Fully automated contrast selection of joint bright- and black-blood late gadolinium enhancement imaging for robust myocardial scar assessment

PURPOSE

Joint bright- and black-blood MRI techniques provide improved scar localization and contrast. Black-blood contrast is obtained after the visual selection of an optimal inversion time (TI) which often results in uncertainties, inter- and intra-observer variability and increased workload. In this work, we propose an artificial intelligence-based algorithm to enable fully automated TI selection and simplify myocardial scar imaging.

METHODS

The proposed algorithm first localizes the left ventricle using a U-Net architecture. The localized left cavity centroid is extracted and a squared region of interest ("focus box") is created around the resulting pixel. The focus box is then propagated on each image and the sum of the pixel intensity inside is computed. The smallest sum corresponds to the image with the lowest intensity signal within the blood pool and healthy myocardium, which will provide an ideal scar-to-blood contrast. The image's corresponding TI is considered optimal. The U-Net was trained to segment the epicardium in 177 patients with binary cross-entropy loss. The algorithm was validated retrospectively in 152 patients, and the agreement between the algorithm and two magnetic resonance (MR) operators' prediction of TI values was calculated using the Fleiss' kappa coefficient. Thirty focus box sizes, ranging from 2.3mm2 to 20.3cm2, were tested. Processing times were measured.

RESULTS

The U-Net's Dice score was 93.0 ± 0.1%. The proposed algorithm extracted TI values in 2.7 ± 0.1 s per patient (vs. 16.0 ± 8.5 s for the operator). An agreement between the algorithm's prediction and the MR operators' prediction was found in 137/152 patients (κ= 0.89), for an optimal focus box of size 2.3cm2.

CONCLUSION

The proposed fully-automated algorithm has potential of reducing uncertainties, variability, and workload inherent to manual approaches with promise for future clinical implementation for joint bright- and black-blood MRI.

Tissue mapping by cardiac magnetic resonance imaging for the prognostication of cardiac amyloidosis: A systematic review and meta-analysis

BACKGROUND

Cardiac amyloidosis is increasingly recognized as a significant contributor to cardiovascular morbidity and mortality. With the emergence of novel therapies, there is a growing interest in prognostication of patients with cardiac amyloidosis using cardiac magnetic resonance imaging (CMR). In this systematic review and meta-analysis, we aimed to examine the prognostic significance of myocardial native T1 and T2, and extracellular volume (ECV).

METHODS

Observational cohort studies or single arms of clinical trials were eligible. MEDLINE, EMBASE and CENTRAL were systematically searched from their respective dates of inception to January 2023. No exclusions were made based on date of publication, study outcomes, or study language. The study populations composed of adult patients (≥18 years old) with amyloid cardiomyopathy. All studies included the use of CMR with and without intravenous gadolinium contrast administration to assess myocardial native T1 mapping, T2 mapping, and ECV in association with the pre-specified primary outcome of all-cause mortality. Data were extracted from eligible primary studies by two independent reviewers and pooled via the inverse variance method using random effects models for meta-analysis.

RESULTS

A total of 3852 citations were reviewed. A final nine studies including a total of 955 patients (mean age 65 ± 10 years old, 32% female, mean left ventricular ejection fraction (LVEF) 59 ± 12% and 24% had NYHA class III or IV symptoms) with cardiac amyloidosis [light chain amyloidosis (AL) 50%, transthyretin amyloidosis (ATTR) 49%, other 1%] were eligible for inclusion and suitable for data extraction. All included studies were single centered (seven with 1.5 T MRI scanners, two with 3.0 T MRI scanners) and non-randomized in design, with follow-up spanning from 8 to 64 months (median follow-up = 25 months); 320 patients died during follow-up, rendering a weighted mortality rate of 33% across studies. Compared with patients with AL amyloid, patients with ATTR amyloid had significantly higher mean left ventricular mass index (LVMi) (102 ± 34 g/m2 vs 127 ± 37 g/m2, p = 0.02). N-terminal pro-brain natriuretic peptide (NT-proBNP), troponin T levels, mean native T1 values, ECV and T2 values did not differ between patients with ATTR amyloid and AL amyloid (all p > 0.25). Overall, the hazard ratios for mortality were 1.33 (95% CI = [1.10, 1.60]; p = 0.003; I2 = 29%) for every 60 ms higher T1 time, 1.16 (95% CI = [1.09, 1.23], p < 0.0001; I2 = 76%) for every 3% higher ECV, and 5.23 (95% CI = [2.27, 12.02]; p < 0.0001; I2 = 0%) for myocardial-to-skeletal T2 ratio below the mean (vs above the mean).

CONCLUSION

Higher native T1 time and ECV, and lower myocardial to skeletal T2 ratio, on CMR are associated with worse mortality in patients with cardiac amyloidosis. Therefore, tissue mapping using CMR may offer a useful non-invasive technique to monitor disease progression and determine prognosis in patients with cardiac amyloidosis.

Protective effect of ginsenoside Rb1 against aconitine cardiotoxicity studied by myocardial injury, action potential, and calcium signaling

Aconitine is the main active component of Aconitum plants. Although aconitine has effects that include strengthening the heart, analgesia, anti-tumor, and immune-regulating effects, aconitine has both efficacy and toxicity, especially cardiotoxicity. Severe effects can include arrhythmia and cardiac arrest, which limits the clinical application of aconitine-containing traditional Chinese medicine. Ginsenoside Rb1(Rb1) is mainly found in plants, such as ginseng and Panax notoginseng, and has cardiovascular-protective and anti-arrhythmia effects. This study aimed to investigate the detoxifying effects of Rb1 on aconitine cardiotoxicity and the electrophysiological effect of Rb1 on aconitine-induced arrhythmia in rats. Pathological analysis, myocardial enzymatic indexes, and Western blotting were used to investigate the ameliorating effect of Rb1 on aconitine cardiotoxicity. Optical mapping was used to evaluate the effect of Rb1 on action potential and calcium signaling after aconitine-induced arrhythmia. Rb1 inhibited pathological damage caused by aconitine, decreased myocardial enzyme levels, and restored the balance of apoptotic protein expression by reducing the expression of Bax and cleaved caspase 3 and increasing the expression of Bcl-2, thereby reducing myocardial damage caused by aconitine. Rb1 also reduced the increase in heart rate caused by aconitine, accelerated action potential conduction and calcium signaling, and reduced the dispersion of action potential and calcium signal conduction. Rb1 reduced the cardiotoxicity of aconitine by attenuating aconitine-induced myocardial injury and inhibiting the aconitine-induced retardation of ventricular action potential and calcium signaling in rats.

Renal and cardiac effects of the PDE9 inhibitor BAY 73-6691 in 5/6 nephrectomized rats

It has been suggested that the novel selective phosphodiesterase 9 (PDE9) inhibitor may improve cardiac and renal function by blocking 3',5'-cyclic guanosine monophosphate (cGMP) degradation. 5/6 nephrectomized (5/6Nx) rats were used to investigate the effects of the PDE9 inhibitor (BAY 73-6691) on the heart and kidney. Two doses of BAY 73-6691 (1 mg/kg/day and 5 mg/kg/day) were given for 95 days. The 5/6Nx rats developed albuminuria, a decrease in serum creatinine clearance (Ccr), and elevated serum troponin T levels. Echocardiographic data showed that 5/6 nephrectomy resulted in increased fractional shortening (FS), stroke volume (SV), and left ventricular ejection fraction (EF). However, 95 days of PDE9 inhibitor treatment did not improve any cardiac and renal functional parameter. Histopathologically, 5/6 nephrectomy resulted in severe kidney and heart damage, such as renal interstitial fibrosis, glomerulosclerosis, and enlarged cardiomyocytes. Telmisartan attenuated renal interstitial fibrosis and glomerulosclerosis as well as improved cardiomyocyte size. However, except for cardiomyocyte size and renal perivascular fibrosis, BAY 73-6691 had no effect on other cardiac and renal histologic parameters. Pathway enrichment analysis using RNA sequencing data of kidney and heart tissue identified chronic kidney disease pathways, such as phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signaling pathway, complement and coagulation cascades, and nuclear factor kappa B (NF-κB) signaling pathway. PDE9i did not affect any of these disease-related pathways. Two dosages of the PDE9 inhibitor BAY 73-6691 known to be effective in other rat models have only limited cardio-renal protective effects in 5/6 nephrectomized rats.

Evaluating a novel accelerated free-breathing late gadolinium enhancement imaging sequence for assessment of myocardial injury

INTRODUCTION

Cardiac magnetic resonance imaging (MRI), including late gadolinium enhancement (LGE), plays an important role in the diagnosis and prognostication of ischemic and non-ischemic myocardial injury. Conventional LGE sequences require patients to perform multiple breath-holds and require long acquisition times. In this study, we compare image quality and assessment of myocardial LGE using an accelerated free-breathing sequence to the conventional standard-of-care sequence.

