American Journal of Physiology-Heart and Circulatory Physiology

Background: Selenium is a vital trace element involved in antioxidant defence and cardiovascular health. Although selenium deficiency is implicated in cardiomyopathies, its early cardiac effects and underlying mechanisms remain poorly defined. Methods: C57BL6/Njr mice were fed either a selenium deficient or control diet for 12 weeks. Systemic selenium status, cardiac function by echocardiography, left ventricular (LV) transcriptomic profiles, redox balance, and circadian pathway markers were assessed, including sex-specific analyses. Results: Selenium deficiency reduced plasma selenium levels without inducing overt cardiac hypertrophy or fibrosis. Echocardiography showed preserved ejection fraction and fractional shortening but reduced global longitudinal strain, indicating early systolic dysfunction. Cardiac stress markers were increased predominantly in male mice. Left ventricular RNA sequencing revealed enrichment of pathways related to cardiac remodelling, redox regulation, mitochondrial function, and circadian rhythm. Additional protein and metabolic analyses supported sex-specific redox circadian alterations, with males showing a more pronounced stress response profile. Conclusions: Dietary selenium deficiency induces early myocardial dysfunction and molecular remodelling before overt cardiac failure. These changes are associated with redox and circadian pathway disruption and show sex specific features, suggesting that selenium contributes to cardiac homeostasis through sex dependent redox circadian regulation.

Background Takotsubo cardiomyopathy (TTC) is a stress-induced cardiomyopathy characterized by acute cardiac dysfunction, inflammation, and hypertrophy, yet no therapy directly targets the underlying myocardial injury. Clinical studies have reported elevated circulating Angiotensin II (Ang II) levels in TTC patients, suggesting dysregulation of the renin-angiotensin system (RAS). Given the established cardioprotective effects of Angiotensin-(1-7) [Ang-(1-7)] in other cardiovascular diseases, we hypothesized that oral administration of Ang-(1-7) could attenuate acute cardiac remodeling during TTC. Methods Female C57BL/6J mice were subjected to a single high-dose isoproterenol (ISO) injection (300 mg/Kg, intraperitoneal) to induce TTC and received daily oral treatment with Ang-(1-7) complexed with hydroxypropyl {beta}-cyclodextrin [Ang-(1-7)-CD] or vehicle (CD), for 4 days, beginning one day before ISO administration. Cardiac proteome alterations were characterized by tandem mass tag (TMT)-based quantitative proteomics. Cardiac hypertrophy was assessed by heart weight normalized to tibial length and cardiomyocyte cross-sectional area. Myocardial inflammation was evaluated by histopathology, CD68 immunostaining, and flow cytometric analysis of infiltrating leukocyte populations. Results We observed a distinct cardiac proteome signature in Ang-(1-7)-treated ISO mice, predicting inhibition of pathways associated with cardiac hypertrophy and adverse remodeling. These molecular changes were accompanied by reduced heart weight normalized to tibial length and smaller cardiomyocyte cross-sectional area compared with vehicle-treated ISO mice. Oral Ang-(1-7) also attenuated myocardial inflammation, as evidenced by lower inflammatory scores, reduced CD68+ macrophage infiltration, decreased numbers of CD45+ leukocytes, and marked suppression of Ly6G+ neutrophil and CCR2+ monocyte recruitment to the heart. These protective effects were associated with improved survival following ISO challenge. MS data are available via ProteomeXchange (PXD082872). Conclusions Oral administration of Ang-(1-7) attenuated acute cardiac hypertrophy and inflammation in experimental TTC while inducing cardiac proteome changes consistent with reduced adverse remodeling. These findings identify activation of the protective RAS axis as a promising therapeutic strategy for limiting myocardial injury during TTC.

Background: Loss- and gain-of-function variants in SCN5A, encoding the cardiac sodium channel Nav1.5, are major causes of inherited cardiac channelopathies. Their pathophysiology has almost exclusively been attributed to altered cardiomyocyte excitability and cardiac conduction. However, growing evidence indicates that autonomic dysfunction contributes to these disorders, raising the possibility that Nav1.5 dysfunction may also affect the intrinsic cardiac nervous system. Objectives: We investigated whether Nav1.5 is functionally expressed in murine intrinsic cardiac neurons and evaluated its contribution to neuronal excitability. Methods: Scn5a expression was investigated by digital PCR and immunocytochemistry in isolated murine intracardiac neurons. Whole-cell patch-clamp recordings were used to characterize sodium currents and action potential properties in wild-type and Scn5a+/- mice. Results: Scn5a transcripts and Nav1.5 protein were detected in intrinsic cardiac neurons. Voltage-clamp recordings identified a tetrodotoxin-resistant sodium current accounting for approximately 8% of the total sodium current and displaying pharmacological and biophysical properties consistent with Nav1.5. Activation and inactivation analyses indicated that Nav1.5 is the predominant sodium conductance available at most polarized membrane potentials. Accordingly, Scn5a haploinsufficiency selectively altered action potential threshold, maximal upstroke velocity, overshoot and duration in neurons resting below -60 mV, whereas more depolarized neurons were essentially unaffected. No structural or neurochemical remodeling of intrinsic cardiac ganglia was detected. Conclusion: Nav1.5 is a functional determinant of intrinsic cardiac neuronal excitability. These findings identify the intrinsic cardiac nervous system as a new cellular target of SCN5A dysfunction and suggest that inherited cardiac sodium channelopathies could involve alterations in both myocardial and intrinsic neuronal electrophysiology.

