Revascularization of chronic hibernating myocardium stimulates myocyte proliferation and partially reverses chronic adaptations to ischemia

Proteomics of the heart

Mass spectrometry-based proteomics is a sophisticated identification tool specializing in portraying protein dynamics at a molecular level. Proteomics provides biologists with a snapshot of context-dependent protein and proteoform expression, structural conformations, dynamic turnover, and protein-protein interactions. Cardiac proteomics can offer a broader and deeper understanding of the molecular mechanisms that underscore cardiovascular disease, and it is foundational to the development of future therapeutic interventions. This review encapsulates the evolution, current technologies, and future perspectives of proteomic-based mass spectrometry as it applies to the study of the heart. Key technological advancements have allowed researchers to study proteomes at a single-cell level and employ robot-assisted automation systems for enhanced sample preparation techniques, and the increase in fidelity of the mass spectrometers has allowed for the unambiguous identification of numerous dynamic posttranslational modifications. Animal models of cardiovascular disease, ranging from early animal experiments to current sophisticated models of heart failure with preserved ejection fraction, have provided the tools to study a challenging organ in the laboratory. Further technological development will pave the way for the implementation of proteomics even closer within the clinical setting, allowing not only scientists but also patients to benefit from an understanding of protein interplay as it relates to cardiac disease physiology.

Clinical impact of multimodality assessment of myocardial viability

Coronary artery disease (CAD) is a prevalent cause of left ventricular dysfunction. Nevertheless, effective elective revascularization, particularly surgical revascularization, can enhance long-term outcomes and, in selected cases, global left ventricular contractility. The assessment of myocardial viability and scars is still relevant in guiding treatment decisions and selecting patients who are likely to benefit most from blood flow restoration. Although the most recent randomized studies challenge the notion of "hibernating myocardium" and the clinical usefulness of assessing myocardial viability, the advancement of imaging techniques still renders this assessment valuable in specific situations. According to the guidelines of the European Society of Cardiology, non-invasive stress imaging may be employed to define myocardial ischemia and viability in patients with CAD and heart failure before revascularization. Currently, several non-invasive imaging techniques are available to evaluate the presence and extent of viable myocardium. The selection of the most suitable technique should be based on the patient, clinical context, and resource availability. This narrative review evaluates the characteristics of available imaging modalities for assessing myocardial viability to determine the most appropriate therapeutic strategy.

Myocardial ischemia/reperfusion: Translational pathophysiology of ischemic heart disease

Ischemic heart disease is the greatest health burden and most frequent cause of death worldwide. Myocardial ischemia/reperfusion is the pathophysiological substrate of ischemic heart disease. Improvements in prevention and treatment of ischemic heart disease have reduced mortality in developed countries over the last decades, but further progress is now stagnant, and morbidity and mortality from ischemic heart disease in developing countries are increasing. Significant problems remain to be resolved and require a better pathophysiological understanding. The present review attempts to briefly summarize the state of the art in myocardial ischemia/reperfusion research, with a view on both its coronary vascular and myocardial aspects, and to define the cutting edges where further mechanistic knowledge is needed to facilitate translation to clinical practice.

Persistent diastolic dysfunction in chronically ischemic hearts following coronary artery bypass graft

OBJECTIVE

A porcine model was used to study diastolic dysfunction in hibernating myocardium (HM) and recovery with coronary artery bypass surgery (CABG).

METHODS

HM was induced in Yorkshire-Landrace juvenile swine (n = 30) by placing a c-constrictor on left anterior descending artery causing chronic myocardial ischemia without infarction. At 12 weeks, animals developed the HM phenotype and were either killed humanely (HIB group; n = 11) or revascularized with CABG and allowed 4 weeks of recovery (HIB+CABG group; n = 19). Control pigs were matched for weight, age, and sex to the HIB group. Before the animals were killed humanely, cardiac magnetic resonance imaging (MRI) was done at rest and during a low-dose dobutamine infusion. Tissue was obtained for histologic and proinflammatory biomarker analyses.