METHODS

In this prospective cohort study, a total of 41 patients post Coronavirus 2019 (COVID-19) infection were included. Studies were performed on a 1.5 Tesla scanner with LGE imaging acquired using a conventional inversion recovery rapid gradient echo (conventional LGE) sequence followed by the novel accelerated free-breathing (FB-LGE) sequence. Image quality was visually scored (ordinal scale from 1 to 5) and compared between conventional and free-breathing sequences using the Wilcoxon rank sum test. Presence of per-segment LGE was identified according to the American Heart Association 16-segment myocardial model and compared across both conventional LGE and FB-LGE sequences using a two-sided chi-square test. The perpatient LGE extent was also evaluated using both sequences and compared using the Wilcoxon rank sum test. Interobserver variability in detection of per-segment LGE and per-patient LGE extent was evaluated using Cohen's kappa statistic and interclass correlation (ICC), respectively.

RESULTS

The mean acquisition time for the FB-LGE sequence was 17 s compared to 413 s for the conventional LGE sequence (P < 0.001). Assessment of image quality was similar between both sequences (P = 0.19). There were no statistically significant differences in LGE assessed using the FB-LGE versus conventional LGE on a per-segment (P = 0.42) and per-patient (P = 0.06) basis. Interobserver variability in LGE assessment for FB-LGE was good for per-segment (= 0.71) and per-patient extent (ICC = 0.92) analyses.

CONCLUSIONS

The accelerated FB-LGE sequence performed comparably to the conventional standard-of-care LGE sequence in a cohort of patients post COVID-19 infection in a fraction of the time and without the need for breath-holding. Such a sequence could impact clinical practice by increasing cardiac MRI throughput and accessibility for frail or acutely ill patients unable to perform breath-holding.

Role of macrophages in regression of myocardial fibrosis following alleviation of left ventricular pressure overload

Sustained hemodynamic pressure overload (PO) produced by murine transverse aortic constriction (TAC) causes myocardial fibrosis; removal of TAC (unTAC) returns left ventricle (LV) hemodynamic load to normal and results in significant, but incomplete regression of myocardial fibrosis. However, the cellular mechanisms that result in these outcomes have not been defined. The objective was to determine temporal changes in myocardial macrophage phenotype in TAC and unTAC and determine whether macrophage depletion alters collagen degradation after unTAC. Myocardial macrophage abundance and phenotype were assessed by immunohistochemistry, flow cytometry, and gene expression by RT-PCR in control (non-TAC), 2 wk, 4 wk TAC, and 2 wk, 4 wk, and 6 wk unTAC. Myocardial cytokine profiles and collagen-degrading enzymes were determined by immunoassay and immunoblots. Initial collagen degradation was detected with collagen-hybridizing peptide (CHP). At unTAC, macrophages were depleted with clodronate liposomes, and endpoints were measured at 2 wk unTAC. Macrophage number had a defined temporal pattern: increased in 2 wk and 4 wk TAC, followed by increases at 2 wk unTAC (over 4 wk TAC) that then decreased at 4 wk and 6 wk unTAC. At 2 wk unTAC, macrophage area was significantly increased and was regionally associated with CHP reactivity. Cytokine profiles in unTAC reflected a proinflammatory milieu versus the TAC-induced profibrotic milieu. Single-cell sequencing analysis of 2 wk TAC versus 2 and 6 wk unTAC revealed distinct macrophage gene expression profiles at each time point demonstrating unique macrophage populations in unTAC versus TAC myocardium. Clodronate liposome depletion at unTAC reduced CHP reactivity and decreased cathepsin K and proMMP2. We conclude that temporal changes in number and phenotype of macrophages play a critical role in both TAC-induced development and unTAC-mediated partial, but incomplete, regression of myocardial fibrosis.NEW & NOTEWORTHY Our novel findings highlight the dynamic changes in myocardial macrophage populations that occur in response to PO and after alleviation of PO. Our data demonstrated, for the first time, a potential benefit of macrophages in contributing to collagen degradation and the partial regression of interstitial fibrosis following normalization of hemodynamic load.

Incidence of Acute Rejection Compared With Endomyocardial Biopsy Complications for Heart Transplant Patients in the Contemporary Era

BACKGROUND

The reference standard of detecting acute rejection (AR) in adult heart transplant (HTx) patients is an endomyocardial biopsy (EMB). The majority of EMBs are performed in asymptomatic patients. However, the incidence of treated AR compared with EMB complications has not been compared in the contemporary era (2010-current).

METHODS

The authors retrospectively analyzed 2769 EMBs obtained in 326 consecutive HTx patients between August 2019 and August 2022. Variables included surveillance versus for-cause indication, recipient and donor characteristics, EMB procedural data and pathological grades, treatment for AR, and clinical outcomes.

RESULTS

The overall EMB complications rate was 1.6%. EMBs performed within 1 mo after HTx compared with after 1 mo from HTx showed significantly increased complications (OR, 12.74, P  < 0.001). The treated AR rate was 14.2% in the for-cause EMBs and 1.2% in the surveillance EMBs. We found the incidence of AR versus EMB complications was significantly lower in the surveillance compared with the for-cause EMB group (OR, 0.05, P  < 0.001). We also found the incidence of EMB complications was higher than treated AR in surveillance EMBs.

CONCLUSIONS

The yield of surveillance EMBs has declined in the contemporary era, with a higher incidence of EMB complications compared with detected AR. The risk of EMB complications was highest within 1 mo after HTx. Surveillance EMB protocols in the contemporary era may need to be reevaluated.

Downward myocardial creep during stress PET imaging is inversely associated with mortality

PURPOSE

The myocardial creep is a phenomenon in which the heart moves from its original position during stress-dynamic PET myocardial perfusion imaging (MPI) that can confound myocardial blood flow measurements. Therefore, myocardial motion correction is important to obtain reliable myocardial flow quantification. However, the clinical importance of the magnitude of myocardial creep has not been explored. We aimed to explore the prognostic value of myocardial creep quantified by an automated motion correction algorithm beyond traditional PET-MPI imaging variables.

METHODS

Consecutive patients undergoing regadenoson rest-stress [82Rb]Cl PET-MPI were included. A newly developed 3D motion correction algorithm quantified myocardial creep, the maximum motion at stress during the first pass (60 s), in each direction. All-cause mortality (ACM) served as the primary endpoint.

RESULTS

A total of 4,276 patients (median age 71 years; 60% male) were analyzed, and 1,007 ACM events were documented during a 5-year median follow-up. Processing time for automatic motion correction was < 12 s per patient. Myocardial creep in the superior to inferior (downward) direction was greater than the other directions (median, 4.2 mm vs. 1.3-1.7 mm). Annual mortality rates adjusted for age and sex were reduced with a larger downward creep, with a 4.2-fold ratio between the first (0 mm motion) and 10th decile (11 mm motion) (mortality, 7.9% vs. 1.9%/year). Downward creep was associated with lower ACM after full adjustment for clinical and imaging parameters (adjusted hazard ratio, 0.93; 95%CI, 0.91-0.95; p < 0.001). Adding downward creep to the standard PET-MPI imaging model significantly improved ACM prediction (area under the receiver operating characteristics curve, 0.790 vs. 0.775; p < 0.001), but other directions did not (p > 0.5).

CONCLUSIONS

Downward myocardial creep during regadenoson stress carries additional information for the prediction of ACM beyond conventional flow and perfusion PET-MPI. This novel imaging biomarker is quantified automatically and rapidly from stress dynamic PET-MPI.

Coronary microvascular dysfunction: prevalence and aetiology in patients with suspected myocardial ischaemia

AIM

To evaluate the prevalence, aetiology, and corresponding morbidity of coronary microvascular dysfunction (CMD) in patients with suspected myocardial ischaemia.

MATERIALS AND METHODS

The present study included 115 patients with suspected myocardial ischaemia who underwent stress perfusion cardiac magnetic resonance imaging. CMD was assessed visually based on the myocardial perfusion results. The CMR-derived myocardial perfusion reserve index (MPRI) and left ventricular (LV) strain parameters obtained using the post-processing software CVI42 were employed to evaluate LV myocardial perfusion and deformation. LV strain parameters included global longitudinal, circumferential, and radial strain (GLS, GCS, and GRS), global systolic/diastolic longitudinal, circumferential, and radial strain rates (SLSR, SCSR, SRSR, DLSR, DCSR, and DRSR).

RESULTS

Of the 115 patients, 12 patients were excluded and 103 patients were finally included in the study. CMD was observed in 79 % (81 patients, aged 53 ± 12 years) of patients. Regarding aetiology, 91 (88 %) patients had non-obstructive coronary artery disease (CAD), eight (8 %) had obstructive CAD, and four (4 %) had hypertrophic cardiomyopathy (HCM). The incidence of CMD was highest (100 %) in patients with HCM, followed by those with non-obstructive CAD (up to 79 %). There were no statistical differences between CMD and non-CMD groups in GCS, GRS, GLS, SRSR, SCSR, SLSR, DCSR, DRSR and DLSR.

CONCLUSION

The incidence of CMD was higher in patients with signs and symptoms of ischaemia. CMD occurred with non-obstructive CAD, obstructive CAD, and HCM, with the highest prevalence of CMD in HCM.

