Using implementation science to evaluate a population-wide genomic screening program: Findings from the first 20,000 In Our DNA SC participants.

We use the implementation science framework RE-AIM (reach, effectiveness, adoption, implementation, and maintenance) to describe outcomes of In Our DNA SC, a population-wide genomic screening (PWGS) program. In Our DNA SC involves participation through clinical appointments, community events, or at home collection. Participants provide a saliva sample that is sequenced by Helix, and those with a pathogenic variant or likely pathogenic variant for CDC Tier 1 conditions are offered free genetic counseling. We assessed key outcomes among the first cohort of individuals recruited. Over 14 months, 20,478 participants enrolled, and 14,053 samples were collected. The majority selected at-home sample collection followed by clinical sample collection and collection at community events. Participants were predominately female, White (self-identified), non-Hispanic, and between the ages of 40-49. Participants enrolled through community events were the most racially diverse and the youngest. Half of those enrolled completed the program. We identified 137 individuals with pathogenic or likely pathogenic variants for CDC Tier 1 conditions. The majority (77.4%) agreed to genetic counseling, and of those that agreed, 80.2% completed counseling. Twelve clinics participated, and we conducted 108 collection events. Participants enrolled at home were most likely to return their sample for sequencing. Through this evaluation, we identified facilitators and barriers to implementation of our state-wide PWGS program. Standardized reporting using implementation science frameworks can help generalize strategies and improve the impact of PWGS.

Efficacy and Safety of Acoramidis in Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Transthyretin amyloid cardiomyopathy is characterized by the deposition of misfolded monomeric transthyretin (TTR) in the heart. Acoramidis is a high-affinity TTR stabilizer that acts to inhibit dissociation of tetrameric TTR and leads to more than 90% stabilization across the dosing interval as measured ex vivo. METHODS: In this phase 3, double-blind trial, we randomly assigned patients with transthyretin amyloid cardiomyopathy in a 2:1 ratio to receive acoramidis hydrochloride at a dose of 800 mg twice daily or matching placebo for 30 months. Efficacy was assessed in the patients who had an estimated glomerular filtration rate of at least 30 ml per minute per 1.73 m2 of body-surface area. The four-step primary hierarchical analysis included death from any cause, cardiovascular-related hospitalization, the change from baseline in the N-terminal pro-B-type natriuretic peptide (NT-proBNP) level, and the change from baseline in the 6-minute walk distance. We used the Finkelstein-Schoenfeld method to compare all potential pairs of patients within strata to generate a P value. Key secondary outcomes were death from any cause, the 6-minute walk distance, the score on the Kansas City Cardiomyopathy Questionnaire-Overall Summary, and the serum TTR level. RESULTS: A total of 632 patients underwent randomization. The primary analysis favored acoramidis over placebo (P<0.001); the corresponding win ratio was 1.8 (95% confidence interval [CI], 1.4 to 2.2), with 63.7% of pairwise comparisons favoring acoramidis and 35.9% favoring placebo. Together, death from any cause and cardiovascular-related hospitalization contributed more than half the wins and losses to the win ratio (58% of all pairwise comparisons); NT-proBNP pairwise comparisons yielded the highest ratio of wins to losses (23.3% vs. 7.0%). The overall incidence of adverse events was similar in the acoramidis group and the placebo group (98.1% and 97.6%, respectively); serious adverse events were reported in 54.6% and 64.9% of the patients. CONCLUSIONS: In patients with transthyretin amyloid cardiomyopathy, the receipt of acoramidis resulted in a significantly better four-step primary hierarchical outcome containing components of mortality, morbidity, and function than placebo. Adverse events were similar in the two groups. (Funded by BridgeBio Pharma; ATTRibute-CM ClinicalTrials.gov number, NCT03860935.).

Effectiveness of the Family Heart Talk Communication Tool in Improving Family Member Screening for Dilated Cardiomyopathy: Results of a Randomized Trial.

