cardiac condition characterized by episodic polymorphic ventricular arrhythmias with a structurally normal heart. These are usually triggered by exercise or emotional stress and can lead to syncope or even sudden cardiac death. Treatment of this condition comprises betablockers in isolation or in addition to other antiarrhythmics, left cardiac sympathetic denervation and/or ICD. Conclusion: This case illustrates the importance of a multidisciplinary approach in this clinical scenario and the benefits of an optimization of the medical treatment, and demonstrates that, even in severely affected patients, a successful pregnancy is possible under close control. However, the risk of arrhythmic events and the course of pregnancy remain largely unknown in patients with CPVT, and further investigation is needed.

Repeatability of ventricular arrhythmia characteristics on the exercise-stress test in RYR2-mediated catecholaminergic polymorphic ventricular tachycardia.

In catecholaminergic polymorphic ventricular tachycardia (CPVT), the exercise-stress test (EST) is the cornerstone for the diagnosis, risk stratification, and assessment of therapeutic efficacy, but its repeatability is unknown. We aimed to test the repeatability of ventricular arrhythmia characteristics on the EST in patients with CPVT. EST-pairs (ESTs performed within 18 months between 2005 and 2021, on the same protocol, and without or on the exact same treatment) of patients with RYR2-mediated CPVT from two specialized centres were included. The primary endpoint was the repeatability of the maximum ventricular arrhythmia score [VAS: 0 for the absence of premature ventricular contractions (PVCs); 1 for isolated PVCs; 2 for bigeminal PVCs; 3 for couplets; and 4 for non-sustained ventricular tachycardia]. Secondary outcomes were the repeatability of the heart rate at the first PVC and the ΔVAS (the absolute difference in VAS between the EST-pairs). A total of 104 patients with 349 EST-pairs were included. The median duration between ESTs was 343 (interquartile range, 189-378) days. Sixty (17.2%) EST-pairs were off therapy. The repeatability of the VAS was moderate {Krippendorf α, 0.56 [95% confidence interval (CI), 0.48-0.64]}, and the repeatability of the heart rate at the first PVC was substantial [intra-class correlation coefficient, 0.78 (95% CI, 0.71-0.84)]. The use of medication was associated with a higher odds for a ΔVAS > 1 (odds ratio = 3.52; 95% CI, 2.46-4.57; P = 0.020). The repeatability of ventricular arrhythmia characteristics was moderate to substantial. This underlines the need for multiple ESTs in CPVT patients and CPVT suspicious patients and it provides the framework for assessing the therapeutic efficacy of novel CPVT therapies.

Abstract 15723: Risk Factors for Beta-Blockers Failure in Catecholaminergic Polymorphic Ventricular Tachycardia

Introduction: Patients with Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) may experience life-threatening arrhythmic events (LAE) despite standard-of-care treatment with beta-blockers (BB), but risk stratification is not well defined. Hypothesis: Both clinical and genetic risk factors predispose to BB failure, including the class of BBs (β1-selective vs. non-selective). Methods: LAE was defined as the composite of sudden cardiac death, aborted cardiac arrest, or hemodynamically non-tolerated ventricular tachycardia. We fitted a Cox proportional hazards regression model with multiple events during BB treatment only with the following explanatory covariates: 1) LAE before diagnosis, 2) unexplained syncope before diagnosis, 3) genotype, and 4) type of BB (as time-dependent variable). Results: We included n=238 CPVT patients: n=135 (57%) probands, n=134 (56%) females, n=216 (91%) RYR2, n=10 (4%) CASQ2, n=5 (2%) RYR2-Loss-of-Function, n=4 (2%) TRDN and n=3 (1%) TECRL. Before the diagnosis, 48/238 (20%) patients experienced an LAE, while 110/238 (46%) patients experienced an unexplained syncope. During a mean follow-up of 9.7±7.6 years of treatment with BB only, 35/238 (15%) patients experienced one or more LAEs (annual rate 4.0%, 95% CI: 3.1%-5.0%), with a mean of 2.1±2.4 LAEs per patient. Multivariable analysis with multiple events at follow-up showed that LAE before diagnosis (HR 3.9; 95%CI: 2.3-6.8; p&lt;0.001), syncope before diagnosis (HR 2.7; 95%CI: 1.5-5.0; p=0.001), TRDN mutations (HR 10.9; 95%CI: 4.2-28.0; p&lt;0.001) and use of β1-selective BBs (HR 3.0; 95%CI: 1.7-5.3; p&lt;0.001) were significantly associated with the occurrence of LAE (Figure). Conclusions: In patients with CPVT, history of LAE and/or unexplained syncope before diagnosis, TRDN mutations and the use of selective BBs are independent risk factors for the occurrence of multiple LAEs at follow-up during BB treatment.