Background: Human induced pluripotent stem cell-derived cardiomyocytes are valuable for cardiac disease modelling and drug testing but remain limited by immature structural and electrophysiological properties in conventional two-dimensional cultures. Three-dimensional cardiac models, including cardioids, provide a more physiological environment through multicellular organization and enable tissue-level functional analysis. Their electrophysiological properties and maturation, however, remain incompletely characterized. Methods: We performed an integrated electrophysiological characterization of human cardioids over the first three weeks of maturation using sharp microelectrode recordings, calcium transient measurements, whole-cell patch clamp recordings, immunofluorescence, transcriptomic analysis, and pharmacological interventions. Results: During maturation, cardioids exhibited progressive electrophysiological maturation, characterized by more physiological resting membrane potentials (-54.0{+/-}3.1mV to -68.1{+/-}1.2mV), increased action potential amplitude (73.5{+/-}4.8mV to 101.7{+/-}2.1mV) and upstroke velocity (44.3{+/-}5mV/ms to 86.6{+/-}8.4mV/ms), and shorter action potential duration (178.9{+/-}8.7ms to 144.0{+/-}4.8ms at 1Hz stimulation). These changes were associated with progressively increased INa density and enhanced SCN5A mRNA and Nav1.5 protein expression, consistent with progressive maturation of cardiac excitability. IKr current and KCNH2/hERG expression were already present at early maturation stages and remained stable, as evidenced by preserved sensitivity to dofetilide-blockade. Pharmacological inhibition of barium- and HMR-sensitive currents altered resting membrane and/or action potential characteristics in intact cardioids, whereas in isolated cardiomyocytes classical IK1 remained undetectable and IKs was small, highlighting a certain degree of persisting immaturity of the model. Conclusions: These findings demonstrate that human cardioids undergo progressive electrophysiological maturation and provide complementary tissue- and cellular-level insights into cardiac function, establishing their suitability for investigating INa and IKr-related cardiac pathologies.

Background: Milrinone, a phosphodiesterase-3 (PDE-3) inhibitor, is widely used to improve cardiac output in pediatric and adult patients. Yet, developmental differences in myocardial responsiveness to milrinone remain incompletely understood. In this study, we examined the impact of postnatal maturation on the acute cardiac effects of milrinone using an intact guinea pig heart model. Methods: Neonatal (0-2 days), juvenile (4-10 days), and adult (> 6 months) guinea pig hearts were excised, Langendorff-perfused, and cardiac metrics were evaluated under basal conditions and in response to acute milrinone treatment (15 minutes, 10 and 100 M sequential concentrations). Pseudo-electrocardiograms were recorded continuously and left ventricular pressure measurements were performed under sinus rhythm and in response to external pacing. Post-rest potentiation was used to assess contractile reserve, and optical action potentials and calcium transients were recorded. Results: Baseline left ventricular developed pressure (LVDP), action potential duration (APD), and calcium transient duration (CaD) increased with postnatal maturation, consistent with developmental cardiomyocyte remodeling and refinement of excitation-contraction coupling. Milrinone increased heart rate in all age groups, with the greatest chronotropic response at 100 M. Milrinone also increased ventricular contractility and relaxation across developmental stages, but the magnitude of the response varied with age and was attenuated during high frequency pacing. Adult hearts had the greatest increase in LVDP during sinus rhythm and robust post-rest potentiation, which were less pronounced in neonatal hearts. APD and CaD were shortened in neonatal and adult hearts, but were minimally affected in juveniles, indicating a non-linear developmental pattern. Conclusions: Milrinone exerts positive chronotropic, inotropic, and lusitropic effects throughout development, but the magnitude and frequency dependence of these responses vary with age. These findings suggest that postnatal maturation influences the cardiac response to PDE3 inhibition. These developmental differences highlight the importance of considering age as a biological factor in pediatric drug selection and dosing.