Targeting a cardiac abundant and fibroblasts-specific piRNA (CFRPi) to attenuate and reverse cardiac fibrosis in pressure-overloaded heart failure

Cardiac fibrosis under chronic pressure overload is an end-stage adverse remodeling of heart. However, current heart failure treatments barely focus on anti-fibrosis and the effects are limited. We aimed to seek for a cardiac abundant and cardiac fibrosis specific piRNA, exploring its underlying mechanism and therapeutic potential. Whole transcriptome sequencing and the following verification experiments identified a highly upregulated piRNA (piRNA-000691) in transverse aortic constriction (TAC) mice, TAC pig, and heart failure human samples, which was abundant in heart and specifically expressed in cardiac fibroblasts. CFRPi was gradually increased along with the progression of heart failure, which was illustrated to promote cardiac fibrosis by gain- and loss-of-function experiments in vitro and in vivo. Knockdown of CFRPi in mice alleviated cardiac fibrosis, reversed decline of systolic and diastolic functions from TAC 6 weeks to 8 weeks. Mechanistically, CFRPi inhibited APLN, a protective peptide that increased in early response and became exhausted at late stage. Knockdown of APLN in vitro notably aggravated cardiac fibroblasts activation and proliferation. In vitro and in vivo evidence both indicated Pi3k-AKT-mTOR as the downstream effector pathway of CFRPi-APLN interaction. Collectively, we here identified CFPPi as a heart abundant and cardiac fibrosis specific piRNA. Targeting CFRPi resulted in a sustainable increase of APLN and showed promising therapeutical prospect to alleviate fibrosis, rescue late-stage cardiac dysfunction, and prevent heart failure.

Berberine inhibits excessive autophagy and protects myocardium against ischemia/reperfusion injury via the RhoE/AMPK pathway

Several studies have shown that berberine (BBR) is effective in protecting against myocardial ischemia‑reperfusion injury (MI/RI). However, the precise molecular mechanism remains elusive. The present study observed the mechanism and the safeguarding effect of BBR against hypoxia/reoxygenation (H/R) myocardial injury in H9c2 cells. BBR pretreatment significantly improved the decrease of cell viability, P62 protein, Rho Family GTPase 3 (RhoE) protein, ubiquinone subunit B8 protein, ubiquinol‑cytochrome c reductase core protein U, the Bcl‑2‑associated X protein/B‑cell lymphoma 2 ratio, glutathione (GSH) and the GSH/glutathione disulphide (GSSG) ratio induced by H/R, while reducing the increase in lactate dehydrogenase, microtubule‑associated protein 1 light 3 protein, caspase‑3 activity, reactive oxygen species, GSSG and malonaldehyde caused by H/R. Transmission electron microscopy and LysoTracker Red DND‑99 staining results showed that BBR pretreatment inhibited H/R‑induced excessive autophagy by mediating RhoE. BBR also inhibited mitochondrial permeability transition, maintained the stability of the mitochondrial membrane potential, reduced the apoptotic rate, and increased the level of caspase‑3. However, the protective effects of BBR were attenuated by pAD/RhoE‑small hairpin RNA, rapamycin (an autophagy activator) and compound C (an AMP‑activated protein kinase inhibitor). These new findings suggested that BBR protects the myocardium from MI/RI by inhibiting excessive autophagy, maintaining mitochondrial function, improving the energy supply and redox homeostasis, and attenuating apoptosis through the RhoE/AMP‑activated protein kinase pathway.

Mechanism of Qili Qiangxin Capsule for Heart Failure Based on miR133a-Endoplasmic Reticulum Stress

OBJECTIVE

To investigate the pharmacological mechanism of Qili Qiangxin Capsule (QLQX) improvement of heart failure (HF) based on miR133a-endoplasmic reticulum stress (ERS) pathway.

METHODS

A left coronary artery ligation-induced HF after myocardial infarction model was used in this study. Rats were randomly assigned to the sham group, the model group, the QLQX group [0.32 g/(kg·d)], and the captopril group [2.25 mg/(kg·d)], 15 rats per group, followed by 4 weeks of medication. Cardiac function such as left ventricular ejection fraction (EF), fractional shortening (FS), left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), the maximal rate of increase of left ventricular pressure (+dp/dt max), and the maximal rate of decrease of left ventricular pressure (-dp/dt max) were monitored by echocardiography and hemodynamics. Hematoxylin and eosin (HE) and Masson stainings were used to visualize pathological changes in myocardial tissue. The mRNA expression of miR133a, glucose-regulated protein78 (GRP78), inositol-requiring enzyme 1 (IRE1), activating transcription factor 6 (ATF6), X-box binding protein1 (XBP1), C/EBP homologous protein (CHOP) and Caspase 12 were detected by RT-PCR. The protein expression of GRP78, p-IRE1/IRE1 ratio, cleaved-ATF6, XBP1-s (the spliced form of XBP1), CHOP and Caspase 12 were detected by Western blot. TdT-mediated dUTP nick-end labeling (TUNEL) staining was used to detect the rate of apoptosis.

RESULTS

QLQX significantly improved cardiac function as evidenced by increased EF, FS, LVSP, +dp/dt max, -dp/dt max, and decreased LVEDP (P<0.05, P<0.01). HE staining showed that QLQX ameliorated cardiac pathologic damage to some extent. Masson staining indicated that QLQX significantly reduced collagen volume fraction in myocardial tissue (P<0.01). Results from RT-PCR and Western blot showed that QLQX significantly increased the expression of miR133a and inhibited the mRNA expressions of GRP78, IRE1, ATF6 and XBP1, as well as decreased the protein expressions of GRP78, cleaved-ATF6 and XBP1-s and decreased p-IRE1/IRE1 ratio (P<0.05, P<0.01). Further studies showed that QLQX significantly reduced the expression of CHOP and Caspase12, resulting in a significant reduction in apoptosis rate (P<0.05, P<0.01).

CONCLUSION

The pharmacological mechanism of QLQX in improving HF is partly attributed to its regulatory effect on the miR133a-IRE1/XBP1 pathway.

In chronic kidney disease altered cardiac metabolism precedes cardiac hypertrophy

Conduit arterial disease in chronic kidney disease (CKD) is an important cause of cardiac complications. Cardiac function in CKD has not been studied in the absence of arterial disease. In an Alport syndrome model bred not to have conduit arterial disease, mice at 225 days of life (dol) had CKD equivalent to humans with CKD stage 4-5. Parathyroid hormone (PTH) and FGF23 levels were one log order elevated, circulating sclerostin was elevated, and renal activin A was strongly induced. Aortic Ca levels were not increased, and vascular smooth muscle cell (VSMC) transdifferentiation was absent. The CKD mice were not hypertensive, and cardiac hypertrophy was absent. Freshly excised cardiac tissue respirometry (Oroboros) showed that ADP-stimulated O2 flux was diminished from 52 to 22 pmol/mg (P = 0.022). RNA-Seq of cardiac tissue from CKD mice revealed significantly decreased levels of cardiac mitochondrial oxidative phosphorylation genes. To examine the effect of activin A signaling, some Alport mice were treated with a monoclonal Ab to activin A or an isotype-matched IgG beginning at 75 days of life until euthanasia. Treatment with the activin A antibody (Ab) did not affect cardiac oxidative phosphorylation. However, the activin A antibody was active in the skeleton, disrupting the effect of CKD to stimulate osteoclast number, eroded surfaces, and the stimulation of osteoclast-driven remodeling. The data reported here show that cardiac mitochondrial respiration is impaired in CKD in the absence of conduit arterial disease. This is the first report of the direct effect of CKD on cardiac respiration.NEW & NOTEWORTHY Heart disease is an important morbidity of chronic kidney disease (CKD). Hypertension, vascular stiffness, and vascular calcification all contribute to cardiac pathophysiology. However, cardiac function in CKD devoid of vascular disease has not been studied. Here, in an animal model of human CKD without conduit arterial disease, we analyze cardiac respiration and discover that CKD directly impairs cardiac mitochondrial function by decreasing oxidative phosphorylation. Protection of cardiac oxidative phosphorylation may be a therapeutic target in CKD.

An enhanced cardio-protective effect of nanoparticles loaded with active components from Polygonum orientale L. against isoproterenol-induced myocardial ischemia in rats

In this study, nanoparticles loaded with active components from Polygonum orientale L. (PO), a traditional Chinese herb known for its anti-myocardial ischemic properties, were investigated for cardio-protective properties. Specifically, OVQ-Nanoparticles (OVQ-NPs) with Orientin (Ori), Vitexin (Vit), and Quercetin (Que) was obtained by double emulsion-solvent evaporation method. The OVQ-NPs exhibited a spherical shape, with a uniform size distribution of 136.77 ± 3.88 nm and a stable ζ-potential of -13.40 ± 2.24 mV. Notably, these nanoparticles exhibited a favorable sustained-release characteristic, resulting in an extended circulation time within the living organism. Consequently, the administration of these nanoparticles resulted in significant improvements in electrocardiograms and heart mass index of myocardial ischemic rats induced by isoproterenol, as well as decreased serum levels of CK, LDH, and AST. Furthermore, the results of histopathological examination, such as H&E staining and TUNEL staining, confirmed a reduced level of cardiac tissue pathology and apoptosis. Moreover, the quantification of biochemical indicators (SOD, MDA, GSH, NO, TNF-α, and IL-6) demonstrated that OVQ-NPs effectively mitigated myocardial ischemia by regulating oxidative stress and inflammatory pathways. In conclusion, OVQ-NPs demonstrate promising therapeutic potential as an intervention for myocardial ischemia, providing a new perspective on traditional Chinese medicine treatment in this area.

