Cardiac Pathology Research Articles

Report of the Working Group on Cardiac, Vascular, Kidney, and Transplantation Pathology of the German Society of Pathology

Background: G Protein-Coupled Receptor Kinase 2 (GRK2) contributes to cardiac dysfunction through β-Adrenoceptor (βAR) desensitization following its upregulation. Inhibition of GRK2 has been shown to improve cardiac function. Nitric oxide (NO), through the formation of S-nitrosothiols (SNOs), serves as an endogenous inhibitor of GRK2 activity. β3-Adrenoceptors (β3ARs), in contrast, resist GRK2 and are upregulated in cardiac pathologies. Activation of β3ARs can confer cardioprotection via NO signaling. Hypothesis: We hypothesized that β3AR activation confers cardioprotection through NO-dependent inhibition of GRK2, and that this protection is lost when GRK2 is resistant to S-nitrosylation. Furthermore, we proposed that proteomic profiling would reveal molecular pathways underlying this mechanism. Methods: Male C57BL/6J wild-type (WT) and GRK2-C340S knock-in (KI) mice, which carry a Cys340Ser mutation making GRK2 resistant to S-nitrosylation, underwent 40 minutes of left anterior descending coronary artery occlusion followed by 24 hours of reperfusion under isoflurane anesthesia. The β3AR agonist CL 316,243 was given at reperfusion onset. Cardiac function was evaluated by echocardiography (ejection fraction, EF; fractional shortening, FS), and infarct size was assessed by TTC staining. Heart tissues were subjected to mass spectrometry-based quantitative proteomics and pathway analysis. Results: In WT mice, CL 316,243 significantly improved EF and FS compared to vehicle-treated controls. These effects were abolished in GRK2-C340S mice, indicating that GRK2 S-nitrosylation is necessary for β3AR-mediated cardioprotection. WT mice also had significantly smaller infarct size compared to KI mice. Proteomic analysis revealed 397 significantly differentially expressed proteins (137 downregulated, 260 upregulated) in CL-treated KI mice versus WT. Additionally, enriched pathway analysis showed an upregulation of the innate immune response (52-associated proteins) and a downregulation of lipolysis regulation (19-associated proteins). Conclusion: β3AR stimulation protects the heart after ischemia/reperfusion through NO-dependent S-nitrosylation of GRK2, which is essential for this effect. However, proteomic analysis revealed that CL-treated KI mice were enriched in novel pathways, including innate immunity and lipid metabolism, proposing a potential mechanism for the loss of protection and, therefore, implicating the β3AR–NO–GRK2 axis as a promising therapeutic target.

Introduction: Sympathetic regulatory aspects of cardiac functions are imbedded in the neural circuits of postganglionic sympathetic neurons residing in the stellate ganglia. Postganglionic neuronal subtypes innervating myocardium regulate cardiac functions and remodel myocardium during cardiac pathology. Hypothesis: In our previous study, leveraged by single-cell RNA sequencing (scRNAseq)analysis and viral tracing, we identified cardiac-innervating neuronal subtypes: NA1a, enriched in Neuropeptide-Y (NPY), and NA1b, enriched in the NPY2r receptor. The NA1a subtype mediates cardiac sympatho-excitation maximally. Therefore, we hypothesize that NPY via NPY2r receptor may play a mechanistic role in cardiac remodeling during cardiac injury. Methods: We used C57BL/6J, Npy-ires-Cre , Npy2r-ires-Cre , and Ai32 strains. Mice were anesthetized with Isoflurane (induction at 3–5%, maintenance at 1–3% vol/vol), intubated, and mechanically ventilated. For chemogenetic experiment, control mice (C57BL/6J) were injected with plasmids pAAV-hSyn-DIO-mCherry, pAAV-hSyn-hM3D(Gq)-mCherry, and pAAV-hSyn-hM4D(Gi)-mCherry in the stellate ganglia. For optogenetic stimulations, Npy-ires-Cre and Npy2r-ires-Cre mice were crossed with Ai32-(ChR2(H134R)/EYFP) and 8-10 weeks old, male, from colonies (N py-ires-Cre ::Ai32 and N py2r-ires-Cre ::Ai32) were chosen. An optical fiber connected to (473nm, 400mW, Optic Engine) was positioned for focal illumination of craniomedial right stellate ganglion stimulation. An electrocardiogram (ECG) was continuously acquired using a differential amplifier (A-M Systems, Model 1700 and Grass, P511) and recorded via PowerLab 8/35. Results: Heart rate was increased (103.53±14.64 bpm, n=3) in hM3D(Gq)-mCherry injected mice and were significantly reduced (~76 bpm) in hM4D(Gi)-mCherry injected C57BL/6J mice post-CNO (1.0mg/kg body-weight) administration compared to those injected with either i saline (0.9%W/V) or the inoculated plasmid pAAV-hSyn-DIO-mCherry and administered with either CNO (1.0mg/kg) or saline (0.9%W/V). N py2r-ires-cre ::Ai32 mice showed the highest change in heart rate (79.265±13.46 bpm, n=6) vs. controls (08.89±4.56 bpm, n=4) at 10 Hz stimulation frequency. Conclusion: Our results indicate that Npy2r-expressing NA1b cardiac-projecting neuronal subtypes, along with NA1a, modulate cardiac sympatho-excitation. These findings suggest that NPY2r may be a novel therapeutic target, either alone or in combination, for sympathetic blockade in cardiac disease.

