Oral anticoagulation in patients with left ventricular thrombus - a systematic review and meta-analysis.

AIMS: Direct oral anticoagulants (DOACs) are increasingly used off-label to treat patients with left ventricular thrombus (LVT). We analyzed available meta-data comparing DOACs and vitamin K antagonists (VKAs) for efficacy and safety. METHODS: We conducted a systematic search and meta-analysis of observational and randomized data comparing DOACs versus VKAs in patients with LVT. Endpoints of interest were stroke or systemic embolism, thrombus resolution, all-cause death, and a composite bleeding endpoint. Estimates were pooled using a random-effect model meta-analysis, and their robustness was investigated using sensitivity and influential analyses. RESULTS: We identified 22 articles (18 observational studies, 4 small randomized clinical trials) reporting on a total of 3,587 patients (2,489 VKA vs. 1,098 DOAC therapy). The pooled estimates for stroke or systemic embolism (OR 0.81; 95% CI [0.57, 1.15]) and thrombus resolution (OR 1.12; 95% CI [0.86; 1.46]) were comparable, and there was low heterogeneity overall across the included studies. DOAC use was associated with lower odds of all-cause death (OR 0.65; 95%CI [0.46; 0.92]) and a composite bleeding endpoint (OR 0.67; 95%CI [0.47; 0.97]). A risk of bias was evident particularly for observational reports, with some publication bias suggested in funnel plots. CONCLUSION: In this comprehensive analysis of mainly observational data, the use of DOACs was not associated with a significant difference in stroke or systemic embolism, or thrombus resolution compared to VKA therapy. The use of DOACs was associated with a lower rate of all-cause death and fewer bleeding events. Adequately sized randomized clinical trials are needed to confirm these findings, which could allow a wider adoption of DOACs in patients with LVT.

New pharmacological agents and novel cardiovascular pharmacotherapy strategies in 2023.

Although cardiovascular diseases (CVDs) are the leading cause of death worldwide, their pharmacotherapy remains suboptimal. Thus, there is a clear unmet need to develop more effective and safer pharmacological strategies. In this review, we summarize the most relevant advances in cardiovascular pharmacology in 2023, including the approval of first-in-class drugs that open new avenues for the treatment of atherosclerotic CVD and heart failure (HF). The new indications of drugs already marketed (repurposing) for the treatment of obstructive hypertrophic cardiomyopathy, hypercholesterolaemia, type 2 diabetes, obesity, and HF; the impact of polypharmacy on guideline-directed drug use is highlighted as well as results from negative clinical trials. Finally, we end with a summary of the most important phase 2 and 3 clinical trials assessing the efficacy and safety of cardiovascular drugs under development for the prevention and treatment of CVDs.

Optogenetic confirmation of transverse-tubular membrane excitability in intact cardiac myocytes.

T-tubules (TT) form a complex network of sarcolemmal membrane invaginations, essential for well-co-ordinated excitation-contraction coupling (ECC) and thus homogeneous mechanical activation of cardiomyocytes. ECC is initiated by rapid depolarization of the sarcolemmal membrane. Whether TT membrane depolarization is active (local generation of action potentials; AP) or passive (following depolarization of the outer cell surface sarcolemma; SS) has not been experimentally validated in cardiomyocytes. Based on the assessment of ion flux pathways needed for AP generation, we hypothesize that TT are excitable. We therefore explored TT excitability experimentally, using an all-optical approach to stimulate and record trans-membrane potential changes in TT that were structurally disconnected, and hence electrically insulated, from the SS membrane by transient osmotic shock. Our results establish that cardiomyocyte TT can generate AP. These AP show electrical features that differ substantially from those observed in SS, consistent with differences in the density of ion channels and transporters in the two different membrane domains. We propose that TT-generated AP represent a safety mechanism for TT AP propagation and ECC, which may be particularly relevant in pathophysiological settings where morpho-functional changes reduce the electrical connectivity between SS and TT membranes. KEY POINTS: Cardiomyocytes are characterized by a complex network of membrane invaginations (the T-tubular system) that propagate action potentials to the core of the cell, causing uniform excitation-contraction coupling across the cell. In the present study, we investigated whether the T-tubular system is able to generate action potentials autonomously, rather than following depolarization of the outer cell surface sarcolemma. For this purpose, we developed a fully optical platform to probe and manipulate the electrical dynamics of subcellular membrane domains. Our findings demonstrate that T-tubules are intrinsically excitable, revealing distinct characteristics of self-generated T-tubular action potentials. This active electrical capability would protect cells from voltage drops potentially occurring within the T-tubular network.

