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Abstract Background: Esophageal mixed neuroendocrine-nonneuroendocrine neoplasms (MiNENs) are now known as a neuroendocrine component mixed with a nonneuroendocrine component in a single neoplasm, one of which is in the form of mixed small cell-squamous cell carcinoma. Collision tumors have been excluded from the category of MiNENs, but difference between mixed and collision small cell-squamous cell carcinoma has never been reported. Methods: We collected six cases and reviewed 11 cases of mixed or collision small cell-squamous cell carcinoma (MCSSC); the data from 17 cases of MCSSC were analyzed to observe their clinicopathological features. Results: Most of the MCSSC patients were middle-aged and elderly, with more men than women, and most of the tumors occurred in the middle and lower esophagus. We found that in mixed cancers, the metastases were a mixture of squamous cell carcinoma and small cell carcinoma, whereas metastatic foci in collisional tumors showed simple cancer components; this phenomenon has never been reported before. Mixed cancers account for a higher proportion of small cell carcinomas, a higher pathological stage, and a worse prognosis than collisional cancers. PD-L1 (22C3) was negative in both squamous cell carcinoma and small cell carcinoma regions ( Conclusions: Mixed and collisional small cell-squamous cell carcinomas are essentially distinct tumors. In the clinical diagnostic of MCSSC, the tumor should be clearly identified as mixed or collisional carcinoma to guide the clinical treatment and prognosis more accurately. Keywords: Collision cancer, esophagus, MiNENs, mixed small cell-squamous cell carcinoma, PD-L1, Author(s): Huajun Sun [1]; Yanfen Shi [2]; Dongni Liang [3]; Juan Liu [1]; Gang Xu [1]; Xudan Yang (corresponding author) [1] Introduction Esophageal neuroendocrine neoplasms (NENs) are extremely rare.[sup.[1]] In [...]

Objective To evaluate the value and characteristics of 18F-FDG PET/CT and enhanced CT in primary pulmonary mucinous adenocarcinoma (PPMA), in order to provide reference for the clinical diagnosis and treatment of the disease. Methods Data of enhanced CT and 18F-FDG PET/CT imaging and clinical information of 25 patients with PPMA confirmed by pathology in China-Japan Friendship Hospital from July 2015 to February 2018 were retrospectively reviewed. Results A total of 25 PPMA patients were enrolled. Among them, 25 patients underwent the examination of 18F-FDG PET/CT imaging, and 6 cases underwent enhanced CT scan. Seven cases had one lesion, which morphologically manifested as a solitary lung lesion with lobulation signs, spinous processes on the edge, and uneven uptake of 18F-FDG with low or no uptake in hollow or cystic density areas; 18 cases showed diffuse multiple lesions in both lungs with different distribution, size and shape, including 5 cases with multiple nodules/masses, 5 with consolidations, and 8 with diversified lesions including nodules, masses, cavities, ground glass opacities, patches, and consolidations. Consolidation shadow is the most typical morphological manifestation of diffusely multiple PPMA (11 cases). The density of consolidation foci was extremely uneven, and all of them contain areas of cystic density. They had low CT value(-71-79 Hu), and characteristic features were found, including pulmonary lobe bulging sign (6 cases), pathological air bronchus sign (4 cases), angiographic sign (3 cases) and surrounding ground glass density(7 cases). The uptake of 18F-FDG varied with the density of lesions. The cystic component was lower than the solid component. Contrast-enhanced CT showed heterogeneous enhancement in 4 cases and no enhancement in 2 cases. The degree of 18F-FDG uptake in lesions dominated by nodules, masses or cavities was not linearly correlated with the degree of CT enhancement, but that in lesions dominated by consolidation was positively correlated with the degree of CT enhancement. Conclusions Contrast-enhanced CT shows PPMA lesions with no enhancement or heterogeneous enhancement. PPMA is often manifested as nodules, patchy shadows, and other space-occupying forms mixed with consolidation shadows on 18F-FDG PET/CT imaging, which has characteristic manifestations, including pulmonary lobe bulge and pathological air bronchi. Angiographic signs and the degree of metabolism are positively correlated with the density of lesions, which are used for differential diagnosis of pulmonary infectious diseases.