Background: Studies have reported association between obesity and sudden cardiac death (SCD) but presume cardiac cause without autopsy. Elucidating causes of SCD by weight status may refine prevention strategies. Question: What are the autopsy causes of community sudden death by weight status? Methods: The POstmortem Systematic InvesTigation of SCD (POST SCD) is an ongoing prospective study using autopsy and clinical records to adjudicate arrhythmic (potentially rescuable with ICD) vs. non-arrhythmic (tamponade, stroke) causes among presumed SCDs (pSCDs) meeting WHO criteria in San Francisco County since 2011. Body mass index (BMI) was categorized as underweight (UW; <18.5), healthy (18.5-24.9), overweight (OW; 25-29.9), or obese (OB; >30). Results: Of 1,115 total pSCDs from 2/1/2011-1/1/2024, 322 (29%) were healthy by BMI, 51 (5%) UW, 344 (31%) OW, and 398 (36%) OB. Compared to healthy BMI, OB victims were younger (mean 56 vs 60 years, p<.001), less likely Asian (11% vs 25%, p<.001), more likely Black (23% vs 16%, p<.03), and had more co-morbidities, including hypertension (55% vs 38%, p<.001), diabetes (28% vs 14%, p<.001), dyslipidemia (30% vs 16%, p<.001), diagnosed coronary artery disease (CAD; 15% vs 9%, p<.01), and chronic kidney disease (11% vs 4%, p<.01). UW pSCDs had similar demographics and co-morbidities as healthy BMI cases. The proportion of pSCDs attributable to arrhythmic causes increased with higher BMI: 27% (UW) to 49% (Healthy) to 58% (OW) to 60% (OB), p<.001. Compared to healthy, OB had more CAD (37% vs 26%, p<.01), cardiac hypertrophy (11% vs 6%, p<.05), and pulmonary embolism (7% vs 2%, p<.01) causes of pSCD. UW BMI victims had more non-cardiac causes (67% vs 49%, p<.01), including infection (16% vs 5%, p<.01) and respiratory failure (10% vs <1%, p<.001). Among arrhythmic deaths, OB cases had fewer normal heart/primary electrical disease causes vs healthy (3% vs 10%, p<.01), but other causes were similar across BMI classes. Conclusions: In this 13-year countywide postmortem study, OB and OW sudden deaths had higher likelihood of arrhythmic causes while UW had more non-cardiac causes than pSCDs with healthy BMI. Among arrhythmic deaths, causes were similar by weight status, but OB victims had more cardiac pathology and pre-existing comorbidities. Awareness of non-cardiac causes in UW and redoubled efforts to screen and treat cardiac risk factors in OB individuals may mitigate sudden death risk at each end of the weight spectrum.

Background: Paediatric cardiology referrals are increasing, placing pressure on district hospital services, with many not meeting criteria for specialist review. This QIP aimed to identify patterns of unnecessary referrals to guide triage and education. Methods: We retrospectively reviewed all first outpatient paediatric cardiology referrals between 2019 and 2024. Of 2,739 patients seen, 1,794 were new referrals. These were analysed by presenting complaint, referral source, and appropriateness based on national and local guidelines. Results: Of the 1,794 referrals, 910 (51%) were for murmurs, 178 (10%) for genetic syndromes, and 84 (5%) for definite cardiac conditions (e.g., Kawasaki disease, hypertension)—all appropriate. Inappropriate referrals were frequent. Of 135 family history referrals for congenital heart disease, 67 (50%) were appropriate, involving first-degree relatives with significant disease. The other 68 (50%) involved second- or third-degree relatives or non-heritable lesions (e.g., PDA, PFO), mostly from neonatal unit. Poor documentation contributed. For cardiomyopathy history (n=44), 25 (57%) were appropriate, while 19 (43%) lacked clear inheritance patterns. Cyanosis or blue extremities (n=28) had only 3 (11%) appropriate referrals; the rest were likely acrocyanosis or Raynaud-type episodes. Only one child had a cardiac condition, already suspected by the presence of a murmur. Of 14 ECG abnormality referrals, only 1 was appropriate. Thirteen were normal but misread in general practice or general paediatrics. Channelopathy family history and non-heritable arrhythmias (n=39) included 17 (44%) appropriate and 22 (56%) inappropriate referrals, often involving distant relatives. Among 362 referrals for chest pain, palpitations, or syncope, only 12 (3.3%) had cardiac pathology. Most symptoms (n=220, 61%) occurred predeominantly at rest. None of these cases had cardiac disease. One child diagnosed with extreme vasovagal syncope needed cardiac input, but general paediatrics could have arranged Holter monitoring before referral. Conclusion: Most of the cardiology referrals could have been reviewed in a general paediatric clinic thereby reducing the waiting times of the cardiac clinic. Targeted education, precise referral standards and guidance will enhance the triage process and ensure that the available cardiac clinic slots are utilized effectively. The impact of these interventions will have to be reassessed in a follow-up review.

