Mechanisms and significance of tissue-specific MICU regulation of the mitochondrial calcium uniporter complex.

Mitochondrial Ca2+ uptake, mediated by the mitochondrial Ca2+ uniporter, regulates oxidative phosphorylation, apoptosis, and intracellular Ca2+ signaling. Previous studies suggest that non-neuronal uniporters are exclusively regulated by a MICU1-MICU2 heterodimer. Here, we show that skeletal-muscle and kidney uniporters also complex with a MICU1-MICU1 homodimer and that human/mouse cardiac uniporters are largely devoid of MICUs. Cells employ protein-importation machineries to fine-tune the relative abundance of MICU1 homo- and heterodimers and utilize a conserved MICU intersubunit disulfide to protect properly assembled dimers from proteolysis by YME1L1. Using the MICU1 homodimer or removing MICU1 allows mitochondria to more readily take up Ca2+ so that cells can produce more ATP in response to intracellular Ca2+ transients. However, the trade-off is elevated ROS, impaired basal metabolism, and higher susceptibility to death. These results provide mechanistic insights into how tissues can manipulate mitochondrial Ca2+ uptake properties to support their unique physiological functions.

Inhibition of Eicosanoid Degradation Mitigates Fibrosis of the Heart.

BACKGROUND: Organ fibrosis due to excessive production of extracellular matrix by resident fibroblasts is estimated to contribute to >45% of deaths in the Western world, including those due to cardiovascular diseases such as heart failure. Here, we screened for small molecule inhibitors with a common ability to suppress activation of fibroblasts across organ systems. METHODS: High-content imaging of cultured cardiac, pulmonary, and renal fibroblasts was used to identify nontoxic compounds that blocked induction of markers of activation in response to the profibrotic stimulus, transforming growth factor-ß1. SW033291, which inhibits the eicosanoid-degrading enzyme, 15-hydroxyprostaglandin dehydrogenase, was chosen for follow-up studies with cultured adult rat ventricular fibroblasts and human cardiac fibroblasts (CF), and for evaluation in mouse models of cardiac fibrosis and diastolic dysfunction. Additional mechanistic studies were performed with CFs treated with exogenous eicosanoids. RESULTS: Nine compounds, including SW033291, shared a common ability to suppress transforming growth factor-ß1-mediated activation of cardiac, pulmonary, and renal fibroblasts. SW033291 dose-dependently inhibited transforming growth factor-ß1-induced expression of activation markers (eg, α-smooth muscle actin and periostin) in adult rat ventricular fibroblasts and normal human CFs, and reduced contractile capacity of the cells. Remarkably, the 15-hydroxyprostaglandin dehydrogenase inhibitor also reversed constitutive activation of fibroblasts obtained from explanted hearts from patients with heart failure. SW033291 blocked cardiac fibrosis induced by angiotensin II infusion and ameliorated diastolic dysfunction in an alternative model of systemic hypertension driven by combined uninephrectomy and deoxycorticosterone acetate administration. Mechanistically, SW033291-mediated stimulation of extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase signaling was required for the compound to block CF activation. Of the 12 exogenous eicosanoids that were tested, only 12(S)-hydroxyeicosatetraenoic acid, which signals through the G protein-coupled receptor, GPR31, recapitulated the suppressive effects of SW033291 on CF activation. CONCLUSIONS: Inhibition of degradation of eicosanoids, arachidonic acid-derived fatty acids that signal through G protein-coupled receptors, is a potential therapeutic strategy for suppression of pathological organ fibrosis. In the heart, we propose that 15-hydroxyprostaglandin dehydrogenase inhibition triggers CF-derived autocrine/paracrine signaling by eicosanoids, including 12(S)-hydroxyeicosatetraenoic acid, to stimulate extracellular signal-regulated kinase 1/2 and block conversion of fibroblasts into activated cells that secrete excessive amounts of extracellular matrix and contribute to heart failure pathogenesis.

Disruption of Phosphodiesterase 3A Binding to SERCA2 Increases SERCA2 Activity and Reduces Mortality in Mice With Chronic Heart Failure.

