Restrictive annuloplasty or replacement on reverse remodeling for nonischemic dilated cardiomyopathy.

BACKGROUND: For patients with nonischemic dilated cardiomyopathy (NIDCM), the indications for and results of mitral surgery remain controversial. We reviewed a strategy of mitral repair and replacement for clinically relevant secondary mitral regurgitation (MR) in patients with NIDCM. METHODS: We retrospectively reviewed 65 patients with advanced NIDCM (LVEF < 40%) who underwent mitral surgery. Of them, 47 (72%) underwent mitral annuloplasty and 18 (28%) replacement for secondary MR. The primary endpoint was postoperative reduction in indexed LV end-systolic volume (LVESVI). RESULTS: At baseline, there was no intergroup difference in LVESVI (123 ± 47 vs. 147 ± 37 ml/m2, P = 0.055), LVEF (27 ± 8% vs. 25 ± 6%, P = 0.41), incidence of severe MR (57% (27/47) vs. 72% (13/18), P = 0.40), or EuroSCORE II score (6.2% vs. 7.6%, P = 0.90). At 6 months, the annuloplasty group reduced LVESVI to a greater degree than the replacement group (P < 0.001), yielding significantly smaller postoperative LVESVI (96 ± 59 vs. 154 ± 61 ml/m2, P < 0.001) and better LVEF (P < 0.001). The rates of moderate/severe recurrent MR were 17% (8/47) and 0%, respectively. Multivariable analysis demonstrated that mitral annuloplasty (OR 6.10, 95% CI 1.14-32.8, P = 0.035) was significantly associated with postoperative LV reverse remodeling. Cumulative survival was not different between the groups (P = 0.26). CONCLUSIONS: In patients with NIDCM, mitral annuloplasty reduced LV volume to a greater degree than did mitral replacement. These findings may assist with surgical options for secondary MR associated with NIDCM.

Implementing a New Algorithm for Reinterpretation of Ambiguous Variants in Genetic Dilated Cardiomyopathy.

Dilated cardiomyopathy is a heterogeneous entity that leads to heart failure and malignant arrhythmias. Nearly 50% of cases are inherited; therefore, genetic analysis is crucial to unravel the cause and for the early identification of carriers at risk. A large number of variants remain classified as ambiguous, impeding an actionable clinical translation. Our goal was to perform a comprehensive update of variants previously classified with an ambiguous role, applying a new algorithm of already available tools. In a cohort of 65 cases diagnosed with dilated cardiomyopathy, a total of 125 genetic variants were classified as ambiguous. Our reanalysis resulted in the reclassification of 12% of variants from an unknown to likely benign or likely pathogenic role, due to improved population frequencies. For all the remaining ambiguous variants, we used our algorithm; 60.9% showed a potential but not confirmed deleterious role, and 24.5% showed a potential benign role. Periodically updating the population frequencies is a cheap and fast action, making it possible to clarify the role of ambiguous variants. Here, we perform a comprehensive reanalysis to help to clarify the role of most of ambiguous variants. Our specific algorithms facilitate genetic interpretation in dilated cardiomyopathy.

Association between dietary selenium and zinc intake and risk of dilated cardiomyopathy in children: a case-control study.

BACKGROUND: Dilated cardiomyopathy (DCMP) is characterized by the enlargement and weakening of the heart and is a major cause of heart failure in children. Infection and nutritional deficiencies are culprits for DCMP. Zinc is an important nutrient for human health due to its anti-oxidant effect that protects cell against oxidative damage. This case-control study aimed to investigate the relationship between dietary intake of zinc and selenium and the risk of DCMP in pediatric patients. METHODS: A total of 36 DCMP patients and 72 matched controls were recruited, and their dietary intakes were assessed via a validated food frequency questionnaire. We used chi-square and sample T-test for qualitative and quantitative variables, respectively. Logistic regression analysis was applied to assess the relationship between selenium and zinc intake with the risk of DCMP. RESULTS: After fully adjusting for confounding factors, analyses showed that selenium (OR = 0.19, CI = 0.057-0.069, P trend < 0.011) and zinc (OR = 0.12, CI = 0.035-0.046, P trend < 0.002) intake were strongly associated with 81% and 88% lower risk of pediatric DCMP, respectively. CONCLUSIONS: This study highlights the protective role of adequate dietary intake of selenium and zinc in decreasing the risk of DCMP in children. Malnutrition may exacerbate the condition and addressing these micronutrient deficiencies may improve the cardiac function. Further studies are recommended to detect the underlying mechanisms and dietary recommendations for DCMP prevention.