Abstract 15666: Survival Benefit of Implantable Cardioverter Defibrillators in Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

Introduction: The effectiveness of implantable cardioverter-defibrillators (ICDs) in reducing mortality in patients with Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is debated.Hypothesis. The ICD confers survival benefit in patients with CPVT. Methods: We included n=238 genotype-proven CPVT patients, of whom 91 (38%) had an ICD implanted. All patients were treated with beta-blocker (BB) monotherapy. Survival probability at the occurrence of a first Life-threatening Arrhythmic Event (LAE, defined as: sudden cardiac death, aborted cardiac arrest or hemodynamically non-tolerated ventricular tachycardia) was compared between ICD carriers and non-ICD carriers. In ICD carriers, the benefit-to-harm ratio (rate of appropriate shocks on LAE over rate of major complications) was investigated. Results: During 1,643 person-years of follow-up, 35/238 (15%) patients experienced a first LAE on BB monotherapy (annual LAE rate 2.1%, 95%CI: 1.5-3.0%). Of the 35 individuals who experienced an LAE, 23 patients had an ICD when the LAE occurred, and all survived after ICD shock. Of the remaining 12 patients who were not carriers of an ICD, 4/12 (33%) died suddenly, 2/12 (17%) survived but suffered anoxic brain injury, while 6/12 (50%) survived without consequences. The probability of dying at the occurrence of a first LAE was 25-fold higher (OR: 24.9, 95% CI: 1.2-513.0; p=0.037) in patients without an ICD, as compared to patients with an ICD. Major complications occurred in 17/91 (19%) patients with an ICD (2.6% per year, 95%CI: 1.5%-4.1%). Comparing the rate of major complication to the rate of appropriate ICD shocks on LAE (LAE rate 5.2% per year, 95%CI: 3.5-7.4%), the benefit-to-harm ratio was 2, favoring the benefit of ICD therapy. Conclusion: The ICD conferred a significant survival benefit in terms of arrhythmic mortality at the occurrence of the first LAE in BB monotherapy.

Catecholaminergic polymorphic ventricular tachycardia: risk modulators in patients treated with beta-blockers