BACKGROUND: Increasing SERCA2 (sarco[endo]-plasmic reticulum Ca2+ ATPase 2) activity is suggested to be beneficial in chronic heart failure, but no selective SERCA2-activating drugs are available. PDE3A (phosphodiesterase 3A) is proposed to be present in the SERCA2 interactome and limit SERCA2 activity. Disruption of PDE3A from SERCA2 might thus be a strategy to develop SERCA2 activators. METHODS: Confocal microscopy, 2-color direct stochastic optical reconstruction microscopy, proximity ligation assays, immunoprecipitations, peptide arrays, and surface plasmon resonance were used to investigate colocalization between SERCA2 and PDE3A in cardiomyocytes, map the SERCA2/PDE3A interaction sites, and optimize disruptor peptides that release PDE3A from SERCA2. Functional experiments assessing the effect of PDE3A-binding to SERCA2 were performed in cardiomyocytes and HEK293 vesicles. The effect of SERCA2/PDE3A disruption by the disruptor peptide OptF (optimized peptide F) on cardiac mortality and function was evaluated during 20 weeks in 2 consecutive randomized, blinded, and controlled preclinical trials in a total of 148 mice injected with recombinant adeno-associated virus 9 (rAAV9)-OptF, rAAV9-control (Ctrl), or PBS, before undergoing aortic banding (AB) or sham surgery and subsequent phenotyping with serial echocardiography, cardiac magnetic resonance imaging, histology, and functional and molecular assays. RESULTS: PDE3A colocalized with SERCA2 in human nonfailing, human failing, and rodent myocardium. Amino acids 277-402 of PDE3A bound directly to amino acids 169-216 within the actuator domain of SERCA2. Disruption of PDE3A from SERCA2 increased SERCA2 activity in normal and failing cardiomyocytes. SERCA2/PDE3A disruptor peptides increased SERCA2 activity also in the presence of protein kinase A inhibitors and in phospholamban-deficient mice, and had no effect in mice with cardiomyocyte-specific inactivation of SERCA2. Cotransfection of PDE3A reduced SERCA2 activity in HEK293 vesicles. Treatment with rAAV9-OptF reduced cardiac mortality compared with rAAV9-Ctrl (hazard ratio, 0.26 [95% CI, 0.11 to 0.63]) and PBS (hazard ratio, 0.28 [95% CI, 0.09 to 0.90]) 20 weeks after AB. Mice injected with rAAV9-OptF had improved contractility and no difference in cardiac remodeling compared with rAAV9-Ctrl after aortic banding. CONCLUSIONS: Our results suggest that PDE3A regulates SERCA2 activity through direct binding, independently of the catalytic activity of PDE3A. Targeting the SERCA2/PDE3A interaction prevented cardiac mortality after AB, most likely by improving cardiac contractility.

The HFSA Advanced Heart Failure and Transplant Cardiology Fellowship Consensus Conference.

There is waning interest among cardiology trainees in pursuing an Advanced Heart Failure/Transplant Cardiology (AHFTC) fellowship as evidenced by fewer applicants in the National Resident Matching Program match to this specialty. This trend has generated considerable attention across the heart failure community. In response, the Heart Failure Society of America convened the AHFTC Fellowship Task Force with a charge to develop strategies to increase the value proposition of an AHFTC fellowship. Subsequently, the HFSA sponsored the AHFTC Fellowship Consensus Conference April 26-27, 2023. Before the conference, interviews of 44 expert stakeholders diverse across geography, site of practice (traditional academic medical center or other centers), specialty/area of expertise, sex, and stage of career were conducted virtually. Based on these interviews, potential solutions to address the declining interest in AHFTC fellowship were categorized into five themes: (1) alternative training pathways, (2) regulatory and compensation, (3) educational improvements, (4) exposure and marketing for pipeline development, and (5) quality of life and mental health. These themes provided structure to the deliberations of the AHFTC Fellowship Consensus Conference. The recommendations from the Consensus Conference were subsequently presented to the HFSA Board of Directors to inform strategic plans and interventions. The HFSA Board of Directors later reviewed and approved submission of this document. The purpose of this communication is to provide the HF community with an update summarizing the processes used and concepts that emerged from the work of the HFSA AHFTC Fellowship Task Force and Consensus Conference.

Cardiomyocyte-Specific Long Noncoding RNA Regulates Alternative Splicing of the Triadin Gene in the Heart.