Familial dilated cardiomyopathy in a child: a case report.

BACKGROUND: Dilated cardiomyopathy (DCM) commonly leads to heart failure (HF) and represents the most common indication for cardiac transplantation in the pediatric population. Clinical manifestations of DCM are mainly the symptoms of heart failure; it is diagnosed by EKG, chest x-ray and echocardiography. For the idiopathic and familial diseases cases of DCM, there are no definite guidelines for treatment in children as they are treated for prognostic improvement. CASE PRESENTATION: We report the case of a 2-year-old girl diagnosed with dilated cardiomyopathy associated with homozygous mutation in the Myosin Light Chain 3 gene admitted for edema in lower extremities, muscle weakness, lethargy and vomiting, and she was found to be in cardiogenic shock. Chest x-ray showed cardiomegaly and EKG showed first degree atrioventricular block. Echocardiogram showed severe biventricular systolic and diastolic dysfunction. After 70 days of hospitalization, the patient went into cardiac arrest with cessation of electrical and mechanical activity of the heart, despite cardiopulmonary resuscitative efforts. CONCLUSION: Although rare, pediatric DCM carries a high risk of morbidity and mortality and a lack of curative therapy.

Dilated cardiomyopathy due to hypocalcaemia: a case report.

BACKGROUND: Hypocalcaemia is a rare, but reversible, cause of dilated cardiomyopathy causing heart failure. Several case reports have been reported on reversible cardiomyopathy secondary to hypocalcaemia. CASE PRESENTATION: We report a case of 54-year-old female Sri Lankan patient who presented with shortness of breath and was diagnosed with heart failure with reduced ejection fraction due to dilated cardiomyopathy. The etiology for dilated cardiomyopathy was identified as hypocalcemic cardiomyopathy, secondary to primary hypoparathyroidism, which was successfully treated with calcium and vitamin D replacement therapy. CONCLUSION: This adds to literature of this rare cause of reversible cardiomyopathy secondary to hypocalcemia reported from the South Asian region of the world. This case highlights the impact of proper treatment improving the heart failure in patients with hypocalcemic cardiomyopathy.

Characterization of Non-Ischemic Dilated Cardiomyopathy in a Native Tanzanian Cohort: MOYO Study.

Background: Non-ischemic dilated cardiomyopathy (NIDCM) is a common cause of heart failure with progressive tendency. The disease occurs in one in every 2,500 individuals in the developed world, with high morbidity and mortality. However, detailed data on the role of NIDCM in heart failure in Tanzania is lacking. Aim: To characterize NIDCM in a Tanzanian cohort with respect to demographics, clinical profile, imaging findings and management. Methods: Characterization of non-ischemic dilated cardioMyOpathY in a native Tanzanian cOhort (MOYO) is a prospective cohort study of NIDCM patients seen at the Jakaya Kikwete Cardiac Institute. Patients aged ≥18 years with a clinical diagnosis of heart failure, an ejection fraction of ≤45% on echocardiography and no evidence of ischemia were enrolled. Clinical data, echocardiography, electrocardiography (ECG), coronary angiography and stress ECG information were collected from February 2020 to March 2022. Results: Of 402 patients, n = 220 (54.7%) were males with a median (IQR) age of 55.0 (41.0, 66.0) years. Causes of NIDCM were presumably hypertensive n = 218 (54.2%), idiopathic n = 116 (28.9%), PPCM n = 45 (11.2%), alcoholic n = 10 (2.5%) and other causes n = 13 (3.2%). The most common presenting symptoms were dyspnea n = 342 (85.1%), with the majority of patients presenting with New York Heart Association (NYHA) Class III n = 195 (48.5%). The mean (SD) left ventricular ejection fraction (LVEF) was 29.4% (±7.7), and severe systolic dysfunction (LVEF <30%) was common n = 208 (51.7%). Compared with other forms of DCM, idiopathic DCM patients were significantly younger, had more advanced NYHA class (p < 0.001) and presented more often with left bundle branch block on ECG (p = 0.0042). There was suboptimal use of novel guidelines recommended medications ARNI n = 10 (2.5%) and SGLT2 2-inhibitors n = 2 (0.5%). Conclusions: In our Tanzanian cohort, the majority of patients with NIDCM have an identified underlying cause, and they present at late stages of the disease. Patients with idiopathic DCM are younger with more severe disease compared to other forms of NIDCM.