BACKGROUND: Managing disease risk among first-degree relatives of probands diagnosed with a heritable disease is central to precision medicine. A critical component is often clinical screening, which is particularly important for conditions like dilated cardiomyopathy (DCM) that remain asymptomatic until severe disease develops. Nonetheless, probands are frequently ill-equipped to disseminate genetic risk information that motivates at-risk relatives to complete recommended clinical screening. An easily implemented remedy for this key issue has been elusive. METHODS: The DCM Precision Medicine Study developed Family Heart Talk, a booklet designed to help probands with DCM communicate genetic risk and the need for cardiovascular screening to their relatives. The effectiveness of the Family Heart Talk booklet in increasing cardiovascular clinical screening uptake among first-degree relatives was assessed in a multicenter, open-label, cluster-randomized, controlled trial. The primary outcome measured in eligible first-degree relatives was completion of screening initiated within 12 months after proband enrollment. Because probands randomized to the intervention received the booklet at the enrollment visit, eligible first-degree relatives were limited to those who were alive the day after proband enrollment and not enrolled on the same day as the proband. RESULTS: Between June 2016 and March 2020, 1241 probands were randomized (1:1) to receive Family Heart Talk (n=621) or not (n=620) within strata defined by site and self-identified race/ethnicity (non-Hispanic Black, non-Hispanic White, or Hispanic). Final analyses included 550 families (n=2230 eligible first-degree relatives) in the Family Heart Talk arm and 561 (n=2416) in the control arm. A higher percentage of eligible first-degree relatives completed screening in the Family Heart Talk arm (19.5% versus 16.0%), and the odds of screening completion among these first-degree relatives were higher in the Family Heart Talk arm after adjustment for proband randomization stratum, sex, and age quartile (odds ratio, 1.30 [1-sided 95% CI, 1.08-∞]). A prespecified subgroup analysis did not find evidence of heterogeneity in the adjusted intervention odds ratio across race/ethnicity strata (P=0.90). CONCLUSIONS: Family Heart Talk, a booklet that can be provided to patients with DCM by clinicians with minimal additional time investment, was effective in increasing cardiovascular clinical screening among first-degree relatives of these patients. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03037632.

Rare Variant Genetics and Dilated Cardiomyopathy Severity: The DCM Precision Medicine Study.

BACKGROUND: Dilated cardiomyopathy (DCM) can lead to advanced disease, defined herein as necessitating a durable left ventricular assist device or a heart transplant (LVAD/HT). DCM is known to have a genetic basis, but the association of rare variant genetics with advanced DCM has not been studied. METHODS: We analyzed clinical and genetic sequence data from patients enrolled between 2016 and 2021 in the US multisite DCM Precision Medicine Study, which was a geographically diverse, multiracial, multiethnic cohort. Clinical evaluation included standardized patient interview and medical record query forms. DCM severity was classified into 3 groups: patients with advanced disease with LVAD/HT; patients with an implantable cardioverter defibrillator (ICD) only; or patients with no ICD or LVAD/HT. Rare variants in 36 DCM genes were classified as pathogenic or likely pathogenic or variants of uncertain significance. Confounding factors we considered included demographic characteristics, lifestyle factors, access to care, DCM duration, and comorbidities. Crude and adjusted associations between DCM severity and rare variant genetic findings were assessed using multinomial models with generalized logit link. RESULTS: Patients' mean (SD) age was 51.9 (13.6) years; 42% were of African ancestry, 56% were of European ancestry, and 44% were female. Of 1198 patients, 347 had LVAD/HT, 511 had an ICD, and 340 had no LVAD/HT or ICD. The percentage of patients with pathogenic or likely pathogenic variants was 26.2%, 15.9%, and 15.0% for those with LVAD/HT, ICD only, or neither, respectively. After controlling for sociodemographic characteristics and comorbidities, patients with DCM with LVAD/HT were more likely than those without LVAD/HT or ICD to have DCM-related pathogenic or likely pathogenic rare variants (odds ratio, 2.3 [95% CI, 1.5-3.6]). The association did not differ by ancestry. Rare variant genetic findings were similar between patients with DCM with an ICD and those without LVAD/HT or ICD. CONCLUSIONS: Advanced DCM was associated with higher odds of rare variants in DCM genes adjudicated as pathogenic or likely pathogenic, compared with individuals with less severe DCM. This finding may help assess the risk of outcomes in management of patients with DCM and their at-risk family members. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03037632.

The prevalent I686T human variant and loss-of-function mutations in the cardiomyocyte-specific kinase gene TNNI3K cause adverse contractility and concentric remodeling in mice.

TNNI3K expression worsens disease progression in several mouse heart pathology models. TNNI3K expression also reduces the number of diploid cardiomyocytes, which may be detrimental to adult heart regeneration. However, the gene is evolutionarily conserved, suggesting a beneficial function that has remained obscure. Here, we show that C57BL/6J-inbred Tnni3k mutant mice develop concentric remodeling, characterized by ventricular wall thickening and substantial reduction of cardiomyocyte aspect ratio. This pathology occurs in mice carrying a Tnni3k null allele, a K489R point mutation rendering the protein kinase-dead, or an allele corresponding to human I686T, the most common human non-synonymous TNNI3K variant, which is hypomorphic for kinase activity. Mutant mice develop these conditions in the absence of fibrosis or hypertension, implying a primary cardiomyocyte etiology. In culture, mutant cardiomyocytes were impaired in contractility and calcium dynamics and in protein kinase A signaling in response to isoproterenol, indicating diminished contractile reserve. These results demonstrate a beneficial function of TNNI3K in the adult heart that might explain its evolutionary conservation and imply that human TNNI3K variants, in particular the widespread I686T allele, may convey elevated risk for altered heart geometry and hypertrophy.

Impact of Donor Hemodynamics on Recipient Survival in Heart Transplantation.