BACKGROUND: Abnormalities in Ca2+ homeostasis are associated with cardiac arrhythmias and heart failure. Triadin plays an important role in Ca2+ homeostasis in cardiomyocytes. Alternative splicing of a single triadin gene produces multiple triadin isoforms. The cardiac-predominant isoform, mouse MT-1 or human Trisk32, is encoded by triadin exons 1 to 8. In humans, mutations in the triadin gene that lead to a reduction in Trisk32 levels in the heart can cause cardiac dysfunction and arrhythmias. Decreased levels of Trisk32 in the heart are also common in patients with heart failure. However, mechanisms that maintain triadin isoform composition in the heart remain elusive. METHODS: We analyzed triadin expression in heart explants from patients with heart failure and cardiac arrhythmias and in hearts from mice carrying a knockout allele for Trdn-as, a cardiomyocyte-specific long noncoding RNA encoded by the antisense strand of the triadin gene, between exons 9 and 11. Catecholamine challenge with isoproterenol was performed on Trdn-as knockout mice to assess the role of Trdn-as in cardiac arrhythmogenesis, as assessed by ECG. Ca2+ transients in adult mouse cardiomyocytes were measured with the IonOptix platform or the GCaMP system. Biochemistry assays, single-molecule fluorescence in situ hybridization, subcellular localization imaging, RNA sequencing, and molecular rescue assays were used to investigate the mechanisms by which Trdn-as regulates cardiac function and triadin levels in the heart. RESULTS: We report that Trdn-as maintains cardiac function, at least in part, by regulating alternative splicing of the triadin gene. Knockout of Trdn-as in mice downregulates cardiac triadin, impairs Ca2+ handling, and causes premature death. Trdn-as knockout mice are susceptible to cardiac arrhythmias in response to catecholamine challenge. Normalization of cardiac triadin levels in Trdn-as knockout cardiomyocytes is sufficient to restore Ca2+ handling. Last, Trdn-as colocalizes and interacts with serine/arginine splicing factors in cardiomyocyte nuclei and is essential for efficient recruitment of splicing factors to triadin precursor mRNA. CONCLUSIONS: These findings reveal regulation of alternative splicing as a novel mechanism by which a long noncoding RNA controls cardiac function. This study indicates potential therapeutics for heart disease by targeting the long noncoding RNA or pathways regulating alternative splicing.

lncExACT1 and DCHS2 Regulate Physiological and Pathological Cardiac Growth.

BACKGROUND: The heart grows in response to pathological and physiological stimuli. The former often precedes cardiomyocyte loss and heart failure; the latter paradoxically protects the heart and enhances cardiomyogenesis. The mechanisms underlying these differences remain incompletely understood. Although long noncoding RNAs (lncRNAs) are important in cardiac development and disease, less is known about their roles in physiological hypertrophy or cardiomyogenesis. METHODS: RNA sequencing was applied to hearts from mice after 8 weeks of voluntary exercise-induced physiological hypertrophy and cardiomyogenesis or transverse aortic constriction for 2 or 8 weeks to induce pathological hypertrophy or heart failure. The top lncRNA candidate was overexpressed in hearts with adeno-associated virus vectors and inhibited with antisense locked nucleic acid-GapmeRs to examine its function. Downstream effectors were identified through promoter analyses and binding assays. The functional roles of a novel downstream effector, dachsous cadherin-related 2 (DCHS2), were examined through transgenic overexpression in zebrafish and cardiac-specific deletion in Cas9-knockin mice. RESULTS: We identified exercise-regulated cardiac lncRNAs, called lncExACTs. lncExACT1 was evolutionarily conserved and decreased in exercised hearts but increased in human and experimental heart failure. Cardiac lncExACT1 overexpression caused pathological hypertrophy and heart failure; lncExACT1 inhibition induced physiological hypertrophy and cardiomyogenesis, protecting against cardiac fibrosis and dysfunction. lncExACT1 functioned by regulating microRNA-222, calcineurin signaling, and Hippo/Yap1 signaling through DCHS2. Cardiomyocyte DCHS2 overexpression in zebrafish induced pathological hypertrophy and impaired cardiac regeneration, promoting scarring after injury. In contrast, murine DCHS2 deletion induced physiological hypertrophy and promoted cardiomyogenesis. CONCLUSIONS: These studies identify lncExACT1-DCHS2 as a novel pathway regulating cardiac hypertrophy and cardiomyogenesis. lncExACT1-DCHS2 acts as a master switch toggling the heart between physiological and pathological growth to determine functional outcomes, providing a potentially tractable therapeutic target for harnessing the beneficial effects of exercise.

Magnitude of troponin elevation in patients with biomarker evidence of myocardial injury: relative frequency and outcomes in a cohort study across a large healthcare system.

