Clinical characterization and natural history of chemotherapy-induced dilated cardiomyopathy.

AIMS: Chemotherapy-induced dilated cardiomyopathy (CI-DCM) is a well-recognized phenotype of non-ischemic dilated cardiomyopathy (DCM), characterized by poor outcomes. However, a detailed comparison between idiopathic DCM (iDCM) and CI-DCM is still lacking. METHODS AND RESULTS: All consecutive DCM patients enrolled in the Trieste Muscle Heart Disease Registry were analysed. CI-DCM and iDCM were defined according to current recommendations. The primary study outcome measure was all-mortality death and secondary outcomes were a) a composite of cardiovascular death/heart-transplantation/ventricular-assist-device implantation, and b) major ventricular arrhythmias. The study included 551 patients (499 iDCM and 52 CI-DCM). At enrolment, compared with iDCM, CI-DCM patients were older (51 ± 14 years vs. 58 ± 3 years, respectively, P < 0.001) and had a higher left ventricular ejection fraction (32% ± 9 vs. 35% ± 10, respectively, P = 0.03). Over a median follow-up of 90 months (IQR 54-140 months), CI-DCM patients had a higher incidence of all-cause mortality compared with iDCM (36.5% vs. 8.4% in CI-DCM and iDCM respectively, P < 0.001), while the incidence of major ventricular arrhythmias was higher in the iDCM group compared with CI-DCM (4% vs. 0%, in CI-DCM and iDCM respectively, P = 0.03). The risk of the composite outcome was comparable between the two groups (P = 0.91). At Cox multivariable analysis, the diagnosis of CI-DCM emerged as independently associated to primary outcome (HR 6.42, 95% C.I. 2.52-16.31, P < 0.001). CONCLUSIONS: In a well-selected DCM cohort, patients with a chemotherapy-induced aetiology had a higher incidence of all-cause mortality compared with iDCM. Conversely, the incidence of life-threatening ventricular arrhythmic events was higher among patients with iDCM.

Mitochondrial Sirtuin-3 (SIRT3) Prevents Doxorubicin-Induced Dilated Cardiomyopathy by Modulating Protein Acetylation and Oxidative Stress.

BACKGROUND: High doses of doxorubicin put cancer patients at risk for developing dilated cardiomyopathy. Previously, we showed that doxorubicin treatment decreases SIRT3 (sirtuin 3), the main mitochondrial deacetylase and increases protein acetylation in rat cardiomyocytes. Here, we hypothesize that SIRT3 expression can attenuate doxorubicin induced dilated cardiomyopathy in vivo by preventing the acetylation of mitochondrial proteins. METHODS: Nontransgenic, M3-SIRT3 (truncated SIRT3; short isoform), and M1-SIRT3 (full-length SIRT3; mitochondrial localized) transgenic mice were treated with doxorubicin for 4 weeks (8 mg/kg body weight per week). Echocardiography was performed to assess cardiac structure and function and validated by immunohistochemistry and immunofluorescence (n=4-10). Mass spectrometry was performed on cardiac mitochondrial peptides in saline (n=6) and doxorubicin (n=5) treated hearts. Validation was performed in doxorubicin treated primary rat and human induced stem cell derived cardiomyocytes transduced with adenoviruses for M3-SIRT3 and M1-SIRT3 and deacetylase deficient mutants (n=4-10). RESULTS: Echocardiography revealed that M3-SIRT3 transgenic mice were partially resistant to doxorubicin induced changes to cardiac structure and function whereas M1-SIRT3 expression prevented cardiac remodeling and dysfunction. In doxorubicin hearts, 37 unique acetylation sites on mitochondrial proteins were altered. Pathway analysis revealed these proteins are involved in energy production, fatty acid metabolism, and oxidative stress resistance. Increased M1-SIRT3 expression in primary rat and human cardiomyocytes attenuated doxorubicin-induced superoxide formation, whereas deacetylase deficient mutants were unable to prevent oxidative stress. CONCLUSIONS: Doxorubicin reduced SIRT3 expression and markedly affected the cardiac mitochondrial acetylome. Increased M1-SIRT3 expression in vivo prevented doxorubicin-induced cardiac dysfunction, suggesting that SIRT3 could be a potential therapeutic target for mitigating doxorubicin-induced dilated cardiomyopathy.

