Cardiac Conduction Research Articles

Circulating CCRR serves as potential novel biomarker for predicting acute myocardial infarction

Abstract Objective Cold regions exhibit a high prevalence of cardiovascular disease, particularly acute myocardial infarction (AMI), which is one of the leading causes of death associated with cardiovascular conditions. Cardiovascular disease is closely linked to the abnormal expression of long non-coding RNA (lncRNA). This study investigates whether circulating levels of lncRNA cardiac conduction regulatory RNA (CCRR) could serve as a biomarker for AMI. Materials and methods We measured circulating CCRR from whole blood samples collected from 68 AMI patients and 69 non-AMI subjects. An AMI model was established using C57BL/6 mice. Quantitative reverse transcription PCR (qRT-PCR) was used to assess CCRR expression. Exosomes were isolated from cardiomyocytes, and their characteristics were evaluated using electron microscope and nanoparticle tracking analysis. The exosome inhibitor GW4869 was employed to examine the effect of exosomal CCRR on cardiac function using echocardiography. Protein expression was detected using Western blot and immunofluorescence staining. Results The circulating level of CCRR was significantly higher in AMI patients (1.93 ± 0.13) than in non-AMI subjects (1.00 ± 0.05, P < 0.001). The area under the ROC curve (AUC) of circulating CCRR was 0.821. Similar changes in circulating CCRR levels were consistently observed in an AMI mouse model. Exosomal CCRR derived from hypoxia-induced cardiomyocytes and cardiac tissue after AMI were increased, a change that was reversed by GW4869. Additionally, CCRR-overexpressing exosomes improved cardiac function in AMI. Conclusion Circulating lncRNA CCRR is a potential predictor of AMI. Exosomal CCRR plays a role in the communication between the heart and other organs through circulation.

Prognostic Significance and Associations of Neural Network-Derived Electrocardiographic Features.

Subtle, prognostically important ECG features may not be apparent to physicians. In the course of supervised machine learning, thousands of ECG features are identified. These are not limited to conventional ECG parameters and morphology. We aimed to investigate whether neural network-derived ECG features could be used to predict future cardiovascular disease and mortality and have phenotypic and genotypic associations. We extracted 5120 neural network-derived ECG features from an artificial intelligence-enabled ECG model trained for 6 simple diagnoses and applied unsupervised machine learning to identify 3 phenogroups. Using the identified phenogroups, we externally validated our findings in 5 diverse cohorts from the United States, Brazil, and the United Kingdom. Data were collected between 2000 and 2023. In total, 1 808 584 patients were included in this study. In the derivation cohort, the 3 phenogroups had significantly different mortality profiles. After adjusting for known covariates, phenogroup B had a 20% increase in long-term mortality compared with phenogroup A (hazard ratio, 1.20 [95% CI, 1.17-1.23]; P<0.0001; phenogroup A mortality, 2.2%; phenogroup B mortality, 6.1%). In univariate analyses, we found phenogroup B had a significantly greater risk of mortality in all cohorts (log-rank P<0.01 in all 5 cohorts). Phenome-wide association study showed phenogroup B had a higher rate of future atrial fibrillation (odds ratio, 2.89; P<0.00001), ventricular tachycardia (odds ratio, 2.00; P<0.00001), ischemic heart disease (odds ratio, 1.44; P<0.00001), and cardiomyopathy (odds ratio, 2.04; P<0.00001). A single-trait genome-wide association study yielded 4 loci. SCN10A, SCN5A, and CAV1 have roles in cardiac conduction and arrhythmia. ARHGAP24 does not have a clear cardiac role and may be a novel target. Neural network-derived ECG features can be used to predict all-cause mortality and future cardiovascular diseases. We have identified biologically plausible and novel phenotypic and genotypic associations that describe mechanisms for the increased risk identified.

Abstract 4137833: The plasma cell-free transcriptome non-invasively profiles the immune response and myocardial damage in immune checkpoint inhibitor-induced myocarditis.

