The Expansion of Genetic Testing in Cardiovascular Medicine: Preparing the Cardiology Community for the Changing Landscape

PURPOSE OF REVIEW

Pathogenic DNA variants underlie many cardiovascular disease phenotypes. The most well-recognized of these include familial dyslipidemias, cardiomyopathies, arrhythmias, and aortopathies. The clinical presentations of monogenic forms of cardiovascular disease are often indistinguishable from those with complex genetic and non-genetic etiologies, making genetic testing an essential aid to precision diagnosis.

RECENT FINDINGS

Precision diagnosis enables efficient management, appropriate use of emerging targeted therapies, and follow-up of at-risk family members. Genetic testing for these conditions is widely available but under-utilized. In this review, we summarize the potential benefits of genetic testing, highlighting the specific cardiovascular disease phenotypes in which genetic testing should be considered, and how clinicians can integrate guideline-directed genetic testing into their practice.

A Practical Guide to Genetic Testing in Inherited Heart Disease

Genetic testing has increasingly been shown to provide critical information regarding the treatment and management of patients with hereditary cardiomyopathies and arrhythmias and is available for a wide variety of conditions. It can provide information regarding arrhythmia risk, lifestyle recommendations, such as exercise avoidance, pharmaceutical therapies, and prognosis. Beyond the proband, genetic testing can be a valuable tool for cascade screening in the family. Genetic testing should be accompanied with genetic counseling, as genetic tests should be accompanied by expert interpretation, support in cascade family evaluation, and psychosocial considerations. Overall, it should be routinely implemented in arrhythmia and cardiomyopathy clinics.

Causes of sudden cardiac death according to age and sex in persons aged 1-49 years

BACKGROUND

Knowledge of causes of sudden cardiac death (SCD) according to age is important in clinical decision making and to lower the risk of SCD in family members of the deceased.

OBJECTIVE

The purpose of this study was to report overall and sex-stratified causes of SCD according to age in persons aged 1-49 years.

METHODS

The study population consisted of all persons in Denmark aged 1-35 years in 2000-2009 and 36-49 years in 2007-2009, which equals 27.1 million person-years. Danish death certificates, discharge summaries, autopsy reports, and data from nationwide registries were used to identify all SCD cases. The SCD cases were divided into 5-year age groups.

RESULTS

In the 10-year study period, there were 14,294 deaths, of which 1362 (10%) were classified as SCD. Potentially inherited cardiac disease accounted for a high proportion (43%-78%) of autopsied SCD in all age groups. A significant proportion (19%-54%) of SCD was caused by sudden arrhythmic death syndrome in all age groups. Autopsy rates in both sudden unexpected death cases and SCD cases declined significantly with increasing age (74% in the youngest age group vs 35% in the oldest).

CONCLUSION

The proportion of SCD cases that were identified with a potentially inherited cardiac disease postmortem was high in all studied age groups, while autopsy rates in sudden and unexpected death cases declined markedly with increasing age. Our findings indicate that diagnoses of inherited heart disease are likely missed in some SCD cases, along with the opportunity for treatment and prevention in surviving relatives.

Role of genetic testing in young patients with idiopathic atrioventricular conduction disease

AIMS

To investigate the role of genetic testing in patients with idiopathic atrioventricular conduction disease requiring pacemaker (PM) implantation before the age of 50 years.

METHODS AND RESULTS

All consecutive PM implantations in Southern Switzerland between 2010 and 2019 were evaluated. Inclusion criteria were: (i) age at the time of PM implantation: < 50 years; (ii) atrioventricular block (AVB) of unknown aetiology. Study population was investigated by ajmaline challenge and echocardiographic assessment over time. Genetic testing was performed using next-generation sequencing panel, containing 174 genes associated to inherited cardiac diseases, and Sanger sequencing confirmation of suspected variants with clinical implication. Of 2510 patients who underwent PM implantation, 15 (0.6%) were young adults (median age: 44 years, male predominance) presenting with advanced AVB of unknown origin. The average incidence of idiopathic AVB computed over the 2010-2019 time window was 0.7 per 100 000 persons per year (95% CI 0.4-1.2). Most of patients (67%) presented with specific genetic findings (pathogenic variant) or variants of uncertain significance (VUS). A pathogenic variant of PKP2 gene was found in one patient (6.7%) with no overt structural cardiac abnormalities. A VUS of TRPM4, MYBPC3, SCN5A, KCNE1, LMNA, GJA5 genes was found in other nine cases (60%). Of these, three unrelated patients (20%) presented the same heterozygous missense variant c.2531G > A p.(Gly844Asp) in TRPM4 gene. Diagnostic re-assessment over time led to a diagnosis of Brugada syndrome and long-QT syndrome in two patients (13%). No cardiac events occurred during a median follow-up of 72 months.

CONCLUSION

Idiopathic AVB in adults younger than 50 years is a very rare condition with an incidence of 0.7 per 100 000 persons/year. Systematic investigations, including genetic testing and ajmaline challenge, can lead to the achievement of a specific diagnosis in up to 20% of patients. Heterozygous missense variant c.2531G > A p.(Gly844Asp) in TRPM4 gene was found in an additional 20% of unrelated patients, suggesting possible association of the variant with the disease.

Anxiety and depression in inherited channelopathy patients with implantable cardioverter-defibrillators

Background

Implantable cardioverter-defibrillators (ICDs) are an effective treatment in some patients with inherited heart disease, including inherited channelopathies, yet they have also been shown to impact patients' psychological health.

Objective

We sought to improve understanding of the level of anxiety and depression as well as device acceptance among inherited channelopathy patients with an ICD.