Oridonin enhances antitumor effects of doxorubicin in human osteosarcoma cells.

BACKGROUND: Doxorubicin is the chemotherapeutic drug of choice in osteosarcoma treatment, but its cumulative administration causes dilated cardiomyopathy. Combination therapy represents a potential strategy to reduce the therapeutic dosage of the chemotherapeutic agent and minimize its side effects. The aim of this study was to evaluate the potential of oridonin, a natural product from the medicinal herb Rabdosia rubescens, to act in combination with doxorubicin for osteosarcoma treatment. To date, there are no reports of the simultaneous administration of both drugs in osteosarcoma therapy. METHODS: The combined administration of different doses of oridonin and doxorubicin, as compared with the drugs alone, were tested in an in vitro model of osteosarcoma. The synergistic effect of the drugs on cell death was assessed by alamarBlue™ and by CompuSyn software. Early and late apoptosis markers (JC-1 fluorescence and Annexin V immunofluorescence), as well as the production of reactive oxygen species, were evaluated by flow cytometry. Western blot was used to assess the expression of anti-apoptotic proteins. RESULTS: Oridonin and doxorubicin presented a synergistic cytotoxic effect in osteosarcoma cells. In the presence of sub-cytotoxic concentrations of the natural product, there was an increased accumulation of intracellular doxorubicin, increased levels of reactive oxygen species (ROS), alteration of mitochondria membrane potential and a higher rate of apoptosis. CONCLUSION: The combined use of oridonin and doxorubicin could help to reduce the clinical dosage of doxorubicin and its dangerous side effects.

Cardiomyogenic Differentiation Potential of Human Dilated Myocardium-Derived Mesenchymal Stem/Stromal Cells: The Impact of HDAC Inhibitor SAHA and Biomimetic Matrices.

Dilated cardiomyopathy (DCM) is the most common type of nonischemic cardiomyopathy characterized by left ventricular or biventricular dilation and impaired contraction leading to heart failure and even patients' death. Therefore, it is important to search for new cardiac tissue regenerating tools. Human mesenchymal stem/stromal cells (hmMSCs) were isolated from post-surgery healthy and DCM myocardial biopsies and their differentiation to the cardiomyogenic direction has been investigated in vitro. Dilated hmMSCs were slightly bigger in size, grew slower, but had almost the same levels of MSC-typical surface markers as healthy hmMSCs. Histone deacetylase (HDAC) activity in dilated hmMSCs was 1.5-fold higher than in healthy ones, which was suppressed by class I and II HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) showing activation of cardiomyogenic differentiation-related genes alpha-cardiac actin (ACTC1) and cardiac troponin T (TNNT2). Both types of hmMSCs cultivated on collagen I hydrogels with hyaluronic acid (HA) or 2-methacryloyloxyethyl phosphorylcholine (MPC) and exposed to SAHA significantly downregulated focal adhesion kinase (PTK2) and activated ACTC1 and TNNT2. Longitudinal cultivation of dilated hmMSC also upregulated alpha-cardiac actin. Thus, HDAC inhibitor SAHA, in combination with collagen I-based hydrogels, can tilt the dilated myocardium hmMSC toward cardiomyogenic direction in vitro with further possible therapeutic application in vivo.

Serine mutations in overexpressed Hsp27 abrogate the protection against doxorubicin-induced p53-dependent cardiac apoptosis in mice.