BACKGROUND: Heart transplantation is the gold-standard therapy for end-stage heart failure, but rates of donor-heart use remain low due to various factors that are often not evidence based. The impact of donor hemodynamics obtained via right-heart catheterization on recipient survival remains unclear. METHODS: The United Network for Organ Sharing registry was used to identify donors and recipients from September 1999-December 2019. Donor hemodynamics data were obtained and analyzed using univariate and multivariable logistical regression, with the primary endpoints being 1- and 5-year post-transplant survival. RESULTS: Of the 85,333 donors who consented to heart transplantation during the study period, 6573 (7.7%) underwent right-heart catheterization, of whom 5531 eventually underwent procurement and transplantation. Donors were more likely to undergo right-heart catheterization if they had high-risk criteria. Recipients who had donor hemodynamic assessment had 1- and 5-year survival rates similar to those without donor hemodynamic assessment (87% vs 86%, 1 year). Abnormal hemodynamics were common in donor hearts but did not impact recipient survival rates, even when risk-adjusted in multivariable analysis. CONCLUSIONS: Donors with abnormal hemodynamics may represent an opportunity to expand the pool of viable donor hearts.

Applying the R = MC2 implementation science heuristic to assess the impact of readiness on reach and implementation of a population-wide genomic screening program.

Population-wide genomic screening for genes that have high penetrance and clinical actionability enhances the opportunity to identify individuals at risk for developing hereditary conditions. Organizational readiness has been shown to influence the likelihood of successful implementation of complex initiatives such as the integration of population-wide genomic screening in clinical settings. We use the organizational readiness heuristic R = MC2 to better understand three factors that influence readiness for implementation of In Our DNA SC, a population-wide genomic screening program: motivation to implement, general capacity of an organization, and innovation-specific capacities. We then assessed the influence of these readiness factors on implementation outcomes of reach (measured through enrollment rate) and implementation (measured through the number of DNA samples collected). Data were collected pre-implementation and captured during the three-month pilot phase of the In Our DNA SC program. We collected administrative data from the electronic health record and quantitatively captured elements of readiness through surveys distributed to provider champions and clinical administrative champions at the 10 sites implementing the population-wide genomic screening program. We facilitated innovation-specific capacity through training offered at each site, as well as technical assistance through weekly meetings with other implementing sites, and resources available to all staff. Forty percent of provider champions attended training and 80% of administrative champions attended training. An average of 3.7 additional staff were trained at each implementing site. Satisfaction with training positively influenced reach (ß = 0.0121, p = 0.0271) but did not impact implementation. Provider engagement (innovation capabilities) was associated with reach (ß = 0.0020, p = 0.0251) and clinical administrator engagement was associated with sample collection rate (ß = 0.2599, ß = 0.038). Readiness to change is considered one of the most important factors in understanding the potential opportunity for implementation. We found that motivation to adopt a population-wide genomic screening program positively impacted the program's reach. The type of champion influenced discrete outcomes, with provider champions positively impacting reach and administrative champions influencing implementation (assessed through sample collection rate). As genomics continues to be integrated into clinical practice, it will be important to understand the contextual factors that influence readiness for implementation and design support throughout the life-course of implementation to ensure the success of large-scale, complex initiatives.

A new prediction model for ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy.

AIMS: Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC) is characterized by ventricular arrhythmias (VAs) and sudden cardiac death (SCD). We aimed to develop a model for individualized prediction of incident VA/SCD in ARVC patients. METHODS AND RESULTS: Five hundred and twenty-eight patients with a definite diagnosis and no history of sustained VAs/SCD at baseline, aged 38.2 ± 15.5 years, 44.7% male, were enrolled from five registries in North America and Europe. Over 4.83 (interquartile range 2.44-9.33) years of follow-up, 146 (27.7%) experienced sustained VA, defined as SCD, aborted SCD, sustained ventricular tachycardia, or appropriate implantable cardioverter-defibrillator (ICD) therapy. A prediction model estimating annual VA risk was developed using Cox regression with internal validation. Eight potential predictors were pre-specified: age, sex, cardiac syncope in the prior 6 months, non-sustained ventricular tachycardia, number of premature ventricular complexes in 24 h, number of leads with T-wave inversion, and right and left ventricular ejection fractions (LVEFs). All except LVEF were retained in the final model. The model accurately distinguished patients with and without events, with an optimism-corrected C-index of 0.77 [95% confidence interval (CI) 0.73-0.81] and minimal over-optimism [calibration slope of 0.93 (95% CI 0.92-0.95)]. By decision curve analysis, the clinical benefit of the model was superior to a current consensus-based ICD placement algorithm with a 20.3% reduction of ICD placements with the same proportion of protected patients (P < 0.001). CONCLUSION: Using the largest cohort of patients with ARVC and no prior VA, a prediction model using readily available clinical parameters was devised to estimate VA risk and guide decisions regarding primary prevention ICDs (www.arvcrisk.com).