Introduction: Myocarditis, defined as an inflammatory injury to the myocardium, is irreversible with a 20% fatality rate in 2 years and a 50% fatality rate in 5 years. The most common causes of myocarditis are viruses, such as influenza A (IAV). IAV is a cardiotropic virus that can disseminate from the lungs to infect heart tissue, particularly during severe infections. Despite the implications for public health, little is known about the underlying mechanisms by which IAV causes heart pathology. Methods: To investigate the role of the novel E3 ligase TRIM47 in IAV-induced myocarditis, we utilized both in vitro and in vivo approaches. In vivo , wild-type (WT) and TRIM47 knockout (KO) mice were challenged intranasally with IAV to induce myocarditis. Survival, heart function (echocardiography), and cardiac pathology (histology, viral load by RT-PCR, cytokine levels by ELISA) were evaluated. In vitro , bone marrow-derived macrophages (BMDM) from WT and TRIM47 KO mice were infected with IAV and interferon production was detected by ELISA. To elucidate molecular mechanisms, co-immunoprecipitation and Western blotting were used to confirm TRIM47-MAVS interaction and ubiquitination patterns. Furthermore, recombinant protein expression, mutagenesis, and co-expression studies were used to map binding sites and identify specific ubiquitination types and sites on MAVS. Results: TRIM47 KO mice exhibited significantly reduced survival rates compared to WT controls following IAV infection, along with higher viral loads, diminished type I interferon levels, and increased histopathological damage in lungs and hearts. Consistently, TRIM47 KO BMDMs produced substantially lower interferon levels upon IAV challenge. Mechanistically, TRIM47 was found to directly bind MAVS at an endogenous level and promoted the ubiquitination of MAVS, facilitating its aggregation and subsequent activating downstream antiviral signaling pathways. Conclusions: Our findings establish macrophage expressed TRIM47 as a critical regulator of the innate immune response to IAV-induced myocarditis. This study provides the first in vivo evidence of TRIM47’s role in controlling IAV-induced myocarditis and highlights the TRIM47- MAVS axis as a promising therapeutic target for viral-associated cardiovascular diseases.

Innovative Use of Carbonated Beverage for Diagnosis of Sliding Hiatus Hernia on Transthoracic Echocardiography: A Case Report. Transthoracic echocardiography (TTE) is a valuable diagnostic tool for evaluating cardiac pathology; however, gastrointestinal structures such as hiatus hernias can occasionally mimic cardiac conditions on TTE. This case highlights the potential for misinterpretation when a well-defined, echo-lucent or echogenic mass is located posterior to the left atrium, as these can be mistakenly attributed to cardiac pathology. We report a 25-year-old female patient presenting with atypical chest symptoms, including palpitations, where initial TTE revealed an extracardiac mass posterior to the left atrium. To further investigate the structure, the patient ingested 200mL of Lucozade, a carbonated beverage. Repeat TTE promptly thereafter demonstrated swirling echogenic contrast within the mass, which moved synchronously with the patient's respiration and peristalsis, confirming the diagnosis of a sliding hiatus hernia. This simple bedside intervention enabled real-time clarification of the finding, obviating the need for additional imaging. The patient was reassured, referred for outpatient gastroenterology assessment, and scheduled for ambulatory ECG monitoring. The case underscores the importance of considering gastrointestinal structures in the differential diagnosis of masses seen on TTE, particularly due to their proximity to the heart. In this case, the ingestion of a carbonated beverage provided dynamic, low-cost contrast enhancement, enabling rapid and accurate diagnosis. The use of a carbonated beverage during TTE can serve as an innovative, cost-effective diagnostic aid when ambiguous extracardiac structures are encountered. This approach may help avoid unnecessary investigations and illustrates the value of creative techniques in everyday clinical practice.