Abstract Background Due to the catecholaminergic nature of arrhythmias that define the Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), beta-blockers (BBs) represent the first line therapy for this severe arrhythmogenic syndrome. Despite optimal BB therapy, a proportion of patients continue to suffer breakthrough life-threatening arrhythmias (LAE). Purpose To evaluate the role different classes of BBs (β1-selective vs. non-selective) in LAE reduction and to identify risk factors for breakthrough LAE while on BB monotherapy. Methods We studied 238 consecutive patients with CPVT and treated with BB monotherapy followed-up prospectively. CPVT was diagnosed according to the 2015 European Society of Cardiology Guidelines. The endpoint was the occurrence of the first LAE (sudden cardiac death, aborted cardiac arrest, or hemodynamically non-tolerated ventricular tachycardia) in BB monotherapy. The follow-up for each patient was calculated from BB therapy start to the occurrence of the endpoint, death from non-arrhythmic cause, the date of last visit, or the initiation of other treatments (i.e.: other antiarrhythmics or left cardiac sympathetic denervation [LCSD]), whichever occurred first. Multivariable Cox proportional hazards model was used to evaluate the effects of history of LAE before diagnosis of CPVT, occurrence of unexplained syncope before diagnosis of CPVT, genotype, and type of BB therapy, as a time-dependent variable, on the risk of experiencing an LAE during BB monotherapy. Results We enrolled 238 CPVT patients (135 probands, 135 females): 226 with typical CPVT (n=216 RYR2; n=10 CASQ2) and 12 with atypical CPVT (n=5 RYR2-Loss-of-Function, n=4 TRDN and n=3 TECRL). Prior to BB monotherapy, 48/238 (20%) patients had survived an LAE, and 110/238 (46%) patients had experienced an unexplained syncope. During 1,629 person-years of follow-up during BB monotherapy, 35 patients experienced an LAE (annual LAE rate 2.1%, 95% CI: 1.5%–3.0%; Figure A). Five-year cumulative probability of experiencing an LAE during BB monotherapy was 11.9% (95% CI: 7.0%-16.6%). In this population, multivariable analysis showed that history of LAE before diagnosis (HR 3.6; 95% CI: 1.6–8.1; p=0.002) and syncope before diagnosis (HR 6.1; 95% CI: 2.5–14.9; p&amp;lt;0.001) were clinical risk factors for LAE occurrence. Patients with TRDN mutations were significantly more likely to suffer LAE (HR 20.9; 95% CI: 2.2–196.3; p=0.008). Using nadolol as the gold standard, the use of β1-selective BBs (HR 3.4; 95% CI: 1.4–8.6; p=0.009), but not propranolol (HR: 0.9; 95% CI: 0.2–3.8; p=0.887), was associated with poorer outcome during BB monotherapy (Figure B). Conclusions In patients with CPVT, selective BBs are associated with a higher risk of LAE as compared to nadolol. Patients who have survived an LAE and/or experienced an unexplained syncope prior to diagnosis, as well as carriers of TRDN mutations are at high risk of BB failure. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ricerca Corrente Funding scheme of the Italian Ministry of Health and Italian Ministry of Research and University Dipartimenti di Eccellenza 2018–2022 grant to the Molecular Medicine Department (University of Pavia).

A gain of function ryanodine receptor 2 mutation (R1760W-RyR2) in catecholaminergic polymorphic ventricular tachycardia.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome associated with Ca2+ leak predominantly caused by ryanodine receptor 2 (RyR2) mutations. We identified a R1760W-RyR2 mutation located between the N-terminal domain and the central domain of RyR2 in a CPVT patient by DNA sequencing. Recombinant mutant RyR2-2801mcherry plasmid generated by the overlap extension polymerase chain reaction and seamless cloning was transfected in HEK293 cells for the cell model. Single-cell luminal and cytosolic Ca2+ imaging was measured by endoplasmic reticulum (ER) luminal Ca2+ -sensitive protein D1ER and Fura-2 AM on a confocal laser scanning microscope, respectively. We found that in RyR2 mutant cells, the propensity for store-overload-induced Ca2+ release (SOICR) was enhanced representing increased Ca2+ oscillations, reduced activation and termination thresholds of spontaneous Ca2+ release; and the sensitivity to cytosolic Ca2+ activation was increased manifesting reduced steady state ER Ca2+ levels. Our results indicated that R1760W-RyR2 mutation induced calcium leak, representing a gain of function. Further, antiarrhythmic drugs propafenone and flecainide significantly suppressed SOICR caused by the R1760W-RyR2 mutation at a concentration of 20 μM, which was lower than the concentration at which carvedilol suppressed SOICR.