Introduction: Cardiovascular disease is the leading cause of death worldwide (Dagenais et al. 2020), and its main risk factor is LDL-C (Hagenbeek et al. 2020). Only a few genes are associated with LDL-C concentrations, and only 2 genes, ANGPTL3 (Musunuru et al. 2010) and LIPC, are associated with familial combined hypocholesterolemia. Our team recently identified the second genetic cause associated with familial combined hypocholesterolemia, a gain-of-function mutant of the LIPC gene encoding hepatic lipase (HL), LIPC-E97G (Dijk et al. 2022). Although the mode of action of this variant remains largely unknown, we have demonstrated that it significantly increases the phospholipase activity of HL and affects lipoprotein metabolism by promoting plasma cholesterol clearance, particularly of LDL and HDL. Objective: The aim of this study was to explore the additive effect of our HL-E97G variant with a pharmacological inhibitor of the ANGPTL3 protein, evinacumab, on cholesterolemia and atherosclerosis. Materiel and methods: Atherosclerosis measurements were performed on Ldlr-/- mice fed a pro-atherogenic diet. These mice received a single injection of a liver-targeting AAV8 expressing the wild-type or E97G human form of the LIPC gene (1.10E11 genome copies/mouse) and a weekly injection of NaCl or evinacumab (25 mg/kg/week). Results: From a therapeutic approach, we demonstrated a cumulative effect of HL-E97G with evinacumab. Atherosclerotic lesions in the aortic arch of Ldlr-/- mice were reduced by 36% (p=0.4897) with evinacumab, by 65% (p-value=0.0028) with HL-E97G, and by 80% (p-value < 0.0001) with the combined therapy. Conclusion: Our data demonstrate that HL-E97G reduces the development of atherosclerosis in mice in an LDLR- and ANGPTL3-independent manner, strongly reinforcing the therapeutic potential of HL-E97G for patients at high risk of cardiovascular disease.

Mitochondrial reactive oxygen species (ROS) are implicated in cardiac dysfunction, but complex dynamic interactions between ROS, intracellular calcium, and electrophysiology make it difficult to resolve mechanisms experimentally. We developed the Zukowski excitation-contraction-mitochondrial-ROS (ECM-ROS) model, a computational model that couples human ventricular electrophysiology with mitochondrial calcium handling, energetics, ROS production, and ROS dependent modulation of the ryanodine receptor, SERCA, L-type calcium current, and late sodium current. Model predictions were evaluated against independent experimental measurements of ROS induced changes in action potential duration and intracellular calcium. We then used the model to characterize ROS calcium feedback across physiological pacing rates and applied it to doxorubicin induced oxidative stress. Increasing cytosolic calcium produced nonlinear amplification of mitochondrial activity and cytosolic ROS, with greater amplification at faster pacing rates. Moderate ROS elevation initially enhanced calcium release, whereas greater oxidative stress depleted sarcoplasmic reticulum calcium stores. During simulated doxorubicin exposure, faster pacing lowered the level of oxidative stress required to produce calcium dysregulation and action potential prolongation. Mitochondrial ROS and calcium accumulation preceded detectable electrophysiological remodeling. In populations incorporating variability in ion channel expression, neither doxorubicin induced oxidative stress nor subtle pharmacological IKr block alone produced early afterdepolarizations. However, early afterdepolarizations were predicted to emerge with combined perturbations. These findings establish a computational framework for investigating bidirectional coupling among mitochondrial function, ROS, calcium handling, and human cardiac electrophysiology. The model generates testable predictions regarding the early detection of oxidative cardiac injury and the physiological conditions that increase susceptibility to arrhythmia.

