BACKGROUND:Patients harboring pathogenic/likely pathogenic (P/LP) variants in the desmoplakin (DSP) gene are at risk of ventricular arrhythmias (VAs). In this population, a risk prediction model estimating the 5-year risk of VAs has been recently developed. OBJECTIVE:This study aimed to provide external validation of this prediction model in a new large, international, multicenter cohort and to test its reliability in patients with and without a history of myocarditis-like episodes. METHODS:All patients with a P/LP pathogenic DSP variant enrolled in the Desmoplakin Specific Effort for a Rare Disease Outcome Study Network with no sustained VA before or at first assessment and who were not used for the development of the DSP-risk score (www.DSP-risk.com) were used to test its performance. Model performance was assessed using the c-statistic in both the overall cohort and stratifying by history of myocarditis-like episodes. RESULTS:450 DSP patients from 30 centers were enrolled (mean age 42.2 ± 17.6; 40.4% female; 18.4% with previous myocarditis-like episode). Over a median of 4.3 years (1.6-10.0), 60 sustained VAs were observed. The DSP-risk score yielded good discrimination both overall (c-statistic, 0.719; 95% confidence interval [CI], 0.706-0.733) and for patients with (c-statistic, 0.719; 95% CI, 0.702-0.737) and without previous myocarditis-like episodes (c-statistic, 0.749; 95% CI, 0.740-0.759). CONCLUSION:In a large independent cohort of DSP patients, this study showed external validity of the DSP-risk score. These findings support the use of the DSP-risk score to facilitate shared decision making regarding implantable cardioverter-defibrillator implantation in the primary prevention of VAs in patients harboring DSP P/LP variants.

Nonsense-mediated decay (NMD) is a conserved RNA quality-control pathway that degrades transcripts containing premature termination codons. Because roughly a third of pathogenic variants in ClinVar can lead to truncated protein synthesis, predicting whether such transcripts undergo NMD is central to interpreting variant effects, yet the canonical 50-55 nucleotide rule explains only about half of observed outcome variability. Using paired whole-genome and RNA-sequencing from 10,306 individual samples in the Trans-Omics for Precision Medicine (TOPMed) program, we quantified NMD efficiency for 5,749 germline truncating variants via allele-specific expression and trained a gradient-boosting classifier, TrunCat, that distinguished NMD-sensitive from NMD-escape transcripts with ∼78% ROC-AUC (Receiver Operating Characteristic - Area Under the Curve). A reduced model using the ten features with the highest mean SHAP (SHapley Additive exPlanations) value as a measure of each feature's average contribution to predictions nearly matched this performance. Applied across large variant databases and a rare-disease cohort, the model produced NMD outcome predictions, with variants of uncertain significance showing higher predicted escape than pathogenic ones. This framework confirms the canonical rule, identifies non-canonical determinants, and offers a scalable resource for interpreting protein-truncating variants.

Heart failure (HF) is a leading global cause of morbidity and mortality, yet the regulatory molecular mechanisms that link genetic variation to cardiac dysfunction remain elusive. To bridge this gap, we created the Trans-Omics for Precision Medicine in Congestive Heart Failure (TOPCHeF) resource, a multi-omics dataset comprising >700 human left-ventricular tissue samples, including dilated cardiomyopathy (DCM), ischemic cardiomyopathy (ICM), and non-failing controls, with paired whole-genome and RNA sequencing. By mapping expression- (eQTL) and splicing- (sQTL) quantitative trait loci directly in diseased human hearts, we identified over 10,000 transcripts with significant eQTL and 8,600 isoforms with significant sQTL, across both coding and non-coding genes, many of which overlap loci previously associated with HF and emerging novel gene associations. Single-locus colocalization with a largescale DCM genome-wide association study revealed 21 expression and 17 splicing-QTL that share causal variants with disease risk. These include known Mendelian cardiomyopathy risk genes such as FLNC and ACTN2, and novel regulatory candidates like CAMK2D, LMF1, MYOZ1, SKI, SYNPO2L, and TKT. Several loci also showed coordinated effects on both gene expression and RNA splicing, implicating calcium signaling, cytoskeletal organization, and metabolic pathways in HF pathogenesis. Together, these results help define the regulatory landscape of the failing human heart and establish TOPCHeF as a foundational resource for connecting genetic variation to transcriptional and splicing molecular mechanisms in HF research.

