Characterization of anthracycline-induced cardiotoxicity by diffusion tensor magnetic resonance imaging.

Anthracyclines are highly potent anti-cancer drugs, but their clinical use is limited by severe cardiotoxic side effects. The impact of anthracycline-induced cardiotoxicity (AIC) on left ventricular (LV) microarchitecture and diffusion properties remains unknown. This study sought to characterize AIC by cardiovascular magnetic resonance diffusion tensor imaging (DTI). Mice were treated with Doxorubicin (DOX; n = 16) for induction of AIC or saline as corresponding control (n = 15). Cardiac function was assessed via echocardiography at the end of the study period. Whole hearts (n = 8 per group) were scanned ex vivo by high-resolution DTI at 7 T. Results were correlated with histopathology and mass spectrometry imaging. Mice with AIC demonstrated systolic dysfunction (LVEF 52 ± 3% vs. 43 ± 6%, P < 0.001), impaired global longitudinal strain (-19.6 ± 2.0% vs. -16.6 ± 3.0%, P < 0.01), and cardiac atrophy (LV mass index [mg/mm], 4.3 ± 0.1 vs. 3.6 ± 0.2, P < 0.01). Regional sheetlet angles were significantly lower in AIC, whereas helix angle and relative helicity remained unchanged. In AIC, fractional anisotropy was increased (0.12 ± 0.01 vs. 0.14 ± 0.02, P < 0.05). DOX-treated mice displayed higher planar and less spherical anisotropy (CPlanar 0.07 ± 0.01 vs. 0.09 ± 0.01, P < 0.01; CSpherical 0.89 ± 0.01 vs. 0.87 ± 0.02, P < 0.05). CPlanar and CSpherical yielded good discriminatory power to distinguish between mice with and without AIC (c-index 0.91 and 0.84, respectively, P for both < 0.05). AIC is associated with regional changes in sheetlet angle but no major abnormalities of global LV microarchitecture. The geometric shape of the diffusion tensor is altered in AIC. DTI may provide a new tool for myocardial characterization in patients with AIC, which warrants future clinical studies to evaluate its diagnostic utility.

Prevalence and prognostic impact of hsCRP elevation are age-dependent in women but not in men undergoing percutaneous coronary intervention.

BACKGROUND: High-sensitivity C-reactive protein (hsCRP) predicts outcomes after percutaneous coronary intervention (PCI). OBJECTIVE: We studied the prevalence and prognostic impact of hsCRP elevation according to age in men and women undergoing PCI. METHODS: We included patients undergoing PCI at our center from 2010 until 2017, excluding those with myocardial infarction (MI) on presentation, neoplastic disease and hsCRP >10 mg/L at baseline. Elevated hsCRP was defined as >3 mg/L. The outcome of interest was major adverse cardiac events (MACE) consisting of all-cause death, MI and target vessel revascularization. The association between hsCRP elevation and outcomes was assessed using adjusted Cox models. RESULTS: 10,432 men and 4,345 women were included. Elevation of hsCRP was present in 25.7% of men and 37.0% of women (p < .01). In men, prevalence of hsCRP elevation was stable across age strata (ptrend  = .42). In women, hsCRP elevation was most prevalent in patients <50 years (44.6%) and decreased stepwise with increasing age (ptrend < .001). After stratifying the population into age quartiles (Q1: <59 years, Q2: 59-66 years, Q3: 67-74 years, Q4: ≥75 years), hsCRP elevation was associated with increased risk of MACE across all age groups in men (HR [95% CI] Q1: 1.49 [1.12-1.98]; Q2: 1.51 [1.21-2.06]; Q3: 1.76 [1.27-2.51]; Q4: 1.43[1.03-1.97]). In women, hsCRP elevation was associated with increased risk of MACE only among older patients (HR [95% CI] Q1: 1.08 [0.64-0.82]; Q2: 1.52 [0.93-2.46]; Q3: 1.65 [1.08-2.50]; Q4: 1.52 [1.02-1.28]). CONCLUSION: Among patients undergoing PCI, prevalence and prognostic value of hsCRP elevation were age-dependent exclusively in women.