Background: Activation of the renin-angiotensin system (RAS) contributes to aortic diseases caused by fibrillin-1 haploinsufficiency (Fbn1C1041G/+). However, whether RAS activation influences mitral valve disease associated with FBN1 variants remains undefined. This study determined whether inhibition or augmentation of the RAS affects mitral valve pathology in Fbn1C1041G/+ mice. Methods: Angiotensinogen (AGT) antisense oligonucleotides (ASOs) were administered for 12 weeks to inhibit the RAS in male and female Fbn1C1041G/+ mice. To augment the RAS, mice were infused with angiotensin II (AngII; 1,000 ng/kg/min) for 28 days. Mitral valve and heart function were monitored by ultrasound. At termination, hearts were dissected free and tissue sectioned to assess mitral valve leaflet thickness and pathology. Results: Mitral valve leaflet thickness was significantly increased in Fbn1C1041G/+ mice compared to Fbn1+/+ littermates of both sexes. ASO-mediated AGT inhibition did not alter this phenotype despite markedly reduced plasma AGT concentrations. AngII infusion increased mitral valve leaflet thickness in Fbn1C1041G/+ mice with increased proteoglycan and collagen content, while exerting minimal effects in Fbn1+/+ mice. Twenty-five percent of AngII-infused Fbn1C1041G/+ mice died of non-vascular causes. Ultrasound showed mitral valve dysfunction in AngII-infused Fbn1C1041G/+ mice. Grossly expanded left atria were common in AngII-infused Fbn1C1041G/+ mice. These markedly enlarged left atria contained increased fibrosis, macrophage accumulation, and platelet-rich masses. Conclusions: Mitral valves of Fbn1C1041G/+ mice did not respond to AGT inhibition but were markedly more susceptible to AngII infusion, with greater increases in thickness and compositional changes than mitral valves of Fbn1+/+ mice. In addition, AngII promoted mitral valve dysfunction that were associated with pronounced left atrial pathology.

Instability of the cardiac electrical system is a major cause of life-threatening arrhythmias. Current safety guidelines have traditionally emphasized QT interval prolongation on the electrocardiogram (ECG) as a primary biomarker of proarrhythmic risk. However, this approach does not capture all forms of electrical instability. In this study, we demonstrate that beat-to-beat variability in action potential duration (APD), a cellular surrogate of the QT interval, better stratifies proarrhythmic risk than mean APD prolongation alone. Using a validated computational model of a human ventricular myocyte, we simulated the effects of the {beta}-adrenergic agonist isoproterenol (ISO). Increasing the ISO concentration shortened mean APD but paradoxically increased beat-to-beat APD variability, measured as the standard deviation of APDs. In our simulations, the emergence of early afterdepolarizations (EADs), abnormal oscillations of the membrane potential during the plateau phase of the action potential, at higher ISO concentrations was consistently preceded by a marked rise in APD variability, even while mean APD was reduced. Mechanistic analysis revealed that ISO-induced enhancement of L-type Ca2+ current (ICaL) and slow delayed rectifier K+ current (IKs) steepens the APD restitution slope, which reflects action potential instability, even when the net effect is a reduction in APD. These results support APD variability as a more sensitive and mechanistically plausible marker of proarrhythmic risk than APD prolongation alone. Our findings suggest that QT interval variability may improve risk stratification and provide a more robust mechanistic foundation for drug safety evaluation.

Background: Aortic stenosis (AS) is a valvular heart disease which imposes chronic pressure overload on the left ventricle (LV). Although LV remodelling may regress following aortic valve replacement, the molecular determinants of reverse remodelling remain poorly understood. This study develops a machine learning-based model using myocardial microRNA (miRNA) expression profiles to predict LV mass normalization one year after valve replacement. Methods: Consensus selection combining Random Forest and Bayesian Network analyses was applied to miRNA sequencing data from LV biopsies of 12 matched patient pairs with AS. Selected miRNAs were qPCR quantified in an extended cohort of 89 AS patients and incorporated into predictive models. Sex-stratified analyses were performed. Model robustness was assessed using bootstrap resampling and cross-validation. Candidate miRNAs and target genes were evaluated in LV from a murine model of pressure overload induced by transverse aortic constriction (TAC). Results: The combined Random Forest-Bayesian Network approach identified a three-miRNA signature (miR-517a-3p, miR-122b-5p, and miR-4683) associated with LV mass normalization after valve replacement. Validation in an extensive cohort demonstrated good overall discrimination and achieved its highest performance in women (AUC >0.80). Functional analyses identified drebrin (DBN1) as a putative target of miR-517a-3p and supported its potential involvement in pressure overload-induced cardiac remodelling. Conclusion: Random Forest and Bayesian Network integrated analyses enabled the identification of a myocardial miRNA signature with sex-dependent predictive value for reverse cardiac remodelling after aortic valve replacement. Functional validation supports the relevance of selected miRNAs and their downstream targets, highlighting their potential as biomarkers and candidate regulators of myocardial recovery.