IMPORTANCE Valsartan has been shown to attenuate phenotypic progression among individuals with early-stage sarcomeric hypertrophic cardiomyopathy (HCM). Myocardial tissue characterization by cardiac magnetic resonance (CMR) imaging may enhance mechanistic insights, but whether valsartan influences these parameters remains uncertain. OBJECTIVE To evaluate the treatment effects of valsartan on myocardial structure, function, and tissue parameters in early-stage sarcomeric HCM. DESIGN, SETTING, AND PARTICIPANTS This prespecified CMR substudy of the VANISH (Valsartan for Attenuating Disease Evolution in Early Sarcomeric Hypertrophic Cardiomyopathy) randomized clinical trial evaluated treatment effects of valsartan vs placebo on myocardial structure, function, and tissue parameters and was conducted from April 2014 through July 2019 at 17 international sites. Individuals aged 8 to 45 years with early-stage HCM aged between 8 and 45 years and with no or minimal symptoms were eligible for inclusion. INTERVENTIONS Treatment with placebo or valsartan (80 mg per day for children weighing <35 kg, 160 mg per day for children weighing >= 35 kg, or 320 mg per day for adults aged 18 years or older). MAIN OUTCOMES AND MEASURES The primary outcome was mean change in CMR parameters between baseline and year 2, including indexed extracellular volume (iECV), indexed intracellular volume (iICV), and late gadolinium enhancement (LGE). Mean between-group differences in CMR parameters between baseline and year 2 were evaluated using multivariable mixed-effects linear regression models. RESULTS Overall, 137 of 178 VANISH participants (77.0%) underwent CMR imaging at baseline and year 2. Among these participants, mean (SD) age was 23 (10) years, and 51 participants (37.2%) were female. Baseline characteristics and CMR parameters were well balanced between treatment groups. Higher LGE, iECV, and iICV at baseline were associated with higher cardiac biomarker levels and more pronounced cardiac remodeling. Between baseline and year 2, valsartan appeared to increase left ventricular (LV) end-diastolic volume index (mean difference [MD], 3.3 mL/m(2); 95% CI, 0.4-6.2; P = .03), suggesting treatment benefit, but did not significantly impact LV mass index (MD, -2.9 g/m(2); 95% CI, -6.1 to 0.2; P = .07) or LV ejection fraction. Similarly, valsartan appeared to reduce decline in right ventricular volumes. Valsartan appeared to significantly reduce iICV progression (MD, -5.0 mL/m(2); 95% CI, -9.7 to -0.4; P = .03), but did not impact iECV (MD, 0.0 mL/m(2); 95% CI, -1.4 to 1.3; P = .95) or LGE progression (MD, 0.5%; 95% CI, -0.4 to 1.3; P = .30). CONCLUSIONS AND RELEVANCE These findings enhance mechanistic insights into the effect of valsartan in early-stage HCM, showing potential benefits on biventricular remodeling and myocardial intracellular volume. Further research to identify cellular mechanisms of valsartan on HCM progression is needed.