Background: Non-human primates (NHPs), particularly aged cynomolgus monkeys, share key physiologic, metabolic and genetic similarities with humans, offering valuable translational models for chronic cardiac diseases. Objective: This study aimed to establish and characterize chronic heart failure phenotypes, and investigate the presence of myocardial amyloidosis in aged NHPs using advanced multimodal imaging and biomarker profiling. Methods: Over 1,000 aged male cynomolgus monkeys underwent comprehensive cardiac evaluation. Ventricular structure and function were assessed by 2D-echocardiography (2D echo) and cardiac magnetic resonance imaging (MRI). Left ventricular myocardial proton density fat fraction (LV-PDFF) and epicardial adipose tissue (EAT) volume were determined. Myocardial amyloidosis was detected via 18F-florbetapir PET-CT. Circulating biomarkers of cardiac injury and inflammation (NT-proBNP, troponin I, hs-CRP, IL-1, IL-6, TNF-α) were measured. Healthy young NHPs served as controls. Results: Left-sided HF was present in 30% of aged NHPs with heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF) was equally represented. HFrEF models showed markedly reduced ejection fraction (EF<60%; 53 ± 4.6% vs. 73 ± 4.3% controls). HFpEF, was defined by normal/preserved EF (≥60%) and diastolic dysfunction markers (E/A<1, e'>7, and E/e'>11 for mild HFpEF; E/A>1, e'/a'<1, e'<7, and E/e'>11 for moderate HFpEF). Reduced MRI LV global longitudinal strain (GLS) and elevated extracellular volume fraction (ECV) were recorded for both HF subtypes indicating myocardial fibrosis. LV-PDFF was increased in HFpEF and HFrEF groups compared to controls. PET-CT identified myocardial amyloidosis in a subset of aged animals, independent of HF classification. Biomarkers of cardiac stress and systemic inflammation were significantly elevated in HF-affected NHPs. Conclusion: This study establishes aged cynomolgus monkeys as a translational model that recapitulates key features of human cardiac dysfunction, including heterogeneous HF phenotypes, and myocardial amyloidosis. The integration of multimodal imaging and biomarker profiling provides a robust platform for preclinical evaluation of novel therapeutics targeting HF subtypes and related cardiac pathologies.

Trypanosoma cruzi is the etiological agent of Chagas' disease, a neglected tropical disease affecting six to eight million people worldwide. The infection has a chronic progression, with cardiac, digestive, or neurological pathologies typically manifesting 10 or more years after the initial infection. However, during the first weeks of infection, the parasite colonizes nearly all tissues and organs of the mammalian host. The circulating trypomastigote stage is responsible for this systemic dissemination. After extravasation, trypomastigotes migrate through the interstitial matrix of target tissues to locate and invade nucleated cells. Although the mechanisms underlying this process are not yet fully elucidated, parasite migration and motility in a three-dimensional environment play crucial roles.This chapter discusses the technical aspects of monitoring trypomastigote motility using 3D collagen-I matrices and time-lapse microscopy. It begins with a straightforward method for isolating collagen-I (Col-I) from rat tail tendons. Next, a protocol is provided to assess the correct co-polymerization of Col-I and trypomastigotes into a three-dimensional structure using confocal reflection microscopy. Finally, we describe the monitoring and analysis of trypomastigote motility patterns through time-lapse microscopy. This protocol enables the real-time observation of live trypomastigotes, facilitating the study of their dynamics within a three-dimensional extracellular environment that closely mimics in vivo conditions. Additionally, the model allows the analysis of trypomastigote trajectories, movement types, and speed. Our protocol provides a valuable platform for investigating T. cruzi trypomastigote motility, offering insights into their dissemination strategies and potential interactions with host tissues.

Background: Left ventricular diastolic dysfunction (LVDD) is integral to diagnostics and risk stratification for both cardiac and extracardiac pathologies, such as heart failure and T2DM. LVDD is evaluated by echocardiography according to the 2016 American Society of Echocardiography (ASE) guidelines. However, without a sole identifying metric, LVDD is assessed by a diagnostic algorithm that relies on secondary characteristics, is laborious, and has potential for interobserver variability. Artificial intelligence (AI) applied to echocardiography has been shown to develop automated, reproducible workflows and detect cardiovascular diseases. Methods: To characterize concordance in clinical evaluations of LVDD, we evaluated historical echocardiogram studies at two academic medical centers for variability between clinician text reports and assessment by ASE guidelines. We then developed a workflow of 8 AI models trained on over 155,000 studies to automate assessment of LVDD (Figure 1). Model performance was evaluated on temporally distinct held-out test sets from two academic medical centers. Results: In 124,524 studies at Cedars-Sinai Medical Center (CSMC) and 1,572 studies at Stanford Healthcare (SHC), clinician assessments of diastolic function had only 30.8% agreement and 32.7% agreement with ASE guidelines, respectively. In a validation cohort of 955 studies from CSMC, our AI workflow demonstrated 76.5% agreement and a weighted Cohen’s kappa of 0.52 with ASE guideline assessment using human measurements (Figure 2). In contrast, the clinician report had 48.5% agreement and weighted kappa of 0.29 with ASE guidelines. In the SHC cohort of 1,572 studies, the AI workflow had 66.7% agreement and weighted kappa of 0.27 with ASE guidelines, while the clinician assessment had 32.7% agreement and weighted kappa of 0.06. Performance was consistent across patient subgroups by sex, age, hypertension, diabetes, obesity, and coronary artery disease (Table 1). Our AI workflow also demonstrated strong performance in predicting elevated left atrial pressure, with AUC of 0.84 and 0.76 in CSMC and SHC, respectively. Conclusion: Clinicians are often inconsistent in evaluating LVDD. We developed an AI pipeline that automates the clinical workflow of grading LVDD and has higher agreement with ASE guidelines than standard-of-care clinician evaluations. Our AI workflow can increase the efficiency and completeness of diastology, contributing to improved diagnosis of heart failure.