Human umbilical cord-derived mesenchymal stromal cells improve myocardial fibrosis and restore miRNA-133a expression in diabetic cardiomyopathy

BACKGROUND

Diabetic cardiomyopathy (DCM) is a serious health-threatening complication of diabetes mellitus characterized by myocardial fibrosis and abnormal cardiac function. Human umbilical cord mesenchymal stromal cells (hUC-MSCs) are a potential therapeutic tool for DCM and myocardial fibrosis via mechanisms such as the regulation of microRNA (miRNA) expression and inflammation. It remains unclear, however, whether hUC-MSC therapy has beneficial effects on cardiac function following different durations of diabetes and which mechanistic aspects of DCM are modulated by hUC-MSC administration at different stages of its development. This study aimed to investigate the therapeutic effects of intravenous administration of hUC-MSCs on DCM following different durations of hyperglycemia in an experimental male model of diabetes and to determine the effects on expression of candidate miRNAs, target mRNA and inflammatory mediators.

METHODS

A male mouse model of diabetes was induced by multiple low-dose streptozotocin injections. The effects on severity of DCM of intravenous injections of hUC-MSCs and saline two weeks previously were compared at 10 and 18 weeks after diabetes induction. At both time-points, biochemical assays, echocardiography, histopathology, polymerase chain reaction (PCR), immunohistochemistry and enzyme-linked immunosorbent assays (ELISA) were used to analyze blood glucose, body weight, cardiac structure and function, degree of myocardial fibrosis and expression of fibrosis-related mRNA, miRNA and inflammatory mediators.

RESULTS

Saline-treated diabetic male mice had impaired cardiac function and increased cardiac fibrosis after 10 and 18 weeks of diabetes. At both time-points, cardiac dysfunction and fibrosis were improved in hUC-MSC-treated mice. Pro-fibrotic indicators (α-SMA, collagen I, collagen III, Smad3, Smad4) were reduced and anti-fibrotic mediators (FGF-1, miRNA-133a) were increased in hearts of diabetic animals receiving hUC-MSCs compared to saline. Increased blood levels of pro-inflammatory cytokines (IL-6, TNF, IL-1β) and increased cardiac expression of IL-6 were also observed in saline-treated mice and were reduced by hUC-MSCs at both time-points, but to a lesser degree at 18 weeks.

CONCLUSION

Intravenous injection of hUC-MSCs ameliorated key functional and structural features of DCM in male mice with diabetes of shorter and longer duration. Mechanistically, these effects were associated with restoration of intra-myocardial expression of miRNA-133a and its target mRNA COL1AI as well as suppression of systemic and localized inflammatory mediators.

Maintaining energy provision in the heart: the creatine kinase system in ischaemia-reperfusion injury and chronic heart failure

The non-stop provision of chemical energy is of critical importance to normal cardiac function, requiring the rapid turnover of ATP to power both relaxation and contraction. Central to this is the creatine kinase (CK) phosphagen system, which buffers local ATP levels to optimise the energy available from ATP hydrolysis, to stimulate energy production via the mitochondria and to smooth out mismatches between energy supply and demand. In this review, we discuss the changes that occur in high-energy phosphate metabolism (i.e., in ATP and phosphocreatine) during ischaemia and reperfusion, which represents an acute crisis of energy provision. Evidence is presented from preclinical models that augmentation of the CK system can reduce ischaemia-reperfusion injury and improve functional recovery. Energetic impairment is also a hallmark of chronic heart failure, in particular, down-regulation of the CK system and loss of adenine nucleotides, which may contribute to pathophysiology by limiting ATP supply. Herein, we discuss the evidence for this hypothesis based on preclinical studies and in patients using magnetic resonance spectroscopy. We conclude that the correlative evidence linking impaired energetics to cardiac dysfunction is compelling; however, causal evidence from loss-of-function models remains equivocal. Nevertheless, proof-of-principle studies suggest that augmentation of CK activity is a therapeutic target to improve cardiac function and remodelling in the failing heart. Further work is necessary to translate these findings to the clinic, in particular, a better understanding of the mechanisms by which the CK system is regulated in disease.

PBX/Knotted 1 homeobox-2 (PKNOX2) is a novel regulator of myocardial fibrosis

Much effort has been made to uncover the cellular heterogeneities of human hearts by single-nucleus RNA sequencing. However, the cardiac transcriptional regulation networks have not been systematically described because of the limitations in detecting transcription factors. In this study, we optimized a pipeline for isolating nuclei and conducting single-nucleus RNA sequencing targeted to detect a higher number of cell signal genes and an optimal number of transcription factors. With this unbiased protocol, we characterized the cellular composition of healthy human hearts and investigated the transcriptional regulation networks involved in determining the cellular identities and functions of the main cardiac cell subtypes. Particularly in fibroblasts, a novel regulator, PKNOX2, was identified as being associated with physiological fibroblast activation in healthy hearts. To validate the roles of these transcription factors in maintaining homeostasis, we used single-nucleus RNA-sequencing analysis of transplanted failing hearts focusing on fibroblast remodelling. The trajectory analysis suggested that PKNOX2 was abnormally decreased from fibroblast activation to pathological myofibroblast formation. Both gain- and loss-of-function in vitro experiments demonstrated the inhibitory role of PKNOX2 in pathological fibrosis remodelling. Moreover, fibroblast-specific overexpression and knockout of PKNOX2 in a heart failure mouse model induced by transverse aortic constriction surgery significantly improved and aggravated myocardial fibrosis, respectively. In summary, this study established a high-quality pipeline for single-nucleus RNA-sequencing analysis of heart muscle. With this optimized protocol, we described the transcriptional regulation networks of the main cardiac cell subtypes and identified PKNOX2 as a novel regulator in suppressing fibrosis and a potential therapeutic target for future translational studies.

Chronological-Programmed Black Phosphorus Hydrogel for Responsive Modulation of the Pathological Microenvironment in Myocardial Infarction

Electroactive hydrogels have garnered extensive interest as a promising approach to myocardial tissue engineering. However, the challenges of spatiotemporal-specific modulation of individual pathological processes and achieving nontoxic bioresorption still remain. Herein, inspired by the entire postinfarct pathological processes, an injectable conductive bioresorbable black phosphorus nanosheets (BPNSs)-loaded hydrogel (BHGD) was developed via reactive oxide species (ROS)-sensitive disulfide-bridge and photomediated cross-linking reaction. Significantly, the chronologically programmed BHGD hydrogel can achieve graded modulation during the inflammatory, proliferative, and maturation phases of myocardial infarction (MI). More details, during early infarction, the BHGD hydrogel can effectively reduce ROS levels in the MI area, inhibit cellular oxidative stress damage, and promote macrophage M2 polarization, creating a favorable environment for damaged myocardium repair. Meanwhile, the ROS-responsive structure can protect BPNSs from degradation and maintain good conductivity under MI microenvironments. Therefore, the BHGD hydrogel possesses tissue-matched modulus and conductivity in the MI area, facilitating cardiomyocyte maturation and electrical signal exchange, compensating for impaired electrical signaling, and promoting vascularization in infarcted areas in the maturation phase. More importantly, all components of the hydrogel degrade into nontoxic substances without adverse effects on vital organs. Overall, the presented BPNS-loaded hydrogel offers an expandable and safe option for clinical treatment of MI.

Focal ischemic myocardial fibrosis assessed by late gadolinium enhancement cardiovascular magnetic resonance in patients with hypertrophic cardiomyopathy

BACKGROUND

In patients with hypertrophic cardiomyopathy (HCM), ischemic myocardial fibrosis assessed by late gadolinium enhancement (I-LGE) using cardiovascular magnetic resonance (CMR) have been reported. However, the clinical significance of I-LGE has not been completely understood. We aim to evaluate the I-LGE differ phenotypically from HCM without LGE or nonischemic myocardial fibrosis assessed by late gadolinium enhancement (NI-LGE) in the left ventricle (LV).

METHODS

The patients with HCM whom was underwent CMR were enrolled, using cine cardiac magnetic resonance to evaluate LV function and LGE to detect the myocardial fibrosis. Three groups were assorted: 1) HCM without LGE; 2) HCM with LGE involved the subendocardial layer was defined as I-LGE; 3) HCM with LGE not involved the subendocardial layer was defined as NI-LGE.

RESULTS

We enrolled 122 patients with HCM in the present study. LGE was detected in 58 of 122 (48%) patients with HCM, and 22 (18%) of patients reported I-LGE. HCM with I-LGE had increased higher left ventricular mass index (LVMI) (P < 0.0001) than HCM with NI-LGE or without LGE. In addition, HCM with I-LGE had a larger LV end- systolic volume (P = 0.045), lower LV ejection fraction (LVEF) (P = 0.026), higher LV myocardial mass (P < 0.001) and thicker LV wall (P < 0.001) more than HCM without LGE alone. The I-LGE were significantly associated with LVEF (OR: 0.961; P = 0.016), LV mass (OR: 1.028; P < 0.001), and maximal end-diastolic LVWT (OR: 1.567; P < 0.001). On multivariate analysis, LVEF (OR: 0.948; P = 0.013) and maximal end-diastolic LVWT (OR: 1.548; P = 0.001) were associated with higher risk for I-LGE compared to HCM without LGE. Noticeably, the maximal end-diastolic LVWT (OR: 1.316; P = 0.011) was the only associated with NI-LGE compared to HCM without LGE.