Introduction: Immune checkpoint inhibitor-induced myocarditis (ICI-m) is a severe complication of cancer immunotherapy, marked by cardiac inflammation. Despite its high mortality rate, diagnosing ICI-m remains challenging due to the lack of sensitive and non-invasive diagnostic modalities. Plasma cell-free mRNA (cf-mRNA) has recently been highlighted as a promising tool for non-invasive tissue profiling. Hypothesis: The plasma cf-mRNA profile contains disease-specific immune and tissue transcriptomic signatures of ICI-m that can be leveraged for disease-specific precision diagnostics. Aims: To establish and validate a novel cf-mRNA bench and bioinformatic pipeline for noninvasive profiling of the immune and tissue landscape of patients with ICI-m. Methods: We isolated, DNase-treated, and sequenced bulk cfRNA from frozen plasma of patients with ICI-treated cancer patients with no autoimmunity (group A, n=5), extracardiac autoimmunity (group B, n=7), and ICI-m with or without extracardiac autoimmunity (group C, n=10). Publicly available healthy control cfRNA was downloaded (n=30) as external controls. We used cell type-specific gene panels curated from single-cell RNA-sequencing datasets of circulating immune cells and cardiac cells for cellular deconvolution of the cf-mRNA. Signature scores of the sum of the counts of each cell type-specific gene were used to compare cell type contributions between patient groups. Results: Cancer and inflammatory gene pathways were significantly enriched in the cf-mRNA of all ICI-treated cancer patients. Cardiac pathways and conduction genes were significantly enriched in group C vs. A and B patients. Signature scores of Temra CD8+ T cells and cardiomyocytes, and gene expression of CCL5 and MYH6 were elevated in group C patients. Our custom ICI-m classifier containing 3 cardiac- and 3 immune cell-specific genes differentiated group C from A (AUC 0.903, 95% CI 0.858-0.903) and B patients (AUC 0.983, 95% CI 0.970-0.983) effectively, outperforming a diagnostic classifier obtained from unsupervised feature selection from all differentially expressed genes. Conclusions: Using our novel plasma cf-mRNA platform, we developed a diagnostic classifier that captures the disease-specific immune and tissue transcriptomic signatures of ICI-m, highlighting the advantages of this disease-specific approach over conventional biomarker discovery, and demonstrating the broader implications of the platform for the field of precision diagnostics.

Single-cell Trajectories and Pseudo-time Analysis Reveal Additional Insights into Rheumatoid Arthritis Disease Progression

As the chicken embryo grows, its increasing metabolic demand drives the development of the cardiovascular system, enabling efficient nutrient delivery through complex molecular and structural formation. Key extracellular matrix (ECM) components, such as hyaluronic acid (HA) and collagen type I alpha 1 (COL1A1), play a crucial role in shaping the biomechanical environment of the heart, particularly the sinoatrial node (SAN). These ECM elements regulate cell adhesion, migration, and the maturation of cardiac progenitor cells (CPCs), essential for the heart's electrical conductivity and rhythmicity. Based on the hypothesis that ECM mechanical properties influence the spatial patterning of conduction-related genes, we analyzed spatial transcriptomics data from chicken hearts at different developmental stages. Collagen-related genes associated with a sturdy ECM showed an increasing trend over time, while soft ECM-related genes responsible for producing proteoglycans and breaking down collagen decreased. Although conduction-related genes did not fully align with ECM trends, intriguing patterns were observed, pointing to potential interactions between ECM remodeling and the construction of the cardiac conduction system. Our findings suggest significant ECM r7emodeling between days 4 and 7, which may influence the heart's structural and functional development.

Abstract 4137975: 9-Year Longitudinal Assessment of the 12-lead Electrocardiogram of Volunteer Firefighters

Introduction: In the US, the most common cause of death among active-duty firefighters is sudden cardiac death (SCD). Underlying heart diseases are important propagator of ventricular tachyarrhythmias that cause SCD. The objective of this abstract is to assess the incidence of underlying heart disease, identified on 12-lead electrocardiograph (ECG), that may place firefighters at greater risk of SCD. Methods: We digitalized 12-lead ECGs recorded among firefighters who visited a firefighter health screening program at least 4 times from 2011-2019. We extracted the interval measurements (Heart Rate, T-axis, QRS-axis, QRS duration, QTc duration) and interpretation statements from each of the 12-lead ECGs and grouped potential propagators of ventricular tachyarrhythmias including left ventricular hypertrophy (LVH), coronary artery disease (CAD), and cardiac conduction disease. We used simple mean imputation to handle missing data. Descriptive statistics including means and frequencies were used to analyze the sample. Results: Among 465 firefighters (90.1% male) with a mean age of 47.1 (±13.6) whom 1,296 12-lead ECGs were analyzed, 21.5% (n=278) of Heart Rate, 0.39% (n=5) T-axis, 26.4% (n=342) QRS-axis, 40.0% (n=518) QRS duration, 5.40% (n=70) QTc duration were abnormal. In addition to intervals, the 12-lead ECGs generated 1,970 interpretation statements of which 28.2% (n=555) were deemed possible pathoanatomical substrates including 3.1% (n=34) LVH, 24.7% (n=137) CAD, and 69.2% (n=384) cardiac conduction diseases. Among cardiac conduction diseases, intraventricular conduction disease was the most prevalent (n=204, 36.8%), followed by vertical axis (n=70, 12.6%), right bundle branch block (n=59, 10.6%), left anterior fascicular block (n=34, 6.1%), and left bundle branch block (n=17, 3.1%). Interestingly, we did not observe a temporal relationship regarding the number of pathoanatomical substrates over the screening period. Conclusions: Nearly 30% of the interpretation statements generated from 12-lead ECGs were indicative of possible pathoanatomical substrates that cause SCD, which reflects the apparently negative effect of fire suppression activity on one’s cardiopulmonary health. Our result justifies the imperative need of effective prevention method for cardiac conduction diseases among firefighters. Further research is needed to collect 12-lead ECG systematically amongst other measures such as diet and BMI which reflect work culture and lifestyle of firefighters.