AIMS:Dilated cardiomyopathy (DCM) has a monogenic aetiology in up to 40% of patients. Understanding the spectrum of genotype-phenotype associations in DCM is crucial for risk stratification and personalized treatment. We aimed to (i) characterize genotype-specific features, (ii) evaluate whether phenotype-based clustering reflects underlying genotype, and (iii) compare the prognostic value of genotype- versus phenotype-based approaches. METHODS AND RESULTS:A multicentre cohort of 534 DCM patients with a (likely) pathogenic variant were grouped by genotype (genotype-first approach) and clustered by clinical phenotype (phenotype-first approach). We compared clinical characteristics, identified genotype-phenotype associations, and evaluated outcomes, including all-cause mortality, heart failure hospitalization, heart transplantation, and malignant ventricular arrhythmias. Using the genotype-first approach, significant genotype-phenotype associations were found for 10 genes. FLNC, LMNA, DSP, and PLN variants were linked to arrhythmias. BAG3, TNNT2, DMD, and TTN were associated with increased cardiac volumes and decreased left ventricular ejection fraction (LVEF). Clustering identified four phenotypic clusters: (1) young, moderately reduced LVEF; (2) arrhythmias, moderate reduced LVEF; (3) low LVEF; (4) arrhythmias, low LVEF. There were no clear correlations between phenotypic clusters and genotype. The genotype-first approach showed that LMNA, FLNC, and BAG3 variants had the highest risk for heart failure and arrhythmogenic adverse outcomes. The phenotype-first approach indicated that clusters 3 and 4 were associated with the worst prognosis. Overall, genotype was the strongest predictor of outcome. CONCLUSIONS:Patients with a genetic form of DCM exhibit clinical and genetic heterogeneity. Genotype-based risk stratification is more accurate compared to a phenotype-first approach, highlighting the importance of broad genetic screening among patients with DCM. Additionally, gene-specific risk prediction should become more prominent in current guidelines on management of genetic DCM patients.

Nonsense mediated decay (NMD) as an RNA surveillance pathway degrades transcripts with variants introducing premature termination codons (i.e., PTC variants),yet a substantial subset of pathogenic PTC variants downstream of the final exon exon junction is predicted to escape NMD (NMD escape) based on the canonical 50 bp rule. Our systematic analysis of germline pathogenic PTC variants from ClinVar revealed 148 autosomal dominant (AD) disease genes enriched for predicted NMD escape alleles. These genes span nonsense (N=63), minus1 frameshift (N=34), and plus1 frameshift (N=22) variants, with 23 genes enriched for two classes and 6 for all three. Although their loss of function intolerance score distributions did not differ from controls (P = 0.407), these genes exhibited significantly higher protein protein interaction (PPI) network centrality (P < 0.05) with their NMD escape regions enriched for PPI interfaces (P < 0.001 for minus1 and nonsense) and low-complexity sequences (P < 0.03 for minus1 and plus1). P/LP variants also produced significantly longer mutant C terminal tails than controls (P < 0.01), increasing potential for functional disruption. Structural modeling of altered C terminal tails revealed recurrent gains of glycine/proline (P < 0.03) and changes in aromatic residue content consistent with altered intrinsic disorder. Integration with neurodevelopmental disorder gene sets identified 25 dosage sensitive genes with predicted NMD escape P/LP variants, seven (28%) encoding condensate-forming proteins. Variant-level modeling in representative genes (e.g., KAT6B) showed altered phase separation propensity driven by truncated and/or altered intrinsically disordered regions. Overall, this study implicates condensate dysregulation as a potential downstream biophysical consequence of NMD escape disease alleles, providing a protein-feature viewer for variant interpretation (https://github.com/schmidtjacob46/NMDesc-protein-viewer). ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported in part by the US National Human Genome Research Institute/National Heart Blood Lung Institute jointly funded Baylor-Hopkins Center for Mendelian Genomics (UM1HG006542), by the National Institutes of Health (NIH) (5R01 HD039056, 5R01 HL091771), by the Genomic Research Elucidates the Genetics of Rare Disease (GREGoR) Program (U01 HG011758) to J.E.P., J.R.L., and R.A.G., and by the National Institute of Neurological Disorders and Stroke (NINDS R35 NS105078) to J.R.L. J.X. was supported by Simons Foundation pilot award (AGT011737). J.S. was supported by the Genomic Research Elucidates the Genetics of Rare Disease (GREGoR) Program (U01 HG011758). S.J was supported by the University of Colorado School of Medicine Translational Research Scholars Program, Simons Foundation pilot award (AGT011737), and the National Institutes of Health grant R35GM133433. Z.C.-A. was supported by the TOPMed NHLBI Fellowship, Simons Foundation pilot award (AGT011737) and the Genomic Research Elucidates the Genetics of Rare Disease (GREGoR) Program (U01 HG011758). S.S.Y. is a Partner Faculty Member of the GREGoR Consortium. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: We used the human genetic variation data available from ClinVar and gnomAD control databases. They are all publicly available. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript.

