Muscle-specific Cand2 is translationally upregulated by mTORC1 and promotes adverse cardiac remodeling.

The mechanistic target of rapamycin (mTOR) promotes pathological remodeling in the heart by activating ribosomal biogenesis and mRNA translation. Inhibition of mTOR in cardiomyocytes is protective; however, a detailed role of mTOR in translational regulation of specific mRNA networks in the diseased heart is unknown. We performed cardiomyocyte genome-wide sequencing to define mTOR-dependent gene expression control at the level of mRNA translation. We identify the muscle-specific protein Cullin-associated NEDD8-dissociated protein 2 (Cand2) as a translationally upregulated gene, dependent on the activity of mTOR. Deletion of Cand2 protects the myocardium against pathological remodeling. Mechanistically, we show that Cand2 links mTOR signaling to pathological cell growth by increasing Grk5 protein expression. Our data suggest that cell-type-specific targeting of mTOR might have therapeutic value against pathological cardiac remodeling.

Reactive Oxidative Species-Modulated Ca2+ Release Regulates ß2 Integrin Activation on CD4+ CD28null T Cells of Acute Coronary Syndrome Patients.

The number and activity of T cell subsets in the atherosclerotic plaques are critical for the prognosis of patients with acute coronary syndrome. ß2 Integrin activation is pivotal for T cell recruitment and correlates with future cardiac events. Despite this knowledge, differential regulation of adhesiveness in T cell subsets has not been explored yet. In this study, we show that in human T cells, SDF-1α-mediated ß2 integrin activation is driven by a, so far, not-described reactive oxidative species (ROS)-regulated calcium influx. Furthermore, we show that CD4+CD28null T cells represent a highly reactive subset showing 25-fold stronger ß2 integrin activation upon SDF-1α stimulation compared with CD28+ T cells. Interestingly, ROS-dependent Ca release was much more prevalent in the pathogenetically pivotal CD28null subset compared with the CD28+ T cells, whereas the established mediators of the classical pathways for ß2 integrin activation (PKC, PI3K, and PLC) were similarly activated in both T cell subsets. Thus, interference with the calcium flux attenuates spontaneous adhesion of CD28null T cells from acute coronary syndrome patients, and calcium ionophores abolished the observed differences in the adhesion properties between CD28+ and CD28null T cells. Likewise, the adhesion of these T cell subsets was indistinguishable in the presence of exogenous ROS/H2O2 Together, these data provide a molecular explanation of the role of ROS in pathogenesis of plaque destabilization.

Myocardial AKT: the omnipresent nexus.

One of the greatest examples of integrated signal transduction is revealed by examination of effects mediated by AKT kinase in myocardial biology. Positioned at the intersection of multiple afferent and efferent signals, AKT exemplifies a molecular sensing node that coordinates dynamic responses of the cell in literally every aspect of biological responses. The balanced and nuanced nature of homeostatic signaling is particularly essential within the myocardial context, where regulation of survival, energy production, contractility, and response to pathological stress all flow through the nexus of AKT activation or repression. Equally important, the loss of regulated AKT activity is primarily the cause or consequence of pathological conditions leading to remodeling of the heart and eventual decompensation. This review presents an overview compendium of the complex world of myocardial AKT biology gleaned from more than a decade of research. Summarization of the widespread influence that AKT exerts upon myocardial responses leaves no doubt that the participation of AKT in molecular signaling will need to be reckoned with as a seemingly omnipresent regulator of myocardial molecular biological responses.

Correction: The Impact of Juvenile Coxsackievirus Infection on Cardiac Progenitor Cells and Postnatal Heart Development.

[This corrects the article DOI: 10.1371/journal.ppat.1004249.].

The impact of juvenile coxsackievirus infection on cardiac progenitor cells and postnatal heart development.