CONCLUSIONS

I-LGE is not uncommon in patients with HCM. HCM with I-LGE was associated with significant LV hypertrophy, extensive LGE and poor LV ejection fraction. We should consider focal ischemic myocardial fibrosis when applying LGE to risk stratification for HCM.

Renalase mediates macrophage-to-fibroblast crosstalk to attenuate pressure overload-induced pathological myocardial fibrosis

A potential antifibrotic mechanism in pathological myocardial remodeling is the recruitment of beneficial functional subpopulations of macrophages or the transformation of their phenotype. Macrophages are required to activate molecular cascades that regulate fibroblast behavior. Identifying mediators that activate the antifibrotic macrophage phenotype is tantamount to identifying the button that retards pathological remodeling of the myocardium; however, relevant studies are inadequate. Circulating renalase (RNLS) is mainly of renal origin, and cardiac myocytes also secrete it autonomously. Our previous studies revealed that RNLS delivers cell signaling to exert multiple cardiovascular protective effects, including the improvement of myocardial ischemia, and heart failure. Here, we further investigated the potential mechanism by which macrophage phenotypic transformation is targeted by RNLS to mediate stress load-induced myocardial fibrosis. Mice subjected to transverse aortic constriction (TAC) were used as a model of myocardial fibrosis. The co-incubation of macrophages and cardiac fibroblasts was used to study intercellular signaling. The results showed that RNLS co-localized with macrophages and reduced protein expression after cardiac pressure overload. TAC mice exhibited improved cardiac function and alleviated left ventricular fibrosis when exogenous RNLS was administered. Flow sorting showed that RNLS is essential for macrophage polarization towards a restorative phenotype (M2-like), thereby inhibiting myofibroblast activation, as proven by both mouse RAW264.7 and bone marrow-derived macrophage models. Mechanistically, we found that activated protein kinase B is a major pathway by which RNLS promotes M2 polarization in macrophages. RNLS may serve as a prognostic biomarker and a potential clinical candidate for the treatment of myocardial fibrosis.

Mineralocorticoid receptor promotes cardiac macrophage inflammaging

Inflammaging, a pro-inflammatory status that characterizes aging and primarily involving macrophages, is a master driver of age-related diseases. Mineralocorticoid receptor (MR) activation in macrophages critically regulates inflammatory and fibrotic processes. However, macrophage-specific mechanisms and the role of the macrophage MR for the regulation of inflammation and fibrotic remodeling in the aging heart have not yet been elucidated. Transcriptome profiling of cardiac macrophages from male/female young (4 months-old), middle (12 months-old) and old (18 and 24 months-old) mice revealed that myeloid cell-restricted MR deficiency prevents macrophage differentiation toward a pro-inflammatory phenotype. Pathway enrichment analysis showed that several biological processes related to inflammation and cell metabolism were modulated by the MR in aged macrophages. Further, transcriptome analysis of aged cardiac fibroblasts revealed that macrophage MR deficiency reduced the activation of pathways related to inflammation and upregulation of ZBTB16, a transcription factor involved in fibrosis. Phenotypic characterization of macrophages showed a progressive replacement of the TIMD4+MHC-IIneg/low macrophage population by TIMD4+MHC-IIint/high and TIMD4-MHC-IIint/high macrophages in the aging heart. By integrating cell sorting and transwell experiments with TIMD4+/TIMD4-macrophages and fibroblasts from old MRflox/MRLysMCre hearts, we showed that the inflammatory crosstalk between TIMD4- macrophages and fibroblasts may imply the macrophage MR and the release of mitochondrial superoxide anions. Macrophage MR deficiency reduced the expansion of the TIMD4- macrophage population and the emergence of fibrotic niches in the aging heart, thereby protecting against cardiac inflammation, fibrosis, and dysfunction. This study highlights the MR as an important mediator of cardiac macrophage inflammaging and age-related fibrotic remodeling.

Post-hoc standardisation of parametric T1 maps in cardiovascular magnetic resonance imaging: a proof-of-concept

BACKGROUND

In cardiovascular magnetic resonance imaging parametric T1 mapping lacks universally valid reference values. This limits its extensive use in the clinical routine. The aim of this work was the introduction of our self-developed Magnetic Resonance Imaging Software for Standardization (MARISSA) as a post-hoc standardisation approach.

METHODS

Our standardisation approach minimises the bias of confounding parameters (CPs) on the base of regression models. 214 healthy subjects with 814 parametric T1 maps were used for training those models on the CPs: age, gender, scanner and sequence. The training dataset included both sex, eleven different scanners and eight different sequences. The regression model type and four other adjustable standardisation parameters were optimised among 240 tested settings to achieve the lowest coefficient of variation, as measure for the inter-subject variability, in the mean T1 value across the healthy test datasets (HTE, N = 40, 156 T1 maps). The HTE were then compared to 135 patients with left ventricular hypertrophy including hypertrophic cardiomyopathy (HCM, N = 112, 121 T1 maps) and amyloidosis (AMY, N = 24, 24 T1 maps) after applying the best performing standardisation pipeline (BPSP) to evaluate the diagnostic accuracy.

FINDINGS

The BPSP reduced the COV of the HTE from 12.47% to 5.81%. Sensitivity and specificity reached 95.83% / 91.67% between HTE and AMY, 71.90% / 72.44% between HTE and HCM, and 87.50% / 98.35% between HCM and AMY.

INTERPRETATION

Regarding the BPSP, MARISSA enabled the comparability of T1 maps independently of CPs while keeping the discrimination of healthy and patient groups as found in literature.

FUNDING

This study was supported by the BMBF / DZHK.

Late/delayed gadolinium enhancement in MRI after intravenous administration of extracellular gadolinium-based contrast agents: is it worth waiting?

The acquisition of images minutes or even hours after intravenous extracellular gadolinium-based contrast agents (GBCA) administration ("Late/Delayed Gadolinium Enhancement" imaging; in this review, further termed LGE) has gained significant prominence in recent years in magnetic resonance imaging. The major limitation of LGE is the long examination time; thus, it becomes necessary to understand when it is worth waiting time after the intravenous injection of GBCA and which additional information comes from LGE. LGE can potentially be applied to various anatomical sites, such as heart, arterial vessels, lung, brain, abdomen, breast, and the musculoskeletal system, with different pathophysiological mechanisms. One of the most popular clinical applications of LGE regards the assessment of myocardial tissue thanks to its ability to highlight areas of acute myocardial damage and fibrotic tissues. Other frequently applied clinical contexts involve the study of the urinary tract with magnetic resonance urography and identifying pathological abdominal processes characterized by high fibrous stroma, such as biliary tract tumors, autoimmune pancreatitis, or intestinal fibrosis in Crohn's disease. One of the current areas of heightened research interest revolves around the possibility of non-invasively studying the dynamics of neurofluids in the brain (the glymphatic system), the disruption of which could underlie many neurological disorders.

Multisize Electrode Field-of-View: Validation by High Resolution Gadolinium-Enhanced Cardiac Magnetic Resonance

BACKGROUND

Voltage mapping to detect ventricular scar is important for guiding catheter ablation, but the field-of-view of unipolar, bipolar, conventional, and microelectrodes as it relates to the extent of viable myocardium (VM) is not well defined.

OBJECTIVES

The purpose of this study was to evaluate electroanatomic voltage-mapping (EAVM) with different-size electrodes for identifying VM, validated against high-resolution ex-vivo cardiac magnetic resonance (HR-LGE-CMR).

METHODS

A total of 9 swine with early-reperfusion myocardial infarction were mapped with the QDOT microcatheter. HR-LGE-CMR (0.3-mm slices) were merged with EAVM. At each EAVM point, the underlying VM in multisize transmural cylinders and spheres was quantified from ex vivo CMR and related to unipolar and bipolar voltages recorded from conventional and microelectrodes.

RESULTS

In each swine, 220 mapping points (Q1, Q3: 216, 260 mapping points) were collected. Infarcts were heterogeneous and nontransmural. Unipolar and bipolar voltage increased with VM volumes from >175 mm3 up to >525 mm3 (equivalent to a 5-mm radius cylinder with height >6.69 mm). VM volumes in subendocardial cylinders with 1- or 3-mm depth correlated poorly with all voltages. Unipolar voltages recorded with conventional and microelectrodes were similar (difference 0.17 ± 2.66 mV) and correlated best to VM within a sphere of radius 10 and 8 mm, respectively. Distance-weighting did not improve the correlation.

CONCLUSIONS

Voltage increases with transmural volume of VM but correlates poorly with small amounts of VM, which limits EAVM in defining heterogeneous scar. Microelectrodes cannot distinguish thin from thick areas of subendocardial VM. The field-of-view for unipolar recordings for microelectrodes and conventional electrodes appears to be 8 to 10 mm, respectively, and unexpectedly similar.