Abstract 4122035: The Distinct Natural History, Phenotype Spectrum, Familial Penetrance and Clinical Outcomes in Desmin ( DES )-Associated Cardiomyopathy

Background: Pathogenic/likely pathogenic variants (P/LP) in the desmin ( DES ) gene cause heterogeneous cardiomyopathy and skeletal myopathy phenotypes. Research Questions: Limited data suggest that patients with P/LP DES variants have a high incidence of major adverse cardiac events (MACEs), including cardiac conduction disease requiring pacemaker implantation (CCD-PM), sustained ventricular arrhythmias (VA), and heart failure (HF) events (HF hospitalization, heart transplant, HF-related death). However, small cohort sizes have limited full clinical characterization. Aims: We aimed to describe the natural history, phenotype spectrum, familial penetrance and MACE in patients with P/LP DES variants identified via clinical genetic testing. Methods: We conducted a systematic review and individual patient data meta-analysis of cardiac and skeletal myopathy phenotypes and MACE (CCD-PM, VA and HF events) in patients with P/LP DES variants by retrieving publications from Medline (PubMed) and Embase. Diagnosis of cardiomyopathy or MACE were both considered evidence of cardiac involvement. Results: Out of 4,212 screened records, 72 met inclusion criteria. In total, 230 patients were included (52.6% male, 52.2% probands, median age: 31 years at first evaluation [22.0; 42.8]). Eighty-five (37.0%) patients showed isolated cardiac involvement, 89 (38.7%) cardiac and skeletal muscle involvement, 39 (17.0%) only skeletal muscle involvement, and 17 (7.4%) had neither phenotype. Overall, 130 (56.5%) patients were diagnosed with a cardiomyopathy and 134 (57.4%) patients developed MACE (96 [41.7%] had CCD-PM, 36 [15.7%] sustained VA, and 43 [18.7%] HF events). Familial cardiac disease penetrance was 69.1% (76/110) in relatives with P/LP DES variants. Out of 40 patients who presented with isolated CCD-PM phenotype, 18 (45.0%) were diagnosed with a cardiomyopathy after 6 [2.0; 16.0] years of follow-up. In multivariable analysis, male sex and non-missense variants were associated with higher risk of sustained VA (HR 2.71, p=0.008, and HR 4.62, p&lt;0.001, respectively) and HF events (HR 2.63, p=0.005, and HR 2.79, p=0.015). Conclusions: DES cardiomyopathy demonstrates a distinct natural history, characterized by high familial penetrance and a high MACE burden. Male patients and those carrying non-missense variants are at higher risk for sustained VA events and may benefit from primary preventive ICD implantation even in the absence of severe LV systolic dysfunction.

ATrial arrhythmias in inhEriTed aRrhythmIa Syndromes: results from the TETRIS study.

Little is known about the distribution and clinical course of patients with inherited arrhythmia syndrome (IAS) and concomitant atrial arrhythmias (AAs). 1) to characterize the distribution of AAs in patients with IAS and 2) evaluate the long-term clinical course of these patients. An international multicenter study was performed and involved 28 centers in 16 countries. Inclusion criteria were: 1) IAS and 2) ECG documentation of AAs. The primary endpoint was a composite of sudden cardiac death, sustained VAs or appropriate ICD interventions. Strokes, inappropriate ICD shocks due to AAs, and the occurrence of sinus node dysfunction were assessed. A total of 522 patients with IAS and AAs were included. Most patients were diagnosed with Brugada syndrome (n=355, 68%) and long-QT syndrome (n=93, 18%). The remaining patients (n=71, 14%) presented with short-QT syndrome, early repolarization syndrome (ERS), catecholaminergic polymorphic ventricular tachycardia (CPVT), progressive cardiac conduction diseases, or idiopathic ventricular fibrillation. Atrial fibrillation (AF) was the most prevalent AA (82%), followed by atrial flutter (9%) and atrial tachycardia (9%). AA was the first clinical manifestation of IAS in 52% of patients. More than one type of AAs was documented in 23% of patients. Nine patients (3%) experienced VA before the diagnosis of IAS, due the use of anti-arrhythmic medications taken for the AA. The incidence of the primary endpoint was 1.4% per year, with a twofold increase observed in patients who experienced their first AA before the age of 20 (OR 2.2, p=0.043). This was consistent across the different forms of IAS. Inappropriate ICD shock due to AAs were reported in 2.8% of patients, strokes in 4.4% and sinus node dysfunction in 9.6%. Among patients with IAS and AAs, AA is the first clinical manifestation in about half of the cases, with more than one form of AAs present in one-fourth of the patients. The occurrence of AA earlier in life may be associated with a higher risk of ventricular arrhythmias. The occurrence of stroke and sinus node dysfunction is not-infrequently in this cohort.