Genetic Architecture of Dilated Cardiomyopathy in Individuals of African and European Ancestry.

Importance: Black patients with dilated cardiomyopathy (DCM) have increased familial risk and worse outcomes than White patients, but most DCM genetic data are from White patients. Objective: To compare the rare variant genetic architecture of DCM by genomic ancestry within a diverse population of patients with DCM. Design: Cross-sectional study enrolling patients with DCM who self-identified as non-Hispanic Black, Hispanic, or non-Hispanic White from June 7, 2016, to March 15, 2020, at 25 US advanced heart failure programs. Variants in 36 DCM genes were adjudicated as pathogenic, likely pathogenic, or of uncertain significance. Exposure: Presence of DCM. Main Outcomes and Measures: Variants in DCM genes classified as pathogenic/likely pathogenic/uncertain significance and clinically actionable (pathogenic/likely pathogenic). Results: A total of 505, 667, and 26 patients with DCM of predominantly African, European, or Native American genomic ancestry, respectively, were included. Compared with patients of European ancestry, a lower percentage of patients of African ancestry had clinically actionable variants (8.2% [95% CI, 5.2%-11.1%] vs 25.5% [95% CI, 21.3%-29.6%]), reflecting the lower odds of a clinically actionable variant for those with any pathogenic variant/likely pathogenic variant/variant of uncertain significance (odds ratio, 0.25 [95% CI, 0.17-0.37]). On average, patients of African ancestry had fewer clinically actionable variants in TTN (difference, -0.09 [95% CI, -0.14 to -0.05]) and other genes with predicted loss of function as a disease-causing mechanism (difference, -0.06 [95% CI, -0.11 to -0.02]). However, the number of pathogenic variants/likely pathogenic variants/variants of uncertain significance was more comparable between ancestry groups (difference, -0.07 [95% CI, -0.22 to 0.09]) due to a larger number of non-TTN non-predicted loss of function variants of uncertain significance, mostly missense, in patients of African ancestry (difference, 0.15 [95% CI, 0.00-0.30]). Published clinical case-based evidence supporting pathogenicity was less available for variants found only in patients of African ancestry (P < .001). Conclusion and Relevance: Patients of African ancestry with DCM were less likely to have clinically actionable variants in DCM genes than those of European ancestry due to differences in genetic architecture and a lack of representation of African ancestry in clinical data sets.

Genetic and Phenotypic Landscape of Peripartum Cardiomyopathy.

BACKGROUND: Peripartum cardiomyopathy (PPCM) occurs in ≈1:2000 deliveries in the United States and worldwide. The genetic underpinnings of PPCM remain poorly defined. Approximately 10% of women with PPCM harbor truncating variants in TTN (TTNtvs). Whether mutations in other genes can predispose to PPCM is not known. It is also not known if the presence of TTNtvs predicts clinical presentation or outcomes. Nor is it known if the prevalence of TTNtvs differs in women with PPCM and preeclampsia, the strongest risk factor for PPCM. METHODS: Women with PPCM were retrospectively identified from several US and international academic centers, and clinical information and DNA samples were acquired. Next-generation sequencing was performed on 67 genes, including TTN, and evaluated for burden of truncating and missense variants. The impact of TTNtvs on the severity of clinical presentation, and on clinical outcomes, was evaluated. RESULTS: Four hundred sixty-nine women met inclusion criteria. Of the women with PPCM, 10.4% bore TTNtvs (odds ratio=9.4 compared with 1.2% in the reference population; Bonferroni-corrected P [P*]=1.2×10-46). We additionally identified overrepresentation of truncating variants in FLNC (odds ratio=24.8, P*=7.0×10-8), DSP (odds ratio=14.9, P*=1.0×10-8), and BAG3 (odds ratio=53.1, P*=0.02), genes not previously associated with PPCM. This profile is highly similar to that found in nonischemic dilated cardiomyopathy. Women with TTNtvs had lower left ventricular ejection fraction on presentation than did women without TTNtvs (23.5% versus 29%, P=2.5×10-4), but did not differ significantly in timing of presentation after delivery, in prevalence of preeclampsia, or in rates of clinical recovery. CONCLUSIONS: This study provides the first extensive genetic and phenotypic landscape of PPCM and demonstrates that predisposition to heart failure is an important risk factor for PPCM. The work reveals a degree of genetic similarity between PPCM and dilated cardiomyopathy, suggesting that gene-specific therapeutic approaches being developed for dilated cardiomyopathy may also apply to PPCM, and that approaches to genetic testing in PPCM should mirror those taken in dilated cardiomyopathy. Last, the clarification of genotype/phenotype associations has important implications for genetic counseling.

Evidence-Based Assessment of Genes in Dilated Cardiomyopathy.