The Prognostic Value of Serum Calcium Levels in Elderly Dilated Cardiomyopathy Patients.

Background: It is unclear whether serum calcium on admission is associated with clinical outcomes in dilated cardiomyopathy (DCM). In this study, we conducted a retrospective study spanning a decade to investigate the prognostic value of baseline calcium in elderly patients with DCM. Methods: A total of 1,089 consecutive elderly patients (age ≥60 years) diagnosed with DCM were retrospectively enrolled from January 2010 to December 2019. Univariate and multivariate analyses were performed to investigate the association of serum calcium with their clinical outcomes. Results: In this study, the average age of the subjects was 68.36 ± 6.31 years. Receiver operating characteristic (ROC) curve analysis showed that serum calcium level had a great sensitivity and specificity for predicting in-hospital death, with an AUC of 0.732. Kaplan-Meier survival analysis showed that patients with a serum calcium >8.62 mg/dL had a better prognosis than those with a serum calcium ≤8.62 mg/dL (log-rank χ2 40.84, p < 0.001). After adjusting for several common risk factors, a serum calcium ≤8.62 mg/dL was related to a higher risk of long-term mortality (HR: 1.449; 95% CI: 1.115~1.882; p = 0.005). Conclusions: Serum calcium level could be served as a simple and affordable tool to evaluate patients' prognosis in DCM.

Epidermal Growth Factor-Like Repeats and Discoidin I-Like Domains 3 Deficiency Attenuates Dilated Cardiomyopathy by Inhibiting Ubiquitin Specific Peptidase 10 Dependent Smad4 Deubiquitination.

BACKGROUND: Dilated cardiomyopathy (DCM) is the leading cause of heart failure with a poor prognosis. Recent studies suggest that endothelial to mesenchymal transition (EndMT) may be involved in the pathogenesis and cardiac remodeling during DCM development. EDIL3 (epidermal growth factor-like repeats and discoidin I-like domains 3) is an extracellular matrix glycoprotein that has been reported to promote EndMT in various diseases. However, the roles of EDIL3 in DCM still remain unclear. METHODS AND RESULTS: A mouse model of DCM and human umbilical vein endothelial cells were used to explore the roles and mechanisms of EDIL3 in DCM. The results indicated that EndMT and EDIL3 were activated in DCM mice. EDIL3 deficiency attenuated cardiac dysfunction and remodeling in DCM mice. EDIL3 knockdown alleviated EndMT by inhibiting USP10 (ubiquitin specific peptidase 10) dependent Smad4 deubiquitination in vivo and in vitro. Recombinant human EDIL3 promoted EndMT via reinforcing deubiquitination of Smad4 in human umbilical vein endothelial cells treated with IL-1ß (interleukin 1ß) and TGF-ß (transforming growth factor beta). Inhibiting USP10 abolished EndMT exacerbated by EDIL3. In addition, recombinant EDIL3 also aggravates doxorubicin-induced EndMT by promoting Smad4 deubiquitination in HUVECs. CONCLUSIONS: Taken together, these results indicate that EDIL3 deficiency attenuated EndMT by inhibiting USP10 dependent Smad4 deubiquitination in DCM mice.