BACKGROUND: Serum troponin levels correlate with the extent of myocyte necrosis in acute myocardial infarction (AMI) and predict adverse outcomes. However, thresholds of cardiac troponin elevation that could portend to poor outcomes have not been established. METHODS: In this cohort study, we characterized all cardiac troponin elevations > 0.04 ng/mL (upper limit of normal [ULN]) from patients hospitalized with an ICD-9/10 diagnosis of AMI across our health system from 2012-2019. We grouped events into exponential categories of peak cardiac troponin and evaluated the association of these troponin categories with all-cause mortality, heart transplants, or durable left ventricular assist devices (LVAD). Patients with cardiac troponin > 10,000 × ULN were manually chart reviewed and described. RESULTS: There were 18,194 AMI hospitalizations with elevated cardiac troponin. Peak troponin was 1-10 × ULN in 21.1%, 10-100 × ULN in 34.8%, 100-1,000 × ULN in 30.1%, 1,000-10,000 × ULN in 13.1%, and > 10,000 × ULN in 0.9% of patients. One-year mortality was 17-21% across groups, except in > 10,000 × ULN group where it was 33% (adjusted hazard ratio (99%CI) for > 10,000 × ULN group compared to all others: 1.86 (1.21, 2.86)). Hazards of one-year transplant and MCS were also significantly elevated in the > 10,000 × ULN group. CONCLUSIONS: Elevation in cardiac troponin levels post AMI that are > 10,000 × ULN was rare but identified patients at particularly high risk of adverse events. These patients may benefit from clarification of goals of care and early referral for advanced heart failure therapies. These data have implications for conversion to newer high-sensitivity cardiac troponin assays whose maximum assay limit is often lower than traditional assays.

Cardiac Amyloidosis: Evolving Diagnosis and Management: A Scientific Statement From the American Heart Association.

Transthyretin amyloid cardiomyopathy (ATTR-CM) results in a restrictive cardiomyopathy caused by extracellular deposition of transthyretin, normally involved in the transportation of the hormone thyroxine and retinol-binding protein, in the myocardium. Enthusiasm about ATTR-CM has grown as a result of 3 simultaneous areas of advancement: Imaging techniques allow accurate noninvasive diagnosis of ATTR-CM without the need for confirmatory endomyocardial biopsies; observational studies indicate that the diagnosis of ATTR-CM may be underrecognized in a significant proportion of patients with heart failure; and on the basis of elucidation of the mechanisms of amyloid formation, therapies are now approved for treatment of ATTR-CM. Because therapy for ATTR-CM may be most effective when administered before significant cardiac dysfunction, early identification of affected individuals with readily available noninvasive tests is essential. This scientific statement is intended to guide clinical practice and to facilitate management conformity by covering current diagnostic and treatment strategies, as well as unmet needs and areas of active investigation in ATTR-CM.

Universal Depression Screen of Ambulatory Heart Transplant Recipients With Referral for Mental Health Intervention: A Quality Improvement Project.

BACKGROUND: Patients with a heart transplant and depression have higher rates of graft failure and noncompliance. LOCAL PROBLEM: The heart transplant clinic had no standardized approach to assess for depression. METHODS: The heart transplant clinic implemented routine use of the Patient Health Questionnaire (PHQ). INTERVENTIONS: Team members were educated via an online module about depression. A process for depression screening and follow-up was developed and implemented. RESULTS: From July 2018 to February 2019, there were 834 visits; PHQ2 screens were completed during 779 (93%) of those visits with 40 (5%) positive screens. All 40 patients had PHQ9 assessment, with 33 patients (4%) exhibiting moderate or severe depressive symptoms. All 33 patients were provided with mental health resources and received follow-up. Median time to administer PHQ2 was 2 minutes (range 1-3 minutes). CONCLUSIONS: Implementation of universal depression screening in a heart transplant clinic is feasible, identifies patients with depression, and does not add significant clinical burden.

Transcriptome signature of ventricular arrhythmia in dilated cardiomyopathy reveals increased fibrosis and activated TP53.

AIMS: One-third of DCM patients experience ventricular tachycardia (VT), but a clear biological basis for this has not been established. The purpose of this study was to identify transcriptome signatures and enriched pathways in the hearts of dilated cardiomyopathy (DCM) patients with VT. METHODS AND RESULTS: We used RNA-sequencing in explanted heart tissue from 49 samples: 19 DCM patients with VT, 16 DCM patients without VT, and 14 non-failing controls. We compared each DCM cohort to the controls and identified the genes that were differentially expressed in DCM patients with VT but not without VT. Differentially expressed genes were evaluated using pathway analysis, and pathways of interest were investigated by qRT-PCR validation, Western blot, and microscopy. There were 590 genes differentially expressed in DCM patients with VT that are not differentially expressed in patients without VT. These genes were enriched for genes in the TGFß1 and TP53 signaling pathways. Increased fibrosis and activated TP53 signaling was demonstrated in heart tissue of DCM patients with VT. CONCLUSIONS: Our study supports that distinct biological mechanisms distinguish ventricular arrhythmia in DCM patients.