Coxsackievirus B (CVB) is an enterovirus that most commonly causes a self-limited febrile illness in infants, but cases of severe infection can manifest in acute myocarditis. Chronic consequences of mild CVB infection are unknown, though there is an epidemiologic association between early subclinical infections and late heart failure, raising the possibility of subtle damage leading to late-onset dysfunction, or chronic ongoing injury due to inflammatory reactions during latent infection. Here we describe a mouse model of juvenile infection with a subclinical dose of coxsackievirus B3 (CVB3) which showed no evident symptoms, either immediately following infection or in adult mice. However following physiological or pharmacologically-induced cardiac stress, juvenile-infected adult mice underwent cardiac hypertrophy and dilation indicative of progression to heart failure. Evaluation of the vasculature in the hearts of adult mice subjected to cardiac stress showed a compensatory increase in CD31+ blood vessel formation, although this effect was suppressed in juvenile-infected mice. Moreover, CVB3 efficiently infected juvenile c-kit+ cells, and cardiac progenitor cell numbers were reduced in the hearts of juvenile-infected adult mice. These results suggest that the exhausted cardiac progenitor cell pool following juvenile CVB3 infection may impair the heart's ability to increase capillary density to adapt to increased load.

Metabolic dysfunction consistent with premature aging results from deletion of Pim kinases.

RATIONALE: The senescent cardiac phenotype is accompanied by changes in mitochondrial function and biogenesis causing impairment in energy provision. The relationship between myocardial senescence and Pim kinases deserves attention because Pim-1 kinase is cardioprotective, in part, by preservation of mitochondrial integrity. Study of the pathological effects resulting from genetic deletion of all Pim kinase family members could provide important insight about cardiac mitochondrial biology and the aging phenotype. OBJECTIVE: To demonstrate that myocardial senescence is promoted by loss of Pim leading to premature aging and aberrant mitochondrial function. METHODS AND RESULTS: Cardiac myocyte senescence was evident at 3 months in Pim triple knockout mice, where all 3 isoforms of Pim kinase family members are genetically deleted. Cellular hypertrophic remodeling and fetal gene program activation were followed by heart failure at 6 months in Pim triple knockout mice. Metabolic dysfunction is an underlying cause of cardiac senescence and instigates a decline in cardiac function. Altered mitochondrial morphology is evident consequential to Pim deletion together with decreased ATP levels and increased phosphorylated AMP-activated protein kinase, exposing an energy deficiency in Pim triple knockout mice. Expression of the genes encoding master regulators of mitochondrial biogenesis, PPARγ (peroxisome proliferator-activated receptor gamma) coactivator-1 α and ß, was diminished in Pim triple knockout hearts, as were downstream targets included in mitochondrial energy transduction, including fatty acid oxidation. Reversal of the dysregulated metabolic phenotype was observed by overexpressing c-Myc (Myc proto-oncogene protein), a downstream target of Pim kinases. CONCLUSIONS: Pim kinases prevent premature cardiac aging and maintain a healthy pool of functional mitochondria leading to efficient cellular energetics.

Pim-1 preserves mitochondrial morphology by inhibiting dynamin-related protein 1 translocation.

Mitochondrial morphological dynamics affect the outcome of ischemic heart damage and pathogenesis. Recently, mitochondrial fission protein dynamin-related protein 1 (Drp1) has been identified as a mediator of mitochondrial morphological changes and cell death during cardiac ischemic injury. In this study, we report a unique relationship between Pim-1 activity and Drp1 regulation of mitochondrial morphology in cardiomyocytes challenged by ischemic stress. Transgenic hearts overexpressing cardiac Pim-1 display reduction of total Drp1 protein levels, increased phosphorylation of Drp1-(S637), and inhibition of Drp1 localization to the mitochondria. Consistent with these findings, adenoviral-induced Pim-1 neonatal rat cardiomyocytes (NRCMs) retain a reticular mitochondrial phenotype after simulated ischemia (sI) and decreased Drp1 mitochondrial sequestration. Interestingly, adenovirus Pim-dominant negative NRCMs show increased expression of Bcl-2 homology 3 (BH3)-only protein p53 up-regulated modulator of apoptosis (PUMA), which has been previously shown to induce Drp1 accumulation at mitochondria and increase sensitivity to apoptotic stimuli. Overexpression of the p53 up-regulated modulator of apoptosis-dominant negative adenovirus attenuates localization of Drp1 to mitochondria in adenovirus Pim-dominant negative NRCMs promotes reticular mitochondrial morphology and inhibits cell death during sI. Therefore, Pim-1 activity prevents Drp1 compartmentalization to the mitochondria and preserves reticular mitochondrial morphology in response to sI.