Introduction: In hypertrophic cardiomyopathy (HCM), wall stress and subclinical myocardial injury related in part to pathological hypercontractility, which in turn are associated with worse outcomes. Cell-free DNA (cfDNA) is released from cardiomyocytes (cfDNA-CM) through irreversible cellular injury and death. We investigated the feasibility of quantifying cfDNA-CM and its relationship to HCM patient characteristics. Methods: We analyzed 57 plasma samples from stable patients with HCM and 10 plasma samples from patients with acute myocardial infarction (AMI). Plasma cfDNA was isolated from both groups. Whole genome bisulfite sequencing (WGBS) libraries were generated and sequenced with short-read sequencing. Methylation patterns were used for tissue deconvolution analysis and cell-specific cfDNA quantification. Results: Yields of cfDNA (p = 0.003) and cfDNA-CM (p = 0.002) fractions were higher in AMI controls than HCM, supporting the validity of the assay. Within the HCM cohort, the median cfDNA yield was 12.22 ng [IQR: 7.77, 18.94]. The cfDNA-CM fraction in this cohort ranged from 0% to 6.4% of total cfDNA. Higher cfDNA-CM tertiles were associated with higher body mass index (BMI, p=0.001), a greater prevalence of BMI 30 kg/m2 (p<0.001), and a higher prevalence of obstructive sleep apnea (p=0.038). No significant differences were observed in other demographic, genetic, and laboratory characteristics. Higher cfDNA-CM tertile was numerically associated with higher New York Heart Association (NYHA) functional class and left ventricular outflow tract (LVOT) obstruction, while circulating biomarkers of wall stress (NT-proBNP) and myocardial injury (troponin) did not differ across tertiles (p=0.83 and p=0.29, respectively). Conclusion: Isolation and quantification of cfDNA as well as detection of cfDNA-CM in chronic stable patients with HCM are feasible. Higher cfDNA-CM fraction was associated with increasing BMI and cardiometabolic comorbidity burden. The absence of association with traditional circulating biomarkers suggests that cfDNA-CM may reflect a distinct domain of myocardial health, injury, and adverse remodeling.

Background: Transthoracic echocardiography (TTE) remains the gold standard for assessing left ventricular (LV) diastolic dysfunction (DD), but noninvasive alternatives are needed to overcome geometric and acoustic limitations. 4D-Flow MRI enables comprehensive assessment of intraventricular pressure differences (IVPDs) and flow propagation velocity (VP). We aimed to evaluate 4D-Flow-derived IVPDs and VP in patients with hypertrophic cardiomyopathy (HCM). Methods: Thirty-eight HCM patients and 38 age- and sex-matched healthy controls underwent TTE and 4D-Flow MRI. Spatiotemporal maps of velocity and IVPDs, decomposed into inertial and convective components, were derived along the main inflow streamline from the mitral valve to the apex. Peak early filling rate (PEFR) was used to normalize IVPDs and VP. Results: While absolute peak flow rates were comparable, HCM patients exhibited significantly faster VP (100.4 vs. 60.2 cm/s, p < 0.01) and higher positive early E IVPD (1.40 vs. 0.92 mmHg, p < 0.01) compared to controls. Normalizing IVPDs by PEFR amplified group differences, revealing a markedly increased flow-normalized E-IVPD (5.13 vs. 2.94 x 103 mmHg.ml1.s, p < 0.001) and deeper reverse ER IVPD (-6.06 vs. -4.61 x 103 mmHg.ml1.s, p < 0.01) in HCM. These differences were primarily driven by the inertial components. Multivariable analysis demonstrated that ER IVPD is independently determined by PEFR and the TTE E/E' ratio (r = 0.65, p < 0.001). Conclusions: 4D-Flow MRI-derived, flow-normalized IVPDs and propagation velocity provide robust, noninvasive markers of altered LV chamber stiffness and impaired diastolic filling in HCM, offering deeper 3D hemodynamic insights into diastolic dysfunction.

Background: Mitral valve prolapse (MVP) causes mitral regurgitation (MR), leading to volume overload and maladaptive left ventricular (LV) remodelling. Objective: To comprehensively characterize markers of maladaptive LV remodelling across MR severity grades in MVP using cardiovascular magnetic resonance (CMR), and their association with functional status. Methods: Patients with MVP undergoing 1.5T CMR (2016-2025) were stratified by MR fraction: mild<20%, moderate 20-39%, and severe [&ge;]40%. Exclusion criteria were significant coronary artery disease, rheumatic valve disease, mitral stenosis, previous mitral valve procedures, endocarditis or signs of primary cardiomyopathy. Global native T1, T2, extracellular volume (ECV), indexed ECV (iECV), indexed intracellular volume (iICV), and late gadolinium enhancement (LGE) were quantified. Indexed LV end-diastolic volume (EDVI) and the EDV-to-LV mass ratio (EDV/LVM-ratio) were also calculated as indices of LV remodelling and adaptive hypertrophy. Functional status was assessed by NYHA class. Results: Among 112 MVP patients (23 mild, 48 moderate, 41 severe MR) and 20 controls, LGE prevalence (17% vs. 46% vs. 51% vs. 0%) and the proportion with LV dilatation (46% vs. 67% vs. 88% vs 15%) rose progressively with MR severity. Increased EDVI, prevalence of LGE, higher EDV/LVM-ratio, global native T1 and iECV showed the strongest associations with more severe MR, whereas EDV/LVM-ratio, iECV and global native T1 were independently related to NYHA class[&ge;]II. Conclusions: CMR markers of maladaptive LV remodelling were abnormal across all MR grades and increased markedly with MR severity. Global native T1, iECV and EDV/LVM-ratio correlated most strongly with symptom burden, rather than MR severity per se.