Defining decreased protein succinylation of failing human cardiac myofibrils in ischemic cardiomyopathy.

Succinylation is a post-translational modification of protein lysine residues with succinyl groups derived from succinyl CoA. Succinylation is considered a significant post-translational modification with the potential to impact protein function which is highly conserved across numerous species. The role of succinylation in the heart, especially in heart failure and myofibril mechanics, remains largely unexplored. Mechanical parameters were measured in myofibrils isolated from failing hearts of ischemic cardiomyopathy patients and non-failing donor controls. We employed mass spectrometry to quantify differential protein expression in myofibrils from failing ischemic cardiomyopathy hearts compared to non-failing hearts. In addition, we combined peptide enrichment by immunoprecipitation with liquid chromatography tandem mass spectrometry to quantitatively analyze succinylated lysine residues in these myofibrils. Several key parameters of sarcomeric mechanical interactions were altered in myofibrils isolated from failing ischemic cardiomyopathy hearts, including lower resting tension and a faster rate of activation. Of the 100 differentially expressed proteins, 46 showed increased expression in ischemic heart failure, while 54 demonstrated decreased expression in ischemic heart failure. Our quantitative succinylome analysis identified a total of 572 unique succinylated lysine sites located on 181 proteins, with 307 significantly changed succinylation events. We found that 297 succinyl-Lys demonstrated decreased succinylation on 104 proteins, while 10 residues demonstrated increased succinylation on 4 proteins. Investigating succinyl CoA generation, enzyme activity assays demonstrated that α-ketoglutarate dehydrogenase and succinate dehydrogenase activities were significantly decreased in ischemic heart failure. An activity assay for succinyl CoA synthetase demonstrated a significant increase in ischemic heart failure. Taken together, our findings support the hypothesis that succinyl CoA production is decreased and succinyl CoA turnover is increased in ischemic heart failure, potentially resulting in an overall decrease in the mitochondrial succinyl CoA pool, which may contribute to decreased myofibril protein succinylation in heart failure.

New insights into resting and exertional right ventricular performance in the healthy heart through real-time pressure-volume analysis.

KEY POINTS: Despite growing interest in right ventricular form and function in diseased states, there is a paucity of data regarding characteristics of right ventricular function - namely contractile and lusitropic reserve, as well as ventricular-arterial coupling, in the healthy heart during rest, as well as submaximal and peak exercise. Pressure-volume analysis of the right ventricle, during invasive cardiopulmonary exercise testing, demonstrates that that the right heart has enormous contractile reserve, with a three- or fourfold increase in all metrics of contractility, as well as myocardial energy production and utilization. The healthy right ventricle also demonstrates marked augmentation in lusitropy, indicating that diastolic filling of the right heart is not passive. Rather, the right ventricle actively contributes to venous return during exercise, along with the muscle pump. Ventricular-arterial coupling is preserved during submaximal and peak exercise in the healthy heart. ABSTRACT: Knowledge of right ventricular (RV) function has lagged behind that of the left ventricle and historically, the RV has even been referred to as a 'passive conduit' of lesser importance than its left-sided counterpart. Pressure-volume (PV) analysis is the gold standard metric of assessing ventricular performance. We recruited nine healthy sedentary individuals free of any cardiopulmonary disease (42 ± 12 years, 78 ± 11 kg), who completed invasive cardiopulmonary exercise testing during upright ergometry, while using conductance catheters inserted into the RV to generate real-time PV loops. Data were obtained at rest, two submaximal levels of exercise below ventilatory threshold, to simulate real-world scenarios/activities of daily living, and maximal effort. Breath-by-breath oxygen uptake was determined by indirect calorimetry. During submaximal and peak exercise, there were significant increases in all metrics of systolic function by three- to fourfold, including cardiac output, preload recruitable stroke work, and maximum rate of pressure change in the ventricle (dP/dtmax ), as well as energy utilization as determined by stroke work and pressure-volume area. Similarly, the RV demonstrated a significant, threefold increase in lusitropic reserve throughout exercise. Ventricular-arterial coupling, defined by the quotient of end-systolic elastance and effective arterial elastance, was preserved throughout all stages of exercise. Maximal pressures increased significantly during exercise, while end-diastolic volumes were essentially unchanged. Overall, these findings demonstrate that the healthy RV is not merely a passive conduit, but actively participates in cardiopulmonary performance during exercise by accessing an enormous amount of contractile and lusitropic reserve, ensuring that VA coupling is preserved throughout all stages of exercise.