Pathological hypertrophy amelioration by PRAS40-mediated inhibition of mTORC1.

Mechanistic target of rapamycin complex 1 (mTORC1), necessary for cellular growth, is regulated by intracellular signaling mediating inhibition of mTORC1 activation. Among mTORC1 regulatory binding partners, the role of Proline Rich AKT Substrate of 40 kDa (PRAS40) in controlling mTORC1 activity and cellular growth in response to pathological and physiological stress in the heart has never been addressed. This report shows PRAS40 is regulated by AKT in cardiomyocytes and that AKT-driven phosphorylation relieves the inhibitory function of PRAS40. PRAS40 overexpression in vitro blocks mTORC1 in cardiomyocytes and decreases pathological growth. Cardiomyocyte-specific overexpression in vivo blunts pathological remodeling after pressure overload and preserves cardiac function. Inhibition of mTORC1 by PRAS40 preferentially promotes protective mTORC2 signaling in chronic diseased myocardium. In contrast, strong PRAS40 phosphorylation by AKT allows for physiological hypertrophy both in vitro and in vivo, whereas cardiomyocyte-specific overexpression of a PRAS40 mutant lacking capacity for AKT-phosphorylation inhibits physiological growth in vivo, demonstrating that AKT-mediated PRAS40 phosphorylation is necessary for induction of physiological hypertrophy. Therefore, PRAS40 phosphorylation acts as a molecular switch allowing mTORC1 activation during physiological growth, opening up unique possibilities for therapeutic regulation of the mTORC1 complex to mitigate pathologic myocardial hypertrophy by PRAS40.

Differential regulation of cellular senescence and differentiation by prolyl isomerase Pin1 in cardiac progenitor cells.

Autologous c-kit(+) cardiac progenitor cells (CPCs) are currently used in the clinic to treat heart disease. CPC-based regeneration may be further augmented by better understanding molecular mechanisms of endogenous cardiac repair and enhancement of pro-survival signaling pathways that antagonize senescence while also increasing differentiation. The prolyl isomerase Pin1 regulates multiple signaling cascades by modulating protein folding and thereby activity and stability of phosphoproteins. In this study, we examine the heretofore unexplored role of Pin1 in CPCs. Pin1 is expressed in CPCs in vitro and in vivo and is associated with increased proliferation. Pin1 is required for cell cycle progression and loss of Pin1 causes cell cycle arrest in the G1 phase in CPCs, concomitantly associated with decreased expression of Cyclins D and B and increased expression of cell cycle inhibitors p53 and retinoblastoma (Rb). Pin1 deletion increases cellular senescence but not differentiation or cell death of CPCs. Pin1 is required for endogenous CPC response as Pin1 knock-out mice have a reduced number of proliferating CPCs after ischemic challenge. Pin1 overexpression also impairs proliferation and causes G2/M phase cell cycle arrest with concurrent down-regulation of Cyclin B, p53, and Rb. Additionally, Pin1 overexpression inhibits replicative senescence, increases differentiation, and inhibits cell death of CPCs, indicating that cell cycle arrest caused by Pin1 overexpression is a consequence of differentiation and not senescence or cell death. In conclusion, Pin1 has pleiotropic roles in CPCs and may be a molecular target to promote survival, enhance repair, improve differentiation, and antagonize senescence.

Fibronectin is essential for reparative cardiac progenitor cell response after myocardial infarction.

RATIONALE: Adoptive transfer of cardiac progenitor cells (CPCs) has entered clinical application, despite limited mechanistic understanding of the endogenous response after myocardial infarction (MI). Extracellular matrix undergoes dramatic changes after MI and therefore might be linked to CPC-mediated repair. OBJECTIVE: To demonstrate the significance of fibronectin (Fn), a component of the extracellular matrix, for induction of the endogenous CPC response to MI. METHODS AND RESULTS: This report shows that presence of CPCs correlates with the expression of Fn during cardiac development and after MI. In vivo, genetic conditional ablation of Fn blunts CPC response measured 7 days after MI through reduced proliferation and diminished survival. Attenuated vasculogenesis and cardiogenesis during recovery were evident at the end of a 12-week follow-up period. Impaired CPC-dependent reparative remodeling ultimately leads to continuous decline of cardiac function in Fn knockout animals. In vitro, Fn protects and induces proliferation of CPCs via ß1-integrin-focal adhesion kinase-signal transducer and activator of transcription 3-Pim1 independent of Akt. CONCLUSIONS: Fn is essential for endogenous CPC expansion and repair required for stabilization of cardiac function after MI.