Small heat shock proteins (sHsps) protect the heart from chemotherapeutics-induced heart failure by inhibiting p53-dependent apoptosis. However, mechanism of such protection has not been elucidated yet. Here we test a hypothesis that serine phosphorylation of sHsps is essential to inhibit the doxorubicin-induced and p53-dependent apoptotic pathway. Three transgenic mice (TG) lines with cardiomyocyte-specific overexpression of human heat shock protein 27 (hHsp27), namely, wild-type [myosin heavy chain (MHC)-hHsp27], S82A single mutant [MHC-mut-hHsp27(S82A)], and trimutant [MHC-mut-hHsp27(S15A/S78A/S82A)] were generated. TG mice were treated with Dox (6 mg/kg body wt; once in a week; 4 wk) along with age-matched nontransgenic (non-TG) controls. The Dox-treated MHC-hHsp27 mice showed improved survival and cardiac function (both MRI and echocardiography) in terms of contractility [ejection fraction (%EF)] and left ventricular inner diameter (LVID) compared with the Dox-treated non-TG mice. However, both MHC-mut-hHsp27(S82A) and MHC-mut-hHsp27(S15A/S78A/S82A) mutants overexpressing TG mice did not show such a cardioprotection. Furthermore, transactivation of p53 was found to be attenuated only in Dox-treated MHC-hHsp27 mice-derived cardiomyocytes in vitro, as low p53 was detected in the nuclei, not in mutant hHsp27 overexpressing cardiomyocytes. Similarly, only in MHC-hHsp27 overexpressing cardiomyocytes, low Bax, higher mechanistic target of rapamycin (mTOR) phosphorylation, and low apoptotic poly(ADP-ribose) polymerase-1 (PARP-1) cleavage (89 kDa fragment) were detected. Pharmacological inhibition of p53 was more effective in mutant TG mice compared with MHC-hHsp27 mice. We conclude that phosphorylation of overexpressed Hsp27 at S82 and its association with p53 are essential for the cardioprotective effect of overexpressed Hsp27 against Dox-induced dilated cardiomyopathy. Only phosphorylated Hsp27 protects the heart by inhibiting p53 transactivation.NEW & NOTEWORTHY Requirement of serine phosphorylation in Hsp27 for cardioprotective effect against Dox is tested in various mutants overexpressing mice. Cardioprotective effect was found to be compromised in Hsp27 serine mutants overexpressed mice compared with wild-type overexpressing mice. These results indicate that cancer patients, who carry these mutations, may have higher risk of aggravated cardiomyopathy on treated with cardiotoxic chemotherapeutics such as doxorubicin.

Intestinal fatty acid-binding protein and osteoprotegerin in anthracycline-induced rabbit models of dilated cardiomyopathy.

Anthracyclines are used for chemotherapy in small animal cancer patients. However, cardiotoxic complications are very common with anthracycline use and induce multi-organ complications. The purpose of this study was to investigate the associations between multi-organ complications, focusing on the liver and intestine, and the serum concentrations of intestinal fatty acid-binding protein (I-FABP) and osteoprotegerin (OPG) in rabbits with daunorubicin-induced dilated cardiomyopathy (DCM). Sixteen New Zealand white male rabbits (16-20 weeks old), weighing 2.4-3.65 kg, were randomly divided into the control (n = 8) and daunorubicin-induced DCM (n = 8) groups. The concentration of serum I-FABP was significantly elevated in the DCM group (201.9 ± 16.6 pg/mL) compared to the control group (152.2 ± 19.9 g/mL). Additionally, the concentration of serum lactate was markedly increased in the DCM group (0.16 ± 0.01 mM) compared to that in the control group (0.02 ± 0.01 mmol/mL). In addition, the OPG concentration was significantly higher in the DCM group (2.44 ± 0.14 ng/mL) than in the control group (0.1 ± 0.08 ng/mL). Although the histopathology of the ileum did not significantly differ between groups, pathological changes were observed in the livers of the DCM group animals. In conclusion, multi-organ complications were recognized in DCM models and were accompanied by elevated serum I-FABP and OPG concentrations.

Drugs of Abuse and Heart Failure.

Substance use is common among those with heart failure (HF) and is associated with worse clinical outcomes. Alcohol, tobacco, cannabis, and cocaine are commonly abused substances that can contribute to the development and worsening of HF. Heavy alcohol consumption can lead to dilated cardiomyopathy, whereas moderate intake may decrease incident HF. Tobacco increases the risk of HF through coronary artery disease and coronary artery disease-independent mechanisms. Continued smoking worsens outcomes for those with HF and cessation is associated with an improved risk of major adverse cardiac events. Cannabis has complex interactions on the cardiovascular system depending on the method of consumption, amount consumed, and content of cannabinoids. Delta-9-tetrahydrocannabinol can increase sympathetic tone, cause vascular dysfunction, and may increase the risk of myocardial infarction. Cannabidiol is cardioprotective in preclinical studies and is a potential therapeutic target. Cocaine increases sympathetic tone and is a potent proarrhythmogenic agent. It increases the risk of myocardial infarction and can also lead to a dilated cardiomyopathy. The use of beta-blockers in those with HF and cocaine use is likely safe and effective. Future studies are needed to further elucidate the impact of these substances both on the development of HF and their effects on those who have HF.