Adipose tissue ATGL modifies the cardiac lipidome in pressure-overload-induced left ventricular failure.

Adipose tissue lipolysis occurs during the development of heart failure as a consequence of chronic adrenergic stimulation. However, the impact of enhanced adipose triacylglycerol hydrolysis mediated by adipose triglyceride lipase (ATGL) on cardiac function is unclear. To investigate the role of adipose tissue lipolysis during heart failure, we generated mice with tissue-specific deletion of ATGL (atATGL-KO). atATGL-KO mice were subjected to transverse aortic constriction (TAC) to induce pressure-mediated cardiac failure. The cardiac mouse lipidome and the human plasma lipidome from healthy controls (n = 10) and patients with systolic heart failure (HFrEF, n = 13) were analyzed by MS-based shotgun lipidomics. TAC-induced increases in left ventricular mass (LVM) and diastolic LV inner diameter were significantly attenuated in atATGL-KO mice compared to wild type (wt) -mice. More importantly, atATGL-KO mice were protected against TAC-induced systolic LV failure. Perturbation of lipolysis in the adipose tissue of atATGL-KO mice resulted in the prevention of the major cardiac lipidome changes observed after TAC in wt-mice. Profound changes occurred in the lipid class of phosphatidylethanolamines (PE) in which multiple PE-species were markedly induced in failing wt-hearts, which was attenuated in atATGL-KO hearts. Moreover, selected heart failure-induced PE species in mouse hearts were also induced in plasma samples from patients with chronic heart failure. TAC-induced cardiac PE induction resulted in decreased PC/ PE-species ratios associated with increased apoptotic marker expression in failing wt-hearts, a process absent in atATGL-KO hearts. Perturbation of adipose tissue lipolysis by ATGL-deficiency ameliorated pressure-induced heart failure and the potentially deleterious cardiac lipidome changes that accompany this pathological process, namely the induction of specific PE species. Non-cardiac ATGL-mediated modulation of the cardiac lipidome may play an important role in the pathogenesis of chronic heart failure.

Cardioprotective Effects of Palmitoleic Acid (C16:1n7) in a Mouse Model of Catecholamine-Induced Cardiac Damage Are Mediated by PPAR Activation.

Palmitoleic acid (C16:1n7) has been identified as a regulator of physiological cardiac hypertrophy. In the present study, we aimed to investigate the molecular pathways involved in C16:1n7 responses in primary murine cardiomyocytes (PCM) and a mouse model of isoproterenol (ISO)-induced cardiac damage. PCMs were stimulated with C16:1n7 or a vehicle. Afterwards, RNA sequencing was performed using an Illumina HiSeq sequencer. Confirmatory analysis was performed in PCMs and HL-1 cardiomyocytes. For an in vivo study, 129 sv mice were orally treated with a vehicle or C16:1n7 for 22 days. After 5 days of pre-treatment, the mice were injected with ISO (25 mg/kg/d s. c.) for 4 consecutive days. Cardiac phenotyping was performed using echocardiography. In total, 129 genes were differentially expressed in PCMs stimulated with C16:1n7, including Angiopoietin-like factor 4 (Angptl4) and Pyruvate Dehydrogenase Kinase 4 (Pdk4). Both Angptl4 and Pdk4 are proxisome proliferator-activated receptor α/δ (PPARα/δ) target genes. Our in vivo results indicated cardioprotective and anti-fibrotic effects of C16:1n7 application in mice. This was associated with the C16:1n7-dependent regulation of the cardiac PPAR-specific signaling pathways. In conclusion, our experiments demonstrated that C16:1n7 might have protective effects on cardiac fibrosis and inflammation. Our study may help to develop future lipid-based therapies for catecholamine-induced cardiac damage.