Cardiac safety assessment of a novel recombinant bispecific antibody targeting the ether-à-go-go related gene 1 (hERG1)-ß1 integrin macromolecular complex.

Introduction: In the last decades, mounting evidence has pointed out the human ether-á-go-go-related gene (hERG1) potassium channel as a novel biomarker in human cancers. However, hERG1 sustains the cardiac repolarizing current IKr and its blockade can induce a prolonged QT interval at the ECG, which increases the risk of life-threatening arrhythmias. This represents a major hindrance for targeting hERG1 for antineoplastic therapeutic purposes. Based on our discovery that hERG1 resides in a macromolecular complex with the ß1 subunit of integrin adhesion receptors only in tumors, and not in the heart, we generated (and patented WO2019/015936) a novel engineered, single chain, bispecific antibody in the format of a diabody (scDb-hERG1-ß1). This antibody has been proven to target with high affinity the hERG1/ß1 integrin complex and to exert a good antineoplastic activity in preclinical mouse models. Methods: In the present study, we evaluated the cardiac safety of the scDb-hERG1-ß1, determining the action potential duration (APD) of human cardiomyocytes, either atrial (from valve-disease patients) or ventricular (from aortic stenosis patients). Cardiac cells were incubated in vitro with i) the scDb-hERG1-ß1, ii) the full length anti-hERG1 monoclonal antibody (mAb-hERG1) and iii) its single chain Fragment variable derivative (scFv-hERG1), from which the scDb-hERG1-ß1 was assembled. All the tests were performed before and after treatment with the specific hERG1 blocker E4031. In addition, we have performed preliminary experiments, analyzing the effects of the scDb-hERG1/ß1 in vivo measuring the QT interval length of the surface ECG after its injection intravenously in farm-pigs. Results: The scDb-hERG1-ß1 did not produce any lengthening of APD compared to control (vehicle) conditions, either in atrial or ventricular cardiomyocytes, whereas both the hERG1-mAb and the scFv-hERG1 produced a significant APD prolongation. The addition of E4031 further prolonged APD. The scDb-hERG1-ß1 did not produce any alterations of the QT (and QTc) interval values, once injected intravenously in farm pigs. Discussion: Overall, the above evidences plead for the cardiac safety of the scDb-hERG1-ß1, suggesting that an application of this antibody for anti-cancer therapy will be untainted by cardiotoxicity.

Recent advances and current limitations of available technology to optically manipulate and observe cardiac electrophysiology.

Optogenetics, utilising light-reactive proteins to manipulate tissue activity, are a relatively novel approach in the field of cardiac electrophysiology. We here provide an overview of light-activated transmembrane channels (optogenetic actuators) currently applied in strategies to modulate cardiac activity, as well as newly developed variants yet to be implemented in the heart. In addition, we touch upon genetically encoded indicators (optogenetic sensors) and fluorescent dyes to monitor tissue activity, including cardiac transmembrane potential and ion homeostasis. The combination of the two allows for all-optical approaches to monitor and manipulate the heart without any physical contact. However, spectral congestion poses a major obstacle, arising due to the overlap of excitation/activation and emission spectra of various optogenetic proteins and/or fluorescent dyes, resulting in optical crosstalk. Therefore, optogenetic proteins and fluorescent dyes should be carefully selected to avoid optical crosstalk and consequent disruptions in readouts and/or cellular activity. We here present a novel approach to simultaneously monitor transmembrane potential and cytosolic calcium, while also performing optogenetic manipulation. For this, we used the novel voltage-sensitive dye ElectroFluor 730p and the cytosolic calcium indicator X-Rhod-1 in mouse hearts expressing channelrhodopsin-2 (ChR2). By exploiting the isosbestic point of ElectroFluor 730p and avoiding the ChR2 activation spectrum, we here introduce a novel optical imaging and manipulation approach with minimal crosstalk. Future developments in both optogenetic proteins and fluorescent dyes will allow for additional and more optimised strategies, promising a bright future for all-optical approaches in the field of cardiac electrophysiology.