Surgical ventricular restoration for rabbit dilated cardiomyopathy model: Preliminary study.

Dilated cardiomyopathy (DCM) is a common cardiovascular disease in dogs. It is primarily treated with beta-blockers. The aim of this preliminary study was to evaluate the efficacy of surgical ventricular restoration on daunorubicin-induced DCM in rabbits. The DCM model was generated in six rabbits by intravenous administration of daunorubicin (4 mg/kg/week) for 6 weeks. Echocardiography was performed before and after left ventricular (LV) reconstruction surgery to evaluate the LV function. The surgery was performed using non-absorbent prosthetic sheets and 5-0 polypropylene sutures, between the left anterior descending branch and the circumflex branch of the left coronary artery. We measured LV function 3 weeks postoperatively and collected the hearts for histopathological examination. We observed significant improvements in the LV internal dimension volume at both end-diastole and end-systole compared to the preoperative values. Fraction shortening showed a substantial improvement from 23.8 ± 1.4% to 30.9 ± 1.3%. In addition, the ejection fraction increased from 35.3% to 51.9%. On histological examination, the left ventricular wall was markedly thin. Furthermore, we observed fibrosis between the myocardial cells around the sutured site. The LV volume and LV functions significantly improved postoperatively. However, further investigation is required to determine the long-term effects of surgical ventricular restoration.

Gemcitabine-induced dilated-cardiomyopathy in patient with platinum-refractory ovarian-cancer: A case report and literature review.

INTRODUCTION: Gemcitabine is a nucleoside analog and pyrimidine antimetabolite that inhibits RNA synthesis, currently approved for use to treat a variety of cancers, among which ovarian cancers. Gemcitabine is considered relatively safe and it is generally well tolerated, with rarely reported cardiac side effects. CASE REPORT: We report a case of gemcitabine induced dilated cardiomyopathy in a 41-year-old woman receiving gemcitabine as second line treatment for platinum-resistant ovarian cancer without pre-existing hypertension or significant cardiac history.Management and Outcome: The patient presented with clinical symptoms and laboratory and imaging results suggestive of congestive cardiac failure, with a left ventricular ejection fraction of 15%. Gemcitabine administration was stopped and Furosemide with ACE-inhibitors and Beta-blocker agents were initiated. At that point the clinical situation improved: symptoms and findings disappeared with gemcitabine cessation. DISCUSSION: Our case demonstrated for the first time objective evidence for dilated cardiomyopathy induced by gemcitabine in a young patient with platinum-resistant ovarian cancer without pre-existing significant cardiac history. Although rare, gemcitabine-induced cardiotoxicity should be promptly recognized in order to take appropriate measures to manage it.

Epinephrine soaked tampons induced transient acute dilated cardiomyopathy during FESS procedure.

BACKGROUND: Epinephrine, in all modes of use, may pose a wide range of cardiotoxic events, ranging from sinus tachycardia to heart failure, life threatening arrhythmias, and even death. Because of daily and extensive use of epinephrine, these unusual and rare events tend to be forgotten by physicians. We present a case of dilated cardiomyopathy that developed following routine use of epinephrine-impregnated tampons during function endoscopic sinus (FESS) surgery. CASE PRESENTATION: A healthy, 24-year-old man with no family history of heart disease has undergone elective surgery under general anesthesia to repair the paranasal sinuses using endoscopic approach. During surgery, soon after being treated with 1: 1000 diluted epinephrine-soaked tampons, an hypertensive crisis was noticed followed by pulseless electrical activity. An extensive examination led to the diagnosis of non-ischemic dilated cardiomyopathy. After several days of heart failure medical therapy, complete resolution of all structural and functional changes was achieved. CONCLUSION: In our case, we present an unusual and rare event of acute dilated cardiomyopathy following the use of epinephrine-soaked tampons during elective FESS surgery. A prompt response was observed after several days of heart failure treatment. Awareness of the epinephrine cardiotoxic potential even in the form of soaked tampons is essential for proper diagnosis and prompt treatment.

Incidental COVID-19 in a heart-kidney transplant recipient with malnutrition and recurrent infections: Implications for the SARS-CoV-2 immune response.