Clinical Characteristics, Genetic Findings and Arrhythmic Outcomes of Patients with Catecholaminergic Polymorphic Ventricular Tachycardia from China: A Systematic Review

Introduction: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited cardiac ion channelopathy. The present study aims to examine the clinical characteristics, genetic basis, and arrhythmic outcomes of CPVT patients from China to elucidate the difference between CPVT patients in Asia and Western countries. Methods: PubMed and Embase were systematically searched for case reports or series reporting on CPVT patients from China until 19 February 2022 using the keyword: “Catecholaminergic Polymorphic Ventricular Tachycardia” or “CPVT”, with the location limited to: “China” or “Hong Kong” or “Macau” in Embase, with no language or publication-type restriction. Articles that did not state a definite diagnosis of CPVT and articles with duplicate cases found in larger cohorts were excluded. All the included publications in this review were critically appraised based on the Joanna Briggs Institute Critical Appraisal Checklist. Clinical characteristics, genetic findings, and the primary outcome of spontaneous ventricular tachycardia/ventricular fibrillation (VT/VF) were analyzed. Results: A total of 58 unique cases from 15 studies (median presentation age: 8 (5.0–11.8) years old) were included. All patients, except one, presented at or before 19 years of age. There were 56 patients (96.6%) who were initially symptomatic. Premature ventricular complexes (PVCs) were present in 44 out of 51 patients (86.3%) and VT in 52 out of 58 patients (89.7%). Genetic tests were performed on 54 patients (93.1%) with a yield of 87%. RyR2, CASQ2, TERCL, and SCN10A mutations were found in 35 (71.4%), 12 (24.5%), 1 (0.02%) patient, and 1 patient (0.02%), respectively. There were 54 patients who were treated with beta-blockers, 8 received flecainide, 5 received amiodarone, 2 received verapamil and 2 received propafenone. Sympathectomy (n = 10), implantable cardioverter-defibrillator implantation (n = 8) and ablation (n = 1) were performed. On follow-up, 13 patients developed VT/VF. Conclusion: This was the first systematic review of CPVT patients from China. Most patients had symptoms on initial presentation, with syncope as the presenting complaint. RyR2 mutation accounts for more than half of the CPVT cases, followed by CASQ2, TERCL and SCN10A mutations.

Modeling neuro-cardiac disorders using patient-specific iPSC and CRISPR/Cas9 technologies

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a severe genetic arrhythmia associated with dysfunction in more than 80% of the type 2 cardiac ryanodine receptor (RyR2). It is characterized by ventricular tachycardia induced by catecholamines, by SNA stimulation (i.e. sympathetic tone), which manifests as syncope or even sudden death in childhood. CPVT patients can also frequently develop neuro-psycho behavioral disorders, including autism. Autism is a neurodevelopmental disorder characterized by difficulties with social interaction and communication, and by restricted and repetitive behavior. Autism appears from an early age. Research suggests that autism develops from a combination of genetic and nongenetic, or environmental, influences. The behavioral and cognitive features of autism are associated with pervasive abnormalities in the central nervous system (CNS). As RyR2 is expressed in heart and brain, and based on our previous work, we hypothesize that leaky RyR2 in CPVT patients affects both the cardiomyocytes and neurons. Using patient-specific induced pluripotent stem cell (hiPSC), we differentiate them into cardiomyocytes and neurons. We performed structural and functional characterizations of the control and CPVT cardiomyocytes and neurons by immunofluorescence, fluorescent confocal microscopy, IonOptix and video-edge capture was done. From the different differentiation protocols, we are able to obtain ventricular cardiomyocytes and neurons from the CNS. CPVT cardiomyocytes exhibit calcium and contractile defects, leaky RyR2 which are typical of CPVT. Surprisingly, CPVT neurons exhibit impaired size, altered intracellular calcium handling, leaky RyR2 and neurotransmitter secretion. From the same CPVT patient, we are able to obtain ventricular cardiomyocytes and CNS neurons. Our preliminary data demonstrate that CPVT cardiomyocytes and neurons exhibit defects including RyR2 leak and neuronal impairment reminiscent of autism. This demonstrates for the first time a potential role of RyR2 mediated calcium leak in autism.