Regulation of cardiac hypertrophic signaling by prolyl isomerase Pin1.

RATIONALE: Cardiac hypertrophy results from the complex interplay of differentially regulated cascades based on the phosphorylation status of involved signaling molecules. Although numerous critical regulatory kinases and phosphatases have been identified in the myocardium, the intracellular mechanism for temporal regulation of signaling duration and intensity remains obscure. In the nonmyocyte context, control of folding, activity, and stability of proteins is mediated by the prolyl isomerase Pin1, but the role of Pin1 in the heart is unknown. OBJECTIVE: To establish the role of Pin1 in the heart. METHODS AND RESULTS: Here, we show that either genetic deletion or cardiac overexpression of Pin1 blunts hypertrophic responses induced by transaortic constriction and consequent cardiac failure in vivo. Mechanistically, we find that Pin1 directly binds to Akt, mitogen activated protein kinase (MEK), and Raf-1 in cultured cardiomyocytes after hypertrophic stimulation. Furthermore, loss of Pin1 leads to diminished hypertrophic signaling of Akt and MEK, whereas overexpression of Pin1 increases Raf-1 phosphorylation on the autoinhibitory site Ser259, leading to reduced MEK activation. CONCLUSIONS: Collectively, these data support a role for Pin1 as a central modulator of the intensity and duration of 2 major hypertrophic signaling pathways, thereby providing a novel target for regulation and control of cardiac hypertrophy.

Mechanistic target of rapamycin complex 2 protects the heart from ischemic damage.

BACKGROUND: The mechanistic target of rapamycin (mTOR) comprises 2 structurally distinct multiprotein complexes, mTOR complexes 1 and 2 (mTORC1 and mTORC2). Deregulation of mTOR signaling occurs during and contributes to the severity of myocardial damage from ischemic heart disease. However, the relative roles of mTORC1 versus mTORC2 in the pathogenesis of ischemic damage are unknown. METHODS AND RESULTS: Combined pharmacological and molecular approaches were used to alter the balance of mTORC1 and mTORC2 signaling in cultured cardiac myocytes and in mouse hearts subjected to conditions that mimic ischemic heart disease. The importance of mTOR signaling in cardiac protection was demonstrated by pharmacological inhibition of both mTORC1 and mTORC2 with Torin1, which led to increased cardiomyocyte apoptosis and tissue damage after myocardial infarction. Predominant mTORC1 signaling mediated by suppression of mTORC2 with Rictor similarly increased cardiomyocyte apoptosis and tissue damage after myocardial infarction. In comparison, preferentially shifting toward mTORC2 signaling by inhibition of mTORC1 with PRAS40 led to decreased cardiomyocyte apoptosis and tissue damage after myocardial infarction. CONCLUSIONS: These results suggest that selectively increasing mTORC2 while concurrently inhibiting mTORC1 signaling is a novel therapeutic approach for the treatment of ischemic heart disease.

An MEK-cofilin signalling module controls migration of human T cells in 3D but not 2D environments.

T cells infiltrate peripheral tissues to execute immunosurveillance and effector functions. For this purpose, T cells first migrate on the two-dimensional (2D) surface of endothelial cells to undergo transendothelial migration. Then they change their mode of movement to undergo migration within the three-dimensional (3D)-extracellular matrix of the infiltrated tissue. As yet, no molecular mechanisms are known, which control migration exclusively in either 2D or 3D environments. Here, we describe a signalling module that controls T-cell chemotaxis specifically in 3D environments. In chemotaxing T cells, Ras activity is spatially restricted to the lamellipodium. There, Ras initiates activation of MEK, which in turn inhibits LIM-kinase 1 activity, thereby allowing dephosphorylation of the F-actin-remodelling protein cofilin. Interference with this MEK-cofilin module by either inhibition of MEK or by knockdown of cofilin reduces speed and directionality of chemotactic migration in 3D-extracellular matrices, but not on 2D substrates. This MEK-cofilin module may have an important function in the tissue positioning of T cells during an immune response.