BACKGROUND: Each of the cardiomyopathies, classically categorized as hypertrophic cardiomyopathy, dilated cardiomyopathy (DCM), and arrhythmogenic right ventricular cardiomyopathy, has a signature genetic theme. Hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy are largely understood as genetic diseases of sarcomere or desmosome proteins, respectively. In contrast, >250 genes spanning >10 gene ontologies have been implicated in DCM, representing a complex and diverse genetic architecture. To clarify this, a systematic curation of evidence to establish the relationship of genes with DCM was conducted. METHODS: An international panel with clinical and scientific expertise in DCM genetics evaluated evidence supporting monogenic relationships of genes with idiopathic DCM. The panel used the Clinical Genome Resource semiquantitative gene-disease clinical validity classification framework with modifications for DCM genetics to classify genes into categories on the basis of the strength of currently available evidence. Representation of DCM genes on clinically available genetic testing panels was evaluated. RESULTS: Fifty-one genes with human genetic evidence were curated. Twelve genes (23%) from 8 gene ontologies were classified as having definitive (BAG3, DES, FLNC, LMNA, MYH7, PLN, RBM20, SCN5A, TNNC1, TNNT2, TTN) or strong (DSP) evidence. Seven genes (14%; ACTC1, ACTN2, JPH2, NEXN, TNNI3, TPM1, VCL) including 2 additional ontologies were classified as moderate evidence; these genes are likely to emerge as strong or definitive with additional evidence. Of these 19 genes, 6 were similarly classified for hypertrophic cardiomyopathy and 3 for arrhythmogenic right ventricular cardiomyopathy. Of the remaining 32 genes (63%), 25 (49%) had limited evidence, 4 (8%) were disputed, 2 (4%) had no disease relationship, and 1 (2%) was supported by animal model data only. Of the 16 evaluated clinical genetic testing panels, most definitive genes were included, but panels also included numerous genes with minimal human evidence. CONCLUSIONS: In the curation of 51 genes, 19 had high evidence (12 definitive/strong, 7 moderate). It is notable that these 19 genes explain only a minority of cases, leaving the remainder of DCM genetic architecture incompletely addressed. Clinical genetic testing panels include most high-evidence genes; however, genes lacking robust evidence are also commonly included. We recommend that high-evidence DCM genes be used for clinical practice and that caution be exercised in the interpretation of variants in variable-evidence DCM genes.

Phenotypic Expression, Natural History, and Risk Stratification of Cardiomyopathy Caused by Filamin C Truncating Variants.

BACKGROUND: Filamin C truncating variants (FLNCtv) cause a form of arrhythmogenic cardiomyopathy: the mode of presentation, natural history, and risk stratification of FLNCtv remain incompletely explored. We aimed to develop a risk profile for refractory heart failure and life-threatening arrhythmias in a multicenter cohort of FLNCtv carriers. METHODS: FLNCtv carriers were identified from 10 tertiary care centers for genetic cardiomyopathies. Clinical and outcome data were compiled. Composite outcomes were all-cause mortality/heart transplantation/left ventricle assist device (D/HT/LVAD), nonarrhythmic death/HT/LVAD, and sudden cardiac death/major ventricular arrhythmias. Previously established cohorts of 46 patients with LMNA and 60 with DSP-related arrhythmogenic cardiomyopathies were used for prognostic comparison. RESULTS: Eighty-five patients carrying FLNCtv were included (42±15 years, 53% men, 45% probands). Phenotypes were heterogeneous at presentation: 49% dilated cardiomyopathy, 25% arrhythmogenic left dominant cardiomyopathy, 3% arrhythmogenic right ventricular cardiomyopathy. Left ventricular ejection fraction was <50% in 64% of carriers and 34% had right ventricular fractional area changes (RVFAC=(right ventricular end-diastolic area - right ventricular end-systolic area)/right ventricular end-diastolic area) <35%. During follow-up (median time 61 months), 19 (22%) carriers experienced D/HT/LVAD, 13 (15%) experienced nonarrhythmic death/HT/LVAD, and 23 (27%) experienced sudden cardiac death/major ventricular arrhythmias. The sudden cardiac death/major ventricular arrhythmias incidence of FLNCtv carriers did not significantly differ from LMNA carriers and DSP carriers. In FLNCtv carriers, left ventricular ejection fraction was associated with the risk of D/HT/LVAD and nonarrhythmic death/HT/LVAD. CONCLUSIONS: Among patients referred to tertiary referral centers, FLNCtv arrhythmogenic cardiomyopathy is phenotypically heterogeneous and characterized by a high risk of life-threatening arrhythmias, which does not seem to be associated with the severity of left ventricular dysfunction.

Tnni3k alleles influence ventricular mononuclear diploid cardiomyocyte frequency.