Simple Summary: Thymic neuroendocrine tumors (Th-NETs) are rare, with limited research on prognostic markers and treatments. Our retrospective study evaluated clinicopathological characteristics and therapeutic strategies for Th-NETs, filling gaps in existing studies. We highlighted the importance of biomarkers such as serum neuron-specific enolase, inflammatory factors, and oxygen 6-methylguanine-DNA methyltransferase, as well as the roles of surgical interventions, postoperative therapies, and temozolomide-based chemotherapy in improving patient survival. Our findings confirmed the crucial role of surgical treatment and the potential benefits of postoperative adjuvant radiotherapy. Furthermore, temozolomide-based chemotherapy demonstrated efficacy in Th-NETs treatment, with the neutrophil-to-lymphocyte ratio and serum neuron-specific enolase proving to be valuable prognostic markers necessitating further research. Background: Thymic neuroendocrine tumors (Th-NETs) are rare and aggressive, with a scarcity of research on predicting patient prognosis. Our study aimed to assess the impact of prognostic markers and temozolomide (TMZ)-based chemotherapy on survival in Th-NETs. Methods: We retrospectively reviewed the medical records of patients diagnosed with Th-NETs between 2013 and 2023 at our institution. We collected clinicopathological data, including tumor pathological grading, staging, serum concentrations of neuron-specific enolase (NSE) and pro-gastrin-releasing peptide, levels of inflammatory factors, and expression of oxygen 6-methylguanine-DNA methyltransferase (MGMT). Treatment details (such as surgery and chemotherapy) and survival outcomes were also documented. Results: A total of 32 patients were included in our study after excluding those without complete available information. The median progression-free survival (PFS) was 12.5 months (95%CI, 8–16 months) for 19 patients who received TMZ-based chemotherapy. Twenty-one patients underwent surgery as the primary treatment, demonstrating a median disease-free survival (DFS) of 51.0 months. The inflammatory factor neutrophil-to-lymphocyte ratio (NLR) was an independent prognostic indicator of DFS in postoperative patients and PFS in TMZ-treated patients. The overall 3-, 5-, and 10-year survival rates were 86.6%, 69.5%, and 33.8%, respectively. Ki67 level exceeding 10% (p = 0.048) and absence of surgical resection (p = 0.003) were significantly associated with worse overall survival (OS). Conclusion: Surgical treatment was currently the primary method for treating Th-NETs, and postoperative adjuvant therapy was an essential consideration for specific patient cohorts. Despite widespread positive MGMT expression, TMZ-based chemotherapy showed promise. Some potential prognostic biomarkers such as NLR and NSE need more attention. [ABSTRACT FROM AUTHOR]

ERK3/MAPK6 activates MAP kinase‐activated protein kinase (MK)‐5 in selected cell types. Male MK5 haplodeficient mice show reduced hypertrophy and attenuated increase in Col1a1 mRNA in response to increased cardiac afterload. In addition, MK5 deficiency impairs cardiac fibroblast function. This study determined the effect of reduced ERK3 on cardiac hypertrophy following transverse aortic constriction (TAC) and fibroblast biology in male mice. Three weeks post‐surgery, ERK3, but not ERK4 or p38α, co‐immunoprecipitated with MK5 from both sham and TAC heart lysates. The increase in left ventricular mass and myocyte diameter was lower in TAC‐ERK3+/− than TAC‐ERK3+/+ hearts, whereas ERK3 haploinsufficiency did not alter systolic or diastolic function. Furthermore, the TAC‐induced increase in Col1a1 mRNA abundance was diminished in ERK3+/− hearts. ERK3 immunoreactivity was detected in atrial and ventricular fibroblasts but not myocytes. In both quiescent fibroblasts and "activated" myofibroblasts isolated from adult mouse heart, siRNA‐mediated knockdown of ERK3 reduced the TGF‐β‐induced increase in Col1a1 mRNA. In addition, intracellular type 1 collagen immunoreactivity was reduced following ERK3 depletion in quiescent fibroblasts but not myofibroblasts. Finally, knocking down ERK3 impaired motility in both atrial and ventricular myofibroblasts. These results suggest that ERK3 plays an important role in multiple aspects of cardiac fibroblast biology. [ABSTRACT FROM AUTHOR]