Long-term prognosis of patients with an SCN5A loss-of-function variant and progressive cardiac conduction disorder or Brugada syndrome

The long-term prognosis of patients with a loss-of-function variant in the cardiac sodium channel gene SCN5A is unknown. This study aimed to evaluate the long-term arrhythmic risk in patients with an SCN5A loss-of-function variant to identify predictors of arrhythmic events. Probands and family members with (likely-)pathogenic SCN5A loss-of-function variants were retrospectively included. Clinical and ECG data at baseline and last follow-up were collected. Patients with a history of cardiac arrest, sustained ventricular tachycardia, symptomatic or documented atrial tachy- or bradyarrhythmia, or arrhythmogenic syncope, were categorized as symptomatic. Arrhythmic events at follow-up were defined as sudden death, aborted cardiac arrest, documented ventricular fibrillation and/or sustained ventricular tachycardia. We included 615 patients (349 males, 242 probands, 157 spontaneous type-1 Brugada-ECG and 111 symptomatic at baseline). During 9.5 (5.0-14.3) years follow-up, arrhythmic events occurred in 41 patients (6.7%), equating an overall event rate of 0.7%/year; 2.0%/year in symptomatic and 0.3%/year in asymptomatic patients. In the overall study population, symptoms at baseline, male sex, and QRS prolongation were identified as independent predictors of arrhythmic events. In asymptomatic patients, also male sex and QRS prolongation were identified as predictors. Asymptomatic women with QRS <100ms did not experience arrhythmic events at follow-up. Key predictors of arrhythmic risk in patients with an SCN5A loss-of-function variant, regardless of a Brugada syndrome diagnosis, are symptoms at baseline, male sex, and prolonged QRS. Our findings may enable more tailored management strategies in patients with an SCN5A loss-of-function variant based on their individual risk profiles.

Desmin-related myopathy manifested by various types of arrhythmias: a case report and literature review.

Desmin is a type III intermediate filament protein specifically expressed in muscle cells, which is encoded by the DES gene. Defects in the desmin protein and cytoskeletal instability may interfere with cardiac muscle conduction signals, a fundamental mechanism for arrhythmias in patients with desmin-related myopathy. This current case report presents a female patient in her early 20s who presented with early-onset complete atrioventricular block and complete left bundle branch block over the previous decade. More recently, she had developed ventricular tachycardia, ventricular fibrillation, atrial fibrillation and other arrhythmias. Echocardiography revealed non-compaction of the ventricular myocardium and pulmonary hypertension. Whole-exome sequencing analysis identified a heterozygous missense mutation in the DES gene: c.1216C>T (p.Arg406Trp). She was eventually diagnosed with arrhythmias due to desmin-related myopathy. A literature review of international databases was undertaken to summarise the clinical characteristics of the cardiac involvement associated with this DES gene mutation.

Catheter ablation in a monochorionic diamniotic twin pregnancy: A case report and literature review.

Preexcitation syndrome is an uncommon congenital cardiac disorder that impairs the normal cardiac conduction system. Radiofrequency ablation is one of the most effective treatments for this condition. Nevertheless, radiofrequency ablation is rare in women with preexcitation syndrome during pregnancy. A 33-year-old woman with monochorionic diamniotic twin pregnancy complicated by sinus arrhythmia with ventricular preexcitation at 14 weeks and 5 days of gestation, with paroxysmal palpitations and shortness of breath at 16 weeks with paroxysmal supraventricular tachycardia with preexcitation syndrome and a heart rate ranging from 180 to 225 beats per minute. The pregnant occurred sudden palpitations and shortness of breath in the shower. Electrocardiography revealed paroxysmal supraventricular tachycardia, and electrophysiological study revealed preexcitation syndrome (dominant accessory route of the left free wall) with atrioventricular reentrant tachycardia. Radiofrequency catheter ablation was performed at 20 weeks. Symptoms of preexcitation syndrome resolved after the radiofrequency catheter ablation, and 2 healthy infants were delivered at 36 weeks and 2 days of gestation by cesarean section. Preexcitation syndrome may result in life-threatening arrhythmias such as supraventricular tachycardia during pregnancy and delivery. It might be efficiently controlled through optimal treatment by a multidisciplinary team, which would effectively minimize arrhythmia risk events during pregnancy and improve maternal-fetal outcomes. Based on the patient's individual situation, radiofrequency ablation may be a procedure in pregnant women with preexcitation syndrome.

Tnni3k regulates cardiomyopathy and cardiac conduction disease through Nfatc1 signaling

Tnni3k regulates cardiomyopathy and cardiac conduction disease through Nfatc1 signaling

Rotary excitation of non-sinusoidal pulsed magnetic fields: Towards non-invasive direct detection of cardiac conduction.