RESULTS

Diastolic peak filling rate was lower in HIB compared with control (5.4 ± 0.7 vs 6.7 ± 1.4 respectively, P = .002), with near recovery with CABG (6.3 ± 0.8, P = .06). Cardiac MRI confirmed preserved global systolic function in all groups. Histology confirmed there was no transmural infarction but showed interstitial fibrosis in the endomysium in both the HIB and HIB+CABG groups compared with normal myocardium. Alpha-smooth muscle actin stain identified increased myofibroblasts in HM that were less apparent post-CABG. Cytokine and proteomic studies in HM showed decreased peroxisome proliferator-activator receptor gamma coactivator 1-alpha (PGC1-α) expression but increased expression of granulocyte-macrophage colony-stimulating factor and nuclear factor kappa-light-chain enhancer of activated B cells (NFκB). Following CABG, PGC1-α and NFκB expression returned to control whereas granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-α, and interferon gamma remained increased.

CONCLUSIONS

In porcine model of HM, increased NFκB expression, enhanced myofibroblasts, and collagen deposition along with decreased PGC1-α expression were observed, all of which tended toward normal with CABG. Estimates of impaired relaxation with MRI within HM during increased workload persisted despite CABG, suggesting a need for adjuvant therapies during revascularization.

An Adjuvant Stem Cell Patch with Coronary Artery Bypass Graft Surgery Improves Diastolic Recovery in Porcine Hibernating Myocardium

Diastolic dysfunction persists despite coronary artery bypass graft surgery (CABG) in patients with hibernating myocardium (HIB). We studied whether the adjunctive use of a mesenchymal stem cells (MSCs) patch during CABG improves diastolic function by reducing inflammation and fibrosis. HIB was induced in juvenile swine by placing a constrictor on the left anterior descending (LAD) artery, causing myocardial ischemia without infarction. At 12 weeks, CABG was performed using the left-internal-mammary-artery (LIMA)-to-LAD graft with or without placement of an epicardial vicryl patch embedded with MSCs, followed by four weeks of recovery. The animals underwent cardiac magnetic resonance imaging (MRI) prior to sacrifice, and tissue from septal and LAD regions were collected to assess for fibrosis and analyze mitochondrial and nuclear isolates. During low-dose dobutamine infusion, diastolic function was significantly reduced in HIB compared to the control, with significant improvement after CABG + MSC treatment. In HIB, we observed increased inflammation and fibrosis without transmural scarring, along with decreased peroxisome proliferator-activated receptor-gamma coactivator (PGC1α), which could be a possible mechanism underlying diastolic dysfunction. Improvement in PGC1α and diastolic function was noted with revascularization and MSCs, along with decreased inflammatory signaling and fibrosis. These findings suggest that adjuvant cell-based therapy during CABG may recover diastolic function by reducing oxidant stress–inflammatory signaling and myofibroblast presence in the myocardial tissue.

Can Percutaneous Coronary Intervention Revive a Failing Heart?

Coronary artery disease (CAD) remains the most common cause of heart failure with reduced ejection fraction; despite its prevalence, there is limited evidence to guide physicians in managing patients with CAD with percutaneous revascularization. The REVIVED-BCIS2 trial (ClinicalTrials.gov identifier: NCT01920048) represents the first randomized trial to assess the value of percutaneous coronary intervention in addition to optimal medical therapy in patients with ischaemic left ventricular systolic dysfunction and stable CAD. In this article, we review the results of the REVIVED-BCIS2 trial and compare them to the ClinicalTrials.gov Identifier: NCT00023595 trial (ClinicalTrials.gov Identifier: NCT00023595), which investigated the benefit of surgical revascularization on such patients. Finally, we suggest a pathway for physicians managing patients with ischaemic left ventricular systolic dysfunction based on the current evidence and highlight potential avenues for future research.