Causal Relationship Between Immune Cells/Cytokines and Dilated Cardiomyopathy.

To date, whether there is any causal relationship between dilated cardiomyopathy (DCM) and the changes in the levels/expression of immune cells/cytokines is still unclear. This study aimed to investigate the causal relationship between the levels of various types of immune cells/cytokines and DCM. Herein, two-sample Mendelian randomization (MR) (TSMR) using R software was conducted. Single nucleotide polymorphisms (SNPs) related to the levels of various types of immune cells/cytokines and DCM were screened based on the genome-wide association studies (GWAS) obtained from open-source databases. The TSMR was conducted using inverse variance weighted (IVW), method, MR-Egger regression, weighted median method, and simple estimator based on mode to explore the causal association between the levels of each immune cell/cytokine and DCM. Sensitivity analysis was conducted using MR-Egger regression and a leave-one-out sensitivity test. A total of 1816 SNPs related to host immune status and DCM were identified. The IVW results showed a relationship between DCM and the circulating levels of basophils/eosinophils, total eosinophils-basophils, lymphocytes, and C-reactive protein (CRP). Increased lymphocytes levels (odds ratio (OR) = 0.91, 95% confidence interval (CI): 0.84-0.97, P = 0.005) were seen as protective against DCM, whereas increased basophil (OR = 1.18, 95% CI: 1.04-1.33, P = 0.022), eosinophil (OR = 1.1, 95% CI: 1.03-1.17, P = 0.007), eosinophil-basophil (OR = 1.09, 95% CI: 1.02-1.17, P = 0.014), and CRP (OR = 1.1, 95% CI: 1.03-1.18, P = 0.013) levels were associated with an increased risk of DCM. These analyses revealed that there may be a relationship between immune cells/select cytokine status and the onset of DCM. Future studies are required to further validate these outcomes in animal models and clinical trials.

Genetic Characterization of Dilated Cardiomyopathy in Romanian Adult Patients.

Dilated cardiomyopathy (DCM) represents a group of disorders affecting the structure and function of the heart muscle, leading to a high risk of heart failure and sudden cardiac death (SCD). DCM frequently involves an underlying genetic etiology. Genetic testing is valuable for risk stratification, treatment decisions, and family screening. Romanian population data on the genetic etiology of DCM are lacking. We aimed to investigate the genetic causes for DCM among Romanian adult patients at tertiary referral centers across the country. Clinical and genetic investigations were performed on adult patients presenting to tertiary hospitals in Romania. The genetic investigations used next-generation sequencing panels of disease-associated DCM genes. A total of 122 patients with DCM underwent genetic testing. The mean age at DCM diagnosis was 41.6 ± 12.4 years. The genetic investigations identified pathogenic or likely pathogenic variants in 50.8% of participants, while 25.4% had variants of unknown significance. Disease-causing variants in 15 genes were identified in people with DCM, with 31 previously unreported variants. Variants in TTN, LMNA, and DSP explained 75% of genetic causes for DCM. In total, 52.4% of patients had a family history of DCM/SCD. Left ventricular ejection fraction of <35% was observed in 41.9% of patients with disease-causing variants and 55% with negative or uncertain findings. Further genotype-phenotype correlations were explored in this study population. The substantial percentage (50.8%) of disease-causing variants identified in patients with DCM acknowledges the importance of genetic investigations. This study highlights the genetic landscape in genes associated with DCM in the Romanian population.

De Novo p.Asp3368Gly Variant of Dystrophin Gene Associated with X-Linked Dilated Cardiomyopathy and Skeletal Myopathy: Clinical Features and In Silico Analysis.