Background:Genetic diagnosis has become increasingly important to guide clinical decision making for patients with dilated cardiomyopathy (DCM). Disease-causing (P/LP) missense variants in the gene RBM20 cause a highly penetrant arrhythmogenic dilated cardiomyopathy (DCM), but the role of truncating RBM20 variants ( RBM20tvs ) is unclear. Objective:Assess the contribution of RBM20tvs to DCM. Methods:We assembled an international cohort of DCM patients with RBM20 variants and used data from the genome-first UK Biobank (UKB) to assess the etiologic fraction, natural history and penetrance of RBM20tvs . Results:The etiologic fraction of RBM20tvs in arrhythmogenic DCM was modest (0.53[0.32,0.67], p=7.5×10 -5 ). RBM20tv DCM patients presented to referral centers later in life than RBM20 P/LP DCM patients (53±10 vs. 34±18 years, p=4×10 -3 ), and were less likely to have a family history of sudden cardiac arrest (20% vs. 65%, p= 0.046) or cardiomyopathy (20% vs. 78% p=5.4×10 -3 ). There was no significant difference in age- and sex-adjusted incident major heart failure or arrhythmia events between RBM20tv and RBM20 P/LP DCM patients, though sex-adjusted lifetime hazard was reduced in RBM20tv DCM (HR 0.15[0.03,0.66],p=0.009). In UKB, lifetime incidence of cardiomyopathy, heart failure, or major ventricular arrhythmia diagnosis was lower in participants with RBM20tvs than in those with TTNtvs (HR 0.55 [0.36,0.84], p=5.9×10 -3 ). Conclusions:RBM20tvs contribute to arrhythmogenic DCM phenotypes, but confer milder disease severity alone than RBM20 P/LP variants, and reduced lifetime disease penetrance compared to TTNtvs . Their potential for additive interactions with other damaging variants should be considered in DCM patients and families.

AIMS:Left ventricular reverse remodelling (LVRR) is a prognostic marker in patients with dilated (DCM) and non-dilated left ventricular cardiomyopathy (NDLVC). The utility of combining late gadolinium enhancement (LGE) and genetic testing in predicting LVRR in DCM/NDLVC remains a knowledge gap. This study aimed to assess an integrated approach including LGE data and genetics to predict LVRR in DCM/NDLVC patients. METHODS AND RESULTS:This multicentre observational study included DCM/NDLVC patients with: (i) baseline echocardiographic left ventricular ejection fraction (LVEF) <50%; (ii) genetic testing; (iii) baseline cardiac magnetic resonance (CMR); (iv) 12-month follow-up echocardiographic data. LVRR was defined as LVEF increase ≥10% or LVEF ≥50% (if baseline LVEF <45%) at 12 months. Outcome measures were: (i) all-cause mortality, heart transplant, or left ventricular assist device implantation (D/HT/LVAD); (ii) sudden cardiac death or major ventricular arrhythmias (SCD/MVA). Arrhythmogenic genes studied were LMNA, DSP, FLNC, and RBM20. Among 1757 DCM/NDLVC with genetic data, 616 met eligibility (462 DCM, 154 NDLVC; age 51 ± 14 years, 34% female). LVRR occurred in 314 patients (51%): 251 (54%) in DCM and 63 (41%) in NDLVC (p = 0.004). Independent predictors of LVRR within 1 year included titin truncating variants, absence of arrhythmogenic genes, and absence of LGE ring-like pattern. In patients with LVEF <35%, only the presence of LGE ring-like pattern and arrhythmogenic genes remained independently related to a lower rate of LVRR and increased SCD/MVA risk. CONCLUSION:In a large genetically and CMR characterized DCM/NDLVC cohort, arrhythmogenic genotypes and LGE ring-like pattern were inversely related to LVRR, particularly in patients with LVEF <35%.