From bedside to bench: lung ultrasound for the assessment of pulmonary edema in animal models.

Traditionally, the lung has been excluded from the ultrasound organ repertoire and, hence, the application of lung ultrasound (LUS) was largely limited to a few enthusiastic clinicians. Yet, in the last decades, the recognition of the previously untapped diagnostic potential of LUS in intensive care medicine has fueled its widespread use as a rapid, non-invasive and radiation-free bedside approach with excellent diagnostic accuracy for many of the most common causes of acute respiratory failure, e.g., cardiogenic pulmonary edema, pneumonia, pleural effusion and pneumothorax. Its increased clinical use has also incited attention for the potential usefulness of LUS in preclinical studies with small animal models mimicking lung congestion and pulmonary edema formation. Application of LUS to small animal models of pulmonary edema may save time, is cost-effective, and may reduce the number of experimental animals due to the possibility of serial evaluations in the same animal as compared with traditional end-point measurements. This review provides an overview of the emerging field of LUS with a specific focus on its application in animal models and highlights future perspectives for LUS in preclinical research.

Accurate assessment of LV function using the first automated 2D-border detection algorithm for small animals - evaluation and application to models of LV dysfunction.

Echocardiography is the most commonly applied technique for non-invasive assessment of cardiac function in small animals. Manual tracing of endocardial borders is time consuming and varies with operator experience. Therefore, we aimed to evaluate a novel automated two-dimensional software algorithm (Auto2DE) for small animals and compare it to the standard use of manual 2D-echocardiographic assessment (2DE). We hypothesized that novel Auto2DE will provide rapid and robust data sets, which are in agreement with manually assessed data of animals.2DE and Auto2DE were carried out using a high-resolution imaging-system for small animals. First, validation cohorts of mouse and rat cine loops were used to compare Auto2DE against 2DE. These data were stratified for image quality by a blinded expert in small animal imaging. Second, we evaluated 2DE and Auto2DE in four mouse models and four rat models with different cardiac pathologies.Automated assessment of LV function by 2DE was faster than conventional 2DE analysis and independent of operator experience levels. The accuracy of Auto2DE-assessed data in healthy mice was dependent on cine loop quality, with excellent agreement between Auto2DE and 2DE in cine loops with adequate quality. Auto2DE allowed for valid detection of impaired cardiac function in animal models with pronounced cardiac phenotypes, but yielded poor performance in diabetic animal models independent of image quality.Auto2DE represents a novel automated analysis tool for rapid assessment of LV function, which is suitable for data acquisition in studies with good and very good echocardiographic image quality, but presents systematic problems in specific pathologies.

Procedural success of transcatheter annuloplasty in ventricular and atrial functional tricuspid regurgitation.

Background: Transcatheter annuloplasty is meant to target annular dilatation and is therefore mainly applied in functional tricuspid regurgitation (TR). Due to recent recognition of varying disease pathophysiology and differentiation of ventricular and atrial functional TR (VFTR and AFTR), comparative data regarding procedural success for both disease entities are required. Methods: In this consecutively enrolled observational cohort study, 65 patients undergoing transcatheter annuloplasty with a Cardioband® device were divided into VFTR (n = 35, 53.8%) and AFTR (n = 30, 46.2%). Procedural success was assessed by comparing changes in annulus dilatation, vena contracta (VC) width, effective regurgitation orifice area (EROA), as well as reduction in TR severity. Results: Overall, improvement of TR by at least two grades was achieved in 59 patients (90.8%), and improvement of TR by at least three grades was realised in 32 patients (49.2%). Residual TR of ≤2 was observed in 52 patients (80.0%). No significant differences in annulus diameter reduction [VFTR: 11 mm (9-13) vs. AFTR: 12 mm (9-16), p = 0.210], VC reduction [12 mm (8-14) vs. 12 mm (7-14), p = 0.868], and EROA reduction [0.62 cm2 (0.45-1.10) vs. 0.54 cm2 (0.40-0.70), p = 0.204] were reported. Improvement by at least two grades [27 (90.0%) vs. 32 (91.4%), p = 1.0] and three grades [14 (46.7%) vs. 18 (51.4%), p = 0.805] was similar in VFTR and AFTR, respectively. No significant difference in the accomplishment of TR grade of ≤2 [21 (70.0%) vs. 31 (88.6%), p = 0.118] was noted. Conclusion: According to our results from a real-world scenario, transcatheter annuloplasty with the Cardioband® device may be applied in both VFTR and AFTR with evidence of significant procedural TR reduction.