Dystrophin (DMD) gene mutations are associated with skeletal muscle diseases such as Duchenne and Becker Muscular Dystrophy (BMD) and X-linked dilated cardiomyopathy (XL-DCM). To investigate the molecular basis of DCM in a 37-year-old woman. Clinical and genetic investigations were performed. Genetic testing was performed with whole exome sequencing (WES) using the Illumina platform. According to the standard protocol, a variant found by WES was confirmed in all available members of the family by bi-directional capillary Sanger resequencing. The effect of the variant was investigated by using an in silico prediction of pathogenicity. The index case was a 37-year-old woman diagnosed with DCM at the age of 33. A germline heterozygous A>G transversion at nucleotide 10103 in the DMD gene, leading to an aspartic acid-glycine substitution at the amino acid 3368 of the DMD protein (c.10103A>G p.Asp3368Gly), was identified and confirmed by PCR-based Sanger sequencing of the exon 70. In silico prediction suggests that this variant could have a deleterious impact on protein structure and functionality (CADD = 30). The genetic analysis was extended to the first-degree relatives of the proband (mother, father, and sister) and because of the absence of the variant in both parents, the p.Asp3368Gly substitution was considered as occurring de novo. Then, the direct sequencing analysis of her 8-year-old son identified as hemizygous for the same variant. The young patient did not present any signs or symptoms attributable to DCM, but reported asthenia and presented with bilateral calf hypertrophy at clinical examination. Laboratory testing revealed increased levels of creatinine kinase (maximum value of 19,000 IU/L). We report an early presentation of dilated cardiomyopathy in a 33-year-old woman due to a de novo pathogenic variant of the dystrophin (DMD) gene (p.Asp3368Gly). Genetic identification of this variant allowed an early diagnosis of a skeletal muscle disease in her son.

Familial Dilated Cardiomyopathy: A Novel MED9 Short Isoform Identification.

Familial dilated cardiomyopathy (DCM) is among the leading indications for heart transplantation. DCM alters the transcriptomic profile. The alteration or activation/silencing of physiologically operating transcripts may explain the onset and progression of this pathological state. The mediator complex (MED) plays a fundamental role in the transcription process. The aim of this study is to investigate the MED subunits, which are altered in DCM, to identify target crossroads genes. RNA sequencing allowed us to identify specific MED subunits that are altered during familial DCM, transforming into human myocardial samples. N = 13 MED subunits were upregulated and n = 7 downregulated. MED9 alone was significantly reduced in patients compared to healthy subjects (HS) (FC = -1.257; p < 0.05). Interestingly, we found a short MED9 isoform (MED9s) (ENSG00000141026.6), which was upregulated when compared to the full-transcript isoform (MED9f). Motif identification analysis yielded several significant matches (p < 0.05), such as GATA4, which is downregulated in CHD. Moreover, although the protein-protein interaction network showed FOG2/ZFPM2, FOS and ID2 proteins to be the key interacting partners of GATA4, only FOG2/ZFPM2 overexpression showed an interaction score of "high confidence" ≥ 0.84. A significant change in the MED was observed during HF. For the first time, the MED9 subunit was significantly reduced between familial DCM and HS (p < 0.05), showing an increased MED9s isoform in DCM patients with respect to its full-length transcript. MED9 and GATA4 shared the same sequence motif and were involved in a network with FOG2/ZFPM2, FOS, and ID2, proteins already implicated in cardiac development.

Assessment of Right Atrial Function Measured with Cardiac MRI Feature Tracking for Predicting Outcomes in Patients with Dilated Cardiomyopathy.