Most genetic variants associated with complex traits and diseases occur in non-coding genomic regions and are hypothesized to regulate gene expression. To understand the genetics underlying gene expression variability, we characterize 14,324 ancestrally diverse RNA-sequencing samples from the NHLBI Trans-Omics for Precision Medicine (TOPMed) program and integrate whole genome sequencing data to perform cis and trans expression and splicing quantitative trait locus (cis-/trans-e/sQTL) analyses in six tissues and cell types, most notably whole blood (N=6,454) and lung (N=1,291). We show this dataset enables greater detection of secondary cis-e/sQTL signals than was achieved in previous studies, and that secondary cis-eQTL and primary trans-eQTL signal discovery is not saturated even though eGene discovery is. Most TOPMed trans-eQTL signals colocalize with cis-e/sQTL signals, suggesting many trans signals are mediated by cis signals. We fine-map European UK BioBank GWAS signals from 164 traits and colocalize the resulting 34,107 fine-mapped GWAS signals with TOPMed e/sQTL signals, finding that of 10,611 GWAS signals with a colocalization, 7,096 GWAS signals colocalize with at least one secondary e/sQTL signal. These results demonstrate that larger e/sQTL analyses will continue to uncover secondary e/sQTL signals, and that these new signals will benefit GWAS interpretation.

BACKGROUND:Nexilin (NEXN)-related cardiomyopathies (CMPs) are largely unexplored. OBJECTIVES:This study investigated the causative role of NEXN in CMPs, examining its phenotypic expression and prognostic profile. METHODS:Twelve referral centers collected phenotypic/genotypic data of patients with NEXN variants. Variant rarity was determined according to gnomAD allele frequency in CMPs. Burden enrichment tested rare NEXN variants in hypertrophic (HCM) and dilated cardiomyopathy (DCM)/nondilated left ventricular cardiomyopathy (NDLVC) CMPs against gnomAD non-Finnish Europeans (NFE). Outcomes of validated variants were detailed, with prognostic comparisons to Titin (TTN)- and Filamin C (FLNC)-related CMP cohorts. RESULTS:Involving 60 NEXN carriers with rare, protein-altering variants, a significant enrichment of NEXN-truncating variants (tvs) was found in the DCM/NDLVC cohort (0.39% vs 0.09% in gnomAD NFE; P = 0.0001), whereas no association was observed with HCM. Patients with DCM/NDLVC with NEXNtv (n = 17; median age: 45 years [Q1-Q3: 36-55 years], 88% probands, 53% male) showed mild left ventricular dilatation (indexed end-diastolic volume 69 mL [Q1-Q3: 46-87 mL]), mildly reduced left ventricular ejection fraction (44% [Q1-Q3: 31%-53%]), and myocardial fibrosis (64%). NYHA functional class I was common (71%). During a 45-month median follow-up (Q1-Q3: 11-130 months), 53% of patients were implanted with an implantable cardioverter-defibrillator and 25% had malignant ventricular arrhythmias (MVAs). Compared with TTN-CMP, NEXN-CMP exhibited earlier and more frequent MVAs at higher ejection fractions, and no significant differences were found against FLNC-CMP. CONCLUSIONS:NEXNtvs were significantly associated with DCM/NDLVC, characterized by mild cardiac abnormalities, infrequent heart failure, common fibrosis, and arrhythmias. This largest NEXN variant carrier cohort to date contributes to defining the causative role of this rare genotype and its associated phenotype.