Corrigendum: Calcium handling maturation and adaptation to increased substrate stiffness in human iPSC-derived cardiomyocytes: the impact of full-length dystrophin deficiency.

[This corrects the article DOI: 10.3389/fphys.2022.1030920.].

Beneficial effects of chronic mexiletine treatment in a human model of SCN5A overlap syndrome.

AIMS: SCN5A mutations are associated with various cardiac phenotypes, including long QT syndrome type 3 (LQT3), Brugada syndrome (BrS), and cardiac conduction disease (CCD). Certain mutations, such as SCN5A-1795insD, lead to an overlap syndrome, with patients exhibiting both features of BrS/CCD [decreased sodium current (INa)] and LQT3 (increased late INa). The sodium channel blocker mexiletine may acutely decrease LQT3-associated late INa and chronically increase peak INa associated with SCN5A loss-of-function mutations. However, most studies have so far employed heterologous expression systems and high mexiletine concentrations. We here investigated the effects of a therapeutic dose of mexiletine on the mixed phenotype associated with the SCN5A-1795insD mutation in HEK293A cells and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). METHODS AND RESULTS: To assess only the chronic effects on trafficking, HEK293A cells transfected with wild-type (WT) SCN5A or SCN5A-1795insD were incubated for 48 h with 10 µm mexiletine followed by wash-out, which resulted in an increased peak INa for both SCN5A-WT and SCN5A-1795insD and an increased late INa for SCN5A-1795insD. Acute re-exposure of HEK293A cells to 10 µm mexiletine did not impact on peak INa but significantly decreased SCN5A-1795insD late INa. Chronic incubation of SCN5A-1795insD hiPSC-CMs with mexiletine followed by wash-out increased peak INa, action potential (AP) upstroke velocity, and AP duration. Acute re-exposure did not impact on peak INa or AP upstroke velocity, but significantly decreased AP duration. CONCLUSION: These findings demonstrate for the first time the therapeutic benefit of mexiletine in a human cardiomyocyte model of SCN5A overlap syndrome.

New pharmacological agents and novel cardiovascular pharmacotherapy strategies in 2022.

Cardiovascular diseases (CVD) remain the leading cause of death worldwide and pharmacotherapy of most of them is suboptimal. Thus, there is a clear unmet clinical need to develop new pharmacological strategies with greater efficacy and better safety profiles. In this review, we summarize the most relevant advances in cardiovascular pharmacology in 2022 including the approval of first-in-class drugs that open new avenues for the treatment of obstructive hypertrophic cardiomyopathy (mavacamten), type 2 diabetes mellitus (tirzepatide), and heart failure (HF) independent of left ventricular ejection fraction (sodium-glucose cotransporter 2 inhibitors). We also dealt with fixed dose combination therapies repurposing different formulations of "old" drugs with well-known efficacy and safety for the treatment of patients with acute decompensated HF (acetazolamide plus loop diuretics), atherosclerotic cardiovascular disease (moderate-dose statin plus ezetimibe), Marfan syndrome (angiotensin receptor blockers plus ß-blockers), and secondary cardiovascular prevention (i.e. low-dose aspirin, ramipril and atorvastatin), thereby filling existing gaps in knowledge, and opening new avenues for the treatment of CVD. Clinical trials confirming the role of dapagliflozin in patients with HF and mildly reduced or preserved ejection fraction, long-term evolocumab to reduce the risk of cardiovascular events, vitamin K antagonists for stroke prevention in patients with rheumatic heart disease-associated atrial fibrillation, antibiotic prophylaxis in patients at high risk for infective endocarditis before invasive dental procedures, and vutrisiran for the treatment of hereditary transthyretin-related amyloidosis with polyneuropathy were also reviewed. Finally, we briefly discuss recent clinical trials suggesting that FXIa inhibitors may have the potential to uncouple thrombosis from hemostasis and attenuate/prevent thromboembolic events with minimal disruption of hemostasis.

