RyR2 Common Gene Variant G1886S and the Risk of Ventricular Arrhythmias in ICD Patients with Heart Failure

Non‑synonymous polymorphisms in the HRC and ADRB1 genes may be associated with all‑cause death in patients with non‑ischemic heart failure

Sudden cardiac death (SCD) is an unpredictable and common mode of death in patients with heart failure (HF). Alterations in calcium handling may lead to malignant arrhythmias, resulting in SCD, and variants in calcium signaling-related genes have a significant association with SCD. Therefore, the aim of the present retrospective cohort study was to investigate the association of Ser96Ala [histidine-rich calcium-binding protein (HRC)], Ser49Gly [β1-adrenergic receptor (ADRB1)], Arg389Gly (ADRB1) and Gly1886Ser [ryanodine receptor 2 (RYR2)] polymorphisms with serious arrhythmic events and overall mortality in patients with HF with reduced left ventricular ejection fraction of non-ischemic etiology. In total, 136 patients with HF underwent physical examination, routine laboratory tests, non-invasive assessment of cardiac function and an invasive electrophysiological study. The primary outcome was the occurrence of serious arrhythmic events, set as either SCD or appropriate implantable cardioverter-defibrillator (ICD) therapy, and the secondary outcome was all-cause death. During a median follow-up of 37 months, arrhythmic events occurred in 26 patients (19%) and 41 patients (30%) died. Patients carrying the Ser allele of the Ser96Ala polymorphism in HRC had worse survival than those with the Ala/Ala genotype (log-rank P=0.043). Despite the difference in survival time, the Ala/Ala genotype was not associated with all-cause death in the regression analysis [unadjusted hazard ratio (HR)=0.17; 95% CI, 0.02-1.21]. Regarding the Ser49Gly and Arg389Gly polymorphisms in ADRB1, homozygosity for the major alleles at both sites (Ser49Ser and Arg389Arg) was associated with a two-fold increased risk of all-cause death compared with the other genotype combinations (unadjusted HR=1.98; 95% CI, 1.02-3.82). However, this association was lost after controlling for clinical covariates. No association was observed for the Gly1886Ser polymorphism in RYR2. Overall, the present findings are concurrent with the hypothesis that the Ser96Ala (HRC), Ser49Gly (ADRB1) and Arg389Gly (ADRB1) polymorphisms may be associated with HF prognosis. In particular, the Ser96Ala polymorphism might aid in risk stratification and patient selection for ICD implantation.

Construction of a risk scoring system using clinical factors and RYR2 polymorphisms for bleeding complications in patients on direct oral anticoagulants

Introduction: Bleeding is one of the most undesirable complications of direct oral anticoagulants (DOACs). While the ryanodine receptor (RYR2) has been related to cardiac diseases, research on bleeding complications is lacking. This study aimed to elucidate the association between RYR2 and bleeding risk to develop the risk scoring system in patients treated with DOACs. Methods: This study was a retrospective analysis of prospectively collected samples. We selected ten SNPs within the RYR2 gene, and two models were constructed (Model I: demographic factors only, Model II: demographic and genetic factors) in multivariable analysis. Independent risk factors for bleeding were used to develop a risk scoring system. Results: A total of 447 patients were included, and 49 experienced either major bleeding or clinically relevant non-major bleeding. In Model I, patients using rivaroxaban and experiencing anemia exhibited an increased bleeding risk after adjusting for covariates. Upon incorporating genetic factors into Model I, a significant association with bleeding was also observed in cases of overdosing on DOACs and in patients with a creatinine clearance (CrCl) < 30 mL/min, in addition to rivaroxaban and anemia (Model II). Among genetic factors, RYR2 rs12594 GG, rs17682073 AA, rs3766871 GG, and rs6678625 T alleles were associated with bleeding complications. The area under the receiver operating characteristic curve (AUROC) of Model I was 0.670, whereas that of Model II increased to 0.803, demonstrating better performance with the inclusion of genetic factors. Using the significant variables in Model II, a risk scoring system was constructed. The predicted bleeding risks for scores of 0, 1-2, 3-4, 5-6, 7-8, and 9-10 points were 0%, 1.2%, 4.6%, 15.7%, 41.7%, and 73.3%, respectively. Conclusion: This study revealed an association between RYR2 and bleeding complications among patients taking DOACs and established a risk scoring system to support individualized DOAC treatment for these patients.

Role of induced pluripotent stem cells in diagnostic cardiology

Ethical concerns about stem cell-based research have delayed important advances in many areas of medicine, including cardiology. The introduction of induced pluripotent stem cells (iPSCs) has supplanted the need to use human stem cells for most purposes, thus eliminating all ethical controversies. Since then, many new avenues have been opened in cardiology research, not only in approaches to tissue replacement but also in the design and testing of antiarrhythmic drugs. This methodology has advanced to the point where induced human cardiomyocyte cell lines can now also be obtained from commercial sources or tissue banks. Initial studies with readily available iPSCs have generally confirmed that their behavioral characteristics accurately predict the behavior of beating cardiomyocytes in vivo. As a result, iPSCs can provide new ways to study arrhythmias and heart disease in general, accelerating the development of new, more effective antiarrhythmic drugs, clinical diagnoses, and personalized medical care. The focus on producing cardiomyocytes that can be used to replace damaged heart tissue has somewhat diverted interest in a host of other applications. This manuscript is intended to provide non-specialists with a brief introduction and overview of the research carried out in the field of heart rhythm disorders.

Catecholaminergic polymorphic ventricular tachycardia patients with multiple genetic variants in the PACES CPVT Registry

BACKGROUND

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is often a life-threatening arrhythmia disorder with variable penetrance and expressivity. Little is known about the incidence or outcomes of CPVT patients with ≥2 variants.

METHODS

The phenotypes, genotypes and outcomes of patients in the Pediatric and Congenital Electrophysiology Society CPVT Registry with ≥2 variants in genes linked to CPVT were ascertained. The American College of Medical Genetics & Genomics (ACMG) criteria and structural mapping were used to predict the pathogenicity of variants (3D model of pig RyR2 in open-state).

RESULTS

Among 237 CPVT subjects, 193 (81%) had genetic testing. Fifteen patients (8%) with a median age of 9 years (IQR 5-12) had ≥2 variants. Sudden cardiac arrest occurred in 11 children (73%), although none died during a median follow-up of 4.3 years (IQR 2.5-6.1). Thirteen patients (80%) had at least two RYR2 variants, while the remaining two patients had RYR2 variants plus variants in other CPVT-linked genes. Among all variants identified, re-classification of the commercial laboratory interpretation using ACMG criteria led to the upgrade from variant of unknown significance (VUS) to pathogenic/likely pathogenic (P/LP) for 5 variants, and downgrade from P/LP to VUS for 6 variants. For RYR2 variants, 3D mapping using the RyR2 model suggested that 2 VUS by ACMG criteria were P/LP, while 2 variants were downgraded to likely benign.

CONCLUSIONS

This severely affected cohort demonstrates that a minority of CPVT cases are related to ≥2 variants, which may have implications on family-based genetic counselling. While multi-variant CPVT patients were at high-risk for sudden cardiac arrest, there are insufficient data to conclude that this genetic phenomenon has prognostic implications at present. Further research is needed to determine the significance and generalizability of this observation. This study also shows that a rigorous approach to variant re-classification using the ACMG criteria and 3D mapping is important in reaching an accurate diagnosis, especially in the multi-variant population.