Teleproctoring for Training in Structural Heart Interventions: Initial Real-World Experience During the COVID-19 Pandemic.

Background Proctoring represents a cornerstone in the acquisition of state-of-the-art cardiovascular interventions. Yet, travel restrictions and containment measures during the COVID-19 pandemic limited on-site proctoring for training and expert support in interventional cardiology. Methods and Results We established a teleproctoring setup for training in a novel patent foramen ovale closure device system (NobleStitch EL, HeartStitch Inc, Fountain Valley, CA) at our institution using web-based real-time bidirectional audiovisual communication. A total of 6 patients with prior paradoxical embolic stroke and a right-to-left shunt of grade 2 or 3 were treated under remote proctorship after 3 cases were performed successfully under on-site proctorship. No major device/procedure-related adverse events occurred, and none of the patients had a residual right-to-left shunt of grade 1 or higher after the procedure. Additionally, we sought to provide an overview of current evidence available for teleproctoring in interventional cardiology. Literature review was performed identifying 6 previous reports on teleproctoring for cardiovascular interventions, most of which were related to the current COVID-19 pandemic. In all reports, teleproctoring was carried out in similar settings with comparable setups; no major adverse events were reported. Conclusions Teleproctoring may represent a feasible and safe tool for location-independent and cost-effective training in a novel patent foramen ovale closure device system. Future prospective trials comparing teleproctoring with traditional on-site proctoring are warranted.

Assessment of Myocardial Microstructure in a Murine Model of Obesity-Related Cardiac Dysfunction by Diffusion Tensor Magnetic Resonance Imaging at 7T.

Background: Obesity exerts multiple deleterious effects on the heart that may ultimately lead to cardiac failure. This study sought to characterize myocardial microstructure and function in an experimental model of obesity-related cardiac dysfunction. Methods: Male C57BL/6N mice were fed either a high-fat diet (HFD; 60 kcal% fat, n = 12) or standard control diet (9 kcal% fat, n = 10) for 15 weeks. At the end of the study period, cardiac function was assessed by ultra-high frequency echocardiography, and hearts were processed for further analyses. The three-dimensional myocardial microstructure was examined ex vivo at a spatial resolution of 100 × 100 × 100 µm3 by diffusion tensor magnetic resonance imaging (DT-MRI) at 7T. Myocardial deformation, diffusion metrics and fiber tract geometry were analyzed with respect to the different myocardial layers (subendocardium/subepicardium) and segments (base/mid-cavity/apex). Results were correlated with blood sample analyses, histopathology, and gene expression data. Results: HFD feeding induced significantly increased body weight combined with a pronounced accumulation of visceral fat (body weight 42.3 ± 5.7 vs. 31.5 ± 2.2 g, body weight change 73.7 ± 14.8 vs. 31.1 ± 6.6%, both P < 0.001). Obese mice showed signs of diastolic dysfunction, whereas left-ventricular ejection fraction and fractional shortening remained unchanged (E/e' 41.6 ± 16.6 vs. 24.8 ± 6.0, P < 0.01; isovolumic relaxation time 19 ± 4 vs. 14 ± 4 ms, P < 0.05). Additionally, global longitudinal strain was reduced in the HFD group (-15.1 ± 3.0 vs. -20.0 ± 4.6%, P = 0.01), which was mainly driven by an impairment in basal segments. However, histopathology and gene expression analyses revealed no myocardial fibrosis or differences in cardiomyocyte morphology. Mean diffusivity and eigenvalues of the diffusion tensor were lower in the basal subepicardium of obese mice as assessed by DT-MRI (P < 0.05). The three-dimensional fiber tract arrangement of the left ventricle (LV) remained preserved. Conclusion: Fifteen weeks of high-fat diet induced alterations in myocardial diffusion properties in mice, whereas no remodeling of the three-dimensional myofiber arrangement of the LV was observed. Obese mice showed reduced longitudinal strain and lower mean diffusivity predominantly in the left-ventricular base, and further investigation into the significance of this regional pattern is required.

