Systematic in-silico evaluation of fibrosis effects on re-entrant wave dynamics in atrial tissue.

Despite the key role of fibrosis in atrial fibrillation (AF), the effects of different spatial distributions and textures of fibrosis on wave propagation mechanisms in AF are not fully understood. To clarify these aspects, we performed a systematic computational study to assess fibrosis effects on the characteristics and stability of re-entrant waves in electrically-remodelled atrial tissues. A stochastic algorithm, which generated fibrotic distributions with controlled overall amount, average size, and orientation of fibrosis elements, was implemented on a monolayer spheric atrial model. 245 simulations were run at changing fibrosis parameters. The emerging propagation patterns were quantified in terms of rate, regularity, and coupling by frequency-domain analysis of correspondent synthetic bipolar electrograms. At the increase of fibrosis amount, the rate of reentrant waves significantly decreased and higher levels of regularity and coupling were observed (p < 0.0001). Higher spatial variability and pattern stochasticity over repetitions was observed for larger amount of fibrosis, especially in the presence of patchy and compact fibrosis. Overall, propagation slowing and organization led to higher stability of re-entrant waves. These results strengthen the evidence that the amount and spatial distribution of fibrosis concur in dictating re-entry dynamics in remodeled tissue and represent key factors in AF maintenance.

Deep learning of left atrial structure and function provides link to atrial fibrillation risk.

Increased left atrial volume and decreased left atrial function have long been associated with atrial fibrillation. The availability of large-scale cardiac magnetic resonance imaging data paired with genetic data provides a unique opportunity to assess the genetic contributions to left atrial structure and function, and understand their relationship with risk for atrial fibrillation. Here, we use deep learning and surface reconstruction models to measure left atrial minimum volume, maximum volume, stroke volume, and emptying fraction in 40,558 UK Biobank participants. In a genome-wide association study of 35,049 participants without pre-existing cardiovascular disease, we identify 20 common genetic loci associated with left atrial structure and function. We find that polygenic contributions to increased left atrial volume are associated with atrial fibrillation and its downstream consequences, including stroke. Through Mendelian randomization, we find evidence supporting a causal role for left atrial enlargement and dysfunction on atrial fibrillation risk.

Analysis of the thickness characteristics of the left atrial posterior wall and its correlation with the low and no voltage areas of the left atrial posterior wall in patients with atrial fibrillation.

OBJECTIVE: To analyze the relationship between the thickness of the left atrial posterior wall and the low and no voltage zones in the left atrial posterior wall in patients with atrial fibrillation (AF). METHODS: 61 patients admitted to our cardiology department for AF and radiofrequency ablation of AF from January 1, 2020 to May 30, 2022 were enrolled according to inclusion and exclusion criteria. The atrial wall thickness was measured by CT scan. Baseline data, preoperative cardiac ultrasound data, preoperative biochemical parameters, low voltage zone (fibrotic zone) and no voltage zone (scar zone) in the left atrial posterior wall area, and various parameters of posterior left atrial wall thickness were collected. RESULTS: The differences of the thickness between the upper, middle and lower mean levels of the left atrial posterior wall were statistically significant (P = 0.004). The results showed that body mass index was weakly positively correlated with the mean level of total left atrial posterior wall thickness (r = 0.426, P = 0.001) and was statistically significant. The remaining indices were positively or negatively correlated with the mean level of total left atrial posterior wall thickness, but none were statistically significant (P > 0.05). CONCLUSIONS: Both left atrial posterior wall low-voltage zone and voltage-free zone were positively correlated with the mean total left atrial posterior wall thickness, and left atrial posterior wall low-voltage zone and voltage-free zone were significantly positively correlated. Body mass index was weakly positively correlated with total left atrial posterior wall thickness.

Acute ST-Elevation Myocardial Infarction in a Young Adult: Rare Presentation of Giant Atrial Myxoma. / Infarto com Supra-ST em Adulto Jovem: Rara Apresentação de Mixoma Atrial Gigante.