Slower Calcium Handling Balances Faster Cross-Bridge Cycling in Human MYBPC3 HCM.

BACKGROUND: The pathogenesis of MYBPC3-associated hypertrophic cardiomyopathy (HCM) is still unresolved. In our HCM patient cohort, a large and well-characterized population carrying the MYBPC3:c772G>A variant (p.Glu258Lys, E258K) provides the unique opportunity to study the basic mechanisms of MYBPC3-HCM with a comprehensive translational approach. METHODS: We collected clinical and genetic data from 93 HCM patients carrying the MYBPC3:c772G>A variant. Functional perturbations were investigated using different biophysical techniques in left ventricular samples from 4 patients who underwent myectomy for refractory outflow obstruction, compared with samples from non-failing non-hypertrophic surgical patients and healthy donors. Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and engineered heart tissues (EHTs) were also investigated. RESULTS: Haplotype analysis revealed MYBPC3:c772G>A as a founder mutation in Tuscany. In ventricular myocardium, the mutation leads to reduced cMyBP-C (cardiac myosin binding protein-C) expression, supporting haploinsufficiency as the main primary disease mechanism. Mechanical studies in single myofibrils and permeabilized muscle strips highlighted faster cross-bridge cycling, and higher energy cost of tension generation. A novel approach based on tissue clearing and advanced optical microscopy supported the idea that the sarcomere energetics dysfunction is intrinsically related with the reduction in cMyBP-C. Studies in single cardiomyocytes (native and hiPSC-derived), intact trabeculae and hiPSC-EHTs revealed prolonged action potentials, slower Ca2+ transients and preserved twitch duration, suggesting that the slower excitation-contraction coupling counterbalanced the faster sarcomere kinetics. This conclusion was strengthened by in silico simulations. CONCLUSIONS: HCM-related MYBPC3:c772G>A mutation invariably impairs sarcomere energetics and cross-bridge cycling. Compensatory electrophysiological changes (eg, reduced potassium channel expression) appear to preserve twitch contraction parameters, but may expose patients to greater arrhythmic propensity and disease progression. Therapeutic approaches correcting the primary sarcomeric defects may prevent secondary cardiomyocyte remodeling.

Acute appendicitis in a patient immunised with COVID-19 vaccine: A case report with morphological analysis.

Although the benefit/risk profile for mRNA COVID-19 vaccines is recognised as extremely favourable, appendicitis is currently considered an adverse event (AE) of special interest. We describe the case of a 58-year-old female who presented with signs and symptoms of appendicitis approximately 48 hours after her first injection of the Pfizer-BioNTech vaccine. Abdominal ultrasound revealed fluid collection in the right iliac fossa and cecal wall thickening. Following the surgical visit, CT scan with contrast showed a distended appendix with thickened walls, suggestive of acute appendicitis. The patient tested negative to upper respiratory COVID-19 reverse transcription-polymerase chain reaction. Clinical trials and observational studies suggest a possible association between appendicitis and COVID-19 vaccines. Th-1 driven granulomatous inflammation reported in our case represents an infrequent nonspecific chronic inflammation of the appendix, especially in the setting of delayed or interval appendectomy. In view of the current paediatric vaccination campaign, we recommend monitoring the safety profile and potential gastrointestinal AEs associated with mRNA COVID-19 vaccines to swiftly manage subjects with gastrointestinal symptoms and prevent potential complications.

Calcium handling maturation and adaptation to increased substrate stiffness in human iPSC-derived cardiomyocytes: The impact of full-length dystrophin deficiency.