Background:Desmoplakin (DSP) cardiomyopathy, caused by variants in the gene DSP, is a unique subtype of cardiomyopathy distinct from typical dilated or arrhythmogenic right ventricular cardiomyopathies. Specific diagnostic and disease staging criteria have yet to be developed for DSP cardiomyopathy. Objective:Utilizing a large cohort of DSP cardiomyopathy patients and their genotype-positive family members, this study aims to develop diagnostic and disease staging criteria for DSP cardiomyopathy. Methods:Patients from the DSP-ERADOS Network with complete rhythm monitoring, electrocardiogram and cardiac magnetic resonance imaging were enrolled. Diagnostic criteria were assessed in initially-presenting patients (probands) and their genotype-positive family members. Early disease criteria (with preserved left ventricular ejection fraction, LVEF) were integrated into standard LVEF-based classifications. Diagnostic and staging criteria were assessed by time-event analyses (major ventricular arrhythmia and heart failure events). Results:A total of 605 patients with complete diagnostic testing were included (mean age 40 yr, 60% female, 40% probands). The most prevalent disease features in probands were premature ventricular contractions (PVCs) >500/24hr (66%), nonsustained ventricular tachycardia (NSVT, 29%), LV late gadolinium enhancement (LGE, 53%), and reduced LVEF (44%). The presence of any one of these features was 97% sensitive for diagnosis (along with a DSP pathogenic variant) and were therefore considered as diagnostic criteria. Using these criteria, 77% of genotype-positive family members were considered clinically affected. Isolated right ventricular (RV) involvement occurred in only 0.7%. The absence of diagnostic criteria identified a low-risk group (composite event rate 0.8%/year, p<0.001). Integration of these criteria into LVEF-based classification improved identification of composite arrhythmia/heart failure events (early: diagnostic criteria with LVEF ≥50%, HR 2.7, p=0.04; intermediate: LVEF 41-49%, HR 3.7, p=0.009; advanced: LVEF ≤40% HR 10.3, p<0.001). LGE was mostly subepicardial (87%). Circumferential (ring-like) LGE was more frequent in intermediate or advanced vs early disease (66% vs 48%, p<0.001). Conclusion:This study identifies genotype-specific diagnostic and disease staging criteria for DSP cardiomyopathy that improve identification of risk for both heart failure and sustained ventricular arrhythmias. This work highlights how gene-specific criteria may be used to refine diagnosis and staging for cardiomyopathy subtypes - a critical step as gene-targeted treatments move toward clinical trials.

Restoration of cardiac function in patients with advanced heart failure is rare, and the molecular processes that regulate recovery are unknown. To identify potential mechanisms, we studied paired myocardial samples before and after left ventricular assist device therapy, where significant cardiac functional recovery occurred in ~25% of patients. We found that expression of the nuclear B isoform of Ca2+/calmodulin-dependent protein kinase IIδ (CaMKIIδ-B) inversely correlated with recovery. Furthermore, increased phosphorylation near the CaMKIIδ-B nuclear localization signal in non-responders prevented its auto-activation dependent nuclear translocation. Expression of a cytoplasm-restricted CaMKIIδ-B in cardiomyocytes dramatically remodeled the phospho-proteome and impaired contractility, while a nuclear-competent version did not. Modulating CaMKIIδ subcellular localization may thus represent a therapeutic strategy for advanced heart failure.