Cardiac tumors are rare entities, among which atrial myxoma (AM) stands as the most frequent, accounting for approximately half of all reported cases. The incidence of AM is estimated to range from 0.001% to 0.3% within the general population, yet only about 0.06% of these cases present with coronary embolic events. We report on a 33-year-old male smoker who experienced acute, severe precordial pain radiating to the left upper limb, lasting for one hour. The electrocardiographic evaluation demonstrated ST-segment elevation in leads D2, D3, and aVF, alongside significantly elevated serum troponin levels, confirming a diagnosis of ST-segment elevation myocardial infarction (STEMI). Subsequent coronary angiography revealed proximal occlusion of the right coronary artery due to thrombus. An initial attempt of thrombus aspiration was unsuccessful, followed by primary angioplasty with balloon inflation without stent placement. Further diagnostic exploration through transthoracic echocardiography identified a homogenous, smooth-surfaced mass measuring 5.2 cm x 2.3 cm attached to the interatrial septum. This mass, characterized by lobulations, prolapsed into the mitral valve and left ventricle during diastole, consistent with AM. Surgical resection of the mass was successfully performed, with the patient being discharged asymptomatic. In the reported case, the patient's profile, notably his age, and gender, diverges from the typical epidemiological characteristics associated with AM. This case adds to the limited number of reports where the inferior wall is affected by the right coronary artery being occluded. This report emphasizes the significance of differential diagnoses in younger patients presenting with STEMI.

Neoplasias cardíacas são raras, tendo como principal representante o mixoma atrial (MA), que corresponde a cerca de metade de todos os casos. O MA tem incidência estimada entre 0.001% e 0.3% na população em geral, no entanto apenas aproximadamente 0,06% desses cursam com eventos embólicos coronarianos. Homem de 33 anos, tabagista, admitido com quadro de precordialgia intensa e irradiação para membro superior esquerdo com duração de uma hora. O eletrocardiograma evidenciou elevação de segmento ST nas derivações D2, D3 e aVF troponina sérica elevada, confirmando infarto com supra desnivelamento do segmento ST (IAMCSST). Foi realizada cineangiocoronariografia, a qual revelou oclusão em terço proximal de artéria coronária direita por trombo. Realizada tentativa de aspiração do trombo, sem sucesso, seguido por angioplastia primária com balão sem colocação de stent. Durante a investigação do quadro, paciente realizou ecocardiograma transtorácico o qual demonstrou massa homogênea de superfície regular, de 5.2 cm x 2.3 cm, aderida ao septo interatrial, com lobulações de características emboligênicas prolapsando para valva mitral e ventrículo esquerdo na diástole, compatível com MA. Foi realizada ressecção cirúrgica com paciente evoluindo assintomático, recebendo alta para seguimento ambulatorial. O caso relatado difere em idade e sexo do perfil epidemiológico típico sendo um dos poucos descritos com acometimento da parede inferior apresentando a artéria coronária direita como culpada. Este relato ratifica a importância do diagnóstico diferencial frente às apresentações de IAMCSST em jovens.

RAS Dataset: A 3D Cardiac LGE-MRI Dataset for Segmentation of Right Atrial Cavity.

The current challenge in effectively treating atrial fibrillation (AF) stems from a limited understanding of the intricate structure of the human atria. The objective and quantitative interpretation of the right atrium (RA) in late gadolinium-enhanced magnetic resonance imaging (LGE-MRI) scans relies heavily on its precise segmentation. Leveraging the potential of artificial intelligence (AI) for RA segmentation presents a promising solution. However, the successful implementation of AI in this context necessitates access to a substantial volume of annotated LGE-MRI images for model training. In this paper, we present a comprehensive 3D cardiac dataset comprising 50 high-resolution LGE-MRI scans, each meticulously annotated at the pixel level. The annotation process underwent rigorous standardization through crowdsourcing among a panel of medical experts, ensuring the accuracy and consistency of the annotations. Our dataset represents a significant contribution to the field, providing a valuable resource for advancing RA segmentation methods.

