Screening first-degree relatives of patients with idiopathic dilated cardiomyopathy

Differences in Cardiac Mechanics among Genetically At-Risk First-Degree Relatives: The DCM Precision Medicine Study

Aims

Among genetically at-risk first-degree relatives (FDRs) of probands with dilated cardiomyopathy (DCM), the ability to detect changes in left ventricular (LV) mechanics with normal LV size and ejection fraction (LVEF) remains incompletely explored. We sought to define a pre-DCM phenotype among at-risk FDRs, including those with variants of uncertain significance (VUSs), using echocardiographic measures of cardiac mechanics.

Methods and Results

LV structure and function, including speckle-tracking analysis for LV global longitudinal strain (GLS), were evaluated in 124 FDRs (65% female; median age 44.9 [IQR: 30.6-60.3] years) of 66 DCM probands of European ancestry sequenced for rare variants in 35 DCM genes. FDRs had normal LV size and LVEF. Negative FDRs of probands with pathogenic or likely pathogenic (P/LP) variants (n=28) were a reference group to which negative FDRs of probands without P/LP variants (n=30), FDRs with only VUSs (n=27), and FDRs with P/LP variants (n=39) were compared. In an analysis accounting for age-dependent penetrance, FDRs below the median age showed minimal differences in LV GLS across groups while those above it with P/LP variants or VUSs had lower absolute values than the reference group (-3.9 [95% CI: -5.7, -2.1] or -3.1 [-4.8, -1.4] %-units) and negative FDRs of probands without P/LP variants (-2.6 [-4.0, -1.2] or -1.8 [-3.1, -0.6]).

Conclusions

Older FDRs with normal LV size and LVEF who harbored P/LP variants or VUSs had lower absolute LV GLS values, indicating that some DCM-related VUSs are clinically relevant. LV GLS may have utility for defining a pre-DCM phenotype.

Clinical Trial Registration

clinicaltrials.gov, NCT03037632.

Echocardiographic Deformation Imaging for Early Detection of Genetic Cardiomyopathies: JACC Review Topic of the Week

Clinical screening of the relatives of patients with genetic cardiomyopathies is challenging, as they often lack detectable cardiac abnormalities at presentation. Life-threatening adverse events can already occur in these early stages of disease, so sensitive tools to reveal the earliest signs of disease are needed. The utility of echocardiographic deformation imaging for early detection has been explored for this population in multiple studies but has not been broadly implemented in clinical practice. The authors discuss contemporary evidence on the utility of deformation imaging in relatives of patients with genetic cardiomyopathies. The available body of data shows that deformation imaging reveals early disease-specific abnormalities in dilated cardiomyopathy, hypertrophic cardiomyopathy, and arrhythmogenic cardiomyopathy. Deformation imaging seems promising to enhance the screening and follow-up protocols in relatives, and the authors propose measures to accelerate its implementation in clinical care.

Contemporary and Future Approaches to Precision Medicine in Inherited Cardiomyopathies: JACC Focus Seminar 3/5

Inherited cardiomyopathies are commonly occurring myocardial disorders that are associated with substantial morbidity and mortality. Clinical management strategies have focused on treatment of heart failure and arrhythmic complications in symptomatic patients according to standardized guidelines. Clinicians are now being urged to implement precision medicine, but what does this involve? Advances in understanding of the genetic underpinnings of inherited cardiomyopathies have brought new possibilities for interventions that are tailored to genes, specific variants, or downstream mechanisms. However, the phenotypic variability that can occur with any given pathogenic variant suggests that factors other than single driver gene mutations are often involved. This is propelling a new imperative to elucidate the nuanced ways in which individual combinations of genetic variation, comorbidities, and lifestyle may influence cardiomyopathy phenotypes. Here, Part 3 of a 5-part precision medicine Focus Seminar series reviews the current status and future opportunities for precision medicine in the inherited cardiomyopathies.

Determining the thresholds for abnormal left ventricular strains in healthy subjects by echocardiography: a meta-analysis

Background

Left ventricular global longitudinal strain (LVGLS), circumferential strain (LVGCS) and radial strain (LVGRS) are echocardiographic parameters with wide clinical applicability. However, the thresholds for abnormal left ventricular (LV) strains, particularly the lower limits of normal (LLN), are not well established. This meta-analysis determined the mean and LLN of two- (2D) and three-dimensional (3D) LV strain in healthy subjects and factors that influence strain measurements.

Methods

We searched PubMed, Embase and Cochrane databases until 31 December 2019 for studies reporting left ventricular (LV) global strain in at least 50 healthy subjects. We pooled means and LLNs of 2D and 3D LV strain using random-effects models, and performed subgroup and meta-regression analysis for LVGLS.

Results

Forty-four studies were eligible totaling 8,910 subjects. The pooled means and LLNs (95% confidence intervals) were -20.1% (-20.7%, -19.6%) and -15.4% (-16.0%, -14.7%) respectively for 2D-LVGLS; -21.9% (-23.4%, -20.3%) and -15.3% (-16.9%, -13.8%) respectively for 2D-LVGCS; and 48.4% (43.8%, 53.0%) and 25.5% (17.8%, 33.1%) respectively for 2D-LVGRS. All pooled analyses demonstrated significant heterogeneity, and means and LLNs of and 3D-LV strains differed marginally from 2D. Only vendor software was associated with differences in pooled means and LLN of 2D-LVGLS.

Conclusions

In conclusion, pooled means and LLNs of 2D- and 3D-LV global strain parameters in healthy subjects were reported. Based on the pooled LLNs, thresholds for abnormal, borderline and normal strains can be defined, such as less negative than -14.7%, between -14.7% and -16.0% and more negative than -16.0% respectively for 2D-LVGLS, and 2D-LVGLS values are only affected by vendor software.

From Hypertrophy to Heart Failure: What Is New in Genetic Cardiomyopathies

PURPOSE

The purpose of this review is to provide an update on the recent advances in the research and clinical care of patients with the major phenotypes of inherited cardiomyopathies-hypertrophic, dilated, and arrhythmogenic. Developments in genetics, risk stratification, therapies, and disease modeling will be discussed.

RECENT

Diagnostic, prognostic, and therapeutic tools which incorporate genetic and genomic data are being steadily incorporated into the routine clinical care of patients with genetic cardiomyopathies. Human pluripotent stem cells are a breakthrough model system for the study of genetic variation associated with inherited cardiovascular disease. Next-generation sequencing technology and molecular-based diagnostics and therapeutics have emerged as valuable tools to improve the recognition and care of patients with hypertrophic, dilated, and arrhythmogenic cardiomyopathies. Improved adjudication of variant pathogenicity and management of genotype-positive/phenotype-negative individuals are imminent challenges in this realm of precision medicine.

Dilated Cardiomyopathy: Genetic Determinants and Mechanisms

Nonischemic dilated cardiomyopathy (DCM) often has a genetic pathogenesis. Because of the large number of genes and alleles attributed to DCM, comprehensive genetic testing encompasses ever-increasing gene panels. Genetic diagnosis can help predict prognosis, especially with regard to arrhythmia risk for certain subtypes. Moreover, cascade genetic testing in family members can identify those who are at risk or with early stage disease, offering the opportunity for early intervention. This review will address diagnosis and management of DCM, including the role of genetic evaluation. We will also overview distinct genetic pathways linked to DCM and their pathogenetic mechanisms. Historically, cardiac morphology has been used to classify cardiomyopathy subtypes. Determining genetic variants is emerging as an additional adjunct to help further refine subtypes of DCM, especially where arrhythmia risk is increased, and ultimately contribute to clinical management.