Asymmetric chromatid segregation in cardiac progenitor cells is enhanced by Pim-1 kinase.

RATIONALE: Cardiac progenitor cells (CPCs) in the adult heart are used for cell-based treatment of myocardial damage, but factors determining stemness, self-renewal, and lineage commitment are poorly understood. Immortal DNA strands inherited through asymmetric chromatid segregation correlate with self-renewal of adult stem cells, but the capacity of CPCs for asymmetric segregation to retain immortal strands is unknown. Cardioprotective kinase Pim-1 increases asymmetric cell division in vivo, but the ability of Pim-1 to enhance asymmetric chromatid segregation is unknown. OBJECTIVE: We aimed to demonstrate immortal strand segregation in CPCs and the enhancement of asymmetric chromatid distribution by Pim-1 kinase. METHODS AND RESULTS: Asymmetric segregation is tracked by incorporation of bromodeoxyuridine. The CPC DNA was labeled for several generations and then blocked in second cytokinesis during chase to determine distribution of immortal versus newly synthesized strands. Intensity ratios of binucleated CPCs with bromodeoxyuridine of ≥70:30 between daughter nuclei indicative of asymmetric chromatid segregation occur with a frequency of 4.57, and asymmetric chromatid segregation is demonstrated at late mitotic phases. Asymmetric chromatid segregation is significantly enhanced by Pim-1 overexpression in CPCs (9.19 versus 4.79 in eGFP-expressing cells; P=0.006). CONCLUSIONS: Asymmetric segregation of chromatids in CPCs is increased nearly two-fold with Pim-1 kinase overexpression, indicating that Pim-1 promotes self-renewal of stem cells.

Favorable safety profile of NOAC therapy in patients after tricuspid transcatheter edge-to-edge repair.

BACKGROUND: Transcatheter edge-to-edge repair for severe tricuspid regurgitation (TR) is a new treatment option (t-TEER). Data on optimal antithrombotic therapy after t-TEER in patients with an indication for anticoagulation are scarce and evidence-based guideline recommendations are lacking. We sought to investigate efficacy and safety of novel oral anticoagulation (NOAC) and vitamin-K-antagonists (VKA) in patients undergoing t-TEER. METHODS: Among 78 consecutive patients with t-TEER of severe TR, 69 patients were identified with concomitant indication for oral anticoagulation. Outcomes of these patients treated with NOAC or VKA were compared over a median follow-up period of 327 (177-460) days. RESULTS: Despite elevated thromboembolic and bleeding risk scores (CHA2DS2-VASc 4.2 ± 1.1, HEMORR2HAGES 3.0 ± 1.0 and HAS-BLED 2.1 ± 0.8), only one major bleeding incidence occurred under NOAC therapy. The risk for overall (NOAC 8% vs. VKA group 26%, p = 0.044) and major bleeding events (NOAC 2% vs. VKA 21%, p = 0.010) was significantly lower in the NOAC compared to the VKA group. No significant difference was found between NOAC and VKA treatment in terms of mortality (NOAC 18% vs. VKA 16%, p = 0.865) or the combined endpoint of death, heart failure hospitalization, stroke, embolism, thrombosis, myocardial infarction, and severe bleeding (NOAC 48% vs. VKA 42%, p = 0.801). A comparison between apixaban (n = 27) and rivaroxaban (n = 16) treated patients revealed no significant differences between NOAC substances (all bleeding events apixaban 7% vs. rivaroxaban 13%, p = 0.638). CONCLUSION: Results of this study indicate that NOACs may offer a favorable risk-benefit profile for patients with concomitant indication for anticoagulation therapy following t-TEER.

Transcatheter Valve Repair for Tricuspid Regurgitation: 1-Year Results from a Large European Real-World Registry.