A rare presentation of primary cardiac myxofibrosarcoma: Case report and literature review.

BACKGROUND: Primary cardiac myxofibrosarcoma is a rare and aggressive malignancy, with the majority of approaching strategies relying on case reports. This article provides insights into its diagnosis and treatment. CASE PRESENTATION: This paper presents the case of a 40-year-old man with sudden onset hemoptysis, leading to the diagnosis of primary cardiac myxofibrosarcoma. Treatment involved open-heart surgery to excise the left atrium tumor, followed by 6 cycles of adjuvant chemotherapy. Unfortunately, brain metastasis developed, leading to the patient's death 1 year after initial diagnosis. CONCLUSION: Primary cardiac myxofibrosarcoma remains a clinical challenge with an unfavorable prognosis. Early diagnosis through advanced imaging is crucial, and research is needed to explore innovative treatments. This case underscores the complexities of managing this rare cardiac malignancy and highlights the necessity for ongoing investigations to enhance patient outcomes.

Naringin activates semaphorin 3A to ameliorate TGF-ß-induced endothelial-to-mesenchymal transition related to atrial fibrillation.

The loss of semaphorin 3A (Sema3A), which is related to endothelial-to-mesenchymal transition (EndMT) in atrial fibrosis, is implicated in the pathogenesis of atrial fibrillation (AF). To explore the mechanisms by which EndMT affects atrial fibrosis and assess the potential of a Sema3A activator (naringin) to prevent atrial fibrosis by targeting transforming growth factor-beta (TGF-ß)-induced EndMT, we used human atria, isolated human atrial endocardial endothelial cells (AEECs), and used transgenic mice expressing TGF-ß specifically in cardiac tissues (TGF-ß transgenic mice). We evaluated an EndMT marker (Twist), a proliferation marker (proliferating cell nuclear antigen; PCNA), and an endothelial cell (EC) marker (CD31) through triple immunohistochemistry and confirmed that both EndMT and EC proliferation contribute to atrial endocardial fibrosis during AF in TGF-ß transgenic mice and AF patient tissue sections. Additionally, we investigated the impact of naringin on EndMT and EC proliferation in AEECs and atrial fibroblasts. Naringin exhibited an antiproliferative effect, to which AEECs were more responsive. Subsequently, we downregulated Sema3A in AEECs using small interfering RNA to clarify a correlation between the reduction in Sema3A and the elevation of EndMT markers. Naringin treatment induced the expression of Sema3A and a concurrent decrease in EndMT markers. Furthermore, naringin administration ameliorated AF and endocardial fibrosis in TGF-ß transgenic mice by stimulating Sema3A expression, inhibiting EndMT markers, reducing atrial fibrosis, and lowering AF vulnerability. This suggests therapeutic potential for naringin in AF treatment.

Atrial proteomic profiling reveals a switch towards profibrotic gene expression program in CREM-IbΔC-X mice with persistent atrial fibrillation.

BACKGROUND: Overexpression of the CREM (cAMP response element-binding modulator) isoform CREM-IbΔC-X in transgenic mice (CREM-Tg) causes the age-dependent development of spontaneous AF. PURPOSE: To identify key proteome signatures and biological processes accompanying the development of persistent AF through integrated proteomics and bioinformatics analysis. METHODS: Atrial tissue samples from three CREM-Tg mice and three wild-type littermates were subjected to unbiased mass spectrometry-based quantitative proteomics, differential expression and pathway enrichment analysis, and protein-protein interaction (PPI) network analysis. RESULTS: A total of 98 differentially expressed proteins were identified. Gene ontology analysis revealed enrichment for biological processes regulating actin cytoskeleton organization and extracellular matrix (ECM) dynamics. Changes in ITGAV, FBLN5, and LCP1 were identified as being relevant to atrial fibrosis and structural based on expression changes, co-expression patterns, and PPI network analysis. Comparative analysis with previously published datasets revealed a shift in protein expression patterns from ion-channel and metabolic regulators in young CREM-Tg mice to profibrotic remodeling factors in older CREM-Tg mice. Furthermore, older CREM-Tg mice exhibited protein expression patterns reminiscent of those seen in humans with persistent AF. CONCLUSIONS: This study uncovered distinct temporal changes in atrial protein expression patterns with age in CREM-Tg mice consistent with the progressive evolution of AF. Future studies into the role of the key differentially abundant proteins identified in this study in AF progression may open new therapeutic avenues to control atrial fibrosis and substrate development in AF.