Novel Therapeutic Approaches Enhance PGC1-alpha to Reduce Oxidant Stress-Inflammatory Signaling and Improve Functional Recovery in Hibernating Myocardium

Ischemic heart disease affects millions of people around the world. Current treatment options, including coronary artery bypass grafting, do not result in full functional recovery, highlighting the need for novel adjunctive therapeutic approaches. Hibernation describes the myocardial response to prolonged ischemia and involves a set of complex cytoprotective metabolic and functional adaptations. PGC1-alpha, a key regulator of mitochondrial energy metabolism and inhibitor of oxidant-stress-inflammatory signaling, is known to be downregulated in hibernating myocardium. PGC1-alpha is a critical component of cellular stress responses and links cellular metabolism with inflammation in the ischemic heart. While beneficial in the acute setting, a chronic state of hibernation can be associated with self-perpetuating oxidant stress-inflammatory signaling which leads to tissue injury. It is likely that incomplete functional recovery following revascularization of chronically ischemic myocardium is due to persistence of metabolic changes as well as prooxidant and proinflammatory signaling. Enhancement of PGC1-alpha signaling has been proposed as a possible way to improve functional recovery in patients with ischemic heart disease. Adjunctive mesenchymal stem cell therapy has been shown to induce PGC1-alpha signaling in hibernating myocardium and could help improve clinical outcomes for patients undergoing bypass surgery.

Bone regeneration after marginal bone resection in two-stage treatment of chronic long bone infection - a combined histopathological and clinical pilot study

INTRODUCTION

In chronic bone infection, marginal bone resection avoids large and difficult to reconstruct bone defects. However, there is still a lack of knowledge on bone regeneration during chronic bone infection and bone healing capability after marginal bone resection. Therefore, the purpose of this study was to investigate the clinical and histopathological outcomes after marginal bone resection in chronic long bone infection. We hypothesized that there is a regenerative bone healing potential after marginal bone resection that results in an acceptable clinical outcome and improved pathohistological bone healing parameters during treatment.

MATERIALS AND METHODS

Nine patients were treated for chronic bone infections in a two-stage manner with marginal bone resection of the infected area and the placement of an antibiotic-loaded polymethyl methacrylate (PMMA) spacer at stage one followed by bone reconstruction at stage two combined with systemic antibiotic therapy. Comparable bone samples were harvested at the border region between vital and necrotic bone area during stage one and the identical location during stage two. Control bone samples were harvested from five healthy patients without bone infection. Clinical outcome in terms of infection eradication and bone consolidation were assessed. The phenotypic changes of osteocyte and morphological changes of lacunar-canalicular network were investigated by histological and immunohistochemical staining between the two observation periods. Furthermore, expression levels of major bone formation and resorption markers were investigated by immunohistochemical and tartrate-resistant acid phosphatase (TRAP) staining.

RESULTS

The clinical results with a follow-up of 12.9 months showed that eight of nine patients (88.9%) achieved bone consolidation after a planned two-stage procedure of marginal resection of necrotic bone and consecutive reconstruction. In four of the nine patients (44.4%), additional marginal debridements after stage two had to be performed. After marginal resection at stage one, the improved bone formation ability at stage two was demonstrated by significantly lower percentage of empty lacunae, significantly more mature osteocytes and higher BMP-2 positive cell density, whereas decreased resorption was indicated by significantly lower osteoclast density and RANKL/OPG ratio. In patients requiring additional debridement compared to patients without additional debridements, a significantly higher percentage of empty lacunae was found at stage one.

CONCLUSION

Marginal bone resection combined with local and systemic antibiotic therapy is a feasible treatment option to avoid large bone defects as bone from the marginal resection area seems to have good regenerative potential. Despite a high revision rate of 44.4%, this technique avoids large bone resection and revisions can be done by further marginal debridements.

Ischemic Cardiomyopathy and Heart Failure After Acute Myocardial Infarction

Purpose of Review

Ischemic cardiomyopathy refers to systolic left ventricular dysfunction in the setting of obstructive coronary artery disease and represents the most common cause of heart failure worldwide. It is often the combination of an irreversible loss of viable mass following an acute myocardial infarction (AMI) with a dysfunctional, but still viable, myocardium in the context of a chronically reduced myocardial blood flow and reduced coronary reserve. Medical treatments aiming at modulating neurohumoral response and restoring blood flow to the ischemic cardiomyocytes were shown to dramatically abate the occurrence of ventricular dysfunction and adverse remodeling in ischemic cardiomyopathy.