Introduction: Treatment response to the standard therapy is low for metastatic pancreatic neuroendocrine tumors (PanNETs) mainly due to the tumor heterogeneity. We investigated the heterogeneity between primary PanNETs and metastases to improve the precise treatment. Methods: The genomic and transcriptomic data of PanNETs were retrieved from the Genomics, Evidence, Neoplasia, Information, Exchange (GENIE), and Gene Expression Omnibus (GEO) database, respectively. Potential prognostic effects of gene mutations enriched in metastases were investigated. Gene set enrichment analysis was performed to investigate the functional difference. Oncology Knowledge Base was interrogated for identifying the targetable gene alterations. Results: Twenty-one genes had significantly higher mutation rates in metastases which included TP53 (10.3% vs. 16.9%, p = 0.035) and KRAS (3.7% vs. 9.1%, p = 0.016). Signaling pathways related to cell proliferation and metabolism were enriched in metastases, whereas epithelial-mesenchymal transition (EMT) and TGF-β signaling were enriched in primaries. Gene mutations were highly enriched in metastases that had significant unfavorable prognostic effects included mutation of TP53 (p < 0.001), KRAS (p = 0.001), ATM (p = 0.032), KMT2D (p = 0.001), RB1 (p < 0.001), and FAT1 (p < 0.001). Targetable alterations enriched in metastases included mutation of TSC2 (15.5%), ARID1A (9.7%), KRAS (9.1%), PTEN (8.7%), ATM (6.4%), amplification of EGFR (6.0%), MET (5.5%), CDK4 (5.5%), MDM2 (5.0%), and deletion of SMARCB1 (5.0%). Conclusion: Metastases exhibited a certain extent of genomic and transcriptomic diversity from primary PanNETs. TP53 and KRAS mutation in primary samples might associate with metastasis and contribute to a poorer prognosis. A high fraction of novel targetable alterations enriched in metastases deserves to be validated in advanced PanNETs. [ABSTRACT FROM AUTHOR]

Increased production of reactive oxygen species plays an essential role in the pathogenesis of several diseases, including cardiac hypertrophy. In our search to identify redox-sensitive targets that contribute to redox signaling, we found that protein tyrosine phosphatase 1B (PTP1B) was reversibly oxidized and inactivated in hearts undergoing hypertrophy. Cardiomyocyte-specific deletion of PTP1B in mice (PTP1B cKO mice) caused a hypertrophic phenotype that was exacerbated by pressure overload. Furthermore, we showed that argonaute 2 (AGO2), a key component of the RNA-induced silencing complex, was a substrate of PTP1B in cardiomyocytes and in the heart. Our results revealed that phosphorylation at Tyr393 and inactivation of AGO2 in PTP1B cKO mice prevented miR-208b–mediated repression of thyroid hormone receptor–associated protein 1 (THRAP1; also known as MED13) and contributed to thyroid hormone–mediated cardiac hypertrophy. In support of this conclusion, inhibiting the synthesis of triiodothyronine (T3) with propylthiouracil rescued pressure overload–induced hypertrophy and improved myocardial contractility and systolic function in PTP1B cKO mice. Together, our data illustrate that PTP1B activity is cardioprotective and that redox signaling is linked to thyroid hormone responsiveness and microRNA-mediated gene silencing in pathological hypertrophy. Protecting the heart with PTP1B: Pressure overload induced by aortic banding causes oxidative stress. Coulis et al. uncovered a pathway by which oxidative stress exacerbates cardiac hypertrophy after aortic banding. In mice subjected to pressure overload, the tyrosine phosphatase PTP1B was inactivated by oxidation, resulting in greater phosphorylation and decreased microRNA loading of Ago2, a component of the RNA-induced silencing complex. This ultimately led to enhanced sensitivity to thyroid hormone and increased cardiac hypertrophy. Mice with a cardiomyocyte-specific deletion of PTP1B had greater cardiac hypertrophy after pressure overload, an effect blunted by blocking thyroid hormone synthesis. Thus, oxidative stress during pressure overload promotes hypertrophy by inactivating PTP1B, altering microRNA processing, and increasing sensitivity to thyroid hormone. [ABSTRACT FROM AUTHOR]