Recent evidence implicates mononuclear diploid cardiomyocytes as a proliferative and regenerative subpopulation of the postnatal heart. The number of these cardiomyocytes is a complex trait showing substantial natural variation among inbred mouse strains based on the combined influences of multiple polymorphic genes. One gene confirmed to influence this parameter is the cardiomyocyte-specific kinase Tnni3k. Here, we have studied Tnni3k alleles across a number of species. Using a newly-generated kinase-dead allele in mice, we show that Tnni3k function is dependent on its kinase activity. In an in vitro kinase assay, we show that several common human TNNI3K kinase domain variants substantially compromise kinase activity, suggesting that TNNI3K may influence human heart regenerative capacity and potentially also other aspects of human heart disease. We show that two kinase domain frameshift mutations in mice cause loss-of-function consequences by nonsense-mediated decay. We further show that the Tnni3k gene in two species of mole-rat has independently devolved into a pseudogene, presumably associated with the transition of these species to a low metabolism and hypoxic subterranean life. This may be explained by the observation that Tnni3k function in mice converges with oxidative stress to regulate mononuclear diploid cardiomyocyte frequency. Unlike other studied rodents, naked mole-rats have a surprisingly high (30%) mononuclear cardiomyocyte level but most of their mononuclear cardiomyocytes are polyploid; their mononuclear diploid cardiomyocyte level (7%) is within the known range (2-10%) of inbred mouse strains. Naked mole-rats provide further insight on a recent proposal that cardiomyocyte polyploidy is associated with evolutionary acquisition of endothermy.

Prevalence and Cumulative Risk of Familial Idiopathic Dilated Cardiomyopathy.

Importance: Idiopathic dilated cardiomyopathy (DCM) aggregates in families, and early detection in at-risk family members can provide opportunity to initiate treatment prior to late-phase disease. Most studies have included only White patients, yet Black patients with DCM have higher risk of heart failure-related hospitalization and death. Objective: To estimate the prevalence of familial DCM among DCM probands and the age-specific cumulative risk of DCM in first-degree relatives across race and ethnicity groups. Design, Setting, and Participants: A family-based, cross-sectional study conducted by a multisite consortium of 25 US heart failure programs. Participants included patients with DCM (probands), defined as left ventricular systolic dysfunction and left ventricular enlargement after excluding usual clinical causes, and their first-degree relatives. Enrollment commenced June 7, 2016; proband and family member enrollment concluded March 15, 2020, and April 1, 2021, respectively. Exposures: The presence of DCM in a proband. Main Outcomes and Measures: Familial DCM defined by DCM in at least 1 first-degree relative; expanded familial DCM defined by the presence of DCM or either left ventricular enlargement or left ventricular systolic dysfunction without known cause in at least 1 first-degree relative. Results: The study enrolled 1220 probands (median age, 52.8 years [IQR, 42.4-61.8]; 43.8% female; 43.1% Black and 8.3% Hispanic) and screened 1693 first-degree relatives for DCM. A median of 28% (IQR, 0%-60%) of living first-degree relatives were screened per family. The crude prevalence of familial DCM among probands was 11.6% overall. The model-based estimate of the prevalence of familial DCM among probands at a typical US advanced heart failure program if all living first-degree relatives were screened was 29.7% (95% CI, 23.5% to 36.0%) overall. The estimated prevalence of familial DCM was higher in Black probands than in White probands (difference, 11.3% [95% CI, 1.9% to 20.8%]) but did not differ significantly between Hispanic probands and non-Hispanic probands (difference, -1.4% [95% CI, -15.9% to 13.1%]). The estimated prevalence of expanded familial DCM was 56.9% (95% CI, 50.8% to 63.0%) overall. Based on age-specific disease status at enrollment, estimated cumulative risks in first-degree relatives at a typical US advanced heart failure program reached 19% (95% CI, 13% to 24%) by age 80 years for DCM and 33% (95% CI, 27% to 40%) for expanded DCM inclusive of partial phenotypes. The DCM hazard was higher in first-degree relatives of non-Hispanic Black probands than non-Hispanic White probands (hazard ratio, 1.89 [95% CI, 1.26 to 2.83]). Conclusions and Relevance: In a US cross-sectional study, there was substantial estimated prevalence of familial DCM among probands and modeled cumulative risk of DCM among their first-degree relatives. Trial Registration: ClinicalTrials.gov Identifier: NCT03037632.

Efficacy and Safety of Angiotensin Receptor Blockers in a Pre-Clinical Model of Arrhythmogenic Cardiomyopathy.