Methods

Eligible patients seen at Johns Hopkins Hospital were sent a survey, which included the Hospital Anxiety and Depression Scale (HADS), Cardiac Anxiety Questionnaire (CAQ), and the Florida Patient Acceptance Survey (FPAS). Student t tests and χ² tests were used to identify associations with abnormal anxiety and depression scores.

Results

Among eligible patients (n = 65), 32 individuals (49%) completed the survey. The rate of device-related complications was 34%, and 41% of patients experienced 1 or more ICD shocks. Twelve patients (38%) had an abnormal HADS anxiety subscore and 5 patients (16%) had an abnormal HADS depression subscore (score ≥ 8). Secondary-prevention ICDs were associated with an abnormal HADS anxiety subscore (P = .03). Experiencing ICD shock(s), device complications, age, sex, and family history of sudden cardiac death were not statistically associated with anxiety or depression. Overall, respondents demonstrated high device acceptance by FPAS (79.9 ± 2.9, maximum total score 100) and moderately high cardiac-specific anxiety by CAQ total score (1.53 ± 0.12).

Conclusion

A high prevalence of generalized anxiety was identified among inherited channelopathy patients with ICDs. High device acceptance and lack of association with ICD shocks or complications indicate that further research is necessary to understand this increased incidence.

Influence of centre expertise on the diagnosis and management of hypertrophic cardiomyopathy: A study from the French register of hypertrophic cardiomyopathy (REMY)

BACKGROUND

Our knowledge of hypertrophic cardiomyopathy (HCM) mainly originates from quarternary centres. The objective is to assess the current management of HCM patients in a large multicentre French register according to the level of expertise.

METHODS AND RESULTS

A total of 1431 HCM patients were recruited across 26 (11 expert and 15 non-expert) centres in REMY, a prospective hospital-based register of adult HCM patients. A sarcomeric origin was suspected in 1284 (89.7%) patients [261 (20.3%) with a reported gene mutation, 242 (18.8%) genotype-negative], while 107 (7.5%) had a diagnosis of non-sarcomeric HCM. Patients managed in non-expert centres were older (P < 0.01) and presented more often with NYHA III/IV class dyspnoea (P < 0.01), congestive heart failure (P < 0.01), low LEVF (P < 0.01), less often with a syncope history (P < 0.01) and lower LV obstruction (P < 0.01) than patients in expert centres. Genotype positive sarcomeric aetiologies were less frequent in non-expert centres (P < 0.01). The use of diagnostic and prognostic tests as cardiac MRI (P < 0.001), genetic (P < 0.001) and alpha-galactosidase A enzyme level testing (P < 0.001), Holter ECG (P < 0.001), and exercise test (P < 0.001), was lower in non-expert centres. Septal ablation procedures using alcohol (P < 0.001) or myectomy (P < 0.001) were more frequent in expert centres.

CONCLUSION

In real life practice, only a minority of HCM patients are identified as sarcomere positive as per genetic testing. The management of HCM patients varies according to the centre's level of expertise, with less access to diagnostic and prognostic tests in non-expert centres. Non-sarcomeric HCM may therefore be overlooked despite specific treatment in some aetiologies.

Genetic Testing in Inherited Heart Diseases: Practical Considerations for Clinicians

PURPOSE OF REVIEW

Genetic testing has become an important element in the care of patients with inherited cardiac conditions (ICCs). The purpose of this review is to provide clinicians with insights into the utility of genetic testing as well as challenges associated with interpreting results.

RECENT FINDINGS

Genetic testing may be indicated for individuals who are affected with or who have family histories of various ICCs. Various testing options are available and determining the most appropriate test for any given clinical scenario is key when interpreting results. Newly published guidelines as well as various publicly accessible tools are available to clinicians to help with interpretation of genetic findings; however the subjectivity with respect to variant classification can make accurate assessment challenging. Genetic information can provide highly useful and relevant information for patients, their family members, and their healthcare providers. Given the potential ramifications of variant misclassification, expertise in both clinical phenotyping and molecular genetics is imperative in order to provide accurate diagnosis, management recommendations, and family risk assessment for this patient population.

Echocardiographic evaluation of pre-diagnostic development in young relatives genetically predisposed to hypertrophic cardiomyopathy

Identification of the first echocardiographic manifestations of hypertrophic cardiomyopathy may be important for clinical management and our understanding of the pathogenesis. We studied the development of pre-diagnostic echocardiographic changes in young relatives to HCM patients during long-term years follow-up. HCM-relatives not fulfilling the diagnostic criteria for HCM and age of <18 years were included in this study. We performed echocardiographic evaluations at inclusion and after 12 ± 1 years follow-up. Based on family screening of 11 sarcomere genes, CRYAB, α-GAL, and titin, we evaluated: (1) non-carriers (known family mutation ruled out-controls), (2) carriers (phenotype negative gene mutation carriers) and (3) phenotype negative relatives with unknown genetic status (relatives from families without identified mutations). At inclusion (age 11 ± 5 years), there were no differences in echocardiographic chamber dimensions, systolic or diastolic function between the three groups. During follow-up (age 23 ± 5 years), carriers (n = 8) developed lower left ventricular end-diastolic dimension (LVEDd) compared to non-carriers (n = 23) (41 ± 4 vs. 46 ± 4 mm; p = 0.04) and a higher ratio of early left ventricular filling velocity and early diastolic velocity of lateral mitral annulus (E/e' 6 ± 1 vs. 5 ± 1; p = 0.003). No significant differences in LVEDd or E/e' were found between relatives with unknown genetic status (n = 24) and non-carriers though Z-scores for these parameters were >2 in a subset of relatives with unknown genetic status. Children carrying pathogenic sarcomere gene mutations develop reduced LVEDd and increased E/e' as first pre-diagnostic echocardiographic manifestations during follow-up into adulthood.