Abstract Background The mechanisms of benefit of mineralocorticoid receptors antagonists in congestive heart failure (CHF) are still debated. We hypothesized that aldosterone contributes to pulmonary remodelling and right ventricular (RV) dysfunction associated with CHF by stimulation of lung myofibroblasts (MYFs) proliferation. Methods Rats with moderate to large myocardial infarcts (MI) and CHF were studied. Two weeks after MI, spironolactone 100 mg/kg/day (n = 21) or no treatment (n = 24) were given for 3 weeks and compared to sham (n = 8). Results Infarct size was similar by ultrasound and pathologic measures in both MI groups. The MI-untreated group developed important lung remodelling with nearly doubling of dry lung weight (p < 0.01), reduced left ventricular (LV) fractional shortening (16 ± 2% vs. 53 ± 1%; mean ± SEM, p < 0.0001), pulmonary hypertension (RV systolic pressure: 40 ± 3 mmHg vs. 27 ± 1 mmHg, p < 0.01) and RV hypertrophy (RV/(LV + septum): 38 ± 3% vs. 24 ± 1%, p < 0.05). Spironolactone had no effect on these parameters and did not improve LV or RV performance (tricuspid annular plane systolic excursion and RV myocardial performance index) measured by echocardiography. CHF induced a restrictive respiratory syndrome with histological lung fibrosis: this was also unaffected by spironolactone. Finally, isolated lung MYFs did not proliferate after exposure to aldosterone. Conclusion Aldosterone does not significantly contribute to pulmonary remodelling and RV dysfunction associated with CHF. Other mechanisms are responsible for the beneficial effects of spironolactone in CHF.

aim of this study was to investigate the anti-cancer effects of Xiaoai Jiedu Recipe (XJR) on HCC development and its underlying mechanisms. Methods: The expression of microRNA-29a (miR-29a) and signal transducer and activator of transcription 3 (STAT3) in HCC tissues and cells was determined by quantitative real-time polymerase chain reaction. The proliferation, migration, and invasion of HCC cells were measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, wound-healing, and transwell assays, respectively. The regulatory relationship between miR-29a and STAT3 in HCC was predicted by TargetScan and analyzed by luciferase reporter and RNA pull-down assays. The protein expression of matrix metalloproteinase (MMP)-2/9 and STAT3 was detected by Western blotting. A xenograft tumor mouse model was established, and tumor weight and volume were measured. Results: The expression of miR-29a was significantly decreased in HCC tissues and cells compared with that in normal tissues and cells. The up-regulation of miR-29a was related with lymph node metastasis and tumor node metastasis stage. XJR treatment significantly increased the expression of miR-29a, decreased cell viability, migration, and invasion, and reduced the protein expression of MMP-2/9 in HCC cells in a concentration-dependent manner. The anti-tumor effect of XJR on HCC cells was reversed by treatment with miR-29a inhibitor. STAT3 was predicted as a target of miR-29a, and its expression was negatively regulated by miR-29a. Moreover, STAT3 knockdown suppressed the malignant behavior of HCC cells, and its anti-tumor function was reversed by treatment with miR-29a inhibitor. Furthermore, XJR treatment inhibited tumor growth in mice through elevating miR-29a expression and inhibiting STAT3 expression. Conclusion: XJR suppressed the development of HCC via regulating miR-29a and STAT3. [ABSTRACT FROM AUTHOR]

Ovarian cancer (OC) is the most aggressive gynecological cancer. Even with the advances in detection and therapeutics, it still remains clinically challenging and there is a pressing need to identify novel therapeutic strategies. In searching for rational molecular targets, we identified metadherin (MTDH), a multifunctional gene associated with several tumor types but previously unrecognized in OC. In this study, we found the MTDH is overexpressed in OC tissues. Through in vitro assays with overexpression cells, we characterized the role of MTDH. We confirmed MTDH stable overexpression significantly increased the expression of TNF-α, IL-6, IL-8, IL-10, and IL-1β. Interestingly, NF-kappa-B (NF-κB) and MTDH were found in a feed-forward loop motif. Thus, our findings support the notion that the MTDH and NF-κB signaling network contributes to OC traits. MTDH represents a new OC-associated gene that can contribute to insights of OC biology and suggests other treatment strategies. [ABSTRACT FROM AUTHOR]