Echocardiographic and pathologic identification of an aorto-left atrial fistula secondary to infective endocarditis in a canine patient.

A dog was presented for lameness, fever, and extreme lethargy. On physical exam, a new heart murmur, arrhythmia, and joint effusion were detected. These findings were not detected two months prior. A diagnostic work-up confirmed septic suppurative inflammation in multiple joints. Echocardiogram revealed aortic valvular endocarditis along with a communication, as a consequence of a fistula, that extended from just below the aortic sinotubular junction to the left atrial lumen. Due to a poor prognosis, humane euthanasia was elected. Necropsy and histopathology confirmed infective endocarditis of the aortic valve and an aorto-left atrial fistulous tract extending from the left coronary sinus of the aortic valve to the lumen of left atrium.

Spontaneous rupture of the right aortic sinus resulting in a sterile aorto-atrial fistula in a pet rabbit (Oryctolagus cuniculus).

Aortocardiac fistula is a broad term used to describe defects between the aorta and other cardiac chambers that can occur in humans and animals. A 1.5-year-old, 1.7 kg, male castrated Holland lop rabbit (Oryctolagus cuniculus) was presented for a two-week history of a heart murmur with corresponding cardiomegaly on radiographs. Physical examination confirmed a grade-V/VI continuous heart murmur on the right sternal border with a regular rhythm and a gallop sound. Echocardiography revealed an aortic-to-right-atrial fistula causing severe left-sided volume overload. Based on the echocardiographic findings, rupture of the right aortic sinus was suspected. Due to the poor prognosis, euthanasia was elected. On necropsy, a fistula was found connecting the right aortic sinus with the right atrium, without evidence of an inflammatory response nor evidence of an infectious etiology. The sudden onset of a heart murmur supported acquired fistulation from a ruptured aortic sinus (also known as the sinus of Valsalva), though a congenital malformation could not be completely excluded.

Unusual presentation and delayed diagnosis of cardiac angiosarcoma.

BACKGROUND: Primary cardiac angiosarcomas are very rare and present aggressively with high rates of metastasis. Given the poor prognosis, particularly once disease has spread, early diagnosis and multidisciplinary treatment is essential. CASE PRESENTATION: We present the case of a 46-year-old male who presented with chest pain, intermittent fevers, and dyspnea. Workup with computed tomography scan and transesophageal echocardiography demonstrated a right atrial pseudoaneurysm. Given the concern for rupture, the patient was taken to the operating room, where resection of the pseudoaneurysm and repair using a bovine pericardial patch was performed. Histopathology report initially demonstrated perivascular lymphocyte infiltrate. Six weeks later, the patient represented with chest pain and new word finding difficulty. Workup revealed multiple solid lung, pericardial, brain, and bone nodules. Eventual biopsy of a cardiophrenic nodule demonstrated angiosarcoma, and rereview of the original pathology slides confirmed the diagnosis of primary cardiac angiosarcoma. CONCLUSIONS: Primary cardiac angiosarcomas are often misdiagnosed given the rarity of these tumors, but early diagnosis and initiation of treatment is essential. The unique presentation of our case demonstrates that clinical suspicion for cardiac angiosarcoma should be maintained for spontaneous pseudoaneurysm originating from the right atrium.

Administration of USP7 inhibitor p22077 alleviates Angiotensin II (Ang II)-induced atrial fibrillation in Mice.