Recent Findings

Novel therapeutic approaches, such as mechanical unloading and modulation of the inflammatory response, appear to be promising. Furthermore, the understanding of the mechanisms by which, despite optimal treatment, heart failure ensues after AMI, with or without adverse remodeling and systolic dysfunction, is a critical step in the search for novel ways to tackle heart failure risk beyond preservation of left ventricular volumes and systolic function.

Summary

In this review article, we explore the principal pathophysiological mechanisms and pathways of heart failure in ischemic cardiomyopathy, therapeutic opportunities, and knowledge gaps in this area.

Coronary blood flow in heart failure: cause, consequence and bystander

Heart failure is a clinical syndrome where cardiac output is not sufficient to sustain adequate perfusion and normal bodily functions, initially during exercise and in more severe forms also at rest. The two most frequent forms are heart failure of ischemic origin and of non-ischemic origin. In heart failure of ischemic origin, reduced coronary blood flow is causal to cardiac contractile dysfunction, and this is true for stunned and hibernating myocardium, coronary microembolization, myocardial infarction and post-infarct remodeling, possibly also for the takotsubo syndrome. The most frequent form of non-ischemic heart failure is dilated cardiomyopathy, caused by genetic mutations, myocarditis, toxic agents or sustained tachyarrhythmias, where alterations in coronary blood flow result from and contribute to cardiac contractile dysfunction. Hypertrophic cardiomyopathy is caused by genetic mutations but can also result from increased pressure and volume overload (hypertension, valve disease). Heart failure with preserved ejection fraction is characterized by pronounced coronary microvascular dysfunction, the causal contribution of which is however not clear. The present review characterizes the alterations of coronary blood flow which are causes or consequences of heart failure in its different manifestations. Apart from any potentially accompanying coronary atherosclerosis, all heart failure entities share common features of impaired coronary blood flow, but to a different extent: enhanced extravascular compression, impaired nitric oxide-mediated, endothelium-dependent vasodilation and enhanced vasoconstriction to mediators of neurohumoral activation. Impaired coronary blood flow contributes to the progression of heart failure and is thus a valid target for established and novel treatment regimens.

Improving Terminology to Describe Coronary Artery Procedures: JACC Review Topic of the Week

Coronary artery disease (CAD) is treated with medical therapy with or without percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). The latter 2 options are commonly referred to as "myocardial revascularization" procedures. We reason that this term is inappropriate because it is suggestive of a single treatment effect of PCI and CABG (ie, the reestablishment of blood flow to ischemic myocardium) and obscures key mechanisms, such as the improvement in coronary flow capability in the absence of ongoing ischemia, the reperfusion in the presence of ischemia, and the prevention of myocardial infarction from CAD progression. We review the current evidence on the topic and suggest the use of a purely descriptive terminology ("invasive treatment by PCI or CABG") which has the potential to improve clinical decision making and guide future trial design.

Coronary revascularisation in patients with ischaemic cardiomyopathy

Heart failure resulting from ischaemic heart disease is associated with a poor prognosis despite optimal medical treatment. Despite this, patients with ischaemic cardiomyopathy have been largely excluded from randomised trials of revascularisation in stable coronary artery disease. Revascularisation has multiple potential mechanisms of benefit, including the reversal of myocardial hibernation, suppression of ventricular arrhythmias and prevention of spontaneous myocardial infarction. Coronary artery bypass grafting is considered the first-line mode of revascularisation in these patients; however, evidence from the Surgical Treatment of Ischaemic Heart Failure (STICH) trial showed a reduction in mortality, though this only became apparent with extended follow-up due to an excess of early adverse events in the surgical arm. There is currently no randomised controlled trial evidence for percutaneous coronary intervention in patients with ischaemic cardiomyopathy; however, the REVIVED-BCIS2 trial has recently completed recruitment and will address this gap in the evidence. Future directions include (1) clinical trials of revascularisation in patients hospitalised with heart failure, (2) defining the role of viability and ischaemia testing in heart failure, (3) studies to enhance the understanding of the mechanistic effects of revascularisation and (4) generating models to refine pre- and post-revascularisation risk prediction.