Background: Left ventricular diastolic dysfunction (LVDD) is present in more than 50% of patients suffering from heart failure. LVDD animal models are limited and its underlying mechanisms remain largely unknown. Aortic valve stenosis (AVS) may cause LVDD, and we recently reported LVDD in an AVS rabbit model. Here we aimed to develop a rabbit model of LVDD without AVS. Methods: Rabbits were fed with a 0.5% cholesterol-enriched diet (n = 9) or normal diet (n = 8) until they developed LVDD defined by a value of the echocardiographic parameter E/Em ratio higher than the mean at baseline + 2SD. Rabbits were then fed a 0.2% cholesterol-enriched diet for 4 weeks (average total diet duration: 20 weeks). Detailed cardiac structure and function measurements were assessed by echocardiography at baseline, weeks 8, 12 and 14 to 20, when applicable. Histological analyses and RT-qPCR were performed on LV samples. Results: The hypercholesterolemic diet induced LVDD without systolic dysfunction or AVS, as shown by multiple echocardiographic parameters, including early filling mitral peak velocity and deceleration rate, Em/Am ratio and E/Em ratio (all p<0.05), and by increased cardiac mRNA expression of brain natriuretic peptide (Bnp). Cardiac expression of mRNA for Nox2, Vcam1, Mmp12, Mmp12/Timp1, and Col1/Col3 ratios was also higher in these rabbits (p<0.05). In contrast, cardiac Sod2 mRNA expression was reduced in hypercholesterolemic rabbits compared to controls. Conclusion: Rabbits fed with a cholesterol-enriched diet develop LVDD with preserved systolic function and evidence of cardiac inflammation and oxidative stress. This rabbit model may be used in future studies to test treatment strategies against LVDD. [ABSTRACT FROM AUTHOR]

Purpose: Inhaled milrinone (iMil) has been used for the treatment of pulmonary hypertension (PH) but its efficacy, safety, and prophylactic effects in facilitating separation from cardiopulmonary bypass (CPB) and preventing right ventricular (RV) dysfunction have not yet been evaluated in a clinical trial. The purpose of this study was to investigate if iMil administered before CPB would be superior to placebo in facilitating separation from CPB.Methods: High-risk cardiac surgical patients with PH were randomized to receive iMil or placebo after the induction of anesthesia and before CPB. Hemodynamic parameters and RV function were evaluated by means of pulmonary artery catheterization and transesophageal echocardiography. The groups were compared for the primary outcome of the level of difficulty in weaning from CPB. Among the secondary outcomes examined were the reduction in the severity of PH, the incidence of RV failure, and mortality.Results: Of the 124 patients randomized, the mean (standard deviation [SD]) EuroSCORE II was 8.0 (2.6), and the baseline mean (SD) systolic pulmonary artery pressure (SPAP) was 53 (9) mmHg. The use of iMil was associated with increases in cardiac output (P = 0.03) and a reduction in SPAP (P = 0.04) with no systemic hypotension. Nevertheless, there was no difference in the combined incidence of difficult or complex separation from CPB between the iMil and control groups (30% vs 28%, respectively; absolute difference, 2%; 95% confidence interval [CI], -14 to 18; P = 0.78). There was also no difference in RV failure between the iMil and control groups (15% vs 14%, respectively; difference, 1%; 95% CI, -13 to 12; P = 0.94). Mortality was increased in patients with RV failure vs those without (22% vs 2%, respectively; P < 0.001).Conclusion: In high-risk cardiac surgery patients with PH, the prophylactic use of iMil was associated with favourable hemodynamic effects that did not translate into improvement of clinically relevant endpoints. This trial was registered at ClinicalTrials.gov; identifier: NCT00819377. [ABSTRACT FROM AUTHOR]

Left ventricular diastolic dysfunction (LVDD) is characterized by the disturbance of ventricle’s performance due to its abnormal relaxation or to its increased stiffness during the diastolic phase. The molecular mechanisms underlying LVDD remain unknown. We aimed to identify normalization genes for accurate gene-expression analysis of LVDD using quantitative real-time PCR (RT-PCR) in a new rabbit model of LVDD. Eighteen rabbits were fed with a normal diet (n = 7) or a 0.5% cholesterol-enriched diet supplemented with vitamin D2 (n = 11) for an average of 14.5 weeks. We validated the presence of LVDD in this model using echocardiography for diastolic function assessment. RT-PCR was performed using cDNA derived from left ventricle samples to measure the stability of 10 genes as candidate reference genes (Gapdh, Hprt1, Ppia, Sdha, Rpl5, Actb, Eef1e1, Ywhaz, Pgk1, and G6pd). Using geNorm analysis, we report that Sdha, Gapdh and Hprt1 genes had the highest stability (M <0.2). By contrast, Hprt1 and Rpl5 genes were found to represent the best combination for normalization when using the Normfinder algorithm (stability value of 0.042). Comparison of both normalization strategies highlighted an increase of natriuretic peptides (Bnp and Anp), monocytes chemotactic protein-1 (Mcp-1) and NADPH oxidase subunit (Nox-2) mRNA expressions in ventricle samples of the hypercholesterolemic rabbits compared to controls (P<0.05). This increase correlates with LVDD echocardiographic parameters and most importantly it molecularly validates the presence of the disease in our model. This is the first study emphasizing the selection of stable reference genes for RT-PCR normalization in a rabbit model of LVDD. [ABSTRACT FROM AUTHOR]

