‘It had to be done’: genetic testing decisions for arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable disease of the heart muscle, causing life‐threatening ventricular arrhythmias, sudden cardiac death and/or biventricular heart failure. Little research examines ARVC genetic test decisions, despite the gravity of the condition. This qualitative study used semi‐structured interviews to explore the testing decisions of 21 individuals across 15 families segregating a well‐studied, particularly lethal form of ARVC caused by a p.S358L TMEM43 mutation. Genetic testing decisions were rarely described as ‘decisions’ per se, but rather ‘something that had to be done’. This perception was attributed to personality type or personal suspicion of carrying the TMEM43 mutation, but most often was described in the context of testing for other family members, usually children. Participants related a strong need to rule out risk, more for children than for themselves, but lingering doubts remained about personal and children's risk for ARVC, even when gene test results were negative. Study findings highlight the interdependent nature of genetic test decisions and suggest that an individualistic conception of autonomy in genetic services may not meet the needs of affected families. Findings also suggest the need for follow‐up support of families affected by ARVC, including for those individuals testing negative for the family mutation.     

Cardiac Magnetic Resonance Normal Reference Values of Biventricular Size and Function in Male Athlete’s Heart

ObjectivesThe aim of this meta-analysis was to derive normal reference values of biventricular size and function estimated by cardiac magnetic resonance (CMR) in competitive athletes.BackgroundExercise-induced enlargement of cardiac chambers is commonly observed in competitive athletes. However, ventricular dilatation is also a common phenotypic expression of life-threatening cardiomyopathies. The use of CMR for the exclusion of pathology is growing. However, normal reference values have not been established for athletes.MethodsThe authors conducted a systematic review of English-language studies in the MEDLINE, Scopus, and Cochrane databases investigating biventricular size and function by CMR in athletes. Athletes were divided into endurance, combined, and mixed groups according to the sport practiced. The potential impact of training volume was also evaluated.ResultsTwenty-seven studies and 983 competitive athletes were included for CMR quantification of biventricular size and function. In this review, normal reference values are presented for biventricular size and function to be applied to male competitive athletes according to the disciplines practiced. A significant impact of training volume was demonstrated for the right ventricle: athletes practicing the largest number of training hours per week were those exhibiting the greatest degree of right ventricular remodeling. Notably, biventricular function was not significantly affected by training volume.ConclusionsThe present meta-analysis defines the normal limits of biventricular size and function estimated by CMR in competitive athletes. The authors suggest using these normal reference values as an alternative to standard upper limits derived from the general population when interpreting CMR images in athletes.     

The electrocardiogram in right ventricular cardiomyopathy/dysplasia. How can the electrocardiogram assist in understanding the pathologic and functional changes of the heart in this disease?

The electrocardiogram (ECG) provides important information to aid in the diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). The ECG changes may be explained by the pathophysiology of the disease. The proximity of the right ventricle (RV) to the anterior chest leads (V₁ to V₄) explains why the characteristic ECG abnormalities are most prominent in those lends. The specific ECG abnormalities reflect the pathophysiology of the disease including T-wave inversion due to scarring of the free wall of the RV, prolonged S-wave duration due to slow depolarization of the terminal part of the QRS because the RV is the last part of the heart to undergo depolatization, and epsilon waves due to slow conduction in the RV. The extent of ECG abnormalities correlate with the degree of structural change in the RV.     

Arrhythmogenic right ventricular cardiomyopathy with biventricular involvement and heart failure in a 9-year old girl

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is seldom recognized clinically in infancy or under the age of 10. We report a case of a 9-year-old girl with ARVC, who presented with signs and symptoms of heart failure and palpitations. Holter monitoring showed frequent premature ventricular beats and echocardiogram revealed dilated and dysfunctional right ventricle with normal tricuspid valve and no evidence of intracardiac shunt. Cardiac magnetic resonance showed classical features of ARVC with both ventricular involvements. After optimization of medical treatment the patient was referred for ICD implantation.     

Identification of sarcomeric variants in probands with a clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC)

1 Aims

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by ventricular arrhythmias and sudden death. Currently 60% of patients meeting Task Force Criteria (TFC) have an identifiable mutation in one of the desmosomal genes. As much overlap is described between other cardiomyopathies and ARVC, we examined the prevalence of rare, possibly pathogenic sarcomere variants in the ARVC population.

2 Methods

One hundred and thirty‐seven (137) individuals meeting 2010 TFC for a diagnosis of ARVC, negative for pathogenic desmosomal variants, TMEM43, SCN5A, and PLN were screened for variants in the sarcomere genes (ACTC1, MYBPC3, MYH7, MYL2, MYL3, TNNC1, TNNI3, TNNT2, and TPM1) through either clinical or research genetic testing.