Myocardial stunning and hibernation revisited

Unlike acute myocardial infarction with reperfusion, in which infarct size is the end point reflecting irreversible injury, myocardial stunning and hibernation result from reversible myocardial ischaemia-reperfusion injury, and contractile dysfunction is the obvious end point. Stunned myocardium is characterized by a disproportionately long-lasting, yet fully reversible, contractile dysfunction that follows brief bouts of myocardial ischaemia. Reperfusion precipitates a burst of reactive oxygen species formation and alterations in excitation-contraction coupling, which interact and cause the contractile dysfunction. Hibernating myocardium is characterized by reduced regional contractile function and blood flow, which both recover after reperfusion or revascularization. Short-term myocardial hibernation is an adaptation of contractile function to the reduced blood flow such that energy and substrate metabolism recover during the ongoing ischaemia. Chronic myocardial hibernation is characterized by severe morphological alterations and altered expression of metabolic and pro-survival proteins. Myocardial stunning is observed clinically and must be recognized but is rarely haemodynamically compromising and does not require treatment. Myocardial hibernation is clinically identified with the use of imaging techniques, and the myocardium recovers after revascularization. Several trials in the past two decades have challenged the superiority of revascularization over medical therapy for symptomatic relief and prognosis in patients with chronic coronary syndromes. A better understanding of the pathophysiology of myocardial stunning and hibernation is important for a more precise indication of revascularization and its consequences. Therefore, this Review summarizes the current knowledge of the pathophysiology of these characteristic reperfusion phenomena and highlights their clinical implications.

Corin Overexpression Reduces Myocardial Infarct Size and Modulates Cardiomyocyte Apoptotic Cell Death

Altered expression of corin, a cardiac transmembrane serine protease, has been linked to dilated and ischemic cardiomyopathy. However, the potential role of corin in myocardial infarction (MI) is lacking. This study examined the outcomes of MI in wild-type vs. cardiac-specific overexpressed corin transgenic (Corin-Tg) mice during pre-MI, early phase (3, 24, 72 h), and late phase (1, 4 weeks) post-MI. Corin overexpression significantly reduced cardiac cell apoptosis (p < 0.001), infarct size (p < 0.001), and inhibited cleavage of procaspases 3, 9, and 8 (p < 0.05 to p < 0.01), as well as altered the expression of Bcl2 family proteins, Bcl-xl, Bcl2 and Bak (p < 0.05 to p < 0.001) at 24 h post-MI. Overexpressed cardiac corin also significantly modulated heart function (ejection fraction, p < 0.0001), lung congestion (lung weight to body weight ratio, p < 0.0001), and systemic extracellular water (edema, p < 0.05) during late phase post-MI. Overall, cardiac corin overexpression significantly reduced apoptosis, infarct size, and modulated cardiac expression of key members of the apoptotic pathway in early phase post-MI; and led to significant improvement in heart function and reduced congestion in late phase post-MI. These findings suggest that corin may be a useful target to protect the heart from ischemic injury and subsequent post-infarction remodeling.

Experimental models of cardiac physiology and pathology

Experimental models of cardiac disease play a key role in understanding the pathophysiology of the disease and developing new therapies. The features of the experimental models should reflect the clinical phenotype, which can have a wide spectrum of underlying mechanisms. We review characteristics of commonly used experimental models of cardiac physiology and pathophysiology in all translational steps including in vitro, small animal, and large animal models. Understanding their characteristics and relevance to clinical disease is the key for successful translation to effective therapies.