Atrial fibrillation impairs atrial contractility, inducing atrial stunning that promotes thromboembolic stroke. Action potential (AP)-prolonging drugs are reported to normalize atrial hypocontractility caused by atrial tachycardia remodeling (ATR). Here, we addressed the role of AP duration (APD) changes in ATR-induced hypocontractility.ATR (7-day tachypacing) decreased APD (perforated patch recording) by ≈50%, atrial contractility (echocardiography, cardiomyocyte video edge detection), and [Ca2+]i transients. ATR AP waveforms suppressed [Ca2+]i transients and cell shortening of control cardiomyocytes; whereas control AP waveforms improved [Ca2+]i transients and cell shortening in ATR cells. However, ATR cardiomyocytes clamped with the same control AP waveform had ≈60% smaller [Ca2+]i transients and cell shortening than control cells. We therefore sought additional mechanisms of contractile impairment. Whole-cell voltage clamp revealed reduced ICaL; ICaL inhibition superimposed on ATR APs further suppressed [Ca2+]i transients in control cells. Confocal microscopy indicated ATR-impaired propagation of the Ca2+ release signal to the cell center in association with loss of t-tubular structures. Myofilament function studies in skinned permeabilized cardiomyocytes showed altered Ca2+ sensitivity and force redevelopment in ATR, possibly due to hypophosphorylation of myosin-binding protein C and myosin light-chain protein 2a (immunoblot). Hypophosphorylation was related to multiple phosphorylation system abnormalities where protein kinase A regulatory subunits were downregulated, whereas autophosphorylation and expression of Ca2+-calmodulin-dependent protein kinase IIδ and protein phosphatase 1 activity were enhanced. Recovery of [Ca2+]i transients and cell shortening occurred in parallel after ATR cessation.Shortening of APD contributes to hypocontractility induced by 1-week ATR but accounts for it only partially. Additional contractility-suppressing mechanisms include ICaL current reduction, impaired subcellular Ca2+ signal transmission, and altered myofilament function associated with abnormal myosin and myosin-associated protein phosphorylation. The complex mechanistic basis of the atrial hypocontractility associated with AF argues for upstream therapeutic targeting rather than interventions directed toward specific downstream pathophysiological derangements. [ABSTRACT FROM AUTHOR]

Objective: Atrial remodeling contributes to the maintenance of atrial fibrillation (AF) in several cardiac disorders. There is evidence that angiotensin-converting enzyme (ACE) inhibitors reduce the prevalence of AF in patients with congestive heart failure (CHF). There have been no studies performed to assess the effects of ACE inhibitors on atrial dimensions and emptying function in relationship to vulnerability to AF in the setting of experimental CHF. Methods: CHF was produced in 20 dogs by rapid right ventricular pacing during 5 weeks. The dogs were randomized to enalapril (EN) therapy (2 mg/kg/day, n=10) or to a control group (n=10). Echocardiography was performed at baseline and weekly thereafter. At the 5-week electrophysiological study, AF was induced by burst pacing and AF duration was measured. Results: Atrial areas increased significantly with CHF. Left atrial (LA) fractional area shortening (FAS) decreased by 42% (P=0.0001) in controls but by 9% (P=NS) in the EN group (P=0.01, EN vs. controls). Similar findings were observed for right atrial (RA) changes (P=0.02). Atrial fibrosis was highly correlated with the decrease in LA FAS (r=0.85, P<0.01) and was reduced by EN (from 11.2±1.6 to 8.3±0.7%, P=0.008). AF duration was 720±461 s for controls and 138±83 s for EN (P=0.001). LA and RA areas and FAS at 5 weeks correlated with AF duration (P≤0.001 for all). FAS decrease in both atria also correlated with AF duration at follow-up (r=0.78 and 0.77 for LA and RA, P≤0.001 for both). Conclusions: Experimental CHF causes structural and functional abnormalities in both atria, which are correlated with AF duration. ACE inhibition attenuates CHF-induced atrial fibrosis and remodeling and reduces associated AF promotion. These results indicate a role for the renin–angiotensin system in arrhythmogenic atrial structural remodeling in CHF. [Copyright &y& Elsevier]