There is a need for high resolution non-invasive imaging methods of physiologic magnetic fields. The purpose of this work is to develop a MRI detection approach for non-sinusoidal magnetic fields based on the rotary excitation (REX) mechanism which was previously successfully applied for the detection of oscillating magnetic fields in the sub-nT range. The new detection concept was examined by means of Bloch simulations, evaluating the interaction effect of spin-locked magnetization and low-frequency pulsed magnetic fields. The REX detection approach was validated under controlled conditions in phantom experiments at 3 T. Gaussian and sinc-shaped stimuli were investigated. In addition, the detection of artificial fields resembling a cardiac QRS complex, which is the most prominent peak visible on a magnetocardiogram, was tested. Bloch simulations demonstrated that the REX method has a high sensitivity to pulsed fields in the resonance case, which is met when the spin-lock frequency coincides with a non-zero Fourier component of the stimulus field. In the experiments, we found that magnetic stimuli of different durations and waveforms can be distinguished by their characteristic REX response spectrum. The detected REX amplitude was proportional to the stimulus peak amplitude (R2 > 0.98) and the lowest field detection was 1 nT. Furthermore, the detection of QRS-like fields with varying QRS durations yielded significant results in a phantom setup (p < 0.001). REX detection can be transferred to non-sinusoidal pulsed magnetic fields and could provide a non-invasive, quantitative tool for spatially resolved assessment of cardiac biomagnetism. Potential applications include the direct detection and characterization of cardiac conduction.

Generation of an iPSC cell line (VANYHHi001-A) from a patient with cardiac arrythmias carrying CACNA1D, SCN5A, and DSP variants

Progressive cardiac conduction defect often associated with variants in sodium voltage-gated channel SCN5A gene and variants in the L-type calcium voltage-gated channel CACNA1D gene are implicated in sinoatrial node dysfunction. We generated an induced pluripotent stem cell line (iPSC) from a 13-year-old patient with history of conduction system disease and ventricular tachycardia, carrying variants in SCN5A (c.2618C > G), CACNA1D (c.3786G > T), and DSP (c.1582C > G). The generated iPSC line exhibited pluripotency markers, differentiated into the three embryonic germ layers, and maintained a normal karyotype. This iPSC line offers insights into the pathophysiological mechanisms of cardiac arrhythmias and personalized therapies development.

Investigating the role of WT1 in Brugada syndrome pathophysiology

Abstract Background Brugada syndrome (BrS) is a heritable arrhythmic disorder presumably caused by conduction slowing in the right ventricular (RV) outflow tract (RVOT). A recent genome-wide association study found an association between common variants on chromosome 11 near WT1, tagged by the SNP rs72905083, and BrS susceptibility. Purpose To study whether WT1 affects cardiac conduction and could therefore represents the underlying association of the chr11 locus with BrS susceptibility. Methods We conducted in silico analyses of omics datasets to identify the likely causal gene at the chr11 BrS locus. Next, we conducted electrophysiological studies in heterozygous young adult (4 months old) Wt1-deficient (Wt1+/-) mice and wild-type littermates to explore the effect of Wt1 on cardiac conduction. To study the potential role of Wt1 in the setting of reduced conduction reserve, we compared aged Scn5a haploinsufficient mice (Scn5a+/-;Wt1+/+, 17 months) with littermates haploinsufficient for both Wt1 and Scn5a (Scn5a+/-;Wt1+/-). Optical mapping was performed in Langendorff-perfused hearts, where conduction was further challenged by acute ajmaline administration or by pacing at the effective refractory period (ERP). Transcriptomic analyses were conducted in Wt1+/- and wild-type mice by RNAseq of PCM1-sorted cardiomyocytes. Results Analysis of omics datasets uncovered WT1 as the likely causal gene since WT1 was the closest gene to, and in fact overlapped, the BrS-associated region; promoter capture Hi-C data in human tissue showed chromatin contact between the promoter of WT1 and the associated region; and H3K27ac ChIP-seq signals (i.e. enhancer activity) of putative cardiac enhancers located within the associated region were correlated with WT1 transcript abundance across multiple tissues (Z-score = 4.32, p=1.57e-05). No differences were observed in ECG parameters or optically mapped epicardial conduction between Wt1+/- mice and wild-type littermates. However, comparison of aged Scn5a+/-;Wt1+/- and Scn5a+/-; Wt1+/+ hearts, in the setting of acute ajmaline challenge or pacing at the ERP, showed faster conduction in RV/RVOT in the presence of Wt1 haploinsufficiency (genotype effect: p=0.057 and p=0.041 for RV and RVOT epicardial conduction, respectively, during ajmaline challenge; p=0.034 for RV epicardial conduction during pacing at ERP). RNAseq of RV/RVOT cardiomyocytes revealed higher Scn5a expression in Wt1+/- vs wild-type (p=0.006). Conclusion We identified WT1 as the gene that most likely underlies the effect of the chr11 BrS susceptibility locus. Functional data revealed protective effects of reduced Wt1 expression in the setting of reduced conduction reserve. Transcriptomic data suggest that this occurs through a transcriptional effect on Scn5a expression.