The clinical course and outcomes of immunocompromised patients, such as transplant recipients, with COVID-19 remain unclear. It has been postulated that a substantial portion of the disease burden seems to be mediated by the host immune activation to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein, we present a simultaneous heart-kidney transplant (SHKT) recipient who was hospitalized for the management of respiratory failure from volume overload complicated by failure to thrive, multiple opportunistic infections, and open non-healing wounds in the setting of worsening renal dysfunction weeks prior to the first case of SARS-CoV-2 being detected in the state of Connecticut. After his third endotracheal intubation, routine nucleic acid testing (NAT) for SARS-CoV-2, in anticipation of a planned tracheostomy, was positive. His hemodynamics, respiratory status, and ventilator requirements remained stable without any worsening for 4 weeks until he had a negative NAT test. It is possible that the immunocompromised status of our patient may have prevented significant immune activation leading up to clinically significant cytokine storm that could have resulted in acute respiratory distress syndrome and multisystem organ failure.

High expression levels and localization of Sox5 in dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a disease that can lead to heart expansion and severe heart failure, but the specific pathogenesis remains unclear. Sox5 is a member of the Sox family with a key role in cardiac function. However, the role of Sox5 in DCM remains unclear. In the present study, wild­type mice were intraperitoneally injected with doxorubicin (Dox) to induce DCM, and heart specimens from human patients with DCM were used to investigate the preliminary role of Sox5 in DCM. The present study demonstrated that, compared with control human hearts, the hearts of patients with DCM exhibited high expression levels of Sox5 and activation of the wnt/ß­catenin pathway. This result was consistent with Dox­induced DCM in mice. Furthermore, in Dox­treated mice, apoptosis was activated during the development of DCM. Inflammation and collagen deposition also increased in DCM mice. The results of the present study indicate that Sox5 may be associated with the development of DCM. Sox5 may be a novel potential factor that regulates DCM.

Self-Maintenance of Cardiac Resident Reparative Macrophages Attenuates Doxorubicin-Induced Cardiomyopathy Through the SR-A1-c-Myc Axis.

RATIONALE: Doxorubicin-induced cardiomyopathy (DiCM) is a primary cause of heart failure and mortality in cancer patients, in which macrophage-orchestrated inflammation serves as an essential pathological mechanism. However, the specific roles of tissue-resident and monocyte-derived macrophages in DiCM remain poorly understood. OBJECTIVE: Uncovering the origins, phenotypes, and functions of proliferative cardiac resident macrophages and mechanistic insights into the self-maintenance of cardiac macrophage during DiCM progression. METHODS AND RESULTS: Mice were administrated with doxorubicin to induce cardiomyopathy. Dynamic changes of resident and monocyte-derived macrophages were examined by lineage tracing, parabiosis, and bone marrow transplantation. We found that the monocyte-derived macrophages primarily exhibited a proinflammatory phenotype that dominated the whole DiCM pathological process and impaired cardiac function. In contrast, cardiac resident macrophages were vulnerable to doxorubicin insult. The survived resident macrophages exhibited enhanced proliferation and conferred a reparative role. Global or myeloid specifically ablation of SR-A1 (class A1 scavenger receptor) inhibited proliferation of cardiac resident reparative macrophages and, therefore, exacerbated cardiomyopathy in DiCM mice. Importantly, the detrimental effect of macrophage SR-A1 deficiency was confirmed by transplantation of bone marrow. At the mechanistic level, we show that c-Myc (Avian myelocytomatosis virus oncogene cellular homolog), a key transcriptional factor for the SR-A1-P38-SIRT1 (Sirtuin 1) pathway, mediated the effect of SR-A1 in reparative macrophage proliferation in DiCM. CONCLUSIONS: The SR-A1-c-Myc axis may represent a promising target to treat DiCM through augmentation of cardiac resident reparative macrophage proliferation.

Effect of bilateral sympathectomy in a rat model of dilated cardiomyopathy induced by doxorubicin.