Quantitative proteomic and phosphoproteomic profiling of ischemic myocardial stunning in swine

Despite decades of research on the pathophysiology of myocardial stunning, protein changes and/or phosphorylation status underlying alterations in cardiac function/structure remain inadequately understood. Here, we utilized comprehensive and quantitative proteomic and phosphoproteomic approaches to explore molecular mechanisms of myocardial stunning in swine. The closed-chest swine (n = 5 pigs) were subjected to a 10-min left anterior descending coronary artery (LAD) occlusion producing regional myocardial stunning. Tissues from the ischemic LAD region and a remote nonischemic area of the left ventricle were collected 1 h after reperfusion. Ion current-based proteomics (IonStar) and quantitative phosphoproteomics were employed in parallel to identify alterations in protein level and site-specific phosphorylation changes. A novel swine heart protein database exhibiting high accuracy and low redundancy was developed here to facilitate comprehensive study. Further informatic investigations identified potential protein-protein interactions in stunned myocardium. In total, we quantified 2,099 protein groups and 4,699 phosphorylation sites with only 0.4% missing values. Proteomic analyses revealed downregulation of contractile function and extracellular matrix remodeling. Meanwhile, alterations in phosphorylation linked with contractile dysfunction and apoptotic cell death were uncovered. NetworKIN/STRING analysis predicted regulatory kinases responsible for altered phosphosites, such as protein kinase C-mediated phosphorylation of cardiac troponin I-S199 and CaMKII-mediated phosphorylation of phospholamban-T17. In summary, the ion current-based proteomics and phosphoproteomics reliably identified novel alterations in protein content and phosphorylation contributing to contractile dysfunction, extracellular matrix (ECM) damage, and programmed cell death in stunned myocardium, which corroborate well with our physiological observations. Moreover, this work developed a comprehensive database of the swine heart proteome, a highly valuable resource for future translational research in porcine models with cardiovascular diseases.NEW & NOTEWORTHY We first used ion current-based proteomics and phosphoproteomics to reliably identify novel alterations in protein expression and phosphorylation contributing to contractile dysfunction, extracellular matrix (ECM) damage, and programmed cell death in stunned myocardium and developed a comprehensive swine heart-specific proteome database, which provides a valuable resource for future research in porcine models of cardiovascular diseases.

Transmural variation in microvascular remodeling following percutaneous revascularization of a chronic coronary stenosis in swine

Remodeling of the coronary microcirculation is known to occur distal to a chronic coronary stenosis, but the reversibility of these changes and their functional significance on maximum myocardial perfusion before and after revascularization is unknown. Accordingly, swine instrumented with a chronic silastic stenosis on the left anterior descending coronary artery to produce hibernating myocardium underwent percutaneous coronary intervention (PCI; n = 8) and were compared with animals with a persistent stenosis (n = 8), as well as sham controls (n = 6). Stenotic animals demonstrated an increased subendocardial arteriolar wall thickness-to-lumen ratio (37.8 ± 3.3 vs. 28.3 ± 1.3% in sham, P = 0.04), reduced lumen area per arteriole (597 ± 88 vs. 927 ± 113 μm2, P = 0.04), and a compensatory increase in arteriolar density (9.4 ± 1.0 vs. 5.3 ± 0.4 arterioles/mm2, P < 0.01). As a result, vasodilated flow immediately after PCI was similar to normally perfused remote regions (5.1 ± 1.0 vs. 4.8 ± 0.9 ml·min-1·g-1, P = 0.87). When assessed 1-mo after PCI, increases in wall thickness-to-lumen diameter (42.2 ± 3.3%) and reductions in lumen area per arteriole (638 ± 59 μm2) remained unchanged, but arteriolar density returned to normal (5.2 ± 0.5 arterioles/mm2). As a result, maximum subendocardial flow during adenosine declined and was lower than remote regions (2.6 ± 0.3 vs. 5.9 ± 1.1 ml·min-1·g-1, P = 0.01). There was no microvascular remodeling in subepicardial arterioles, and maximum perfusion remained unchanged. These data demonstrate that subendocardial microvascular remodeling occurs distal to a chronic epicardial stenosis. The regression of arteriolar density without increases in luminal area may precipitate stress-induced subendocardial ischemia in the absence of a physiologically significant stenosis.NEW & NOTEWORTHY Swine with a chronic coronary stenosis exhibit subendocardial microvascular remodeling distal to a critical stenosis characterized by an increase in arteriolar wall thickness and reduction in lumen area with a compensatory increase in arteriolar density. The present study is the first to demonstrate that subendocardial arteriolar density normalizes 1-mo after revascularization, but the lumen area of individual arterioles remains reduced. This leads to a reduction in maximal subendocardial perfusion at this time point despite initial normalization of vasodilator reserve after revascularization. This pattern of chronic microvascular structural remodeling could contribute to recurrent subendocardial ischemia in the absence of coronary restenosis during tachycardia and increases in myocardial oxygen demand.