Improving early mortality risk detection in light-chain cardiac amyloidosis patients with routine echocardiographic indicators and mayo staging

Abstract Background Light-chain cardiac amyloidosis (AL-CA) is a fatal cardiomyopathy caused by the deposition of monoclonal immunoglobulin light-chain in the cardiac fibers, conduction system, valves, and other parts of the heart. The Mayo 2004 staging system is widely used to assess the prognosis of AL-CA. Those in the highest-risk categories, Mayo 2004 stage IIIb, exhibit extremely poor responses to conventional treatment regimens, resulting in high early mortality rates. However, within the same stage, prognostic outcomes among patients can still vary significantly. Hence, a more detailed stratification of high-risk patients is crucial for pinpointing those at extreme risk. Objective To investigate whether conventional echocardiographic measurements can enhance the identification of high-risk patients with early mortality in AL-CA on the basis of existing risk stratification. Methods Continuous enrollment of patients diagnosed with AL-CA at our center from May 2020 to December 2022. Clinical data, echocardiography, and follow-up results of the patients were collected. Logistic regression analyses were used to identify risk factors for early mortality, with risk factor thresholds calculated using Receiver Operating Characteristic (ROC) curves. Kaplan-Meier survival analysis was employed to assess endpoint events. The diagnostic efficacy of the model was evaluated using the area under the ROC curve and the Integrated Discrimination Improvement (IDI). Results A total of 76 patients were included with an average age of 59±10 years. Among them, 51 were male (67.1%). The median follow-up duration was 10 months (ranging from 5 to 20 months). Early mortality, defined as death within 6 months, occurred in 20 patients (26.3%). Twenty-three patients were categorized under the Mayo 2004 stage IIIb (30.3%). The 6-month mortality rate for patients in the Mayo 2004 stage IIIb was 56.5%. The sensitivity of early diastolic transmitral flow velocity to early diastolic mitral annular tissue velocity ratio divided left ventricular ejection fraction [(E/e’) /LVEF] in predicting early mortality in patients with AL-CA is 63%, and the specificity is 92%.When compared to the Mayo 2004 stage IIIb alone, (E/e')/LVEF≥0.5 combined with the Mayo 2004 stage IIIb had an area under the curve of 0.731 and 0.824, respectively, in the ROC curve. The IDI was 0.113 (95% CI: 0.013-0.213, P=0.026), representing an 11.3% enhancement in the predictive value of early mortality in AL-CA patients. Conclusion Routine echocardiography derived E/e' to LVEF ratio offered added prognostic value for early mortality beyond Mayo staging.Kaplan-Meier survival curve

Machine learning prediction for prognosis and long-term effectiveness for transcatheter ventricular septal defect closure: a 5-year single center experience

Abstract Background Transcatheter therapy, with minimal invasiveness and rapid recovery advantages, has emerged as the primary choice for treating perimembranous ventricular septal defect. However, patients receiving transcatheter occlusion may confront conduction abnormalities due to the occluder's proximity to the cardiac conduction bundle during implantation. Few have assessed the risks of postoperative conduction block (CB) via robust machine learning models. Purpose The purpose of this study was to evaluate our long-term follow up results of pmVSD occlusion and establish a prediction model to identify risk predictors of conduction abnormalities via robust machine learning methods. Methods Five methods including logistic regression with a stepwise selection of variables, lasso regularization; random forest; gradient descent boosting (GBM); and support vector machine, were used to train models for predicting risks of late-onset and persistent conduction block through 5 years of follow-up and were validated using 5-fold cross-validation. Receiver-operating characteristic curves and Brier scores were utilized to evaluate model discrimination and calibration, respectively. The top prediction variables were identified by using the best performing models, using the relative influence score of each variable in 5-fold cross-validation. Results The GBM model performed the best with an AUC of 0.82 (95% confidence interval [CI]: 0.75 to 0.89) for predicting late-onset CB (Brier score: 0.0204), and 0.70 (95% CI: 0.62 to 0.78) for persistent CB (Brier score: 0.0003) over entire study period. Conduction block on admission, advanced age and aortic regurgitation before discharge were strongly associated with late-onset CB, whereas decreased left ventricular ejection fraction, enlarged left ventricle end diastolic diameter at 1-month follow-up were the most significant predictors of persistent CB. Conclusions These models predict the risks of temporary and persistent postoperative conduction block in patients with pmVSD occlusion and shed light on preventing long-term complications.Study FlowchartCentral Illustration

Cells of the adult mouse cardiac conduction system in wild type and Nkx2-5 heterozygous loss-of-function mutation