Background: The Bruce treadmill protocol is a commonly used protocol for treadmill-based exercise testing in children. However, normative data for endurance time dating from 1978 remains the clinical reference, despite shifting population anthropometrics and fitness levels. This review evaluates trends in endurance times of healthy children since 1978. Research Question: How have reference values for endurance time using the standard Bruce protocol changed over time for children ages 4-18? Methods: A systematic search relevant to the research question from the Semantic Scholar corpus was conducted. We retrieved 499 papers and screened in those that met the following criteria: (1) subjects aged 4-18 years old with no identified cardiac or pulmonary pathology, (2) non-metabolic maximal effort exercise tests (achieved ≥85% predicted peak heart rate), (3) utilization of the standard Bruce protocol, (4) endurance times reported by age group, and (5) written in English. Endurance times were grouped into three age (years) categories (4-9, 10-15, 16-18). Bootstrap resampling was performed to estimate the mean and standard deviation for each age group, gender, and time period by repeatedly resampling endurance times with replacement (10,000 iterations). The bootstrapped mean was calculated as the average of these resampled means, while the bootstrapped standard deviation was derived from their standard deviation. Results: Eight studies (n = 1,947) were included in the final analysis. Endurance times declined over time in both North America (1970s–2000s) and Europe (1990s–2010s). In North America, mean reductions were observed across all combined age groups: 4–9 years (–1.27 min), 10–15 years (–1.57 min), and 16–18 years (–1.00 min). European cohorts showed similar declines in younger groups: 4–9 years (–1.36 min) and 10–15 years (–2.28 min). The 16–18 European group was only assessed at one time period, precluding trend analysis. Conclusion: Prior studies point to a decline in fitness in pediatric patients over time. This review of the literature affirms this finding and also highlights regional differences in anthropometrics and fitness trends. Given that current reference values are based on outdated data, there is a need to re-evaluate endurance time standards for modern pediatric populations. This data also points to a critical need to address declines in fitness in children in the current era.

Cardiovascular diseases in dogs have diverse causes and may progress rapidly to life-threatening complications. This review outlines the relevant pathological conditions involving the cardiovascular system in dogs, especially the myocardium, including myocarditis caused by canine parvovirus (CPV-2), heartworm disease (Dirofilaria immitis), hemangiosarcoma, and polyarteritis nodosa (PAN). CPV-2 affects the myocardium of puppies during the early weeks of life, leading to necrosis, fibrosis, and congestive heart failure. Heartworm disease is caused by adult D. immitis residing mainly in the pulmonary arteries, inducing pulmonary hypertension, right ventricular overload, and vascular damage, with the severity being related to the worm burden and duration of infestation. Hemangiosarcoma is a malignant vascular tumor, most frequently originating in the spleen or right atrium, often diagnosed at an advanced stage, with widespread metastases. Polyarteritis nodosa in dogs is a necrotizing, systemic vasculitis of medium-sized arteries that may affect the coronary arteries of the heart. Its pathogenesis is still unclear, though an immune-mediated mechanism is suspected. By presenting these lesions, the review underscores the many factors that can trigger cardiovascular diseases in dogs, as well as the clinical significance and the need for further research into their pathogenesis and treatment.

Background: Hypertrophic cardiomyopathy (HCM) lacks targeted pharmacotherapy. We employed RNA-seq of human HCM myocardium combined with Connectivity Map screening to identify repurposable drugs modulating hypertrophy-associated pathways. Hypothesis: L-canavanine(LCA), identified through HCM transcriptome screening, directly binds CDC42 to inhibit GTP-loading and downstream JNK signaling, thereby reversing pathological hypertrophy. Goals/Aims (1) Determine in vivo therapeutic efficacy of LCA in pressure-overload cardiac hypertrophy (2) Elucidate direct molecular target and binding mechanism of LCA (3) Delineate the CDC42-JNK signaling pathway in hypertrophy regression Methods: We identified L-canavanine (LCA) through Connectivity Map analysis of dysregulated pathways in human hypertrophic cardiomyopathy (HCM) myocardium (RNA-seq; n=15 HCM vs. 8 controls). In vivo , C57BL/6J mice undergoing transverse aortic constriction (TAC) were randomized to sham, vehicle, or LCA treatment (4 weeks; n=6/group). Cardiac hypertrophy was monitored by serial echocardiography and validated by histology (fibrosis/cross-sectional area). In vitro , target engagement was confirmed by cellular thermal shift assay (CETSA) coupled with surface plasmon resonance and mutagenesis. CDC42-GTP activity and JNK signaling were assessed in human HCM samples and phenylephrine-stimulated cardiomyocytes. Rescue experiments employed CDC42 overexpression and JNK activation to investigate underlying mechanisms. Results: L-canavanine ameliorated pressure overload-induced cardiac pathology in mice, reducing left ventricular hypertrophy (LVPWd), myocardial fibrosis, and cardiomyocyte size post-TAC. LCA directly bound CDC42 with high affinity (SPR), stabilizing its structure (CETSA). Critical CDC42 mutations (Thr3Ala/Pro73Ala/Gln74Ala/Asp76Ala) abolished binding. Mechanistically, LCA suppressed CDC42-JNK signaling, decreasing GTP-CDC42 and JNK phosphorylation (p-JNK/JNK). Rescue experiments confirmed causality: CDC42 overexpression reversed LCA-mediated JNK inhibition, and JNK activation (anisomycin) blocked LCA's anti-hypertrophic effects.Thus, LCA attenuates cardiac remodeling via direct CDC42 targeting and JNK pathway disruption. Conclusion: LCA ameliorates pathological hypertrophy by binding CDC42 at Thr3/Pro73/Gln74/Asp76, inhibiting GTP loading and JNK signaling. This establishes CDC42 as a novel therapeutic target for HCM.