Pharmacological inhibition of adipose tissue adipose triglyceride lipase by Atglistatin prevents catecholamine-induced myocardial damage.

AIMS: Heart failure (HF) is characterized by an overactivation of ß-adrenergic signalling that directly contributes to impairment of myocardial function. Moreover, ß-adrenergic overactivation induces adipose tissue lipolysis, which may further worsen the development of HF. Recently, we demonstrated that adipose tissue-specific deletion of adipose triglyceride lipase (ATGL) prevents pressure-mediated HF in mice. In this study, we investigated the cardioprotective effects of a new pharmacological inhibitor of ATGL, Atglistatin, predominantly targeting ATGL in adipose tissue, on catecholamine-induced cardiac damage. METHODS AND RESULTS: Male 129/Sv mice received repeated injections of isoproterenol (ISO, 25 mg/kg BW) to induce cardiac damage. Five days prior to ISO application, oral Atglistatin (2 mmol/kg diet) or control treatment was started. Two and twelve days after the last ISO injection cardiac function was analysed by echocardiography. The myocardial deformation was evaluated using speckle-tracking-technique. Twelve days after the last ISO injection, echocardiographic analysis revealed a markedly impaired global longitudinal strain, which was significantly improved by the application of Atglistatin. No changes in ejection fraction were observed. Further studies included histological-, WB-, and RT-qPCR-based analysis of cardiac tissue, followed by cell culture experiments and mass spectrometry-based lipidome analysis. ISO application induced subendocardial fibrosis and a profound pro-apoptotic cardiac response, as demonstrated using an apoptosis-specific gene expression-array. Atglistatin treatment led to a dramatic reduction of these pro-fibrotic and pro-apoptotic processes. We then identified a specific set of fatty acids (FAs) liberated from adipocytes under ISO stimulation (palmitic acid, palmitoleic acid, and oleic acid), which induced pro-apoptotic effects in cardiomyocytes. Atglistatin significantly blocked this adipocytic FA secretion. CONCLUSION: This study demonstrates cardioprotective effects of Atglistatin in a mouse model of catecholamine-induced cardiac damage/dysfunction, involving anti-apoptotic and anti-fibrotic actions. Notably, beneficial cardioprotective effects of Atglistatin are likely mediated by non-cardiac actions, supporting the concept that pharmacological targeting of adipose tissue may provide an effective way to treat cardiac dysfunction.

Percutaneous Edge-to-Edge Tricuspid Valve Repair in a Patient with Cor Triatriatum Dexter: A Case Report.