BACKGROUND:In hypertrophic cardiomyopathy (HCM), the mechanisms through which pathogenic sarcomere variants (G+) lead to left ventricular hypertrophy (LVH) are not understood. METHODS:VANISH (Valsartan for Attenuating Disease Evolution in Early Sarcomeric Hypertrophic Cardiomyopathy) was a multicenter, double-blind, placebo-controlled, randomized trial testing valsartan's ability to attenuate phenotypic progression in early sarcomeric (G+LVH+) and subclinical HCM (G+LVH‒). The outcome was a composite z-score reflecting change in cardiac remodeling from baseline to year 2 (end of study). Baseline and year 2 blood samples were used to quantify 276 proteins using a proximity extension assay (Olink, Sweden). We explored relative differences in protein abundance between early and subclinical HCM at baseline. In addition, we compared proteomic changes between baseline and year 2 in subclinical HCM participants who experienced phenotypic conversion to early HCM (convertors) versus nonconvertors; early HCM participants receiving valsartan versus placebo; and in association with changes in the phenotypic progression z-score. Comparisons were made using the t-test, Mann-Whitney U test, linear mixed models, and generalized linear models, correcting for multiple testing using a 5% false discovery rate. RESULTS:Circulating proteins were analyzed in 192 participants (32 subclinical and 160 early HCM [81 allocated to valsartan]). NT-proBNP (N-terminal pro-B-type natriuretic peptide) differentiated early from subclinical HCM and tracked with phenotypic progression in early HCM (1-unit worsening in z-score associated with a 27% increase in NT-proBNP [95% CI, 17-37%]). Some extracellular matrix remodeling proteins showed a higher abundance (eg, tissue-type plasminogen activator) in early compared with subclinical HCM or tracked with disease progression (decorin) in early HCM. Some growth factors had a higher relative abundance in early HCM (eg, fibroblast growth factor-21). While no individual protein was able to distinguish phenotypic convertors from nonconvertors, multiprotein panels including lipocalin 2, lectin-like oxidized low-density lipoprotein receptor 1, and either NT-proBNP or interleukin-17 receptor A, could distinguish these groups. CONCLUSIONS:NT-proBNP was the most informative protein, showing a higher abundance in early compared with subclinical HCM and tracking with the phenotypic progression z-score in early-stage HCM. Studying pathways involving growth factors and extracellular matrix remodeling may yield additional insights into the mechanisms behind disease progression in sarcomevere variant carriers and early HCM. REGISTRATION:URL: https://www.clinicaltrials.gov; Unique identifier: NCT01912534.

Heart failure (HF) is a major contributor to the global burden of cardiovascular disease. Current treatments for HF do not regenerate or restore cardiac muscle function, leaving cardiac transplantation as the only definitive treatment for end-stage HF. Subsequently, there is a tremendous need for alternative HF treatments as well as methods to effectively and selectively deliver those therapies to the heart. We have engineered an injectable reverse thermal gel (RTG) functionalized with carbon nanotubes (CNTs) to create a thermoresponsive conductive hydrogel or RTG-CNT. The RTG-CNT transitions from a liquid solution to a gel-based matrix upon reaching body temperature, a unique quality that allows for rapid injection of the liquid polymeric solution followed by gel localization in situ. Previously, we demonstrated the potential use of the RTG-CNT hydrogel for cardiac tissue engineering applications using three-dimensional (3D) cocultures of primary cardiac cells. Here, we performed a preclinical study to assess the biocompatibility of our RTG-CNT hydrogel in vivo by using hydrogel intracardial injection in a mouse model and in vitro by using 3D cultures of human-induced pluripotent stem cell-derived cardiomyocytes. In this report, we present compelling results that demonstrate the RTG-CNT hydrogel biocompatibility and its potential for use in cardiac tissue engineering applications.