BACKGROUND: Tricuspid valve transcatheter edge-to-edge repair has emerged as a valuable treatment option for patients with severe tricuspid regurgitation (TR). OBJECTIVES: This study aims to investigate the safety and effectiveness of the PASCAL transcatheter valve repair system in treating severe TR in a real-world patient population. METHODS: The PASTE (PASCAL for Tricuspid Regurgitation-a European registry) study is an investigator-initiated, multicenter, retrospective, and prospective observational cohort analysis conducted across 16 European heart valve centers including consecutive patients treated with the PASCAL transcatheter valve repair system from February 2019 to November 2023. Echocardiographic assessments were performed at baseline, discharge, and follow-up, and were subjected to centralized analysis. RESULTS: The study included 1,059 high-risk patients (mean age 79 ± 9 years; 53% female; TRI-SCORE risk 23% ± 18%; 87% NYHA functional class III/IV) with multiple comorbidities. Severe or higher graded TR was observed in 96% of patients. Intraprocedural success according to Tricuspid Valve Academic Research Consortium criteria was achieved in 85%, and TR reduced to ≤moderate in 87%. Independent predictors for a postprocedure residual TR of >moderate were coaptation gaps ≥8 mm (OR: 1.67; 95% CI: 1.03-2.72; P = 0.038), tenting height ≥10 mm (OR: 2.18; CI: 1.30-3.65; P = 0.003), the presence of a transvalvular lead (OR: 1.91; 95% CI: 1.19-3.05; P = 0.007), right ventricular dilatation >42 mm (OR: 3.35; 95% CI: 1.37-9.1; P = 0.009) and massive/torrential TR at baseline (OR: 4.59; 95% CI: 2.35-8.96; P < 0.001). At 1 year, 83% of patients showed ≤moderate TR. Significant clinical improvements included enhanced NYHA functional class (66% class I/II vs 17% at baseline; P < 0.001). Patients treated with the first-generation PASCAL system (n = 570) and with the new PASCAL Precision system (n = 489) had similar clinical profiles and TR severity at baseline. However, the Precision cohort showed greater TR reduction to trace/mild (63% vs 49%; P < 0.001), shorter procedure times (median 93 minutes [Q1-Q3: 69-130 minutes] vs 120 minutes [Q1-Q3: 82-165 minutes]; P < 0.001), and higher clinical success rates according to the Tricuspid Valve Academic Research Consortium at 30 days and 1 year (87% vs 81% [P = 0.021] and 56% vs 50% [P = 0.044], respectively). Higher center experience (≥21 patients/year) resulted in higher intraprocedural and clinical success. CONCLUSIONS: The PASCAL system effectively treats severe TR in high-risk patients, offering sustained TR reduction and significant clinical improvements at 1-year follow-up. (PASCAL for Tricuspid Regurgitation-a European registry [PASTE]; NCT05328284).

Impact of Pulmonary Hypertension on Outcomes after Transcatheter Tricuspid Valve Edge-to-Edge Repair.

BACKGROUND: Data regarding the association of pulmonary hypertension (PH) and outcomes in patients undergoing transcatheter tricuspid valve edge-to-edge repair (T-TEER) are scarce. OBJECTIVES: To 1) investigate the impact of PH on outcomes after T-TEER and 2) to shed further light into the role of pre- and postcapillary PH in patients undergoing T-TEER for relevant tricuspid regurgitation (TR). METHODS: The study included patients from the EuroTR registry (NCT06307262) who underwent T-TEER for relevant TR from 2016 until 2023 with available invasive evaluation of sPAP using right heart catheterization. Study endpoints were procedural TR reduction, improvement in New York Heart Association (NYHA) function class and a combined endpoint of death or heart failure hospitalization (HFH) at two-years. RESULTS: Among a total of 1230 patients (mean age 78.6 ±7.0 years; 51.4% women) increasing systolic pulmonary artery pressure (sPAP) was independently associated with increasing rates of two-year death or HFH (hazard ratio 1.027, 95% confidence interval 1.003-1.052, p=0.030; median survival follow up 343 (114-645) days). No significant survival differences were observed for patients with pre- vs. postcapillary PH. Sensitivity analysis revealed a sPAP value of 46 mmHg as optimized threshold for prediction of death or HFH. Being observed in 526 patients (42.8%), elevated sPAP > 46 mmHg was associated with more severe heart failure symptoms at baseline and follow-up. Importantly, NYHA functional class and TR severity significantly improved irrespective of PH. CONCLUSION: PH is an important outcome predictor in patients undergoing T-TEER for relevant TR. In contrast to previous studies, no significant differences were observed for patients with pre- and postcapillary PH in terms of survival free from HFH.