Background: Numerous studies indicate an association between cardiac dilation and autoimmune processes. Still, a deeper understanding of the mechanisms linking immune regulation and pathophysiological processes in the heart is required. Programmed cell death protein 1 (PD-1) is an immune checkpoint regulator. PD-1 knockout (PD-1 KO) in mice leads to heart dilation in only some mice. Purpose: This study investigated differences between PD-1 KO mice with and without a cardiac phenotype. Methods: Female and male mice aged 3-14 weeks were included, n=12 PD-1 KO mice showing cardiac dilation (PD-1 dil), n=16 with non-dilated hearts (PD-1 ctrl) and n=11 BALB/c mice (ctrl). B cell activating factor (BAFF) levels were measured in serum via ELISA. Heart weights were normalized. Proteome analysis and gene expression profiling were conducted using the apical third of the heart, significant alterations (fold change of ≥|1.5|, adjusted p-value <0.05) were analysed. Results: Cardiac dilation occurred in 6% of PD-1 KO mice. Heart weights and BAFF levels of PD-1 dil were significantly higher compared to PD-1 ctrl and ctrl (heart weight: 12.9/6.9/6.8 mg/mm; BAFF: 25.9/19.7/15.2 ng/ml). Proteomics analysis revealed more than 1,100 significantly altered proteins (PD-1 dil vs. PD-1 ctrl: 504↓, 623↑; PD-1 dil vs. ctrl: 676↓, 702↑). Only 19 proteins were differentially abundant comparing both ctrls (4↓, 15↑). Principal component analysis clearly distinguished PD-1 dil from both ctrl groups, which in turn strongly overlapped. Activation z-score analysis showed an inhibition of mainly mitochondrial functions (z≤-2) in PD-1 dil vs. PD-1 ctrl and in PD-1 dil vs. ctrl. In these comparison groups, some of the most significantly enriched terms associated with cardiovascular diseases were cardiac fibrosis, dilation and inflammation. A regulation of proteins associated with immunological diseases was observed in both comparisons. Moderate correlation between datasets for proteome and transcriptome was observed (PD-1 dil vs. PD-1 ctrl: r=0.5, p<0.0001; PD-1 dil vs. ctrl: r=0.41, p<0.0001). Conclusion: PD-1 KO mice show an inconsistent phenotype. Thereby PD-1 dil and PD-1 ctrl display significant differences in immune regulation and cardiac pathways, underscoring immunological influences on the development of cardiac pathologies. Future studies will focus on identifying molecular mechanisms that lead to the described phenotype.

Background: Effective treatment of cardiac diseases requires a deep understanding of disease-relevant cellular mechanisms that drive pathology in the human heart. Traditional cell lines often lack the complexity and genetic context necessary to capture these mechanisms. Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes provide a physiologically relevant and genetically diverse platform to model human cardiac disease biology. Evotec’s iPSC platform enables detailed study of disease processes critical for identifying therapeutic targets and developing novel treatments. Methods&Results: We developed a robust, scalable human iPSC-based cardiomyocyte platform integrating a genetically diverse bank of well-characterized iPSC lines and optimized cardiac differentiation protocols. The platform enables the generation of multiple human-relevant cardiac cell types and model systems, including cardiomyocytes, cardiac fibroblasts, 2D co-cultures of these cell types, 3D cardiac spheroids, and engineered heart tissue (EHT). Genome editing technologies, including CRISPR/Cas9 and RNA interference, are routinely applied at both iPSC and cardiomyocyte stages. These tools enable the introduction of disease-relevant mutations to model specific cardiac pathologies, as well as the validation and exploration of novel target gene functions within a human cellular context. To assess disease mechanisms and potential target effects, we use multi-electrode arrays (MEA) for electrophysiology, xCELLigence and FlexCyte for contractility, and calcium transient assays. This enables high-throughput, quantitative, and physiologically relevant phenotyping. Pharmacological testing with well-characterized compounds confirms the platform’s sensitivity to cardiac functional changes. Conclusion: Evotec’s iPSC cardiomyocyte platform, combined with the Evotec Heart Atlas, offers a human-relevant system for cardiac disease modeling, drug target validation, and mechanistic insights. Together, these platforms accelerate cardiovascular therapy discovery and increase clinical success through improved human and disease relevance.