Background: Mitral regurgitation (MR) is a common complication of mitral valve prolapse (MVP) and increases left ventricular (LV) preload, promotes LV remodeling and hypertrophy, but its impact on myocardial perfusion and coronary microvascular dysfunction remains unclear. Objectives: To assess myocardial perfusion using, for the first time, quantitative cardiac magnetic resonance (CMR) perfusion mapping in patients with significant MR due to MVP. Methods: Patients with significant primary MR, without coronary artery disease were prospectively enrolled and compared to age- and sex-matched controls without MR. All underwent 1.5T CMR including cine imaging, adenosine stress perfusion, native T1, native T2, extracellular volume (ECV) mapping and late gadolinium enhancement (LGE). Myocardial perfusion reserve (MPR) was calculated as the ratio of stress to rest myocardial perfusion. Results: In total 33 patients and 33 controls were included (age 56{+/-}13 vs. 58{+/-}12 years, 46% women in both groups). Patients with MR had increased LV mass and volumes, higher native T1 and ECV and a higher prevalence of LGE (36% vs 0%). No differences were observed in global myocardial perfusion at rest (0.88{+/-}0.27 vs. 0.85{+/-}0.30, p=0.52), at stress (2.6{+/-}0.56 vs. 2.8{+/-}0.73 ml/min/g, p=0.29) or for MPR (3.1{+/-}0.75 vs. 3.4{+/-}1.0, p=0.24). In age- and sex-adjusted linear regression, higher NYHA class was associated with lower MPR (0.60, p=0.04). Conclusion: In patients with significant MR due to MVP, myocardial perfusion appears preserved despite LV volume overload. However, lower MPR in symptomatic patients suggests that microvascular dysfunction may emerge in a more advanced disease stage.

Background This study presents reference ranges for cardiovascular magnetic resonance (CMR)-derived myocardial strain from the Healthy Hearts Consortium, while evaluating variations by demographic characteristics (age, sex, and ethnicity) and technical factors (scanner vendor, magnetic field strength). We derived reference ranges and centile-based categories for ventricular, atrial, and rapid strain parameters. The prognostic relevance of these categories was assessed by examining their associations with incident cardiovascular events. Methods The dataset included 9,088 CMR studies. Automated image analysis pipelines were established using suiteHEART (NeoSoft Inc.) and cvi42 (Circle Cardiovascular Imaging). A three-step quality control framework was applied including exclusion of incomplete data, visual assessment of image and segmentation quality, and statistical outlier removal. Ventricular strain and strain rate were measured using both software solutions. Additional cvi42 derived metrics included velocity and displacement, annular plane systolic excursion metrics, and rapid strain parameters. Age- and sex-specific reference ranges were generated using lambda-mu-sigma (LMS) modeling with penalized splines. Reference ranges were defined as values between the 2.5th and 97.5th percentiles. For lower-tail classification, values below the 2.5th percentile were considered mildly out-of-range and values below the 0.5th percentile at least moderately out-of-range. Differences across scanner vendors (Siemens, Philips, GE) and magnetic field strengths (1.5 T vs. 3 T) were evaluated using adjusted linear models. The prognostic relevance of selected cvi42-derived categories was evaluated in approximately 45,000 UK Biobank participants using Cox regression adjusted for age, sex, and body mass index. Results After quality control, 8,975 CMR examinations (cvi42) and 8,992 (suiteHEART) were available for analysis; these represent software-specific analytic cohorts. Most exclusions occurred during visual quality control. Women had higher absolute ventricular and atrial strain values than men across all age groups. Left ventricular (LV) longitudinal strain and strain rate were slightly lower in older ages, whereas circumferential and radial parameters remained largely stable. Left atrial strain was also lower in older age groups, while right atrial strain did not vary by age. Annular plane systolic excursion and rapid strain metrics showed similar sex-specific patterns, with modestly lower atrial and displacement values in older groups. Ethnicity-related differences were modest, heterogeneous, and substantially smaller in magnitude than age- and sex-related differences. Technical effects were parameter specific. While LV longitudinal and circumferential strains were largely unaffected, radial strain was higher at 3 T and showed vendor-related differences. LMS-derived reference ranges and centile thresholds were applied both across all ethnicities and within ethnicity-specific analyses, and are presented stratified by age and sex. In the prognostic analysis, centile categories were most consistently associated with incident heart failure. LV longitudinal, circumferential, and radial strain below the 0.5th centile were associated with significantly increased risk of incident heart failure (HRs: 9.9 to 12.4, 95% CIs 7.00-13.90 to 8.49-18.06). Conclusion This study provides age- and sex-specific reference ranges and centile-based categories for CMR-derived strain parameters in a large reference population. Age and sex represent the primary determinants of myocardial deformation, whereas scanner-related effects are parameter-specific. Values in the lower extremes of the healthy reference distribution, particularly for LV strain, are associated with increased risk of incident heart failure. These findings enable standardized, centile-based classification of myocardial strain, facilitating consistent interpretation and improving risk stratification in research and clinical practice.