BACKGROUND: Tricuspid regurgitation is gaining importance due to its high morbidity and mortality. Especially in the elderly, novel technologies in percutaneous therapies have become valuable options due to the commonly present high surgical risk. CASE PRESENTATION: We report a case of a 78-year-old female suffering from massive tricuspid regurgitation with repetitive right-sided heart failure hospitalizations. As the patient was very frail and deemed as high surgical risk, we used the TriClip® system to improve her symptomatic status. During diagnostic work-up, an additional membrane separating the right atrium, consistent with the definition of a cor triatriatum dexter, was found. Although increasing the complexity of the procedure, implantation of 3 clips with reduction of tricuspid regurgitation to a mild-to-moderate degree was achieved without any notable complications. The patient was discharged with ameliorated symptoms on the fourth postoperative day. CONCLUSIONS: Our case highlights the feasibility of percutaneous edge-to-edge tricuspid valve repair in an elderly woman with cor triatriatum dexter. Accurate echocardiographic visualization is an absolute requirement to gain access to the tricuspid valve without interacting with prevailing additional membranes.

Liver X Receptor Agonist AZ876 Induces Beneficial Endogenous Cardiac Lipid Reprogramming and Protects Against Isoproterenol-Induced Cardiac Damage.

Background It is known that dietary intake of polyunsaturated fatty acids may improve cardiac function. However, relatively high daily doses are required to achieve sufficient cardiac concentrations of beneficial omega-3 fatty acids. The liver X receptor (LXR) is a nuclear hormone receptor and a crucial regulator of lipid homeostasis in mammals. LXR activation has been shown to endogenously reprogram cellular lipid profiles toward increased polyunsaturated fatty acids levels. Here we studied whether LXR lipid reprogramming occurs in cardiac tissue and exerts cardioprotective actions. Methods and Results Male 129SV mice were treated with the LXR agonist AZ876 (20 µmol/kg per day) for 11 days. From day 6, the mice were injected with the nonselective ß-agonist isoproterenol for 4 consecutive days to induce diastolic dysfunction and subendocardial fibrosis while maintaining systolic function. Treatment with isoproterenol led to a marked impairment of global longitudinal strain and the E/e' ratio of transmitral flow to mitral annular velocity, which were both significantly improved by the LXR agonist. Histological examination showed a significant reduction in isoproterenol-induced subendocardial fibrosis by AZ876. Analysis of the cardiac lipid composition by liquid chromatography-high resolution mass spectrometry revealed a significant increase in cardiac polyunsaturated fatty acids levels and a significant reduction in saturated fatty acids by AZ876. Conclusions The present study provides evidence that the LXR agonist AZ876 prevents subendocardial damage, improves global longitudinal strain and E/e' in a mouse model of isoproterenol-induced cardiac damage, accompanied by an upregulation of cardiac polyunsaturated fatty acids levels. Cardiac LXR activation and beneficial endogenous cardiac lipid reprogramming may provide a new therapeutic strategy in cardiac disease with diastolic dysfunction.

Myocardial Infarction After High-Dose Catecholamine Application-A Case Report From an Experimental Imaging Study.

Although heart failure following myocardial infarction (MI) represents a major health burden, underlying microstructural and functional changes remain incompletely understood. Here, we report on a case of unexpected MI after treatment with the catecholamine isoproterenol in an experimental imaging study in mice using different state-of-the-art imaging modalities. The decline in cardiac function was documented by ultrahigh-frequency echocardiography and speckle-tracking analyses. Myocardial microstructure was studied ex vivo at a spatial resolution of 100 × 100 × 100 µm3 using diffusion tensor magnetic resonance imaging (DT-MRI) and histopathologic analyses. Two weeks after ISO treatment, the animal showed an apical aneurysm accompanied by reduced radial strain in corresponding segments and impaired global systolic function. DT-MRI revealed a loss of contractile fiber tracts together with a disarray of remaining fibers as corresponding microstructural correlates. This preclinical case report provides valuable insights into pathophysiology and morphologic-functional relations of heart failure following MI using emerging imaging technologies.

Prognostic Impact of High-Sensitivity C-Reactive Protein in Patients Undergoing Percutaneous Coronary Intervention According to BMI.