Transcription-independent Induction of ERBB1 through Hypoxia-inducible Factor 2A Provides Cardioprotection during Ischemia and Reperfusion.

BACKGROUND: During myocardial ischemia, hypoxia-inducible factors are stabilized and provide protection from ischemia and reperfusion injury. Recent studies show that myocyte-specific hypoxia-inducible factor 2A promotes myocardial ischemia tolerance through induction of epidermal growth factor, amphiregulin. Here, the authors hypothesized that hypoxia-inducible factor 2A may enhance epidermal growth factor receptor 1 (ERBB1) expression in the myocardium that could interface between growth factors and its effect on providing tolerance to ischemia and reperfusion injury. METHODS: Human myocardial tissues were obtained from ischemic heart disease patients and normal control patients to compare ERBB1 expression. Myocyte-specific Hif2a or ErbB1 knockout mice were generated to observe the effect of Hif2a knockdown in regulating ERBB1 expression and to examine the role of ERBB1 during myocardial ischemia and reperfusion injury. RESULTS: Initial studies of myocardial tissues from patients with ischemic heart disease showed increased ERBB1 protein (1.12 ± 0.24 vs. 13.01 ± 2.20, P < 0.001). In contrast, ERBB1 transcript was unchanged. Studies using short hairpin RNA repression of Hif2A or Hif2a Myosin Cre+ mice directly implicated hypoxia-inducible factor 2A in ERBB1 protein induction during hypoxia or after myocardial ischemia, respectively. Repression of RNA-binding protein 4 abolished hypoxia-inducible factor 2A-dependent induction of ERBB1 protein. Moreover, ErbB1 Myosin Cre+ mice experienced larger infarct sizes (22.46 ± 4.06 vs. 46.14 ± 1.81, P < 0.001) and could not be rescued via amphiregulin treatment. CONCLUSIONS: These findings suggest that hypoxia-inducible factor 2A promotes transcription-independent induction of ERBB1 protein and implicates epidermal growth factor signaling in protection from myocardial ischemia and reperfusion injury.

Relationship between nocturnal blood pressure patterns and end organ damage and diastolic dysfunction in heart transplant recipients.

BACKGROUND: We assessed the relationship between circadian blood pressure (BP) patterns and clinical outcomes in a contemporary cohort of adult heart transplant recipients. METHODS: This retrospective, cross-sectional study included adult heart transplant recipients at least 6 months post-transplant. Ambulatory BP measurements were recorded over 24 hours. Nondippers were defined as a decline in average nighttime BP ≤ 10% compared with daytime. Primary outcomes were the presence of end organ damage, that is, microalbuminuria, chronic kidney disease, and/or left ventricular hypertrophy. Secondary outcomes were measures of diastolic dysfunction (ie, mitral valve deceleration time, e/e', E/A, and isovolumetric relaxation time), microalbumin/creatinine ratio, eGFR, interventricular septal thickness, and left ventricular posterior wall thickness. RESULTS: Of 30 patients, 53.3% (n = 16) were systolic nondippers and 40% (n = 12) were diastolic nondippers. Diastolic nondippers had three times higher urine microalbumin/creatinine ratios than diastolic dippers (P = .03). Systolic nondippers had 16.3% lower mitral valve deceleration time (P = .05) than systolic dippers, while diastolic nondippers had 20.4% higher e/e' (P = .05) than diastolic dippers. There were no significant relationships between BP dipping status and any of the primary outcomes. CONCLUSIONS: These data suggest that systolic and diastolic nondipping BP patterns are associated with subclinical kidney damage and diastolic dysfunction in heart transplant recipients.

Presence of any degree of coronary artery disease among liver transplant candidates is associated with increased rate of post-transplant major adverse cardiac events.