Background Right atrial (RA) function strain is increasingly acknowledged as an important predictor of adverse events in patients with diverse cardiovascular conditions. However, the prognostic value of RA strain in patients with dilated cardiomyopathy (DCM) remains uncertain. Purpose To evaluate the prognostic value of RA strain derived from cardiac MRI (CMR) feature tracking (FT) in patients with DCM. Materials and Methods This multicenter, retrospective study included consecutive adult patients with DCM who underwent CMR between June 2010 and May 2022. RA strain parameters were obtained using CMR FT. The primary end points were sudden or cardiac death or heart transplant. Cox regression analysis was used to determine the association of variables with outcomes. Incremental prognostic value was evaluated using C indexes and likelihood ratio tests. Results A total of 526 patients with DCM (mean age, 51 years ± 15 [SD]; 381 male) were included. During a median follow-up of 41 months, 79 patients with DCM reached the primary end points. At univariable analysis, RA conduit strain was associated with the primary end points (hazard ratio [HR], 0.82 [95% CI: 0.76, 0.87]; P < .001). In multivariable Cox analysis, RA conduit strain was an independent predictor for the primary end points (HR, 0.83 [95% CI: 0.77, 0.90]; P < .001). A model combining RA conduit strain with other clinical and conventional imaging risk factors (C statistic, 0.80; likelihood ratio, 92.54) showed improved discrimination and calibration for the primary end points compared with models with clinical variables (C statistic, 0.71; likelihood ratio, 37.12; both P < .001) or clinical and imaging variables (C statistic, 0.75; likelihood ratio, 64.69; both P < .001). Conclusion CMR FT-derived RA conduit strain was an independent predictor of adverse outcomes among patients with DCM, providing incremental prognostic value when combined in a model with clinical and conventional CMR risk factors. Published under a CC BY 4.0 license. Supplemental material is available for this article.

Use of cardiac contractility modulation combined with left bundle branch pacing CRT-P in a female with a 22-year history of non-ischemic dilated cardiomyopathy: A case report.

Cardiac contractility modulation (CCM) is a novel device-based therapy used to treat patients with heart failure with reduced ejection fraction (HFrEF). In both randomized clinical trials and real-life studies, CCM has been shown to improve exercise tolerance and quality of life, reverse left ventricular remodeling, and reduce hospitalization in patients with HFrEF. In this case report, we describe for the first time the use of CCM combined with left bundle branch pacing (LBBP) cardiac resynchronization therapy pacemaker (CRT-P) implantation therapy in a female with a 22-year history of non-ischemic dilated cardiomyopathy. With the optimal medical therapy and cardiac resynchronization therapy (CRT) strategies, the patient's quality of life initially recovered to some extent, but began to deteriorate in the past year. Additionally, heart transplantation was not considered due to economic reasons and late stage systolic heart failure. This is the first case of CCM implantation in Fujian Province and the first report of a combined CCM and left bundle branch pacing CRT-P implantation strategy in a patient with non-ischemic etiology dilated cardiomyopathy in China.

HTRA1-driven detachment of type I collagen from endoplasmic reticulum contributes to myocardial fibrosis in dilated cardiomyopathy.

BACKGROUND: The aberrant secretion and excessive deposition of type I collagen (Col1) are important factors in the pathogenesis of myocardial fibrosis in dilated cardiomyopathy (DCM). However, the precise molecular mechanisms underlying the synthesis and secretion of Col1 remain unclear. METHODS AND RESULTS: RNA-sequencing analysis revealed an increased HtrA serine peptidase 1 (HTRA1) expression in patients with DCM, which is strongly correlated with myocardial fibrosis. Consistent findings were observed in both human and mouse tissues by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunohistochemistry, and immunofluorescence analyses. Pearson's analysis showed a markedly positive correlation between HTRA1 level and myocardial fibrosis indicators, including extracellular volume fraction (ECV), native T1, and late gadolinium enhancement (LGE), in patients with DCM. In vitro experiments showed that the suppression of HTRA1 inhibited the conversion of cardiac fibroblasts into myofibroblasts and decreased Col1 secretion. Further investigations identified the role of HTRA1 in promoting the formation of endoplasmic reticulum (ER) exit sites, which facilitated the transportation of Col1 from the ER to the Golgi apparatus, thereby increasing its secretion. Conversely, HTRA1 knockdown impeded the retention of Col1 in the ER, triggering ER stress and subsequent induction of ER autophagy to degrade misfolded Col1 and maintain ER homeostasis. In vivo experiments using adeno-associated virus-serotype 9-shHTRA1-green fluorescent protein (AAV9-shHTRA1-GFP) showed that HTRA1 knockdown effectively suppressed myocardial fibrosis and improved left ventricular function in mice with DCM. CONCLUSIONS: The findings of this study provide valuable insights regarding the treatment of DCM-associated myocardial fibrosis and highlight the therapeutic potential of targeting HTRA1-mediated collagen secretion.