Cardiomyocytes differentiated from human induced Pluripotent Stem Cells (hiPSC- CMs) are a unique source for modelling inherited cardiomyopathies. In particular, the possibility of observing maturation processes in a simple culture dish opens novel perspectives in the study of early-disease defects caused by genetic mutations before the onset of clinical manifestations. For instance, calcium handling abnormalities are considered as a leading cause of cardiomyocyte dysfunction in several genetic-based dilated cardiomyopathies, including rare types such as Duchenne Muscular Dystrophy (DMD)-associated cardiomyopathy. To better define the maturation of calcium handling we simultaneously measured action potential and calcium transients (Ca-Ts) using fluorescent indicators at specific time points. We combined micropatterned substrates with long-term cultures to improve maturation of hiPSC-CMs (60, 75 or 90 days post-differentiation). Control-(hiPSC)-CMs displayed increased maturation over time (90 vs 60 days), with longer action potential duration (APD), increased Ca-T amplitude, faster Ca-T rise (time to peak) and Ca-T decay (RT50). The progressively increased contribution of the SR to Ca release (estimated by post-rest potentiation or Caffeine-induced Ca-Ts) appeared as the main determinant of the progressive rise of Ca-T amplitude during maturation. As an example of severe cardiomyopathy with early onset, we compared hiPSC-CMs generated from a DMD patient (DMD-ΔExon50) and a CRISPR-Cas9 genome edited cell line isogenic to the healthy control with deletion of a G base at position 263 of the DMD gene (c.263delG-CMs). In DMD-hiPSC-CMs, changes of Ca-Ts during maturation were less pronounced: indeed, DMD cells at 90 days showed reduced Ca-T amplitude and faster Ca-T rise and RT50, as compared with control hiPSC-CMs. Caffeine-Ca-T was reduced in amplitude and had a slower time course, suggesting lower SR calcium content and NCX function in DMD vs control cells. Nonetheless, the inotropic and lusitropic responses to forskolin were preserved. CRISPR-induced c.263delG-CM line recapitulated the same developmental calcium handling alterations observed in DMD-CMs. We then tested the effects of micropatterned substrates with higher stiffness. In control hiPSC-CMs, higher stiffness leads to higher amplitude of Ca-T with faster decay kinetics. In hiPSC-CMs lacking full-length dystrophin, however, stiffer substrates did not modify Ca-Ts but only led to higher SR Ca content. These findings highlighted the inability of dystrophin-deficient cardiomyocytes to adjust their calcium homeostasis in response to increases of extracellular matrix stiffness, which suggests a mechanism occurring during the physiological and pathological development (i.e. fibrosis).

Pharmacological basis of the antifibrotic effects of pirfenidone: Mechanistic insights from cardiac in-vitro and in-vivo models.

Pirfenidone is a small drug with marked antifibrotic activity approved for the treatment of Idiopathic pulmonary fibrosis. Recently, its peculiar pharmacological profile has attracted attention for its potential therapeutic benefit for extra-pulmonary disorders characterized by pathological fibrosis, such as kidney, liver, and cardiac failure. A major pitfall of pirfenidone is the lack of consistent understanding of its mechanism of action, regardless of the target. In addition to the increasing attention to the role of inflammation and its mediators in several processes, a better knowledge of the variety of fibroblasts' population, of signals controlling their activation and trans-differentiation, and of crosstalk with other cell resident and non-resident cell types is needed for prevention, treatment and possibly reverse of fibrosis. This review will focus on pirfenidone's pharmacological profile and its effects on cardiac fibroblasts.

Paradoxical prolongation of QT interval during exercise in patients with hypertrophic cardiomyopathy: cellular mechanisms and implications for diastolic function.