Atrial fibrillation (AF), the most common cardiac arrhythmia, is an important contributor to mortality and morbidity. Ubquitin-specific protease 7 (USP7), one of the most abundant ubiquitin-specific proteases (USP), participated in many cellular events, such as cell proliferation, apoptosis, and tumourigenesis. However, its role in AF remains unknown. Here, the mice were treated with Ang II infusion to induce the AF model. Echocardiography was used to measure the atrial diameter. Electrical stimulation was programmed to measure the induction and duration of AF. The changes in atrial remodeling were measured using routine histologic analysis. Here, a significant increase in USP7 expression was observed in Ang II-stimulated atrial cardiomyocytes and atrial tissues, as well as in atrial tissues from patients with AF. The administration of p22077, the inhibitor of USP7, attenuated Ang II-induced inducibility and duration of AF, atrial dilatation, connexin dysfunction, atrial fibrosis, atrial inflammation, and atrial oxidase stress, and then inhibited the progression of AF. Mechanistically, the administration of p22077 alleviated Ang II-induced activation of TGF-ß/Smad2, NF-κB/NLRP3, NADPH oxidases (NOX2 and NOX4) signals, the up-regulation of CX43, ox-CaMKII, CaMKII, Kir2.1, and down-regulation of SERCA2a. Together, this study, for the first time, suggests that USP7 is a critical driver of AF and revealing USP7 may present a new target for atrial fibrillation therapeutic strategies.

The Role of Immune Cells Driving Electropathology and Atrial Fibrillation.

Atrial fibrillation (AF) is the most common progressive cardiac arrhythmia worldwide and entails serious complications including stroke and heart failure. Despite decades of clinical research, the current treatment of AF is suboptimal. This is due to a lack of knowledge on the mechanistic root causes of AF. Prevailing theories indicate a key role for molecular and structural changes in driving electrical conduction abnormalities in the atria and as such triggering AF. Emerging evidence indicates the role of the altered atrial and systemic immune landscape in driving this so-called electropathology. Immune cells and immune markers play a central role in immune remodeling by exhibiting dual facets. While the activation and recruitment of immune cells contribute to maintaining atrial stability, the excessive activation and pronounced expression of immune markers can foster AF. This review delineates shifts in cardiac composition and the distribution of immune cells in the context of cardiac health and disease, especially AF. A comprehensive exploration of the functions of diverse immune cell types in AF and other cardiac diseases is essential to unravel the intricacies of immune remodeling. Usltimately, we delve into clinical evidence showcasing immune modifications in both the atrial and systemic domains among AF patients, aiming to elucidate immune markers for therapy and diagnostics.

Robust, high-density lesion mapping in the left atrium with near-infrared spectroscopy.

Significance: Radiofrequency ablation (RFA) procedures for atrial fibrillation frequently fail to prevent recurrence, partially due to limitations in assessing extent of ablation. Optical spectroscopy shows promise in assessing RFA lesion formation but has not been validated in conditions resembling those in vivo. Aim: Catheter-based near-infrared spectroscopy (NIRS) was applied to porcine hearts to demonstrate that spectrally derived optical indices remain accurate in blood and at oblique incidence angles. Approach: Porcine left atria were ablated and mapped using a custom-fabricated NIRS catheter. Each atrium was mapped first in phosphate-buffered saline (PBS) then in porcine blood. Results: NIRS measurements showed little angle dependence up to 60 deg. A trained random forest model predicted lesions with a sensitivity of 81.7%, a specificity of 86.1%, and a receiver operating characteristic curve area of 0.921. Predicted lesion maps achieved a mean structural similarity index of 0.749 and a mean normalized inner product of 0.867 when comparing maps obtained in PBS and blood. Conclusions: Catheter-based NIRS can precisely detect RFA lesions on left atria submerged in blood. Optical parameters are reliable in blood and without perpendicular contact, confirming their ability to provide useful feedback during in vivo RFA procedures.