3 Results

Six probands (6/137, 4%) were found to carry rare variants in the sarcomere genes. These variants have low prevalence in controls, are predicted damaging by Polyphen‐2, and some of the variants are known pathogenic hypertrophic cardiomyopathy mutations. Sarcomere variant carriers had a phenotype that did not differ significantly from desmosomal mutation carriers. As most of these probands were the only affected individuals in their families, however, segregation data are noninformative.

4 Conclusion

These data show variants in the sarcomere can be identified in individuals with an ARVC phenotype. Although rare and predicted damaging, proven functional and segregational evidence that these variants can cause ARVC is lacking. Therefore, caution is warranted in interpreting these variants when identified on large next‐generation sequencing panels for cardiomyopathies.     

中国人心律失常性右心室发育不良或心肌病的临床特点

目的总结分析中国致心律失常性右心室发育不良或心肌病(ARVD/C)患者的临床特征。方法分析中国ARVD/C注册研究组收集的中国24个省市1994~2005年间发现的96例ARVD/C患者的临床资料,包括人口统计学、病史、家族史、临床表现、心电图(12导联、24小时动态心电图)和超声心动图以及治疗情况,部分患者接受右心室造影、心脏磁共振成像(MRI)和心内膜心肌活组织检查。结果96例患者的平均年龄(37±15)岁,男性75例(78.1%);其中37例(38.5%)患者有晕厥病史,70例(72.9%)患者仅有心悸症状。14例患者(14.6%)因劳力诱发了猝死(SD),发生SD的年龄(34±11)岁,其中78.6%(11/14)为男性患者;55例患者(57.3%)心电图记录到起源于右心室(RV)的室性心动过速(VT)。除1例患者外,其余95例(99.0%)超声心动图结果异常,主要为RV扩大;30例(31.25%)患者的心电图中可见epsilon波,47例(49.0%)患者V1~3导联T波倒置;有症状的室性心律失常患者接受胺碘酮(n=26)、美西律(n=21)、β阻滞剂(n=14)、维拉帕米(n=4)或采用其他抗心律失常治疗。31.52%的患者(29/96)应用抗心律失常药物治疗无效,19例患者接受射频消融治疗,但其中有11例患者出现VT复发。4例患者植入植入式心脏自动起搏除颤器(ICD)。结论根据国际工作组的诊断指标,在中国只有严重的ARVD病例才能被诊断;30%以上的患者应用抗心律失常药物的疗效很差,57.89%的患者应用射频消融治疗无效,需要植入ICD,但ICD植入率在中国仅占4.17%。     

致心律失常性右室心肌病14例临床分析

目的：提高对致心律失常性右室心肌病（ARVC）的诊断、治疗及预后的认识。方法：对1993－2001年入住复旦大学附属中山医院的14例致心律失常性右室心肌病的病例进行回顾性分析并随访。观察ARVC的临床表现及心电图、超声心动图、电生理检查等表现，评价ARVC的治疗方法和预后。结果：14例患者均以室性心律失常起病。心电图及超声心动图是正确诊断的重要方法。随访中有3例死亡，2例出现右心衰竭。1例在射频消融治疗后无须药物治疗室性心律失常明显减少。其余均需药物长期维持治疗。结论：致心律失常性右室心肌病以室性心律失常为主要表现，发作时常伴严重血流动力学障碍。心电图有特征性改变，其诊断主要依靠超声心动图。治疗以药物为主，射频消融未显示优越性。晚电位阳性、有过阿斯综合征、右室整体收缩功能异常者预后不良。     

Role of genetic testing in arrhythmogenic right ventricular cardiomyopathy/dysplasia

Barahona-Dussault C, Benito B, Campuzano O, Iglesias A, Leung TL, Robb L, Talajic M, Brugada R. Role of genetic testing in arrhythmogenic right ventricular cardiomyopathy/dysplasia.
In a cohort of patients with confirmed or suspected arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), genetic testing is useful in confirming the diagnosis, particularly in individuals who do not completely fulfil Task Force criteria for the disease, thereby also enabling the adoption of preventive measures in family members. Due to the high percentage of novel mutations that are expected to be identified in ARVC/D, the use of genetic screening technology based on the identification of known mutations seems to have very restricted value. Our results support that the presence of certain genetic variations could play a role in the final phenotype of patients with ARVC/D, where single and compound mutation carriers would have more symptomatic forms of the disease and the polymorphism P366L could be associated to a more benign phenotype.