Arrhythmogenic Cardiomyopathy (ACM) is a familial heart disease, characterized by contractile dysfunction, ventricular arrhythmias (VAs), and the risk of sudden cardiac death. Currently, implantable cardioverter defibrillators and antiarrhythmics are the mainstays in ACM therapeutics. Angiotensin receptor blockers (ARBs) have been highlighted in the treatment of heart diseases, including ACM. Yet, recent research has additionally implicated ARBs in the genesis of VAs and myocardial lipolysis via the peroxisome proliferator-activated receptor gamma (PPARγ) pathway. The latter is of particular interest, as fibrofatty infiltration is a pathological hallmark in ACM. Here, we tested two ARBs, Valsartan and Telmisartan, and the PPAR agonist, Rosiglitazone, in an animal model of ACM, homozygous Desmoglein-2 mutant mice (Dsg2mut/mut). Cardiac function, premature ventricular contractions (PVCs), fibrofatty scars, PPARα/γ protein levels, and PPAR-mediated mRNA transcripts were assessed. Of note, not a single mouse treated with Rosiglitazone made it to the study endpoint (i.e., 100% mortality: n = 5/5). Telmisartan-treated Dsg2mut/mut mice displayed the preservation of contractile function (percent ejection fraction [%EF]; 74.8 ± 6.8%EF) compared to Vehicle- (42.5 ± 5.6%EF) and Valsartan-treated (63.1 ± 4.4%EF) mice. However, Telmisartan-treated Dsg2mut/mut mice showed increased cardiac wall motion abnormalities, augmented %PVCs, electrocardiographic repolarization/depolarization abnormalities, larger fibrotic lesions, and increased expression of PPARy-regulated gene transcripts compared to their Dsg2mut/mut counterparts. Alternatively, Valsartan-treated Dsg2mut/mut mice harbored fewer myocardial scars, reduced %PVC, and increased Wnt-mediated transcripts. Considering our findings, caution should be taken by physicians when prescribing medications that may increase PPARy signaling in patients with ACM.

Hypermobile Ehlers-Danlos syndromes: Complex phenotypes, challenging diagnoses, and poorly understood causes.

The Ehlers-Danlos syndromes (EDS) are a group of heritable, connective tissue disorders characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. There is phenotypic and genetic variation among the 13 subtypes. The initial genetic findings on EDS were related to alterations in fibrillar collagen, but the elucidation of the molecular basis of many of the subtypes revealed several genes not involved in collagen biosynthesis or structure. However, the genetic basis of the hypermobile type of EDS (hEDS) is still unknown. hEDS is the most common type of EDS and involves generalized joint hypermobility, musculoskeletal manifestations, and mild skin involvement along with the presence of several comorbid conditions. Variability in the spectrum and severity of symptoms and progression of patient phenotype likely depend on age, gender, lifestyle, and expression domains of the EDS genes during development and postnatal life. In this review, we summarize the current molecular, genetic, epidemiologic, and pathogenetic findings related to EDS with a focus on the hypermobile type.

Tafamidis Treatment for Patients with Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Transthyretin amyloid cardiomyopathy is caused by the deposition of transthyretin amyloid fibrils in the myocardium. The deposition occurs when wild-type or variant transthyretin becomes unstable and misfolds. Tafamidis binds to transthyretin, preventing tetramer dissociation and amyloidogenesis. METHODS: In a multicenter, international, double-blind, placebo-controlled, phase 3 trial, we randomly assigned 441 patients with transthyretin amyloid cardiomyopathy in a 2:1:2 ratio to receive 80 mg of tafamidis, 20 mg of tafamidis, or placebo for 30 months. In the primary analysis, we hierarchically assessed all-cause mortality, followed by frequency of cardiovascular-related hospitalizations according to the Finkelstein-Schoenfeld method. Key secondary end points were the change from baseline to month 30 for the 6-minute walk test and the score on the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS), in which higher scores indicate better health status. RESULTS: In the primary analysis, all-cause mortality and rates of cardiovascular-related hospitalizations were lower among the 264 patients who received tafamidis than among the 177 patients who received placebo (P<0.001). Tafamidis was associated with lower all-cause mortality than placebo (78 of 264 [29.5%] vs. 76 of 177 [42.9%]; hazard ratio, 0.70; 95% confidence interval [CI], 0.51 to 0.96) and a lower rate of cardiovascular-related hospitalizations, with a relative risk ratio of 0.68 (0.48 per year vs. 0.70 per year; 95% CI, 0.56 to 0.81). At month 30, tafamidis was also associated with a lower rate of decline in distance for the 6-minute walk test (P<0.001) and a lower rate of decline in KCCQ-OS score (P<0.001). The incidence and types of adverse events were similar in the two groups. CONCLUSIONS: In patients with transthyretin amyloid cardiomyopathy, tafamidis was associated with reductions in all-cause mortality and cardiovascular-related hospitalizations and reduced the decline in functional capacity and quality of life as compared with placebo. (Funded by Pfizer; ATTR-ACT ClinicalTrials.gov number, NCT01994889 .).

Management of heart failure in cardiac amyloidosis using an ambulatory diuresis clinic.