The impact of coronary artery disease (CAD) among liver transplant candidates (LTC) on post-LT clinical outcomes remains unclear. The aim of this study is to determine association of presence and severity of CAD on post-LT major adverse cardiac events (MACE) including cardiac-associated mortality. We conducted a retrospective cohort analysis of 231 patients who underwent diagnostic coronary angiogram (DCA) during their LT evaluation at a tertiary medical center from 2012-2017. Patients were analyzed based on degree of CAD (no CAD, non-obstructive CAD [< 50% stenosis], obstructive CAD [≥50% stenosis]) per DCA results. MACE were noted at 30 days, 1 year, 3 years, and 5 years post-LT, and Kaplan-Meier curves were used to determine post-LT MACE-free probability. LTC with any CAD, including non-obstructive CAD, had lower MACE-free probability at all post-LT time points (0.94 vs 0.65 at 30 days, P = .001; 0.87 vs 0.59 at 1 year, P = .002; 0.87 vs 0.41 at 3 years, P < .001; 0.87 vs 0.37 at 5 years, P < .001). Identification of and medical intervention for non-obstructive CAD should be considered in all LTC, though further studies are necessary to determine optimal medical interventions to mitigate MACE risk in this cohort.

Increased myocyte calcium sensitivity in end-stage pediatric dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is the most common cause of heart failure (HF) in children, resulting in high mortality and need for heart transplantation. The pathophysiology underlying pediatric DCM is largely unclear; however, there is emerging evidence that molecular adaptations and response to conventional HF medications differ between children and adults. To gain insight into alterations leading to systolic dysfunction in pediatric DCM, we measured cardiomyocyte contractile properties and sarcomeric protein phosphorylation in explanted pediatric DCM myocardium (N = 8 subjects) compared with nonfailing (NF) pediatric hearts (N = 8 subjects). Force-pCa curves were generated from skinned cardiomyocytes in the presence and absence of protein kinase A. Sarcomeric protein phosphorylation was quantified with Pro-Q Diamond staining after gel electrophoresis. Pediatric DCM cardiomyocytes demonstrate increased calcium sensitivity (pCa50 =5.70 ± 0.0291), with an associated decrease in troponin (Tn)I phosphorylation compared with NF pediatric cardiomyocytes (pCa50 =5.59 ± 0.0271, P = 0.0073). Myosin binding protein C and TnT phosphorylation are also lower in pediatric DCM, whereas desmin phosphorylation is increased. Pediatric DCM cardiomyocytes generate peak tension comparable to that of NF pediatric cardiomyocytes [DCM 29.7 mN/mm2, interquartile range (IQR) 21.5-49.2 vs. NF 32.8 mN/mm2, IQR 21.5-49.2 mN/mm2; P = 0.6125]. In addition, cooperativity is decreased in pediatric DCM compared with pediatric NF (Hill coefficient: DCM 1.56, IQR 1.31-1.94 vs. NF 1.94, IQR 1.36-2.86; P = 0.0425). Alterations in sarcomeric phosphorylation and cardiomyocyte contractile properties may represent an impaired compensatory response, contributing to the detrimental DCM phenotype in children.NEW & NOTEWORTHY Our study is the first to demonstrate that cardiomyocytes from infants and young children with dilated cardiomyopathy (DCM) exhibit increased calcium sensitivity (likely mediated by decreased troponin I phosphorylation) compared with nonfailing pediatric cardiomyocytes. Compared with published values in adult cardiomyocytes, pediatric cardiomyocytes have notably decreased cooperativity, with a further reduction in the setting of DCM. Distinct adaptations in cardiomyocyte contractile properties may contribute to a differential response to pharmacological therapies in the pediatric DCM population.

Pediatric Heart Transplantation: Transitioning to Adult Care (TRANSIT): Feasibility of a Pilot Randomized Controlled Trial.

BACKGROUND: Young-adult heart transplant recipients transferring to adult care are at risk for poor health outcomes. We conducted a pilot randomized controlled trial to determine the feasibility of and to test a transition intervention for young adults who underwent heart transplantation as children and then transferred to adult care. METHODS: Participants were randomized to the transition intervention (4 months long, focused on heart-transplant knowledge, self-care, self-advocacy, and social support) or usual care. Self-report questionnaires and medical records data were collected at baseline and 3 and 6 months after the initial adult clinic visit. Longitudinal analyses comparing outcomes over time were performed using generalized estimating equations and linear mixed models. RESULTS: Transfer to adult care was successful and feasible (ie, excellent participation rates). The average patient standard deviation of mean tacrolimus levels was similar over time in both study arms and < 2.5, indicating adequate adherence. There were no between-group or within-group differences in percentage of tacrolimus bioassays within target range (> 50%). Average overall adherence to treatment was similarly good in both groups. Rates of appointment keeping through 6 months after transfer declined over time in both groups. CONCLUSIONS: The feasibility of the study was demonstrated. Our transition intervention did not improve outcomes.

Transcriptome analysis of human heart failure reveals dysregulated cell adhesion in dilated cardiomyopathy and activated immune pathways in ischemic heart failure.