Residual tricuspid regurgitation after tricuspid transcatheter edge-to-edge repair: Insights into the EuroTR registry.

AIMS: Data on the prognostic impact of residual tricuspid regurgitation (TR) after tricuspid transcatheter edge-to-edge repair (T-TEER) are scarce. The aim of this analysis was to evaluate 2-year survival and symptomatic outcomes of patients in relation to residual TR after T-TEER. METHODS AND RESULTS: Using the large European Registry of Transcatheter Repair for Tricuspid Regurgitation (EuroTR registry) we investigated the impact of residual TR on 2-year all-cause mortality and New York Heart Association (NYHA) functional class at follow-up. The study further identified predictors for residual TR ≥3+ using a logistic regression model. The study included a total of 1286 T-TEER patients (mean age 78.0 ± 8.9 years, 53.6% female). TR was successfully reduced to ≤1+ in 42.4%, 2+ in 40.0% and 3+ in 14.9% of patients at discharge, while 2.8% remained with TR ≥4+ after the procedure. Residual TR ≥3+ was an independent multivariable predictor of 2-year all-cause mortality (hazard ratio 2.06, 95% confidence interval 1.30-3.26, p = 0.002). The prevalence of residual TR ≥3+ was four times higher in patients with higher baseline TR (vena contracta >11.1 mm) and more severe tricuspid valve tenting (tenting area >1.92 cm2). Of note, no survival difference was observed in patients with residual TR ≤1+ versus 2+ (76.2% vs. 73.1%, p = 0.461). The rate of NYHA functional class ≥III at follow-up was significantly higher in patients with residual TR ≥3+ (52.4% vs. 40.5%, p < 0.001). Of note, the degree of TR reduction significantly correlated with the extent of symptomatic improvement (p = 0.012). CONCLUSIONS: T-TEER effectively reduced TR severity in the majority of patients. While residual TR ≥3+ was associated with worse outcomes, no differences were observed for residual TR 1+ versus 2+. Symptomatic improvement correlated with the degree of TR reduction.

Fibronectin contributes to pathological cardiac hypertrophy but not physiological growth.

Ability of the heart to undergo pathological or physiological hypertrophy upon increased wall stress is critical for long-term compensatory function in response to increased workload demand. While substantial information has been published on the nature of the fundamental molecular signaling involved in hypertrophy, the role of extracellular matrix protein Fibronectin (Fn) in hypertrophic signaling is unclear. The objective of the study was to delineate the role of Fn during pressure overload-induced pathological cardiac hypertrophy and physiological growth prompted by exercise. Genetic conditional ablation of Fn in adulthood blunts cardiomyocyte hypertrophy upon pressure overload via attenuated activation of nuclear factor of activated T cells (NFAT). Loss of Fn delays development of heart failure and improves survival. In contrast, genetic deletion of Fn has no impact on physiological cardiac growth induced by voluntary wheel running. Down-regulation of the transcription factor c/EBPß (Ccaat-enhanced binding protein ß), which is essential for induction of the physiological growth program, is unaffected by Fn deletion. Nuclear NFAT translocation is triggered by Fn in conjunction with up-regulation of the fetal gene program and hypertrophy of cardiomyocytes in vitro. Furthermore, activation of the physiological gene program induced by insulin stimulation in vitro is attenuated by Fn, whereas insulin had no impact on Fn-induced pathological growth program. Fn contributes to pathological cardiomyocyte hypertrophy in vitro and in vivo via NFAT activation. Fn is dispensable for physiological growth in vivo, and Fn attenuates the activation of the physiological growth program in vitro.