Abstract Background Specialised cardiomyocytes in the cardiac conduction system (CCS) generate and spread the electrical impulse that initiates synchronised heartbeats. Disrupted signal transduction in the atrioventricular (AV) node, a key electrical connection between atria and ventricles, causes AV block. AV block potentially leads to electromechanical uncoupling and sudden cardiac death. Nkx2-5 encodes a cardiac transcription factor that is critical for embryonic CCS formation. Heterozygous loss-of-function mutation of Nkx2-5 (Nkx2-5+/–) results in a hypoplastic CCS in humans and mice and progressive AV block. Purpose We aimed to create a cell atlas of the adult mouse CCS and define the consequences of Nkx2-5 haploinsufficiency on the structural organisation and transcript expression of CCS cells. Methods We performed single-nucleus RNA sequencing on the sinoatrial nodes, AV nodes, His bundles, right bundle branches (RBB) and moderator bands of 17 wild type and 14 Nkx2-5+/– mice (aged 13 to 35 weeks, 5159 CCS cells). Employing single-molecule fluorescent RNA in situ hybridisation (smFISH), we validated selected transcripts and examined the spatial organisation of identified cell populations. Results In the AV node, we identified two subpopulations of pacemaker cells that were spatially separated in the proximal and distal pacemaker region (Fig1). Within these subpopulations, expressed transcripts indicated an atrial-to-ventricular gradient of electrical activity, corresponding to their respective topography. We determined two subpopulations in the His bundle and RBB that were enriched for either slow or fast conduction markers. Spatially, the slow-conducting populations seemed to surround the fast-conducting ones and might act as electrical isolation (Fig1). In Nkx2-5+/- cells of the pacemaker AV node, His bundle, RBB and Purkinje fibres, genes involved in Slit-Robo signalling were dysregulated. Slit-Robo signalling was previously reported in neuronal differentiation and embryonic heart lumen formation. Slit ligand 3 was downregulated in Nkx2-5+/- pacemaker AV node cells (Slit3, log2FC = -2.22, p = 7.0e-42), as was the roundabout guidance receptor 1 (Robo1, log2FC = -0.96, p = 1.6e-4). By contrast, there was upregulation of neural EGF-like 1 (Nell1, log2FC = 3.18, p = 5.3e-6), an alternative ligand of roundabout guidance receptors. Altered Nell1 and Slit3 expressions were confirmed by smFISH (Fig2). Conclusions Our cell atlas defines new CCS cell populations with informative transcriptomic profiles and spatial organisation, providing insights into subpopulations in the AV junction where electrical signals switch from slow to fast conduction. We identified disrupted Slit-Robo signalling in Nkx2-5+/-, possibly impairing differentiation and maturation of the CCS and altering electrophysiologic functions. Our normative anatomical and transcription data on the CCS can inform future studies of cardiac electrophysiology and arrhythmias.Fig1 - Subpopulations in AV junctionFig2 - Nell1 smFISH in pacemaker AV node

Prognostic role of ECG patterns in Anderson Fabry disease

Abstract Background Anderson Fabry disease (AFD) is an X-linked lysosomal storage disorder leading to a deficiency in α-galactosidase A and globotriasylceramide (Gb3) deposition in different organs. Cardiac involvement is extremely common. It has been shown that the ECG abnormalities are directly correlated with the progressive accumulation of glycosphingolipids in the myocardium and cardiac conduction system. However, it is still unclear whether the ECG alterations are correlated with clinical events. Purpose To evaluate the prognostic role of ECG patterns in an unselected population of patients with AFD. Methods We conducted a retrospective multicenter study enrolling 215 consecutive patients. Based on the baseline ECG the study population was divided into the following five groups: 1) normal ECG or minimal alterations; 2) left ventricular hypertrophy (LVH) without signs of overload; 3) isolated negative T waves in the inferior and/or lateral leads; 4) LVH with signs of overload with or without incomplete right bundle branch block (RBBB); 5) complete RBBB. The primary endpoint was the composite of sudden cardiac death, resuscitated cardiac arrest, sustained ventricular tachycardia, and heart failure. Results Median age of study population was 45 years (32-57), and 86 patients (40%) were men. The rate of classic phenotype was 68%. Patients with ECG patterns 3 and 4 were older at baseline, more frequently affected by arterial hypertension, mostly male and showed greater left ventricular thickening, At a median follow up of 60 months (25-83) the overall Kaplan-Meier survival free from the primary endpoint was 57%: the Kaplan-Meier survival estimates of ECG groups were 66%, 75%, 68%, 27% e 52% respectively (log Rank 0.0026). On multivariable analysis patients belonging to either 3 or 4 group showed an increased risk of primary endpoint (HR= 2.45; 95% CI 1.04-5.78, p=0.040) compared to other groups. Conclusion ECG at baseline may be a useful tool to predict the risk of cardiovascular events in Anderson-Fabry Disease. Future studies should investigate if ECG may be useful also to evaluate the clinical response to specific therapy.