OBJECTIVE: The study objective was to evaluate the effect of bilateral sympathectomy on ventricular remodeling and function in a rat model of dilated cardiomyopathy induced by doxorubicin. METHODS: Dilated cardiomyopathy was induced in male Wistar rats by weekly intraperitoneal injection of doxorubicin (2 mg/kg) for 9 weeks. Animals were divided into 4 groups: dilated cardiomyopathy; bilateral sympathectomy, submitted on day 15 of the protocol to bilateral sympathectomy; angiotensin-converting enzyme inhibitor, treated with enalapril through day 15 until the end of the experimental protocol; and sham, nonsubmitted through doxorubicin protocol, with weekly intraperitoneal injections of saline solution (0.9%). The left ventricular function was assessed, and the heart was collected for posterior analyses. RESULTS: The dilated cardiomyopathy group presented a significant decrease in the myocardial efficiency when compared with the sham group (33.4% vs 71.2%). Only the bilateral sympathectomy group was able to preserve it (57.5%; P = .0001). A significant dilatation in the left ventricular chamber was observed in the dilated cardiomyopathy group (15.9 µm2) compared with the sham group (10.2 µm2; P = .0053). Sympathectomy and enalapril prevented ventricular remodeling (9.5 and 9.6 µm2, respectively; P = .0034). There was a significant increase in interstitial myocardial fibrosis in the dilated cardiomyopathy group (14.8%) when compared with the sham group (2.4%; P = .0001). This process was significantly reduced with sympathectomy and enalapril (8.7 and 3.9%, respectively; P = .0001). CONCLUSIONS: Bilateral sympathectomy was effective in preventing remodeling and left ventricular dysfunction in a rat model of dilated cardiomyopathy induced by doxorubicin.

Development of anthracycline-induced dilated cardiomyopathy due to mutation on LMNA gene in a breast cancer patient: a case report.

BACKGROUND: Anthracyclines are highly effective anticancer medication prescribed for the treatment of breast cancer. Nevertheless, the use of anthracyclines as chemotherapeutic agents involves a risk for development of cardiac toxicity which may cause restrictive and dilated cardiomyopathy. Currently, genetic predisposition is not considered as a risk factor for cardiotoxicity associated to the use of anthracyclines. CASE PRESENTATION: We report the case of a 37-years old Panamanian female patient diagnosed with breast cancer who developed clinical signs of severe heart failure after treatment with doxorubicin. A diagnosis of anthracycline induced cardiomyopathy was made and treatment was initiated accordingly. A whole exome sequencing study performed to the patient showed the presence of a missense mutation in LMNA gene, which codifies for lamin A/C. Our results points to a correlation between the LMNA variant and the anthracycline cardiotoxicity developed by the woman. Improvement of the clinical symptoms and the left ventricle ejection fraction was observed after proper treatment. CONCLUSIONS: This case report suggests for the first time a potential genetic predisposition for anthracyclines induced cardiomyopathy in patients with mutations in LMNA gene. Perhaps chemotherapies accelerate or deliver the "second-hit" in the development of DCM in patients with genetic mutations. More data is needed to understand the contribution of LMNA variants that predispose to DCM in patients receiving cardiotoxic therapies.

Effects of pulmonary artery banding in doxorubicin-induced left ventricular cardiomyopathy.

OBJECTIVE: Central pulmonary banding has been proposed as a novel alternative for the treatment of left ventricular dilated cardiomyopathy in children. We sought to investigate the effects of central pulmonary banding in an experimental model of doxorubicin-induced left ventricular dilated cardiomyopathy. METHODS: Four-month-old sheep (n = 28) were treated with intermittent intracoronary injections of doxorubicin (0.75 mg/kg/dose) into the left main coronary artery. A total dose of up to 2.15 mg/kg of doxorubicin was administered until signs of left ventricular dilation with functional impairment occurred by transthoracic echocardiography evaluation. Animals that survived were treated with surgical central pulmonary banding through a left anterior thoracotomy or sham surgery. Transthoracic echocardiography and pressure-volume loop measurements were used to compare left ventricular function preoperatively and 3 months later. Macroscopic and microscopic histologic examinations followed after hearts were harvested. RESULTS: Nine animals from the central pulmonary banding group and 8 animals from the sham group survived and were included in the final analysis. Both groups showed similar inflammation and fibrosis upon histologic examination consistent with the toxic myocardial effects of doxorubicin. There were no differences in the echocardiographic measurements before central pulmonary banding or sham operation. Baseline measurements before the central pulmonary banding/sham operation were considered as 100%. The central pulmonary banding group had better left ventricular ejection fraction (102.5% ± 21.6% vs 76.7% ± 11.7%, P = .01), with a tendency for smaller left ventricular end-diastolic (101.2% ± 7.4% vs 120.4% ± 10.8%, P = .18) and significantly smaller end-systolic (100.3% ± 12.9% vs 116.5 ± 9.6%, P = .02) diameter of the left ventricle in comparison with the sham animals at 3 months. The end-systolic volume (101.4% ± 31.6% vs 143.4% ± 28.6%, P = .02) was significantly lower in the central pulmonary banding group 3 months postoperatively. Fractional shortening in the long axis (118.5% ± 21.5% vs 85.2% ± 22.8%, P = .016) and short axis (122.5% ± 18% vs 80.9% ± 13.6%, P = .0005) revealed significantly higher values in the central pulmonary banding group. In the conductance catheter measurements, no significant differences were seen between the groups for the parameters of systolic and diastolic function. CONCLUSIONS: Central pulmonary artery banding in the setting of experimental toxic left ventricular dilated cardiomyopathy improved left ventricular echocardiographic function and dimensions.