Takotsubo syndrome: left atrial and ventricular myocardial strain impairment in the subacute and convalescent phases assessed by CMR.

BACKGROUND: We investigated the differences in impairment of left ventricle (LV) and left atrium (LA) contractile dysfunction between subacute and convalescent takotsubo syndrome (TTS), using myocardial strain analysis by cardiac magnetic resonance (CMR) feature-tracking technique. METHODS: We retrospectively selected 50 patients with TTS clinical-radiological diagnosis who underwent CMR within 30 days since symptoms onset: 19 studied during the early subacute phase (sTTS, ≤ 7 days) and 31 during the convalescence (cTTS, 8-30 days). We measured the following: LV global longitudinal, circumferential, and radial strain (lvGLS, lvGCS, lvGRS) and strain rate (SR) and LA reservoir (laS_r), conduit (laS_cd), and booster pump strain (laS_bp) and strain rate (laSR_r, laSR_cd, laSR_bp). Patients were compared with 30 age- and sex-matched controls. RESULTS: All patients were women (mean age 63 years). TTS patients showed altered LV- and LA-strain features, compared to controls. sTTS was associated with increased laS_bp (12.7% versus 9.8%) and reduced lvEF (47.4% versus 54.8%), lvGLS (-12.2% versus 14.6%), and laS_cd (7.0% versus 9.5%) compared to cTTS (p ≤ 0.029). The interval between symptoms onset and CMR was correlated with laS_bp (r = -0.49) and lvGLS (r = 0.47) (p = 0.001 for both). At receiver operating characteristics analysis, laS_bp was the best discriminator between sTTS and cTTS (area under the curve [AUC] 0.815), followed by lvGLS (AUC 0.670). CONCLUSIONS: LA dysfunction persists during the subacute and convalescence of TTS. laS_bp increases in subacute phase with progressive decrease during convalescence, representing a compensatory mechanism of LV dysfunction and thus a useful index of functional recovery. RELEVANCE STATEMENT: Atrial strain has the potential to enhance the delineation of cardiac injury and functional impairment in TTS patients, assisting in the identification of individuals at higher risk and facilitating the implementation of more targeted and personalized medical therapies. KEY POINTS: • In TTS, after ventricular recovery, atrial dysfunction persists assessable with CMR feature tracking. • Quantitative assessment of atrial strain discriminates atrial functions: reservoir, conduit, and booster pump. • Atrial booster pump changes after acute TTS, regardless of ventricular function. • Atrial strain may serve as a temporal marker in TTS.

Cardiac-specific overexpression of CREM-IbΔC-X via CRISPR/Cas9 in mice presents a new model of atrial cardiomyopathy with spontaneous atrial fibrillation.

Atrial cardiomyopathy (ACM) forms the substrate for atrial fibrillation (AF) and underlies the potential for atrial thrombus formation and subsequent stroke. However, generating stable animal models that accurately replicate the entire progression of atrial lesions, particularly the onset of AF, presents significant challenges. In the present study, we found that the isoform of CRE-binding protein modulator (CREM-IbΔC-X), which is involved in the regulation of cardiac development and atrial rhythm, was highly expressed in atrial biopsies from patients with AF. Building upon this finding, we employed CRISPR/Cas9 technology to create a mouse model with cardiac-specific overexpression of CREM-IbΔC-X (referred to as CS-CREM mice). This animal model effectively illustrated the development of ACM through electrophysiological and structural remodelings over time. Proteomics and Chip-qPCR analysis of atrial samples revealed significant upregulation of cell-matrix adhesion and extracellular matrix structural components, alongside significant downregulation of genes related to atrial functions in the CS-CREM mice. Furthermore, the corresponding responses to anti-arrhythmia drugs, i.e., amiodarone and propafenone, suggested that CS-CREM mice could serve as an ideal in vivo model for drug testing. Our study introduced a novel ACM model with spontaneous AF by cardiac-specifically overexpressing CREM-IbΔC-X in mice, providing valuable insights into the mechanisms and therapeutic targets of ACM.