MRI-derived extracellular volume as a biomarker of cancer therapy cardiotoxicity: systematic review and meta-analysis

OBJECTIVES

MRI-derived extracellular volume (ECV) allows characterization of myocardial changes before the onset of overt pathology, which may be caused by cancer therapy cardiotoxicity. Our purpose was to review studies exploring the role of MRI-derived ECV as an early cardiotoxicity biomarker to guide timely intervention.

MATERIALS AND METHODS

In April 2022, we performed a systematic search on EMBASE and PubMed for articles on MRI-derived ECV as a biomarker of cancer therapy cardiotoxicity. Two blinded researchers screened the retrieved articles, including those reporting ECV values at least 3 months from cardiotoxic treatment. Data extraction was performed for each article, including clinical and technical data, and ECV values. Pooled ECV was calculated using the random effects model and compared among different treatment regimens and among those who did or did not experience overt cardiac dysfunction. Meta-regression analyses were conducted to appraise which clinical or technical variables yielded a significant impact on ECV.

RESULTS

Overall, 19 studies were included. Study populations ranged from 9 to 236 patients, for a total of 1123 individuals, with an average age ranging from 12.5 to 74 years. Most studies included patients with breast or esophageal cancer, treated with anthracyclines and chest radiotherapy. Pooled ECV was 28.44% (95% confidence interval, CI, 26.85-30.03%) among subjects who had undergone cardiotoxic cancer therapy, versus 25.23% (95%CI 23.31-27.14%) among those who had not (p = .003).

CONCLUSION

A higher ECV in patients who underwent cardiotoxic treatment could imply subclinical changes in the myocardium, present even before overt cardiac pathology is detectable.

CLINICAL RELEVANCE STATEMENT

The ability to detect subclinical changes in the myocardium displayed by ECV suggests its use as an early biomarker of cancer therapy-related cardiotoxicity.

KEY POINTS

• Cardiotoxicity is a common adverse effect of cancer therapy; therefore, its prompt detection could improve patient outcomes. • Pooled MRI-derived myocardial extracellular volume was higher in patients who underwent cardiotoxic cancer therapy than in those who did not (28.44% versus 25.23%, p = .003). • MRI-derived myocardial extracellular volume represents a potential early biomarker of cancer therapy cardiotoxicity.

Detecting early-warning biomarkers associated with heart-exosome genetic-signature for acute myocardial infarction: A source-tracking study of exosome

The genetic information of plasma total-exosomes originating from tissues have already proven useful to assess the severity of coronary artery diseases (CAD). However, plasma total-exosomes include multiple sub-populations secreted by various tissues. Only analysing the genetic information of plasma total-exosomes is perturbed by exosomes derived from other organs except the heart. We aim to detect early-warning biomarkers associated with heart-exosome genetic-signatures for acute myocardial infarction (AMI) by a source-tracking analysis of plasma exosome. The source-tracking of AMI plasma total-exosomes was implemented by deconvolution algorithm. The final early-warning biomarkers associated with heart-exosome genetic-signatures for AMI was identified by integration with single-cell sequencing, weighted gene correction network and machine learning analyses. The correlation between biomarkers and clinical indicators was validated in impatient cohort. A nomogram was generated using early-warning biomarkers for predicting the CAD progression. The molecular subtypes landscape of AMI was detected by consensus clustering. A higher fraction of exosomes derived from spleen and blood cells was revealed in plasma exosomes, while a lower fraction of heart-exosomes was detected. The gene ontology revealed that heart-exosomes genetic-signatures was associated with the heart development, cardiac function and cardiac response to stress. We ultimately identified three genes associated with heart-exosomes defining early-warning biomarkers for AMI. The early-warning biomarkers mediated molecular clusters presented heterogeneous metabolism preference in AMI. Our study introduced three early-warning biomarkers associated with heart-exosome genetic-signatures, which reflected the genetic information of heart-exosomes carrying AMI signals and provided new insights for exosomes research in CAD progression and prevention.

Calsyntenin-1 Promotes Doxorubicin-induced Dilated Cardiomyopathy in Rats

PURPOSE

Doxorubicin is an important cancer chemotherapeutic agent with severe cardiotoxic effects that eventually lead to dilated cardiomyopathy (DCM). Calsyntenin-1(CLSTN1) plays a critical role in the nervous system, but its relevance in cardiovascular diseases is unknown. We investigated the significance of CLSTN1 in doxorubicin-induced DCM.

METHODS

CLSTN1 expression in doxorubicin-induced DCM rats and H9c2 cells was determined using western blotting. To further explore the functions of CLSTN1, a cardiac-specific CLSTN1 overexpression rat model was constructed. The rats were subjected to analysis using echocardiographic, hemodynamic, and electrocardiographic parameters. Potential downstream molecules in CLSTN1 overexpression heart tissue were investigated using proteomics and western blotting. Finally, a knockdown of CLSTN1 was constructed to investigate the rescue function on doxorubicin-induced cell toxicity.

RESULTS

CLSTN1 protein expression increased drastically in doxorubicin-induced DCM rats and H9c2 cells. Under doxorubicin treatment, CLSTN1 protein-specific overexpression in the heart muscle promoted cardiac chamber enlargement and heart failure, while the knockdown of CLSTN1 reduced doxorubicin-induced cardiomyocyte toxicity in vitro. At the mechanistic level, overexpression of CLSTN1 downregulated SERCA2 expression and increased the phosphorylation levels of PI3K-Akt and CaMK2.

CONCLUSION

Our findings demonstrated that CLSTN1 promotes the pathogenesis of doxorubicin-induced DCM. CLSTN1 could be a therapeutic target to prevent the development of doxorubicin-induced DCM.

Current experimental and early investigational agents for cardiac fibrosis: where are we at?

INTRODUCTION

Myocardial fibrosis (MF) is induced by factors activating pro-fibrotic pathways such as acute and prolonged inflammation, myocardial ischemic events, hypertension, aging process, and genetically-linked cardiomyopathies. Dynamics and characteristics of myocardial fibrosis development are very different. The broad range of myocardial fibrosis presentations suggests the presence of multiple potential targets.

AREA COVERED

Heart failure treatment involves medications primarily aimed at counteracting neurohormonal activation. While these drugs have demonstrated efficacy against MF, not all specifically target inflammation or fibrosis progression with some exceptions such as RAAS inhibitors. Consequently, new therapies are being developed to address this issue. This article is aimed to describe anti-fibrotic drugs currently employed in clinical practice and emerging agents that target specific pathways, supported by evidence from both preclinical and clinical studies.

EXPERT OPINION

Despite various preclinical findings suggesting the potential utility of new drugs and molecules for treating cardiac fibrosis in animal models, there is a notable scarcity of clinical trials investigating these effects. However, the pathology of damage and repair in the heart muscle involves a complex network of interconnected inflammatory pathways and various types of immune cells. Our comprehension of the positive and negative roles played by specific immune cells and cytokines is an emerging area of research.

Exogenous Transforming Growth Factor-β1 and Its Helminth-Derived Mimic Attenuate the Heart's Inflammatory Response to Ischemic Injury and Reduce Mature Scar Size

Coronary reperfusion after acute ST-elevation myocardial infarction (STEMI) is standard therapy to salvage ischemic heart muscle. However, subsequent inflammatory responses within the infarct lead to further loss of viable myocardium. Transforming growth factor (TGF)-β1 is a potent anti-inflammatory cytokine released in response to tissue injury. The aim of this study was to investigate the protective effects of TGF-β1 after MI. In patients with STEMI, there was a significant correlation (P = 0.003) between higher circulating TGF-β1 levels at 24 hours after MI and a reduction in infarct size after 3 months, suggesting a protective role of early increase in circulating TGF-β1. A mouse model of cardiac ischemia reperfusion was used to demonstrate multiple benefits of exogenous TGF-β1 delivered in the acute phase. It led to a significantly smaller infarct size (30% reduction, P = 0.025), reduced inflammatory infiltrate (28% reduction, P = 0.015), lower intracardiac expression of inflammatory cytokines IL-1β and chemokine (C-C motif) ligand 2 (>50% reduction, P = 0.038 and 0.0004, respectively) at 24 hours, and reduced scar size at 4 weeks (21% reduction, P = 0.015) after reperfusion. Furthermore, a low-fibrogenic mimic of TGF-β1, secreted by the helminth parasite Heligmosomoides polygyrus, had an almost identical protective effect on injured mouse hearts. Finally, genetic studies indicated that this benefit was mediated by TGF-β signaling in the vascular endothelium.

STEAM-SASHA: a novel approach for blood- and fat-suppressed native T1 measurement in the right ventricular myocardium

OBJECTIVE

The excellent blood and fat suppression of stimulated echo acquisition mode (STEAM) can be combined with saturation recovery single-shot acquisition (SASHA) in a novel STEAM-SASHA sequence for right ventricular (RV) native T1 mapping.

MATERIALS AND METHODS

STEAM-SASHA splits magnetization preparation over two cardiac cycles, nulling blood signal and allowing fat signal to decay. Breath-hold T1 mapping was performed in a T1 phantom and twice in 10 volunteers using STEAM-SASHA and a modified Look-Locker sequence at peak systole at 3T. T1 was measured in 3 RV regions, the septum and left ventricle (LV).