Mechanisms of toxic cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy is a frequent disease responsible for 40-50% of cases of heart failure. Idiopathic cardiomyopathy is a primary disorder often related to familial/genetic predisposition. Before the diagnosis of idiopathic cardiomyopathy is made, clinicians must not only rule out viral and immune causes, but also toxic causes such as drugs, environmental agents, illicit substances and natural toxins. OBJECTIVE: The objective of this review is to present recent data on the mechanisms underlying toxic cardiomyopathy. METHODS: The US National Library of Medicine Pubmed database was searched from 1980 to December 2017 utilizing the combinations of the search terms "toxic cardiomyopathy", "drugs", "anticancer drugs", "azidothymidine", "rosiglitazone", "carbon monoxide", "alcohol", "illicit drugs", "cocaine", "metamfetamine", "metals", "venom". A total of 339 articles were screened and papers that dealt with the pathophysiology of toxic cardiomyopathy, either in animal models or in clinical practice were selected, with preference being given to more recently published papers, which left 92 articles. Anticancer drugs: The mechanisms of anthracycline-induced cardiotoxicity are primarily related to their mechanisms of action as anticancer drugs, mainly the inhibition of topoisomerase II ß and DNA cleavage. Additional metabolic or oxidative stress factors may play a part, together with interference with iron metabolism. The more recent drugs, trastuzumab and imatinib, also influence stress pathways. Antiretroviral agents: Azidothymidine is cardiotoxic as a result of mitochondrial toxicity. In addition to energy depletion, azidothymidine also increases the production of mitochondrial reactive oxygen species (ROS). Antidiabetic drugs: The cardiotoxicity of thiazolidinedione antidiabetic drugs is still under investigation, though interference with mitochondrial respiration or oxidative stress is suspected. Cocaine: Among the multiple mechanisms involved in cocaine-related cardiotoxicity, excessive sympathetic stimulation with increased myocardial oxygen consumption is well documented in the acute form of left ventricular dysfunction. As for cocaine-related cardiomyopathy, the role of apoptosis and ROS is under investigation. Ethanol: The aetiology of ethanol-related cardiotoxicity is multifactorial, with individual susceptibility being important. It involves apoptosis, alterations of the excitation-contraction coupling in cardiac myocytes, structural and functional alterations of the mitochondria and sarcoplasmic reticulum, changes in cytosolic calcium flows, changes in calcium sensitivity of myofilaments, alterations of mitochondrial oxidation, deregulation of protein synthesis, decrease of contractile proteins and disproportion between the different types of myofibrils, changes in the regulation of myosin ATPase, up-regulation of the L-type calcium channels, increase of oxidative stress, and induction of ANP and p21 mRNA expression in ventricular myocardium. Metamfetamines: Catecholamine-mediated toxicity is the probable cause, with a possible role for genetic susceptibility. Carbon monoxide: In addition to hypoxic injury, carbon monoxide is also directly toxic to the mitochondria, with impairment of mitochondrial respiratory chain at the cytochrome c oxidase level, decrease of glutathione concentrations and of ATP production. There is no evidence for a delayed dilated cardiomyopathy in survivors of an acute exposure. Metals: Cobalt-related cardiomyopathy probably results from interference with energy production and contractile mechanisms, but additional factors (nutrition, hypothyroidism) are often required. Antimony may cause lethal oxidative stress and cell death mediated by elevation in intra-cellular calcium. Proposed mechanisms for mercury toxicity include glutathione depletion, production of ROS, and interruption in selenium-dependent endogenous enzymatic reactions. The existence of a lithium-induced cardiomyopathy is still debated. Scorpion venom: Catecholamine release is the probable cause of acute cardiomyopathy following scorpion envenomation. CONCLUSIONS: The mechanisms behind toxic cardiomyopathy are complex and multifactorial but include interference with myocardial cell bioenergetics and intracellular calcium handling, the generation of ROS, neurohormonal stress, and induction of apoptosis.