OBJECTIVES: The aim of this study was to determine the prevalence and prognostic implications of elevated high-sensitivity C-reactive protein (hsCRP) in patients undergoing percutaneous coronary intervention (PCI) according to body mass index (BMI). BACKGROUND: Whereas elevated hsCRP predicts adverse clinical outcome after PCI in the general population, the impact of BMI on its prognostic utility remains unclear. METHODS: Data from 14,140 patients who underwent PCI between January 2009 and June 2017 at a large tertiary care center were analyzed. Patients were divided into 4 BMI categories: normal (BMI 18.5 to <25 kg/m2, n = 2,808), overweight (BMI 25 to <30 kg/m2, n = 6,015), obese (BMI 30 to <35 kg/m2, n = 3,490), and severely obese (BMI ≥35 kg/m2, n = 1,827). Elevated hsCRP was defined as >3 mg/l. The primary endpoint of interest was the occurrence of major adverse cardiac events (MACE; defined as death, myocardial infarction, or target vessel revascularization) within 1 year after PCI. RESULTS: Elevated hsCRP was present in 18.9%, 23.6%, 33.3%, and 47.7% of the normal, overweight, obese, and severely obese groups, respectively. MACE rates were consistently higher in patients with elevated hsCRP across all BMI categories (normal, 13.4% vs. 8.3%; overweight, 11.2% vs. 7.2%; obese, 10.6% vs. 7.5%; severely obese, 11.9% vs. 6.5%; p < 0.01 for all). After multivariate adjustment, hsCRP elevation remained significantly associated with MACE independent of BMI (hazard ratios: normal, 1.43 [95% confidence interval: 1.04 to 1.95]; overweight, 1.56 [95% confidence interval: 1.21 to 1.88]; obese, 1.40 [95% confidence interval: 1.06 to 1.84]; severely obese, 1.92 [95% confidence interval: 1.35 to 2.75]; p < 0.05 for all). CONCLUSIONS: Among patients undergoing PCI, the prevalence of hsCRP elevation progressively increased with higher BMI. Measurement of hsCRP facilitates prognostic risk assessment for adverse outcome after PCI across a broad range of BMI.

Characterization of Myocardial Microstructure and Function in an Experimental Model of Isolated Subendocardial Damage.

Subendocardial damage is among the first cardiac manifestations of hypertension and is already present in asymptomatic disease states. Accordingly, markers of subendocardial impairment may facilitate early detection of cardiac damages and risk stratification under these conditions. This study aimed to investigate the impact of subendocardial damage on myocardial microstructure and function to elucidate early pathophysiologic processes and to identify corresponding diagnostic measures. Mice (n=38) were injected with isoproterenol to induce isolated subendocardial scarring or saline as corresponding control. Cardiac function and myocardial deformation were determined by high-frequency echocardiography. The cardiac stress response was assessed in a graded exercise test and during dobutamine stress echocardiography. Myocardial microstructure was studied ex vivo by 7 T diffusion tensor magnetic resonance imaging at a spatial resolution of 100×100×100 µm 3 . Results were correlated with histology and biomarker expression. Subendocardial fibrosis was accompanied by diastolic dysfunction, impaired longitudinal deformation (global peak longitudinal strain [LS]: -12.5±0.5% versus -15.6±0.5%; P<0.001) and elevated biomarker expression (ANP [atrial natriuretic peptide], Galectin-3, and ST2). Systolic function and cardiac stress response remained preserved. Diffusion tensor magnetic resonance imaging revealed a left-shift in helix angle towards lower values in isoproterenol-treated animals, which was mainly determined by subepicardial myofibers (mean helix angle: 2.2±0.8° versus 5.9±1.0°; P<0.01). Longitudinal strain and subepicardial helix angle were highly predictive for subendocardial fibrosis (sensitivity, 82%-92% and specificity, 89%-90%). The results indicate that circumscribed subendocardial damage alone can cause several hallmarks observed in cardiovascular high-risk patients. Microstructural remodeling under these conditions involves also remote regions, and corresponding changes in longitudinal strain and helix angle might serve as diagnostic markers.