RESULTS

In phantoms, MOLLI under-estimated while STEAM-SASHA over-estimated T1, on average by 3.0% and 7.0% respectively, although at typical 3T myocardial T1 (T1 > 1200 ms) STEAM-SASHA was more accurate. In volunteers, T1 was higher using STEAM-SASHA than MOLLI in the LV and septum (p = 0.03, p = 0.006, respectively), but lower in RV regions (p > 0.05). Inter-study, inter-observer and intra-observer coefficients of variation in all regions were < 15%. Blood suppression was excellent with STEAM-SASHA and noise floor effects were minimal.

DISCUSSION

STEAM-SASHA provides accurate and reproducible T1 in the RV with excellent blood and fat suppression. STEAM-SASHA has potential to provide new insights into pathological changes in the RV in future studies.

Interleukin-22 inhibits cardiac fibrosis by regulating fibroblast metabolic reprogramming in myocardial infarction

Cardiac fibrosis, a significant characteristic of cardiovascular diseases, leads to ventricular remodeling and impaired cardiac function. In this study, we aimed to investigate the role of Interleukin-22 (IL-22) in myocardial fibrosis following myocardial infarction (MI) and to explore the underlying metabolic mechanisms. Here we analyzed the single-cell sequencing data and found that the level of aerobic glycolysis was significantly higher in cardiac fibrosis in MI patient, which we validated through in vivo experiments. Utilizing MI mouse model, these experiments revealed decreased serum IL-22 levels and increased levels of AngII and TGF-β1. However, treatment with exogenous IL-22 reversed these changes, reduced infarct size, and fibrosis. In vitro experiments demonstrated that IL-22 inhibited AngII-induced fibroblast-to-myofibroblast transition (FMT) by suppressing the expression of α-SMA, Cola1, and Cola3. Metabolic analysis indicated that IL-22 decreased the expression of glycolytic enzymes and reduced lactate production in cardiac fibroblasts. Further in vivo experiments confirmed the inhibitory effect of IL-22 on Pyruvate kinase isoform M2 (PKM2) levels in heart tissue. Additionally, IL-22 activated the c-Jun N-terminal kinase (JNK) pathway, while inhibition of JNK partially reversed IL-22's effect on PKM2 activity. These findings suggest that IL-22 mitigates cardiac fibrosis and FMT by inhibiting aerobic glycolysis by activating the JNK/PKM2 pathway. Our study highlights IL-22 as a potential therapeutic target for myocardial fibrosis and cardiovascular diseases, providing insights into its role in regulating fibrosis and glycolysis. These findings pave the way for developing targeted therapies and investigating additional metabolic pathways for improved treatment outcomes in the field of cardiovascular diseases.

DNMT1 methylation of LncRNA-ANRIL causes myocardial fibrosis pyroptosis by interfering with the NLRP3/Caspase-1 pathway

Myocardial fibrosis is a common pathological manifestation that occurs in various cardiac diseases. The present investigation aims to reveal how DNMT1/lncRNA-ANRIL/NLRP3 influences fibrosis and cardiac fibroblast pyroptosis. Here, we used ISO to induce myocardial fibrosis in mice, and LPS and ATP to induce myocardial fibroblast pyroptosis. The results showed that DNMT1, Caspase-1, and NLRP3 expression were significantly increased in fibrotic murine myocardium and pyroptotic cardiac fibroblasts, whereas LncRNA-ANRIL expression was decreased. DNMT1 overexpression decreased the level of LncRNA-ANRIL while increasing the levels of NLRP3 and Caspase-1. Contrarily, silencing DNMT1 increased the LncRNA-ANRIL and decreased the levels of NLRP3 and Caspase-1. Silencing LncRNA-ANRIL increased the levels of NLRP3 and Caspase-1. The present findings suggest that DNMT1 can methylate LncRNA-ANRIL during the development of myocardial fibrosis and CFs cell scorching, resulting in low LncRNA-ANRIL expression, thereby influencing myocardial fibrosis and cardiac fibroblast pyroptosis.

Lymphocytic Myocarditis with Increased Left Ventricular Thickness: A Rare Presentation Mimicking Cardiac Amyloidosis

BACKGROUND Lymphocytic myocarditis is an inflammatory condition of the heart that may present with a wide spectrum of symptoms and signs, ranging from asymptomatic to life-threatening cardiogenic shock and ventricular arrhythmia. Lymphocytic myocarditis usually presents as chamber dilation. However, increased left ventricular thickness is relatively rare. We present a case of lymphocytic myocarditis with increased left ventricular thickness which mimics the presentation of cardiac amyloidosis. CASE REPORT An 80-year-old Chinese man presented to the emergency room due to recurrent chest tightness. Wheezing and crackling were heard in both lungs, along with bilateral lower-extremity edema. He had elevated cardiac troponin T and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels. Bedside echocardiogram showed left ventricular diastolic dysfunction and increased left ventricular thickness. Holter monitoring showed paroxysmal atrial fibrillation (AF) and atrial flutter. ⁹⁹ᵐTechnetium-pyrophosphate scintigraphy showed grade 1 myocardial uptake. Endomyocardial biopsy revealed lymphocytic myocarditis. The patient was put on steroids, managed with diuretics to alleviate the symptoms of congestion, and amiodarone for conversion of AF to sinus rhythm. He had no deterioration of cardiac function in the follow-ups, but there was still asymmetric interventricular septal hypertrophy. CONCLUSIONS Lymphocytic myocarditis may lead to increased left ventricular thickness in some rare cases. In the setting of unexplained increased left ventricular thickness, one should consider lymphocytic myocarditis as a differential diagnosis. In addition, endomyocardial biopsy should be performed as early as possible to confirm the diagnosis and identify the type of inflammation, which helps with treatment and prognosis.

Surface entrenched β-sitosterol niosomes for enhanced cardioprotective activity against isoproterenol induced cardiotoxicity in rats

Cardiotoxicity (CT) is a severe condition that negatively impacts heart function. β-sitosterol (BS) is a group of phytosterols and known for various pharmacological benefits, such as managing diabetes, cardiac protection, and neuroprotection. This study aims to develop niosomes (NS) containing BS, utilizing cholesterol as the lipid and Tween 80 as the stabilizer. The research focuses on designing and evaluating both conventional BS-NS and hyaluronic acid (HA) modified NS (BS-HA-NS) to enhance the specificity and efficacy of BS within cardiac tissue. The resulting niosomal formulation was spherical, with a size of about 158.51 ± 0.57 nm, an entrapment efficiency of 93.56 ± 1.48 %, and a drug loading of 8.07 ± 1.62 %. To evaluate cytotoxicity on H9c2 heart cells, the MTT assay was used. The cellular uptake of BS-NS and BS-HA-NS was confirmed by confocal microscopy on H9c2 cardiac cells. Administering BS-NS and BS-HA-NS intravenously at a dose of 10 mg/kg showed the ability to significantly decrease the levels of cardiac troponin-I (cTn-I), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), and lipid peroxidation (MDA). Tissue histopathology indicated a substantial potential for repairing cardiac tissue after treatment with BS-NS and BS-HA-NS and strong cardioprotection against ISO induced myocardial tissue damages. Thus, enhancing BS's therapeutic effectiveness through niosome surface modification holds promise for mitigating cardiac damage resulting from CT.

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.

SwinUNet: a multiscale feature learning approach to cardiovascular magnetic resonance parametric mapping for myocardial tissue characterization

Objective.Cardiovascular magnetic resonance (CMR) can measure T1 and T2 relaxation times for myocardial tissue characterization. However, the CMR procedure for T1/T2 parametric mapping is time-consuming, making it challenging to scan heart patients routinely in clinical practice. This study aims to accelerate CMR parametric mapping with deep learning.Approach. A deep-learning model, SwinUNet, was developed to accelerate T1/T2 mapping. SwinUNet used a convolutional UNet and a Swin transformer to form a hierarchical 3D computation structure, allowing for analyzing CMR images spatially and temporally with multiscale feature learning. A comparative study was conducted between SwinUNet and an existing deep-learning model, MyoMapNet, which only used temporal analysis for parametric mapping. The T1/T2 mapping performance was evaluated globally using mean absolute error (MAE) and structural similarity index measure (SSIM). The clinical T1/T2 indices for characterizing the left-ventricle myocardial walls were also calculated and evaluated using correlation and Bland-Altman analysis.Main results. We performed accelerated T1 mapping with ≤4 heartbeats and T2 mapping with 2 heartbeats in reference to the clinical standard, which required 11 heartbeats for T1 mapping and 3 heartbeats for T2 mapping. SwinUNet performed well in all the experiments (MAE < 50 ms, SSIM > 0.8, correlation > 0.75, and Bland-Altman agreement limits < 100 ms for T1 mapping; MAE < 1 ms, SSIM > 0.9, correlation > 0.95, and Bland-Altman agreement limits < 1.5 ms for T2 mapping). When the maximal acceleration was used (2 heartbeats), SwinUNet outperformed MyoMapNet and gave measurement accuracy similar to the clinical standard.Significance. SwinUNet offers an optimal solution to CMR parametric mapping for assessing myocardial diseases quantitatively in clinical cardiology.

