Objectives
The aim of this study was to perform a meta‐analysis to compare the outcomes of patients undergoing TAVR with and without balloon post‐dilation (PD).
Background
PD is a commonly used ...technique in TAVR to minimize paravalvular regurgitation (PVR), albeit supported by little evidence.
Methods
Systematic review and meta‐analysis of 6 studies comparing 889 patients who had PD compared to 4118 patients without PD.
Results
Patients undergoing PD were more likely male (OR 1.92; 95% CI, 1.41‐2.61; P < 0.001) and to have coronary artery disease (OR 1.31; 95% CI, 1.03‐1.68; P = 0.03) than those patients not requiring PD. There were no significant differences in 30‐day mortality (OR 1.24; 95% CI, 0.88‐1.74; P = 0.22) and myocardial infarction (OR 0.93; 95% CI, 0.46‐1.90; P = 0.85). Patients undergoing TAVR did not have higher 1‐year mortality rates (OR 0.98; 95% CI, 0.61‐1.56; P = 0.92). The incidence of stroke was significantly greater in patients with PD (OR, 1.71; 95% CI, 1.10‐2.66). PD was able to reduce the incidence of moderate‐severe PVR by 15 fold (OR 15.0; 95% CI, 4.2‐54.5; P < 0.001), although rates of moderate‐severe PVR were still higher after PD than patients who did not require PD (OR 3.64; 95% CI, 1.96‐6.75; P < 0.001).
Conclusions
PD significantly improves rates of PVR, however careful patient selection is needed to minimize increased risk of strokes.
The "super-relaxed state" (SRX) of myosin represents a 'reserve' of motors in the heart. Myosin heads in the SRX are bound to the thick filament and have a very low ATPase rate. Changes in the SRX ...are likely to modulate cardiac contractility. We previously demonstrated that the SRX is significantly reduced in mouse cardiomyocytes lacking cardiac myosin binding protein-C (cMyBP-C). Here, we report the effect of mutations in the cMyBP-C gene (MYBPC3) using samples from human patients with hypertrophic cardiomyopathy (HCM). Left ventricular (LV) samples from 11 HCM patients were obtained following myectomy surgery to relieve LV outflow tract obstruction. HCM samples were genotyped as either MYBPC3 mutation positive (MYBPC3mut) or negative (HCMsmn) and were compared to eight non-failing donor hearts. Compared to donors, only MYBPC3mut samples display a significantly diminished SRX, characterised by a decrease in both the number of myosin heads in the SRX and the lifetime of ATP turnover. These changes were not observed in HCMsmn samples. There was a positive correlation (p < 0.01) between the expression of cMyBP-C and the proportion of myosin heads in the SRX state, suggesting cMyBP-C modulates and maintains the SRX. Phosphorylation of the myosin regulatory light chain in MYBPC3mut samples was significantly decreased compared to the other groups, suggesting a potential mechanism to compensate for the diminished SRX. We conclude that by altering both contractility and sarcomeric energy requirements, a reduced SRX may be an important disease mechanism in patients with MYBPC3 mutations.
Poor access to human left ventricular myocardium is a significant limitation in the study of heart failure (HF). Here, we utilise a carefully procured large human heart biobank of cryopreserved left ...ventricular myocardium to obtain direct molecular insights into ischaemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM), the most common causes of HF worldwide. We perform unbiased, deep proteomic and metabolomic analyses of 51 left ventricular (LV) samples from 44 cryopreserved human ICM and DCM hearts, compared to age-, gender-, and BMI-matched, histopathologically normal, donor controls. We report a dramatic reduction in serum amyloid A1 protein in ICM hearts, perturbed thyroid hormone signalling pathways and significant reductions in oxidoreductase co-factor riboflavin-5-monophosphate and glycolytic intermediate fructose-6-phosphate in both; unveil gender-specific changes in HF, including nitric oxide-related arginine metabolism, mitochondrial substrates, and X chromosome-linked protein and metabolite changes; and provide an interactive online application as a publicly-available resource.
The use of extracorporeal cardiopulmonary resuscitation (E-CPR) for the treatment of patients with out-of-hospital cardiac arrest who do not respond to conventional cardiopulmonary resuscitation CPR) ...has increased significantly in the past 10 years, in response to case reports and observational studies reporting encouraging results. However, no randomized controlled trials comparing E-CPR with conventional CPR have been published to date. The evidence from systematic reviews of the available observational studies is conflicting. The inclusion criteria for published E-CPR studies are variable, but most commonly include witnessed arrest, immediate bystander CPR, an initial shockable rhythm, and an estimated time from CPR start to establishment of E-CPR (low-flow time) of <60 minutes. A shorter low-flow time has been consistently associated with improved survival. In an effort to reduce low-flow times, commencement of E-CPR in the prehospital setting has been reported and is currently under investigation. The provision of an E-CPR service, whether hospital based or prehospital, carries considerable cost and technical challenges. Despite increased adoption, many questions remain as to which patients will derive the most benefit from E-CPR, when and where to implement E-CPR, optimal post-arrest E-CPR care, and whether this complex invasive intervention is cost-effective. Results of ongoing trials are awaited to determine whether E-CPR improves survival when compared with conventional CPR.
Despite in-depth knowledge of the molecular mechanisms controlling embryonic heart development, little is known about the signals governing postnatal maturation of the human heart.
Single-nucleus RNA ...sequencing of 54 140 nuclei from 9 human donors was used to profile transcriptional changes in diverse cardiac cell types during maturation from fetal stages to adulthood. Bulk RNA sequencing and the Assay for Transposase-Accessible Chromatin using sequencing were used to further validate transcriptional changes and to profile alterations in the chromatin accessibility landscape in purified cardiomyocyte nuclei from 21 human donors. Functional validation studies of sex steroids implicated in cardiac maturation were performed in human pluripotent stem cell-derived cardiac organoids and mice.