Gradual hypertensive response in aortic alterations and myocardial inflammatory activation in progressing HFpEF in mice

Abstract Introduction Hypertension is the most common comorbidity in patients affected by heart failure with preserved ejection fraction (HFpEF). Early effects of pressure overload and its contribution to the gradual development of cardiac and vascular pathology leading to HFpEF are not well recognized, as patients are diagnosed when the disease has already advanced and show symptoms. Several hypertensive HFpEF mouse models possessing the hallmarks of the clinical-like phenotype are available. Nonetheless, initial and gradual pathological manifestations of hypertensive HFpEF have not been comprehensively described. Purpose This study aimed to investigate the gradual progression of HFpEF phenotype development in mice from the early manifestation of cardiac and vascular pathology to global cardiac dysfunction to multiorgan syndrome in response to hypertension. Methods Hypertensive HFpEF was induced by angiotensin II infusion in C57BL/6JOlaHsd 18-20-week-old male mice that were given low, moderate and high doses (0.5mg/kg/day - 1.5 mg/kg/day) subcutaneously for 4 weeks. Cardiac physiology and alterations in haemodynamics were assessed with echocardiography of heart and aorta, weekly ECG monitoring, and blood pressure measurements from the mouse tail. Extensive histology and immunohistochemistry analyses of cardiac tissue, microvasculature, lungs and kidneys were performed. Results In the low dose group, loss of aortic wall flexibility and presence of aortic root dilatation were detected. This group also demonstrated initiation of concentric remodelling process with the upsurge in macrophage infiltration in myocardium, but the signs of diastolic dysfunction were not yet present. The high dose group exhibited characteristic HFpEF features with diastolic dysfunction, left ventricular hypertrophy and fibrosis. Pathology in cardiac conduction system was noticed in all groups, with prominent ECG waveform abnormalities already on week one. However, only the high dose group experienced non-recovery in impulse propagation, accompanied by significant prolongation of ventricular depolarization. Conclusion This study demonstrates that change in aortic root dimensions and aortic wall dynamics are the first hypertension-sensitive alterations together with myocardial inflammatory cell infiltration that may contribute to myocardial remodelling and subsequent development of HFpEF and systemic effects. Hypertensive angiotensin II-induced HFpEF is a relevant mouse model, recapitulating not only hallmarks of cardiac pathology but also an extensive range of vascular and multiorgan alterations, demonstrating similarities with the clinical phenotype.

Can variants of genes associated with familial heart block predict conduction disease in the general population? A UK Biobank study.

Abstract Background Progressive familial heart block is a genetic disease that can present with worsening cardiac conduction disease (CCD) and risk of life-threatening bradycardia. The prevalence, penetrance, and expressivity of known rare pathogenic/likely pathogenic variants (P/LP) in the general population is unclear. In addition, the role of common genetic variation in this phenotypic expression is unknown. Understanding this is essential for patient management in clinic. Purpose 1). To investigate the prevalence of variants linked with early-onset CCD and phenotypic expression in a large biobank. 2). To investigate whether a PR interval polygenic risk score (PRS) improves risk prediction. Methods Early-onset conduction disease P/LP or variants of uncertain significance (VUS) were identified from ClinVar, genetic testing reports at a teaching hospital (6 variants), and the literature, mapping to 22 genes. From the full UK Biobank prospective cohort, 469,511 participants passed genetic quality control and were assigned to P/LP, VUS, or genotype negative (G-) groups, using whole exome sequencing analysed with bcftools. A PR-PRS was constructed using weights from a published meta-analysis excluding UKB data. The primary outcome was CCD (atrioventricular (AV) block, bundle branch block, pacemaker or ICD implantation) and secondary outcomes were high-grade AV block or pacemaker insertion, compared with lifetime risk Cox proportional hazards controlled for sex and age as a timescale. Results 55% of participants were female, 95% had European ancestry, and average age at censor was 71 years. There were 25 P/LP carriers, and 8,862 with a VUS, in 6 genes (MYH7, SCN5A, TNNI3K, TRPM4, TTN, and LMNA). Major demographic factors were the same between groups. CCD was significantly more prevalent in P/LP individuals (28% vs 5.8% in VUS vs 5.5% in G-; p&amp;lt;0.001) with a hazard ratio of HR 6.47 [95% CI=3.09-13.6] vs G-. This was driven by AV block and pacemaker implantation (HR 23.2 [95% CI=8.69-61.8] and 13.4 [95% CI=6.01-29.8], respectively). Results were similar in an unrelated subset and controlling for ischaemic heart disease and heart failure. The 7 P/LP individuals with conduction disease were mostly linked to a single LMNA variant (4 out of 6 carriers with penetrant disease). In the full cohort, the PR-PRS was predictive of CCD (HR=1.07 [95% CI=1.06-1.08]), AV block (HR=1.09 [95% CI=1.06-1.13]), and pacemaker implantation (HR=1.04 [95% CI=1.02-1.06]). When combined with P/LP status, both PR-PRS (HR=1.07 [95% CI=1.06-1.08]) and P/LP (HR=6.42 [95% CI=3.06-13.5]) were independent predictors of CCD. Conclusion(s) Rare variant carrier status predicts a 6.5-fold increased lifetime risk of CCD, a 23-fold increased risk of AV block and 13-fold risk for pacemaker requirement. However, phenotypic expression for some variants is highly variable. A PR-PRS captures risk independent of P/LP variants and warrants further investigation with updated PRS construction methods.