Selective Mineralocorticoid Receptor Cofactor Modulation as Molecular Basis for Finerenone's Antifibrotic Activity.

Mineralocorticoid receptor antagonists (MRAs) reduce morbidity and mortality in chronic heart failure. Novel nonsteroidal MRAs are currently developed and need to be pharmacologically characterized in comparison to classical steroidal MRAs. A mouse model of cardiac fibrosis induced by short-term isoproterenol injection was used to compare the nonsteroidal MRA finerenone and the steroidal MRA eplerenone in equi-efficient systemic MR blocking dosages. Molecular mechanisms were studied in MR-expressing H9C2/MR+ cardiomyocytes and in MR transcriptional cofactor binding assays. Both MRAs significantly inhibited an isoproterenol-mediated increase of left ventricular mass. Isoproterenol-induced cardiac fibrosis and macrophage invasion were potently blocked by finerenone, whereas eplerenone had no significant effect. Speckle tracking echocardiography revealed a significant improvement of global longitudinal peak strain by finerenone, an effect less prominent with eplerenone. Antifibrotic actions of finerenone were accompanied by a significant inhibition of profibrotic cardiac TNX (tenascin-X) expression, a regulation absent with eplerenone. Finally, we show a higher potency/efficacy and inverse agonism of finerenone versus eplerenone in MR transcriptional cofactor binding assays indicating differential MR cofactor modulation by steroidal and nonsteroidal MRAs. This study demonstrates that the nonsteroidal MRA finerenone potently prevents cardiac fibrosis and improves strain parameters in mice. Cardiac antifibrotic actions of finerenone may result from the inhibition of profibrotic TNX gene expression mediated by differential MR cofactor binding. Selective MR cofactor modulation provides a molecular basis for distinct (pre)-clinical actions of nonsteroidal and steroidal MRAs.

Application of Speckle-Tracking Echocardiography in an Experimental Model of Isolated Subendocardial Damage.

BACKGROUND: The subendocardium is highly vulnerable to damage and is thus affected even in subclinical disease stages. Therefore, methods reflecting subendocardial status are of great clinical relevance for the early detection of cardiac damage and the prevention of functional impairment. The aim of this study was to investigate the potential ability of myocardial strain parameters to evaluate changes within the subendocardium. METHODS: Male 129/Sv mice were injected with isoproterenol (ISO; n = 32) to induce isolated subendocardial fibrotic lesions or saline as appropriate control (n = 15). Transthoracic echocardiography was performed using a 30-MHz linear-frequency transducer coupled to a high-resolution imaging system, and acquired images were analyzed for conventional and strain parameters. The degree of collagen content within the different cardiac layers was quantified by histologic analysis and serum levels of tissue inhibitor of metalloproteinase-1, a biomarker for fibrosis, were assessed. RESULTS: ISO treatment induced a marked increase in subendocardial collagen content in response to cell loss (control vs ISO, 0.6 ± 0.3% vs 5.8 ± 0.9%; P < .001) and resulted in a moderate increase in left ventricular wall thickness with preserved systolic function. Global longitudinal peak strain (LS) and longitudinal strain rate were significantly decreased in ISO-treated animals (LS, -15.49% vs -11.49% [P = .001]; longitudinal strain rate, -4.81 vs -3.88 sec-1 [P < .05]), whereas radial and circumferential strain values remained unchanged. Global LS was associated with subendocardial collagen content (r = 0.46, P = .01) and tissue inhibitor of metalloproteinase-1 serum level (r = 0.52, P < .05). Further statistical analyses identified global LS as a superior predictor for the presence of subendocardial fibrosis (sensitivity, 84%; specificity, 80%; cutoff value, -14.4%). CONCLUSION: Assessment of LS may provide a noninvasive method for the detection of subendocardial damage and may consequently improve early diagnosis of cardiac diseases.