Identification of endocrine-disrupting chemicals targeting key DCM-associated genes via bioinformatics and machine learning.

Dilated cardiomyopathy (DCM) is a primary cause of heart failure (HF), with the incidence of HF increasing consistently in recent years. DCM pathogenesis involves a combination of inherited predisposition and environmental factors. Endocrine-disrupting chemicals (EDCs) are exogenous chemicals that interfere with endogenous hormone action and are capable of targeting various organs, including the heart. However, the impact of these disruptors on heart disease through their effects on genes remains underexplored. In this study, we aimed to explore key DCM-related genes using machine learning (ML) and the construction of a predictive model. Using the Gene Expression Omnibus (GEO) database, we screened differentially expressed genes (DEGs) and performed enrichment analyses of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to DCM. Through ML techniques combining maximum relevance minimum redundancy (mRMR) and least absolute shrinkage and selection operator (LASSO) logistic regression, we identified key genes for predicting DCM (IL1RL1, SEZ6L, SFRP4, COL22A1, RNASE2, HB). Based on these key genes, 79 EDCs with the potential to affect DCM were identified, among which 4 (3,4-dichloroaniline, fenitrothion, pyrene, and isoproturon) have not been previously associated with DCM. These findings establish a novel relationship between the EDCs mediated by key genes and the development of DCM.

Altered myocardial lipid regulation in junctophilin-2-associated familial cardiomyopathies.

Myocardial lipid metabolism is critical to normal heart function, whereas altered lipid regulation has been linked to cardiac diseases including cardiomyopathies. Genetic variants in the JPH2 gene can cause hypertrophic cardiomyopathy (HCM) and, in some cases, dilated cardiomyopathy (DCM). In this study, we tested the hypothesis that JPH2 variants identified in patients with HCM and DCM, respectively, cause distinct alterations in myocardial lipid profiles. Echocardiography revealed clinically significant cardiac dysfunction in both knock-in mouse models of cardiomyopathy. Unbiased myocardial lipidomic analysis demonstrated significantly reduced levels of total unsaturated fatty acids, ceramides, and various phospholipids in both mice with HCM and DCM, suggesting a common metabolic alteration in both models. On the contrary, significantly increased di- and triglycerides, and decreased co-enzyme were only found in mice with HCM. Moreover, mice with DCM uniquely exhibited elevated levels of cholesterol ester. Further in-depth analysis revealed significantly altered metabolites from all the lipid classes with either similar or opposing trends in JPH2 mutant mice with HCM or DCM. Together, these studies revealed, for the first time, unique alterations in the cardiac lipid composition-including distinct increases in neutral lipids and decreases in polar membrane lipids-in mice with HCM and DCM were caused by distinct JPH2 variants. These studies may aid the development of novel biomarkers or therapeutics for these inherited disorders.

DILATED CARDIOMYOPATHY IN SLENDER-TAILED MEERKATS (SURICATA SURICATTA) UNDER HUMAN CARE.

Meerkats (Suricata suricatta) housed at two accredited zoological institutions in the United States were evaluated via echocardiography, thoracic radiography, and blood biomarkers-taurine and feline N-terminal pro-B-type natriuretic peptide-to determine the prevalence and severity of dilated cardiomyopathy (DCM) in both populations. In total, 24 meerkats were evaluated and 7 were diagnosed with DCM based on the following parameters: left ventricular internal diameter at end diastole > 1.30 cm, left ventricular internal diameter at end systole > 1.10 cm, and a fractional shortening of <18%. Echocardiographic parameters were identified and reported for normal and affected meerkats, whereas thoracic radiographs were not useful for screening for DCM. Meerkats with DCM were treated with pimobendan and/or benazepril and furosemide if indicated. Seven meerkats died during the study period, with the majority exhibiting myocardial fibrosis. Of the blood parameters tested, elevated taurine levels were associated with DCM. Further research is necessary to characterize the etiology of DCM in meerkats.