No adverse association between exercise exposure and diffuse myocardial fibrosis in male endurance athletes

The potential association between endurance exercise and myocardial fibrosis is controversial. Data on exercise exposure and diffuse myocardial fibrosis in endurance athletes are scarce and conflicting. We aimed to investigate the association between exercise exposure and markers of diffuse myocardial fibrosis by cardiovascular magnetic resonance imaging (CMR) in endurance athletes. We examined 27 healthy adult male competitive endurance athletes aged 41 ± 9 years and 16 healthy controls in a cross sectional study using 3 Tesla CMR including late gadolinium enhancement and T1 mapping. Athletes reported detailed exercise history from 12 years of age. Left ventricular total mass, cellular mass and extracellular mass were higher in athletes than controls (86 vs. 58 g/m2, 67 vs. 44 g/m2 and 19 vs. 13 g/m2, all p < 0.01). Extracellular volume (ECV) was lower (21.5% vs. 23.8%, p = 0.03) and native T1 time was shorter (1214 ms vs. 1268 ms, p < 0.01) in the athletes. Increasing exercise dose was independently associated with shorter native T1 time (regression coefficient - 24.1, p < 0.05), but expressed no association with ECV. Our results indicate that diffuse myocardial fibrosis has a low prevalence in healthy male endurance athletes and do not indicate an adverse dose-response relationship between exercise and diffuse myocardial fibrosis in healthy athletes.

An Autopsy Case of Fulminant Myocarditis with Massive Left Ventricular Calcification

Myocardial calcification in myocarditis is rare and may be linked to poor outcomes. We herein report a case of fulminant myocarditis with massive myocardial calcification and its pathological outcomes at autopsy. A 49-year-old man experienced chest pain and was diagnosed with acute myocarditis. His cardiac function did not recover despite mechanical circulatory support in combination with V-A extracorporeal membrane oxygenation and IMPELLA CP®. He eventually developed sepsis and gastrointestinal bleeding and died on day 27. Diffuse myocardial calcification was observed on computed tomography at autopsy. The pathological autopsy depicted that calcification filled every myocardial cell in the left ventricle.

Establishment of nonobstructive coronary microcirculatory disorders in rabbits using three established methods and a comparative study

To compare the merits and drawbacks of three approaches for establishing a rabbit model of nonobstructive coronary microcirculatory disease, namely, open thoracic subtotal ligation of coronary arteries, ultrasound-guided cardiac microsphere injection, and sodium laurate injection. New Zealand rabbits were allocated to four groups: a normal group (Blank group), an Open-chest group (Open-chest), a microsphere group (Echo-M), and a sodium laurate group (Echo-SL), each comprising 10 rabbits. The rabbits were sacrificed 24 h after the procedures, and their echocardiography, stress myocardial contrast echocardiography, pathology, and surgical times were compared. The results demonstrated varying degrees of reduced cardiac function in all three experimental groups, the Open-chest group exhibiting the most significant decline. The myocardial filling in the affected areas was visually analyzed by myocardial contrast echocardiography, revealing sparse filling at rest but more after stress. Quantitative analysis of perfusion parameters (β, A, MBF) in the affected myocardium showed reduced values, the Open-chest group having the most severe reductions. No differences were observed in stress myocardial acoustic imaging parameters between the Echo-M and Echo-SL groups. Among the pathological presentations, the Open-chest model predominantly exhibited localized ischemia, while the Echo-M model was characterized by mechanical physical embolism, and the Echo-SL model displayed in situ thrombosis as the primary pathological feature. Inflammatory responses and collagen deposition were observed in all groups, with the severity ranking of Open-chest > Echo-SL > Echo-M. The ultrasound-guided intracardiac injection method used in this experiment outperformed open-chest surgery in terms of procedural efficiency, invasiveness, and maneuverability. This study not only optimizes established cardiac injection techniques but also offers valuable evidence to support clinical investigations through a comparison of various modeling methods.

Sex-Linked Differences in Cardiac Atrophy After Mechanical Unloading Induced by Heterotopic Heart Transplantation

No information is available about sex-related differences in unloading-induced cardiac atrophy. We aimed to compare the course of unloading-induced cardiac atrophy in intact (without gonadectomy) male and female rats, and in animals after gonadectomy, to obtain insight into the influence of sex hormones on this process. Heterotopic heart transplantation (HT((x)) was used as a model for heart unloading. Cardiac atrophy was assessed as the weight ratio of heterotopically transplanted heart weight (HW) to the native HW on days 7 and 14 after HTx in intact male and female rats. In separate experimental groups, gonadectomy was performed in male and female recipient animals 28 days before HT(x) and the course of cardiac atrophy was again evaluated on days 7 and 14 after HT(x). In intact male rats, HT(x) resulted in significantly greater decreases in whole HW when compared to intact female rats. The dynamics of the left ventricle (LV) and right ventricle (RV) atrophy after HT(x) was quite similar to that of whole hearts. Gonadectomy did not have any significant effect on the decreases in whole HW, LV, and RV weights, with similar results in male and female rats. Our results show that the development of unloading-induced cardiac atrophy is substantially reduced in female rats when compared to male rats. Since gonadectomy did not alter the course of cardiac atrophy after HTx, similarly in both male and female rats, we conclude that sex-linked differences in the development of unloading-induced cardiac atrophy are not caused by the activity of sex hormones.

Early detection of myocardial involvement by non-contrast T1ρ mapping of cardiac magnetic resonance in type 2 diabetes mellitus

Objective

This study aims to determine the effectiveness of T1ρ in detecting myocardial fibrosis in type 2 diabetes mellitus (T2DM) patients by comparing with native T1 and extracellular volume (ECV) fraction.

Methods

T2DM patients (n = 35) and healthy controls (n = 30) underwent cardiac magnetic resonance. ECV, T1ρ, native T1, and global longitudinal strain (GLS) values were assessed. Diagnostic performance was analyzed using receiver operating curves.

Results

The global ECV and T1ρ of T2DM group (ECV = 32.1 ± 3.2%, T1ρ = 51.6 ± 3.8 msec) were significantly higher than those of controls (ECV = 26.2 ± 1.6%, T1ρ = 46.8 ± 2.0 msec) (all P < 0.001), whether there was no significant difference in native T1 between T2DM and controls (P = 0.264). The GLS decreased significantly in T2DM patients compared with controls (-16.5 ± 2.4% vs. -18.3 ± 2.6%, P = 0.015). The T1ρ and native T1 were associated with ECV (Pearson's r = 0.50 and 0.25, respectively, both P < 0.001); the native T1, T1ρ, and ECV were associated with hemoglobin A1c (Pearson's r = 0.41, 0.52, and 0.61, respectively, all P < 0.05); and the ECV was associated with diabetes duration (Pearson's r = 0.41, P = 0.016). The AUC of ECV, T1ρ, GLS, and native T1 were 0.869, 0.810, 0.659, and 0.524, respectively.

Conclusion

In T2DM patients, T1ρ may be a new non-contrast cardiac magnetic resonance technique for identifying myocardial diffuse fibrosis, and T1ρ may be more sensitive than native T1 in the detection of myocardial diffuse fibrosis.

Quantitative Assessment of Myocardial Edema by MR T2 Mapping in Children With Kawasaki Disease

BACKGROUND

Few studies assessed myocardial inflammation using Cardiovascular Magnetic Resonance Imaging in Kawasaki disease (KD) patients.

PURPOSE

To quantify myocardial edema in KD patients using T2 mapping and explore the independent predictors of T2 values.

STUDY TYPE

Prospective.

SUBJECTS

Ninety KD patients including 40 in acute phase (26 males, 65.0%) and 50 in chronic phase (34 males, 68.0%). Thirty-one healthy volunteers (21 males, 70.0%).

FIELD STRENGTH/SEQUENCE

3.0 T T2-weighted Turbo Spin Echo-Short Time of Inversion Recovery sequence, True fast imaging with steady precession flash sequence and fast low-angle shot 3D spoiled gradient echo sequence.

ASSESSMENT

T2 values were compared among KD groups and controls.

STATISTICAL TEST

Student's t test and Fisher's exact test; One-way analysis of variance; Pearson correlation analysis; Receiver operating curve analysis; Multivariable linear regression.

RESULTS

Global T2 value of KD patients in acute phase was the highest, followed by those of chronic-phase patients and controls (38.83 ± 2.41 msec vs. 37.55 ± 2.28 msec vs. 36.05 ± 1.64 msec). Regional T2 values showed a same trend. There were no significant differences in global and regional T2 values between KD patients with and without coronary artery (CA) dilation, no matter in acute or chronic phase (all KD patients: P = 0.51, 0.51, 0.53, 0.72; acute KD: P = 0.61, 0.37, 0.33, 0.83; chronic KD: P = 0.65, 0.79, 0.62, 0.79). No significant difference was observed in global T2 values between KD patients with Z score > 5.0 and 2.0 < Z score ≤ 5.0 (P = 0.65). Multivariate analysis demonstrated that stage of disease (β = -0.123) and heart rate (β = 0.280) were independently associated with global T2 values.

DATA CONCLUSION

The degree of myocardial edema was more severe in acute-phase than in chronic-phase KD patients. Myocardial edema persists in patients regardless of the existence or degree of CA dilation.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.