Our data identify the progesterone receptor as a key mediator of sex-dependent transcriptional programs during cardiomyocyte maturation. Functional validation studies in human cardiac organoids and mice demonstrate that the progesterone receptor drives sex-specific metabolic programs and maturation of cardiac contractile properties.
These data provide a blueprint for understanding human heart maturation in both sexes and reveal an important role for the progesterone receptor in human heart development.
Background Cardiac fibrosis is the excessive deposition of extracellular matrix in the heart, triggered by a cardiac insult, aging, genetics, or environmental factors. Molecular imaging of the ...cardiac extracellular matrix with targeted probes could improve diagnosis and treatment of heart disease. However, although this technology has been used to demonstrate focal scarring arising from myocardial infarction, its capacity to demonstrate extracellular matrix expansion and diffuse cardiac fibrosis has not been assessed. Methods and Results Here, we report the use of collagen-targeted peptides labeled with near-infrared fluorophores for the detection of diffuse cardiac fibrosis in the β2-AR (β-2-adrenergic receptor) overexpressing mouse model and in ischemic human hearts. Two approaches were evaluated, the first based on a T peptide that binds matrix metalloproteinase-2-proteolyzed collagen IV, and the second on the cyclic peptide EP-3533, which targets collagen I. The systemic and cardiac uptakes of both peptides (intravenously administered) were quantified ex vivo by near-infrared imaging of whole organs, tissue sections, and heart lysates. The peptide accumulation profiles corresponded to an immunohistochemically-validated increase in collagen types I and IV in hearts of transgenic mice versus littermate controls. The T peptide could encouragingly demonstrate both the intermediate (7 months old) and severe (11 months old) cardiomyopathic phenotypes. Co-immunostainings of fluorescent peptides and collagens, as well as reduced collagen binding of a control peptide, confirmed the collagen specificity of the tracers. Qualitative analysis of heart samples from patients with ischemic cardiomyopathy compared with nondiseased donors supported the collagen-enhancement capabilities of these peptides also in the clinical settings. Conclusions Together, these observations demonstrate the feasibility and translation potential of molecular imaging with collagen-binding peptides for noninvasive imaging of diffuse cardiac fibrosis.
Omecamtiv mecarbil (OM) enhances systolic function in vivo by directly binding the myosin cross-bridges (XBs) in the sarcomere. However, the mechanistic details governing OM-induced modulation of XB ...behavior in failing human myocardium are unclear.
The effects of OM on steady state and dynamic XB behavior were measured in chemically skinned myocardial preparations isolated from human donor and heart failure (HF) left ventricle. HF myocardium exhibited impaired contractile function as evidenced by reduced maximal force, magnitude of XB recruitment (
), and a slowed rate of XB detachment (
) at submaximal Ca
activations. Ca
sensitivity of force generation (pCa
) was higher in HF myocardium when compared with donor myocardium, both prior to and after OM incubations. OM incubation (0.5 and 1.0 μmol/L) enhanced force generation at submaximal Ca
activations in a dose-dependent manner. Notably, OM induced a slowing in
with 1.0 μmol/L OM but not with 0.5 μmol/L OM in HF myocardium. Additionally, OM exerted other differential effects on XB behavior in HF myocardium as evidenced by a greater enhancement in
and slowing in the time course of cooperative XB recruitment (
), which collectively prolonged achievement of peak force development (
), compared with donor myocardium.
Our findings demonstrate that OM augments force generation but also prolongs the time course of XB transitions to force-bearing states in remodeled HF myocardium, which may extend the systolic ejection time in vivo. Optimal OM dosing is critical for eliciting enhanced systolic function without excessive prolongation of systolic ejection time, which may compromise diastolic filling.
The disrupted organisation of the ryanodine receptors (RyR) and junctophilin (JPH) is thought to underpin the transverse tubule (t-tubule) remodelling in a failing heart. Here, we assessed the ...nanoscale organisation of these two key proteins in the failing human heart. Recently, an advanced feature of the t-tubule remodelling identified large flattened t-tubules called t-sheets, that were several microns wide. Previously, we reported that in the failing heart, the dilated t-tubules up to ~1 μm wide had increased collagen, and we hypothesised that the t-sheets would also be associated with collagen deposits. Direct stochastic optical reconstruction microscopy (dSTORM), confocal microscopy, and western blotting were used to evaluate the cellular distribution of excitation-contraction structures in the cardiac myocytes from patients with idiopathic dilated cardiomyopathy (IDCM) compared to myocytes from the non-failing (NF) human heart. The dSTORM imaging of RyR and JPH found no difference in the colocalisation between IDCM and NF myocytes, but there was a higher colocalisation at the t-tubule and sarcolemma compared to the corbular regions. Western blots revealed no change in the JPH expression but did identify a ~50% downregulation of RyR (
p
= 0.02). The dSTORM imaging revealed a trend for the smaller t-tubular RyR clusters (~24%) and reduced the t-tubular RyR cluster density (~35%) that resulted in a 50% reduction of t-tubular RyR tetramers in the IDCM myocytes (
p
< 0.01). Confocal microscopy identified the t-sheets in all the IDCM hearts examined and found that they are associated with the reticular collagen fibres within the lumen. However, the size and density of the RyR clusters were similar in the myocyte regions associated with t-sheets and t-tubules. T-tubule remodelling is associated with a reduced RyR expression that may contribute to the reduced excitation-contraction coupling in the failing human heart.
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