BACKGROUND: Recurrent congestion in cardiac amyloidosis (CA) remains a management challenge, often requiring high dose diuretics and frequent hospitalizations. Innovative outpatient strategies are needed to effectively manage heart failure (HF) in patients with CA. Ambulatory diuresis has not been well studied in restrictive cardiomyopathy. Therefore, we aimed to examine the outcomes of an ambulatory diuresis clinic in the management of congestion related to CA. METHODS AND RESULTS: We retrospectively studied patients with CA seen in an outpatient HF disease management clinic for (1) safety outcomes of ambulatory intravenous (IV) diuresis and (2) health care utilization. Forty-four patients with CA were seen in the clinic a total of 203 times over 6 months. Oral diuretics were titrated at 96 (47%) visits. IV diuretics were administered at 56 (28%) visits to 17 patients. There were no episodes of severe acute kidney injury or symptomatic hypotension. There was a significant decrease in emergency department and inpatient visits and associated charges after index visit to the clinic. The proportion of days hospitalized per 1000 patient days of follow-up decreased as early as 30 days (147.3 vs 18.1/1000 patient days of follow-up, P< .001) and persisted through 180 days (33.6 vs 22.9/1000 patient days of follow-up, P< .001) pre- vs post-index visit to the clinic. CONCLUSIONS: We demonstrate the feasibility of ambulatory IV diuresis in patients with CA. Our findings also suggest that use of a HF disease management clinic may reduce acute care utilization in patients with CA. Leveraging multidisciplinary outpatient HF clinics may be an effective alternative to hospitalization in patients with HF due to CA, a population who otherwise carries a poor prognosis and contributes to high health care burden.

FLNC truncations cause arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease that affects predominantly the right ventricle and is part of the spectrum of arrythmogenic cardiomyopathies (ACMs). ARVC is a genetic condition; however, a pathogenic gene variant is found in only half of patients. OBJECTIVE: Filamin C gene truncations (FLNCtv) have recently been identified in dilated cardiomyopathy with ventricular arrhythmia and sudden cardiac death, a phenotype partially overlapping with ARVC and part of the ACM spectrum. We hypothesised that FLNCtv could be a novel gene associated with ARVC. METHODS: One hundred fifty-six patients meeting 2010 ARVC Task Force Criteria and lacking variants in known ARVC genes were evaluated for FLNC variants. Available family members were tested for cosegregation. RESULTS: We identified two unique FLNCtv variants in two families (c.6565 G>T, p.Glu2189Ter and c.8107delG, p.Asp2703ThrfsTer69), with phenotypes of dominant RV disease fulfilling 'definite' diagnosis of ARVC according to the 2010 Task Force Criteria. Variants in other cardiomyopathy genes were excluded in both kindreds, and segregation analysis revealed that p.Asp2703ThrfsTer69 was a de novo variant. In both families, the disease phenotype was characterised by prominent ventricular arrhythmias and sudden cardiac arrest. CONCLUSION: The identification of FLNCtv as a novel cause of ARVC in two unrelated families expands the spectrum of ARVC non-desmosome disease genes for this disorder. Our findings should prompt inclusion of FLNC genetic testing in ARVC to improve diagnostic yield and testing of at-risk relatives in ARVC.

Therapeutic Modulation of the Immune Response in Arrhythmogenic Cardiomyopathy.

BACKGROUND: Inflammation is a prominent feature of arrhythmogenic cardiomyopathy (ACM), but whether it contributes to the disease phenotype is not known. METHODS: To define the role of inflammation in the pathogenesis of ACM, we characterized nuclear factor-κB signaling in ACM models in vitro and in vivo and in cardiac myocytes from patient induced pluripotent stem cells. RESULTS: Activation of nuclear factor-κB signaling, indicated by increased expression and nuclear accumulation of phospho-RelA/p65, occurred in both an in vitro model of ACM (expression of JUP2157del2 in neonatal rat ventricular myocytes) and a robust murine model of ACM (homozygous knock-in of mutant desmoglein-2 [Dsg2mut/mut]) that recapitulates the cardiac manifestations seen in patients with ACM. Bay 11-7082, a small-molecule inhibitor of nuclear factor-κB signaling, prevented the development of ACM disease features in vitro (abnormal redistribution of intercalated disk proteins, myocyte apoptosis, release of inflammatory cytokines) and in vivo (myocardial necrosis and fibrosis, left ventricular contractile dysfunction, electrocardiographic abnormalities). Hearts of Dsg2mut/mut mice expressed markedly increased levels of inflammatory cytokines and chemotactic molecules that were attenuated by Bay 11-7082. Salutary effects of Bay 11-7082 correlated with the extent to which production of selected cytokines had been blocked. Nuclear factor-κB signaling was also activated in cardiac myocytes derived from a patient with ACM. These cells produced and secreted abundant inflammatory cytokines under basal conditions, and this was also greatly reduced by Bay 11-7082. CONCLUSIONS: Inflammatory signaling is activated in ACM and drives key features of the disease. Targeting inflammatory pathways may be an effective new mechanism-based therapy for ACM.