BACKGROUND: Current heart failure (HF) treatment is based on targeting symptoms and left ventricle dysfunction severity, relying on a common HF pathway paradigm to justify common treatments for HF patients. This common strategy may belie an incomplete understanding of heterogeneous underlying mechanisms and could be a barrier to more precise treatments. We hypothesized we could use RNA-sequencing (RNA-seq) in human heart tissue to delineate HF etiology-specific gene expression signatures. RESULTS: RNA-seq from 64 human left ventricular samples: 37 dilated (DCM), 13 ischemic (ICM), and 14 non-failing (NF). Using a multi-analytic approach including covariate adjustment for age and sex, differentially expressed genes (DEGs) were identified characterizing HF and disease-specific expression. Pathway analysis investigated enrichment for biologically relevant pathways and functions. DCM vs NF and ICM vs NF had shared HF-DEGs that were enriched for the fetal gene program and mitochondrial dysfunction. DCM-specific DEGs were enriched for cell-cell and cell-matrix adhesion pathways. ICM-specific DEGs were enriched for cytoskeletal and immune pathway activation. Using the ICM and DCM DEG signatures from our data we were able to correctly classify the phenotypes of 24/31 ICM and 32/36 DCM samples from publicly available replication datasets. CONCLUSIONS: Our results demonstrate the commonality of mitochondrial dysfunction in end-stage HF but more importantly reveal key etiology-specific signatures. Dysfunctional cell-cell and cell-matrix adhesion signatures typified DCM whereas signals related to immune and fibrotic responses were seen in ICM. These findings suggest that transcriptome signatures may distinguish end-stage heart failure, shedding light on underlying biological differences between ICM and DCM.

Pediatric Heart Transplantation: Transitioning to Adult Care (TRANSIT): Baseline Findings.

Young adult solid organ transplant recipients who transfer from pediatric to adult care experience poor outcomes related to decreased adherence to the medical regimen. Our pilot trial for young adults who had heart transplant (HT) who transfer to adult care tests an intervention focused on increasing HT knowledge, self-management and self-advocacy skills, and enhancing support, as compared to usual care. We report baseline findings between groups regarding (1) patient-level outcomes and (2) components of the intervention. From 3/14 to 9/16, 88 subjects enrolled and randomized to intervention (n = 43) or usual care (n = 45) at six pediatric HT centers. Patient self-report questionnaires and medical records data were collected at baseline, and 3 and 6 months after transfer. For this report, baseline findings (at enrollment and prior to transfer to adult care) were analyzed using Chi-square and t-tests. Level of significance was p < 0.05. Baseline demographics were similar in the intervention and usual care arms: age 21.3 ± 3.2 vs 21.5 ± 3.3 years and female 44% vs 49%, respectively. At baseline, there were no differences between intervention and usual care for use of tacrolimus (70 vs 62%); tacrolimus level (mean ± SD = 6.5 ± 2.3 ng/ml vs 5.6 ± 2.3 ng/ml); average of the within patient standard deviation of the baseline mean tacrolimus levels (1.6 vs 1.3); and adherence to the medical regimen [3.6 ± 0.4 vs 3.5 ± 0.5 (1 = hardly ever to 4 = all of the time)], respectively. At baseline, both groups had a modest amount of HT knowledge, were learning self-management and self-advocacy, and perceived they were adequately supported. Baseline findings indicate that transitioning HT recipients lack essential knowledge about HT and have incomplete self-management and self-advocacy skills.

Defining Ambulatory Advanced Heart Failure: MedaMACS and Beyond.

PURPOSE OF REVIEW: Extended survival with LVADs has generated interest in implantation for ambulatory patients with advanced heart failure (HF) prior to dependence on inotropes, though we remain limited in our ability to define and advance indications in this less sick advanced HF population. RECENT FINDINGS: The MedaMACS and ROADMAP studies have informed prognosis and decision-making for ambulatory patients with advanced HF. Sicker INTERMACS profiles are consistently associated with high risk of death or rescue LVAD. Appropriately selected patients in profile 4 should be considered for LVADs based on their high mortality and poor quality of life. These studies also shed light on discordant perceptions of HF disease severity between patients and their physicians. For ambulatory patients with HF not at imminent risk of death, shared decision-making about LVAD requires measured and individualized consideration of risk and benefit beyond survival. Future studies, including the ongoing REVIVAL study, should provide additional prognostic information in this patient population and should aid patients, caregivers, and physicians as they contemplate complex decisions regarding LVAD therapy.