Background: Cardiometabolic disease is a leading cause of death, and most therapies suppress established pathology rather than restore functional capacity. Pulsed electromagnetic field (PEMF) therapy is a non-invasive stimulus touted as a potential complementary approach that may engage adaptive responses, with practical potential for home-based use. We systematically reviewed and meta-analysed PEMF effects on cardiometabolic outcomes. Methods: We searched seven electronic databases and Google Scholar from inception to 31 August 2026 for studies of PEMF in adults, healthy or with cardiometabolic conditions. Between-group differences were rescaled into minimal clinically important difference (MCID) units to facilitate comparison across diverse outcomes. Established anchor-based MCIDs were used where available; otherwise, 0.5 pooled within-arm SD was used. Effects were pooled using multilevel random-effects models with study-clustered robust variance, with subgroup, sensitivity, and exploratory dose-response analyses. The review was registered with PROSPERO (CRD420261404575). Results: Ten studies (353 participants) were included. PEMF was associated with an overall benefit of 0.54 MCID units (95% CI 0.08-1.00). Effects were largest in hypertension (1.24 MCID units, 0.52-1.96), with no observed heterogeneity across two double-blind trials (I2=0%). Exploratory multivariable meta-regression associated greater cumulative exposure and lower frequency with larger effects. Conclusions: PEMF therapy may offer a non-invasive, non-pharmacological adjunct for improving cardiometabolic outcomes, with potential for home-based use. The most compelling signal was observed in hypertension, where the pooled effect exceeded one clinically important difference, although confirmation in larger trials is required.

Arterial stiffness and endothelial dysfunction are non-traditional risk markers after stroke, yet reliability and minimal detectable change (MDC) of pulse wave velocity (PWV) and flow-mediated dilation (FMD) have not been established. We examined test-retest reliability and MDC of carotid-femoral (cfPWV), carotid-radial (crPWV), and femoral-dorsalis pedis PWV (ffPWV), and absolute and relative brachial artery FMD in people >12 months post-stroke. Seventeen individuals (n=4(24%) females; 63.9{+/-}8.6 years; 4.5{+/-}2.8 years post-stroke) completed two bilateral assessments of PWV via applanation tonometry and FMD via duplex ultrasound within one week. Intraclass correlation coefficients (ICC2,1) were calculated via two-way random-effects models, and MDC derived at 68%, 90%, and 95% confidence levels. We found good-to-excellent reliability for cfPWV in paretic (ICC2,1=0.85; 95%CI:0.59,0.95) and non-paretic (ICC2,1=0.94; 95%CI:0.82,0.98) limbs, with MDC95% values of 2.23 and 1.68 m/s, respectively. crPWV and ffPWV exhibited poor reliability bilaterally (ICC2,1=0.12-0.33). Relative FMD showed-moderate reliability for paretic (ICC2,1=0.50; 95%CI:-0.20,0.85) and non-paretic (ICC=0.59; 95%CI:0.04,0.84) limbs, with MDC95% values of 6.88% and 7.65%, respectively. Reliability for absolute FMD was poor (ICC2,1=0.11-0.44). These findings support cfPWV as a reliable vascular assessments in individuals >12 months post-stroke, and provide stroke-specific MDC values to guide interpretability in future trials.