Introduction/Background: Cardiac tamponade is typically associated with large pericardial effusions; however, even small effusions can result in significant hemodynamic compromise, particularly in the setting of rapid fluid accumulation and underlying cardiac pathology. Uremic pericarditis is a rare but serious complication of advanced kidney dysfunction which can progress to tamponade in non-dialyzed patients. We present a case of a elderly man with complex cardiovascular and renal comorbidities who developed obstructive shock from cardiac tamponade despite a small pericardial effusion. This case highlights the diagnostic challenge of recognizing tamponade physiology when classic echocardiographic findings are absent and emphasizes the need to integrate clinical signs and hemodynamics when standard treatments, like dialysis, are not feasible. Case Report: A 75-year-old man was admitted for acute heart failure complicated by cardiorenal syndrome requiring diuresis. Pleuritic chest pain and hypotension later developed, prompting upgrade to the ICU. Severe uremia, EKG findings, and a small pericardial effusion on TTE suggested uremic pericarditis. Swan-Ganz catheterization showed diastolic normalization of pressures consistent with tamponade physiology. Pericarditis therapy was initiated with prednisone and colchicine; anticoagulation was stopped. The patient’s clinical status subsequently improved. Discussion: This case illustrates a rare progression from cardiorenal syndrome and uremic pericarditis leading to cardiac tamponade (Fig.1). Despite a small pericardial effusion and lack of classic echocardiographic signs (Fig.2), rapid fluid accumulation likely resulted in tamponade physiology, supported by hemodynamic and clinical findings. Based on ESC guidelines, typical management involves HD. However, successful use of anti-inflammatory treatment in place of dialysis was utilized due to contraindications. Upon readmission, the absence of tamponade signs suggested a slower effusion progression, reinforcing the initial diagnosis of rapid-onset tamponade in a vulnerable myocardium. Conclusion: This case illustrates the complexity of a small pericardial effusion in the setting of severe uremia and cardiac vulnerability leading to cardiac tamponade. It emphasizes the need for vigilance in recognizing atypical tamponade presentations, while supporting consideration of anti-inflammatory therapy when dialysis cannot be immediately utilized.

Background: Transthyretin cardiac amyloidosis (ATTR-CM) is becoming a more prominent and recognized etiology for diastolic heart failure. The debut of disease-modifying therapies have emphasized the importance of early diagnosis in disease course. Screening criteria have highlighted increased left ventricular wall thickness (LVWT) over 1.2 cm as a threshold to suspect cardiac amyloidosis. However, we previously demonstrated that left ventricular wall thickness may be an unreliable screening marker in these patients and highly variable. We aimed to 1) characterize the diagnostic journey of patients with ATTR-CM with LVWT ≤ 1.2 cm and 2) determine alternative screening pathways to better capture more patients with ATTR-CM. Methods: Our study extracted a cohort from a database of all patients diagnosed with ATTR-CM at single large academic center from January 2006 to March 2024. For each of these 1845 patients, dimensions were abstracted from the echocardiogram closest to the diagnosis date. A cohort of 319 (17.2%) patients diagnosed with ATTR-CM with normal posterior wall thickness (≤ 1.2 cm) were sub-selected and evaluated by manual chart abstraction to categorize pre-specified diagnostic pathways. Data were then evaluated to compare the prevalence of various diagnostic pathways. Results: Among 319 patients with diagnosed ATTR-CM, 198 (62.1%) patients were diagnosed with routine evaluation for restrictive cardiomyopathy and 37 (11.6%) were diagnosed as a part of our mandated ATTR-CM screening for TAVR (Table 1). Seventy-two patients were diagnosed with tissue pathology (8.8% with carpal tunnel pathology, 4.4% with intraoperative cardiac pathology, and 3.4% with other noncardiac pathology). Conclusion: Wall thickness may be an unreliable marker in screening patients with ATTR-CM. Clinicians should maintain a high degree of suspicion of and vigilance among select patients with undifferentiated heart failure and lower thresholds for upfront evaluation with imaging or biopsy.