Early myocardial changes induced by doxorubicin in the nonfailing dilated ventricle.

Several studies have demonstrated that administration of doxorubicin (DOXO) results in cardiotoxicity, which eventually progresses to dilated cardiomyopathy. The present work aimed to evaluate the early myocardial changes of DOXO-induced cardiotoxicity. Male New Zealand White rabbits were injected intravenously with DOXO twice weekly for 8 wk [DOXO-induced heart failure (DOXO-HF)] or with an equivolumetric dose of saline (control). Echocardiographic evaluation was performed, and myocardial samples were collected to evaluate myocardial cellular and molecular modifications. The DOXO-HF group presented cardiac hypertrophy and higher left ventricular cavity diameters, showing a dilated phenotype but preserved ejection fraction. Concerning cardiomyocyte function, the DOXO-HF group presented a trend toward increased active tension without significant differences in passive tension. The myocardial GSSG-to-GSH ratio and interstitial fibrosis were increased and Bax-to- Bcl-2 ratio presented a trend toward an increase, suggesting the activation of apoptosis signaling pathways. The macromolecule titin shifted toward the more compliant isoform (N2BA), whereas the stiffer one (N2B) was shown to be hypophosphorylated. Differential protein analysis from the aggregate-enriched fraction through gel liquid chromatography-tandem mass spectrometry revealed an increase in the histidine-rich glycoprotein fragment in DOXO-HF animals. This work describes novel and early myocardial effects of DOXO-induced cardiotoxicity. Thus, tracking these changes appears to be of extreme relevance for the early detection of cardiac damage (as soon as ventricular dilation becomes evident) before irreversible cardiac function deterioration occurs (reduced ejection fraction). Moreover, it allows for the adjustment of the therapeutic approach and thus the prevention of cardiomyopathy progression. NEW & NOTEWORTHY Identification of early myocardial effects of doxorubicin in the heart is essential to hinder the development of cardiac complications and adjust the therapeutic approach. This study describes doxorubicin-induced cellular and molecular modifications before the onset of dilated cardiomyopathy. Myocardial samples from doxorubicin-treated rabbits showed a tendency for higher cardiomyocyte active tension, titin isoform shift from N2B to N2BA, hypophosphorylation of N2B, increased apoptotic genes, left ventricular interstitial fibrosis, and increased aggregation of histidine-rich glycoprotein.

Intravenous mesenchymal stem cell-derived exosomes ameliorate myocardial inflammation in the dilated cardiomyopathy.

Mesenchymal stem cells (MSCs) have been shown to be efficacy to attenuating cardiovascular inflammation; however, there are many limitations to stem cell treatment. Present study was to prove MSC-derived exosomes (MSC-Exos) could alleviating inflammatory cardiomyopathy by improving the inflammatory microenvironment of myocardium, especially by regulating the activity of macrophages. Mice were intraperitoneal injected of doxorubicin (DOX) to establish a dilated cardiomyopathy (DCM) model, and then received intravenous injection of either MSC-Exos or PBS as control. Mice receiving MSC-Exos showed improved cardiac function via echocardiography and attenuated cardiac dilation via HE staining, as well as reduced cardiomyocytes apoptosis. Expression levels of inflammatory factors were reduced. And there was a significant decrease of the inflammatory cells infiltration in the MSC-Exos treatment group comparing to the PBS group. Meanwhile, MSC-Exos could remarkably attenuate the pro-inflammatory macrophages amount in both blood and heart, which was proved that MSC-Exos relied on the JAK2-STAT6 pathway mediating macrophages activation. MSC-Exos improved the inflammatory microenvironment of dilated cardiomyopathy by regulating the polarization of the macrophage, which may hold promise for dilated cardiomyopathy clinical therapy.