Background: Ascending thoracic aortic aneurysm (ATAA) is characterized by progressive biomechanical remodeling that is incompletely captured by maximum aortic diameter. The relationships between age, sex, aortic valve phenotype (BAV vs TAV), and aneurysmal mechanics remains incompletely understood. Methods: Ascending aortic specimens from 54 patients undergoing elective ATAA repair were evaluated. Biaxial testing quantified Green strain and local stiffness at membrane tensions of 60 and 120 N/m. Opening angle was used to assess circumferential residual stress and stretch. Associations with age were evaluated using Pearson correlations, and differences between sex and valve phenotype were also explored. Multivariable linear regression models including age, sex, and valve phenotype were used to evaluate their adjusted associations with each mechanical outcome. Results: Increasing age was associated with increased local stiffness and reduced Green strain and remained the strongest determinant of biaxial mechanical properties after adjustment. Compared with tricuspid aortic valve specimens, BAV specimens exhibited lower Green strain together with lower local stiffness. Females demonstrated greater Green strain in unadjusted analyses; however, after adjustment, sex remained associated only with longitudinal Green strain at 60 N/m. None of the evaluated clinical characteristics consistently explained opening angle or residual stretch. Conclusions: Age was the predominant clinical determinant of biaxial mechanical remodeling in ATAA, whereas valve phenotype demonstrated selective associations and sex contributed comparatively little after adjustment. Circumferential residual stress appeared largely independent of these clinical characteristics, suggesting that residual stress and biaxial mechanics capture complementary aspects of aneurysmal remodeling.

Background: Cardiovascular (CV) screening is critical for personnel deploying to Antarctica, where geographic isolation and limited medical care make the management of acute cardiovascular events challenging. The utility of contemporary risk prediction tools such as the AHA PREVENT equations in this unique population remains uncertain. Methods: We retrospectively analyzed 154 individuals referred for enhanced CV evaluation before deployment to the U.S. Antarctic Program (USAP). Participants were evaluated across three temporal cohorts (2018-2020, 2021-2023, and 2024-2026). Demographics, CV risk factors, cardiac testing, and deployment clearance outcomes were collected. Risk was estimated using the Framingham Risk Score (FRS), AHA/ACC Pooled Cohort Equations (PCE), and AHA PREVENT risk models. Results: The cohort was predominantly male (79.9%; mean age 44.6 {+/-} 14.6 years), and abnormal ECG was the most common referral trigger (70.8%). Median 10-year risk was low by PREVENT and FRS and borderline elevated by PCE (PREVENT 2.7% [IQR 1.1-6.6], FRS 2.3% [IQR 0.5-7.1], and PCE 6.1% [IQR 2.4-9.2]). Among 72 participants with all scores, 51% were classified discordantly; PREVENT ASCVD agreed closely with FRS (=0.77) but poorly with PCE (=0.24-0.35), which consistently estimated higher risk. PCE was calculable in 52.6% versus 70.8% for PREVENT. Overall, 132 participants (85.7%) were cleared for deployment, while 8 (5.2%) were not physically qualified (NPQ); 6 of these NPQs were due to cardiovascular causes. Of 22 cardiac medical evacuations during the study period, 21 involved individuals without prior advanced cardiovascular screening. One screened individual was evacuated for symptoms subsequently found to have no cardiac cause. Conclusions: Risk calculators disagree substantially in the fitness-selected population. We recommend PREVENT as the primary risk-stratification tool as it is the most contemporary derivation, incorporates renal function, is race-agnostic, extends to heart failure, applies from age 30, and agrees closely with FRS, easing transition. Targeted imaging, including coronary artery calcium scoring, may supplement intermediate-risk candidates.

The biomechanical properties of the human aorta play a key role in cardiovascular function and disease, yet their population-wide trends and variations remain largely unknown. To fill this crucial gap, we quantified variations in aortic size, stiffness and stresses across 57,434 individuals from the UK Biobank using two-dimensional cine MR imaging and a combined deep-learning, probabilistic and biomechanical modelling framework. Aortic diameter and distensibility (inverse of stiffness) were calculated for the ascending and descending aorta, and their conditional distributions were characterised as a function of age, sex, body size and blood pressure. These observations were integrated with ex-vivo tissue mechanics to infer stress distributions across the aortic wall and the associated uncertainty. Our analysis revealed several new relationships. Larger aortas were found to be stiffer, and greater body size (height and/or weight) was associated with larger aortas with no change in stiffness. Aortic distensibility was negatively associated with systolic, but not diastolic, blood pressure. Apparent sex differences in aortic size were substantially reduced after accounting for body size. Importantly, the maximum stress was found to depend not only on aortic size, as previously thought, but also on distensibility, with lower distensibility associated with higher stresses. The results provide first-of-their-kind population-scale reference distributions for human aortic stiffness, which will improve the personalisation of computational models and digital twins. The correlation between stress and distensibility strongly supports progressing beyond the current diameter-based criteria (based on the law of Laplace) and for the inclusion of stiffness in the clinical risk assessment of aortic diseases. Overall, this study forms the foundation for personalised quantitative medicine and biomechanically informed risk stratification of aortic aneurysms and dissections.