Introduction/Background: Aging is a significant risk factor for cardiac pathologies, such as heart failure, arrhythmias, and myocardial infarction. p38 MAPKs regulate cardiac remodeling and are implicated in age-related cardiac dysfunction. However, the isoform-specific roles of p38 kinases in the heart are not fully understood. While p38β has been shown to provide cardioprotection in models of doxorubicin-induced cardiotoxicity and ischemia/reperfusion injury, its role in cardiac aging remains unclear. Research Questions/Hypothesis: The systemic genetic deletion of p38β exacerbates age-related cardiac dysfunction. Methods/Approach: Wild-type and p38β knockout (p38β -/- ) male and female mice on the C57BL/6J genetic background, aged 13.5 to 20 months, were evaluated using echocardiography and electrocardiography to assess cardiac structural, mechanical, and electrical function. Multiparametric optical mapping of transmembrane potential and intracellular calcium was performed, followed by an arrhythmia induction protocol consisting of S1S2, S1S2S3S4, short-burst, and long-burst pacing. Results/Data (descriptive and inferential statistics): Compared to their wild-type counterparts, p38β -/- mice displayed an increase in left ventricular (LV) mass (p = 0.0137) and thicker LV anterior walls during both systole (p = 0.0390) and diastole (p = 0.0398). Electrocardiographic alterations included a prolonged P wave (p = 0.0081), QT interval (p = 0.0003), QTc interval duration (p = 0.0003), and a shortened QRS complex duration (p = 0.0012). Optical mapping revealed a prolonged action potential duration at 30% repolarization (p < 0.0001), increased transverse conduction velocity (p = 0.025), and a trend toward slower longitudinal conduction velocity (p = 0.0685). Additionally, optical mapping showed impaired calcium handling, characterized by a prolonged calcium rise time (p = 0.0205) and calcium transient duration at 50% (p = 0.0639) and 80% (p < 0.0001) reuptake. Arrhythmia inducibility studies revealed an increase in non-sustained arrhythmias in p38β -/- hearts (p = 0.0188). Conclusion(s): The systemic genetic deletion of p38β exacerbates age-related structural and electrophysiological remodeling of the heart, demonstrating the protective role of p38β in cardiac aging.

Background: Purulent pericarditis is a very rare manifestation of infective endocarditis (IE) with a high mortality rate, particularly in the setting of Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. Even more perplexing is the rapid progression to hemodynamically significant cardiac tamponade in the context of early negative echocardiographic studies. This case demonstrates a unique presentation of MRSA endocarditis with an initial negative echocardiogram complicated by purulent pericarditis and pericardial tamponade. Case Presentation: A 44-year-old woman with a history of intravenous drug use presented with altered mentation and multifocal intracranial hemorrhages. Imaging demonstrated cavitating lung lesions, wedge-shaped areas of decreased perfusion within the bilateral kidneys, raising suspicion for septic emboli. Serial blood cultures were positive for MRSA. Despite ongoing fevers, leukocytosis, and persistent bacteremia, both initial transthoracic and transesophageal echocardiograms (TTE/TEE) did not demonstrate vegetations or significant pericardial effusion. Due to persistent bacteremia and worsening hemodynamics, a repeat TEE was performed, which revealed a new, large circumferential pericardial effusion with right atrial systolic collapse, right ventricular diastolic collapse, plethoric IVC, a 1.4 × 0.8 cm highly mobile vegetation on the mitral valve subvalvular apparatus, and multiple large echogenic structures in the pericardial space concerning for vegetation. Pericardiocentesis revealed a purulent, MRSA-positive fluid, confirming purulent pericarditis. The antibiotics regimen was intensified and the patient was transferred to a higher level of care facility for cardiac surgery evaluation. Conclusion: This case underscores the importance of maintaining a high index of suspicion for infective endocarditis in patients presenting with atypical symptoms, particularly in those with a history of intravenous drug use and persistent MRSA bacteremia. Clinicians must remain vigilant for evolving cardiac pathology despite initially reassuring imaging results. The integration of clinical judgment and advanced imaging techniques is essential for optimizing patient outcomes in such challenging scenarios.

Calcins represent a class of novel peptide ligands for ryanodine receptors (RyRs), demonstrating therapeutic potential against Ca2+ dysregulation-related cardiac diseases. Nevertheless, their biological effects beyond RyR modulation and underlying mechanisms remain unexplored. This study employed Opicalcin1 (OpiCa1), the most bioactive calcin member, revealing that while it reduced cytosolic Ca2+ in H9c2 cardiomyocytes, it concurrently diminished cell viability and promoted apoptosis. Transcriptomics and Western blot analyses identified suppression of the negatively regulatory PI3K/Akt pathway as the mechanistic basis. In acute/chronic in vivo studies, high-dose OpiCa1 (≥50 mg/kg i.v.) exhibited minimal impact on body weight, histopathology, and organ indices, while accompanied with subtle alterations in serum indicators, including slight elevations in AST, ALT, and LDH, alongside mild reductions in CK-MB and TBIL-Z. These findings unveil OpiCa1’s modulation on cardiomyocyte viability through PI3K/Akt inhibition with minimal systemic impact, providing new insights into non-RyR-mediated actions of calcins and critical toxicological support for developing calcin-based therapies targeting Ca2+-dysregulated cardiac pathologies.