BACKGROUND:Dilated cardiomyopathy (DCM) is a genetically heterogeneous disease, presenting diverse clinical phenotypes and outcomes based on the underlying gene affected. The influence of sex on the gene-specific long-term prognosis of patients with genetic DCM remains unclear. This study aims to determine the effect of sex on the long-term prognosis per underlying genogroup. METHODS:A retrospective cohort study was conducted using data from 4 international referral centers. Baseline and longitudinal clinical data of patients with DCM, with a median follow-up of 6.7 years (interquartile range, 3.5-11.9 years), were collected. The study included men and women with DCM who had undergone genetic testing. Patients were categorized into 7 genotype groups: cytoskeletal/Z-disk, desmosomal, nuclear envelope, motor sarcomeric, TTN, other genetic, and genotype negative. The main outcomes measured were left ventricular reverse remodeling, mortality, heart failure hospitalization, heart transplantation, and malignant ventricular arrhythmias. RESULTS:Among 1716 patients, 1130 (66%) were men and 510 (30%) had a (likely) pathogenic variant. Ventricular remodeling was gene-dependent in women, with TTN patients exhibiting the highest rate (P=0.003) and desmosomal patients the lowest (P=0.04) compared with the genotype-negative group. After a median follow-up of 6.7 years, 334 men (29%) and 140 women (24%) reached the primary end point. Men with a (likely) pathogenic variant had the poorest prognosis, showing a higher rate of major adverse events (adjusted hazard ratio, 1.48 [95% CI, 1.12-1.95]; P=0.02) and malignant ventricular arrhythmias (adjusted hazard ratio, 1.83 [95% CI, 1.16-2.88]; P=0.009) compared with genotype-negative women. Prognosis varied by gene in men (log-rank P<0.0001) but not in women (log-rank P=0.1). The cytoskeletal/Z-disk, desmosomal, and nuclear envelope groups had the worst prognosis in men. CONCLUSIONS:The genetic architecture and sex are critical predictors of left ventricular reverse remodeling and long-term prognosis in DCM. These factors should be integrated into individualized risk prediction models to enhance clinical outcomes in patients with DCM.

BACKGROUND:Heart rate (HR) affects heart failure outcomes, via uncertain mechanisms that may include left ventricular remodeling. However, in human ventricular myocardium, HR change has not been associated with a particular remodeling molecular phenotype. METHODS:Patients with nonischemic dilated cardiomyopathy (N=22) in sinus rhythm and refractory to β-blockade for both HR lowering and reverse remodeling were randomized 2:1 double-blind to the HCN4 (hyperpolarization-activated cyclic nucleotide-gated potassium channel 4) channel inhibitor ivabradine or placebo for 24 weeks treatment while maintaining target doses of β-blockers. Reverse remodeling was measured by left ventricular ejection fraction (LVEF), and myocardial gene expression by sequencing RNA extracted from endomyocardial biopsies. The primary statistical analysis was between HR change categories divided at the median, which resulted in Decreased HR (N=90) and Unchanged HR (N=8) groups. RESULTS:Respective HRs at baseline and 24 weeks were as follows: Decreased HR, 82.9±6.8 and 69.7±8.0 beats per minute (P=0.0005) and Unchanged HR, 80.8±5.7 and 79.2±11.6 beats per minute (P=0.58). All completing Decreased HR subjects were treated with ivabradine, whereas in the Unchanged HR group, 3 received ivabradine and 5 placebo. In Decreased HR, LVEF increased from 29.4±8.8% at baseline to 44.2±9.4% at 24 weeks (P=0.0003), compared with respective values of 26.6±11.4% and 29.2±12.0% (P=0.28) in Unchanged HR. HR and LVEF changes were not different from a previously conducted β-blocker nonischemic dilated cardiomyopathy study subdivided into LVEF responders and nonresponders. However, differentially expressed genes (N=151) in the Decreased versus Unchanged HR groups were >99% nonconcordant and therefore individually unique compared with β-blocker HR/LVEF responders versus nonresponders (2 shared differentially expressed genes). Multiple unique differentially expressed genes in Decreased HR including NRG1 upregulation are considered cardioprotective or involved in cardiac development. CONCLUSIONS:In patients with nonischemic dilated cardiomyopathy in sinus rhythm, HR lowering per se (1) is associated with substantial left ventricular reverse remodeling; (2) its absence can cause β-blocker reverse remodeling nonresponse; and (3) when from HCN4 channel inhibition, results in a unique molecular phenotype. REGISTRATION:URL: https://www.clinicaltrials.gov; Unique identifier: NCT02973594.