Aims: Ventricular cardiomyocytes from hypertrophic cardiomyopathy (HCM) patient hearts show prolonged action potential duration (APD), impaired intracellular Ca2+ homeostasis and abnormal electrical response to beta -adrenergic stimulation. We sought to determine whether this behaviour is associated with abnormal changes of repolarization during exercise and worsening of diastolic function, ultimately explaining the intolerance to exercise experienced by some patients without obstruction. Methods and results: Non-obstructive HCM patients (178) and control subjects (81) underwent standard exercise testing, including exercise echocardiography. Ventricular myocytes were isolated from myocardial samples of 23 HCM and eight non-failing non-hypertrophic surgical patients. The APD shortening in response to high frequencies was maintained in HCM myocytes, while ß-adrenergic stimulation unexpectedly prolonged APDs, ultimately leading to a lesser shortening of APDs in response to exercise. In HCM vs. control subjects, we observed a lesser shortening of QT interval at peak exercise (QTc: +27 ± 52 ms in HCM, -4 ± 50 ms in controls, P < 0.0001). In patients showing a marked QTc prolongation (>30 ms), the excessive shortening of the electrical diastolic period was linked with a limited increase of heart-rate and deterioration of diastolic function at peak effort. Conclusions: Abnormal balance of Ca2+- and K+-currents in HCM cardiomyocytes determines insufficient APD and Ca2+-transient shortening with exercise. In HCM patients, exercise-induced QTc prolongation was associated with impaired diastolic reserve, contributing to the reduced exercise tolerance. Our results support the idea that severe electrical cardiomyocyte abnormalities underlie exercise intolerance in a subgroup of HCM patients without obstruction.

Genotype-Driven Pathogenesis of Atrial Fibrillation in Hypertrophic Cardiomyopathy: The Case of Different TNNT2 Mutations.

Atrial dilation and atrial fibrillation (AF) are common in Hypertrophic CardioMyopathy (HCM) patients and associated with a worsening of prognosis. The pathogenesis of atrial myopathy in HCM remains poorly investigated and no specific association with genotype has been identified. By re-analysis of our cohort of thin-filament HCM patients (Coppini et al. 2014) AF was identified in 10% of patients with sporadic mutations in the cardiac Troponin T gene (TNNT2), while AF occurrence was much higher (25-75%) in patients carrying specific "hot-spot" TNNT2 mutations. To determine the molecular basis of arrhythmia occurrence, two HCM mouse models expressing human TNNT2 variants (a "hot-spot" one, R92Q, and a "sporadic" one, E163R) were selected according to the different pathophysiological pathways previously demonstrated in ventricular tissue. Echocardiography studies showed a significant left atrial dilation in both models, but more pronounced in the R92Q. In E163R atrial trabeculae, in line with what previously observed in ventricular preparations, the energy cost of tension generation was markedly increased. However, no changes of twitch amplitude and kinetics were observed, and there was no atrial arrhythmic propensity. R92Q atrial trabeculae, instead, displayed normal ATP consumption but markedly increased myofilament calcium sensitivity, as previously observed in ventricular preparations. This was associated with reduced inotropic reserve and slower kinetics of twitch contractions and, importantly, with an increased occurrence of spontaneous beats and triggered contractions that represent an intrinsic arrhythmogenic mechanism promoting AF. The association of specific TNNT2 mutations with AF occurrence depends on the mutation-driven pathomechanism (i.e., increased atrial myofilament calcium sensitivity rather than increased myofilament tension cost) and may influence the individual response to treatment.

Sex-Related Differences in Genetic Cardiomyopathies.

Cardiomyopathies are a heterogeneous collection of diseases that have in common primary functional and structural abnormalities of the heart muscle, often genetically determined. The most effective categorization of cardiomyopathies is based on the presenting phenotype, with hypertrophic, dilated, arrhythmogenic, and restrictive cardiomyopathy as the prototypes. Sex modulates the prevalence, morpho-functional manifestations and clinical course of cardiomyopathies. Aspects as diverse as ion channel expression and left ventricular remodeling differ in male and female patients with myocardial disease, although the reasons for this are poorly understood. Moreover, clinical differences may also result from complex societal/environmental discrepancies between sexes that may disadvantage women. This review provides a state-of-the-art appraisal of the influence of sex on cardiomyopathies, highlighting the many gaps in knowledge and open research questions.

Facing the challenge of polypharmacy when prescribing for older people with cardiovascular disease. A review by the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy.