Generation of an induced pluripotent stem cell line from a Chinese Han child with catecholaminergic polymorphic ventricular tachycardia

TECRL, first reported in a Sudanese family with catecholaminergic polymorphic ventricular tachycardia (CPVT) in 2016. TECRL, is an endoplasmic reticulum (ER) protein preferentially expressed in the heart, playing a role in cardiomyocyte calcium homeostasis. Using Sendaivirus-mediated reprogramming, we generated an induced pluripotent stem cell (iPSC) line from the CPVT patient’s peripheral blood mononuclear cell. The iPSC exhibited stable amplification, expressed pluripotent markers, and differentiated spontaneously into three layers in vitro. Additionally, the iPSC line maintained a normal karyotype, retained the pathogenic TECRL mutation, and the cell resource facilitated a platform to explore the CPVT mechanisms related to TECRL mutations.

Identifying Features of Cardiac Disease Phenotypes Based on Mechanical Function in a Catecholaminergic Polymorphic Ventricular Tachycardia Model.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is characterized by an arrhythmogenic mechanism involving disruption of calcium handling. This genetic disease can lead to sudden death in children and young adults during physical or emotional stress. Prior CPVT studies have focused on calcium handling, but mechanical functionality has rarely been investigated in vitro. In this research we combine stem cell-derived cardiomyocytes from a CPVT patient (RyR2-H2464D mutation) and a healthy familial control with an engineered culture platform to evaluate mechanical function of cardiomyocytes. Substrates with Young’s modulus ranging from 10 to 50 kPa were used in conjunction with microcontact printing of ECM proteins into defined patterns for subsequent attachment. Digital Image Correlation (DIC) was used to evaluate collections of contracting cells. The amplitude of contractile strain was utilized as a quantitative indicator of functionality and disease severity. We found statistically significant differences: the maximum contractile strain was consistently higher in patient samples compared to control samples on all substrate stiffnesses. Additionally, the patient cell line had a statistically significantly slower intrinsic contraction rate than the control, which agrees with prior literature. Differences in mechanical strain have not been previously reported, and hypercontractility is not a known characteristic of CPVT. However, functional changes can occur as the disease progresses, thus this observation may not represent behavior observed in adolescent and adult patients. These results add to the limited studies of mechanical function of CPVT CMs reported in literature and identify functional differences that should be further explored.

Clinical characteristics, outcomes, and genetic findings of patients with catecholaminergic polymorphic ventricular tachycardia in Hong Kong: A systematic review

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare cardiac ion channelopathy. This was the first systematic review of published works on the clinical characteristics, outcomes, and genetic findings of patients with CPVT from Hong Kong. PubMed and Embase were searched electronically from their inception until February 2022. The Joanna Briggs Institute Critical Appraisal Checklist was used to critically appraise included studies. Studies written in English describing at least one patient with CPVT were included. Studies describing overlapping CPVT patients from previous reports were excluded. Two studies describing 17 patients with CPVT were included. All included studies were rated of acceptable quality. The largest case series evaluated 16 CPVT patients with a mean presentation age of 11 ± 4 years. Of these, 15 patients (93.8%) were symptomatic at initial presentation. Ten patients presented with both premature ventricular complexes (PVCs) and ventricular tachycardia/ventricular fibrillation (VT/VF), whereas one had PVCs without VT/VF. Among the 14 patients (87.5%) who underwent genetic testing, eight (57.1%) tested positive for the ryanodine receptor 2 (RyR2) gene. Over a mean follow-up duration of 116 ± 36 months, six patients (37.5%) had incident VT/VF. In a 5-year review of autopsy data retrieved from public mortuaries for 289 sudden cardiac death patients, one CPVT patient (0.03%) was identified. All patients with CPVT in Hong Kong presented at or below 19 years old, of whom a majority were initially symptomatic or had incident VT/VF events. Novel genetic variants in the RyR2 gene not reported beyond our locality were identified.