Population ageing has resulted in an increasing number of older people living with chronic diseases (multimorbidity) requiring five or more medications daily (polypharmacy). Ageing produces important changes in the cardiovascular system and represents the most potent single cardiovascular risk factor. Cardiovascular diseases (CVDs) constitute the greatest burden for older people, their caregivers, and healthcare systems. Cardiovascular pharmacotherapy in older people is complex because age-related changes in body composition, organ function, homeostatic mechanisms, and comorbidities modify the pharmacokinetic and pharmacodynamic properties of many commonly used cardiovascular and non-cardiovascular drugs. Additionally, polypharmacy increases the risk of adverse drug reactions and drug interactions, which in turn can lead to increased morbi-mortality and healthcare costs. Unfortunately, evidence of drug efficacy and safety in older people with multimorbidity and polypharmacy is limited because these individuals are frequently underrepresented/excluded from clinical trials. Moreover, clinical guidelines are largely written with a single-disease focus and only occasionally address the issue of coordination of care, when and how to discontinue treatments, if required, or how to prioritize recommendations for patients with multimorbidity and polypharmacy. This review analyses the main challenges confronting healthcare professionals when prescribing in older people with CVD, multimorbidity, and polypharmacy. Our goal is to provide information that can contribute to improving drug prescribing, efficacy, and safety, as well as drug adherence and clinical outcomes.

Optical clearing in cardiac imaging: A comparative study.

The optical clearing of the cardiac tissue has always been a challenging goal to obtain successful three-dimensional reconstructions of entire hearts. Typically, the developed protocols are targeted at the clearing of the brain; cardiac tissue requires proper arrangements to the original protocols, which are usually tough and time-consuming to figure out. Here, we present the application of three different clearing methodologies on mouse hearts: uDISCO, CLARITY, and SHIELD. For each approach, we describe the required optimizations that we have developed to improve the outcome; in particular, we focus on comparing the features of the tissue after the application of each methodology, especially in terms of tissue preservation, transparency, and staining. We found that the uDISCO protocol induces strong fiber delamination of the cardiac tissue, thus reducing the reliability of structural analyses. The CLARITY protocol confers a high level of transparency to the heart and allows deep penetration of the fluorescent dyes; however, it requires long times for the clearing and the tissue loses its robustness. The SHIELD methodology, indeed, is very promising for tissue maintenance since it preserves its consistency and provides ideal transparency, but further approaches are needed to obtain homogeneous staining of the whole heart. Since the CLARITY procedure, despite the disadvantages in terms of tissue preservation and timings, is actually the most suitable approach to image labeled samples in depth, we optimized and performed the methodology also on human cardiac tissue from control hearts and hearts with hypertrophic cardiomyopathy.

Genetic characterization of juvenile sudden cardiac arrest and death in Tuscany: The ToRSADE registry.

Background: Sudden cardiac arrest (SCA) in young people represents a dramatic event, often leading to severe neurologic outcomes or sudden cardiac death (SCD), and is frequently caused by genetic heart diseases. In this study, we report the results of the Tuscany registry of sudden cardiac death (ToRSADE) registry, aimed at monitoring the incidence and investigating the genetic basis of SCA and SCD occurring in subjects < 50 years of age in Tuscany, Italy. Methods and results: Creation of the ToRSADE registry allowed implementation of a repository for clinical, molecular and genetic data. For 22 patients, in whom a genetic substrate was documented or suspected, blood samples could be analyzed; 14 were collected at autopsy and 8 from resuscitated patients after SCA. Next generation sequencing (NGS) analysis revealed likely pathogenetic (LP) variants associated with cardiomyopathy (CM) or channelopathy in four patients (19%), while 17 (81%) carried variants of uncertain significance in relevant genes (VUS). In only one patient NGS confirmed the diagnosis obtained during autopsy: the p.(Asn480Lysfs*20) PKP2 mutation in a patient with arrhythmogenic cardiomyopathy (AC). Conclusion: Systematic genetic screening allowed identification of LP variants in 19% of consecutive patients with SCA/SCD, including subjects carrying variants associated with hypertrophic cardiomyopathy (HCM) or AC who had SCA/SCD in the absence of structural cardiomyopathy phenotype. Genetic analysis combined with clinical information in survived patients and post-mortem evaluation represent an essential multi-disciplinary approach to manage juvenile SCD and SCA, key to providing appropriate medical and genetic assistance to families, and advancing knowledge on the basis of arrhythmogenic mechanisms in inherited cardiomyopathies and channelopathies.