Association of circulating BMP9 with coronary heart disease and hypertension in Chinese populations

Background

Bone morphogenetic protein9 (BMP9) has been reported to have a role in vascular development. However, there is still a lack of information regarding the association between circulating BMP9 levels and cardiovascular disease in humans. The goal of this study is to measure circulating BMP9 concentrations in patients with essential hypertension (HTN), coronary heart disease (CHD) and HTN + CHD, and evaluates the relationship between circulating BMP9 and these cardiovascular diseases.

Methods

A total of 417 individuals were recruited for this cross-sectional study from June 2015 to December 2017. These subjects were screened for HTN and CHD. Circulating BMP9 concentrations were measured by ELISA.

Results

Circulating BMP9 concentrations were significantly low in HTN, CHD and HTN + CHD individuals relative to those of the healthy individuals. Circulating BMP9 correlated negatively with SBP, FIns and HOMA-_IR in HTN patients and correlated negatively with FBG and 2 h-BG in CHD patients. In both HTN and CHD patients, circulating BMP9 correlated negatively with BMI, WHR, FAT%, BP and TG. Multivariate logistic regression analysis showed that circulating BMP9 levels were associated with HTN, HTN + CHD and CHD. Individuals with low quartile of circulating BMP9 had a significantly high risk of HTN or/and CHD as compared with those in high quartile.

Conclusions

BMP9 is likely to be a biomarker for cardiovascular disease in humans, and it may play a role in the progression of cardiovascular disease.

Trial registration

ChiCTR-OPC-14005324.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1095-2) contains supplementary material, which is available to authorized users.

Actual Problems of Diagnostics of Viable Myocardium

The article presents modern analysis of the studies and reflects the key problems concerning the feasibility of performing cardiac MRI for assessment of myocardial viability in patients with history of myocardial infarction (with postinfarction cardiosclerosis), as well as the effectiveness of the method for predicting restoration of the function of hibernating myocardium after myocardial revascularization.

Viability testing to guide myocardial revascularisation in patients with heart failure

Myocardial revascularisation has the potential to restore ventricular function and improve survival in patients with heart failure due to underlying coronary artery disease. Viability testing is routinely used to identify which patients are likely to benefit, given that revascularisation may entail substantial procedural risk. However, while the concept of viability testing and revascularisation of patients with ‘hibernating myocardium’ is strongly supported by observational series, randomised studies have failed to demonstrate clear benefit. This divergence in the evidence base is reflected in current European and US guidelines, in which viability testing has a class II recommendation. In this article, we review the current evidence for routine viability testing prior to revascularisation of patients with heart failure, outline its use in clinical practice and discuss ongoing trials in the field.

The combined effect of serum cystatin C and dyslipidemia on hypertension in a large health check-up population in China

OBJECTIVE: Some studies have reported that both serum cystatin C (Cys C) and dyslipidemia are independently associated with hypertension. However, the combined effect of the two factors is still unknown. The present study was aimed at investigating the effect of Cys C combined with dyslipidemia on hypertension in a large health check-up population in China. METHODS: A total of 203 233 health check-up subjects from January 2011 to July 2016 were recruited into this cross-sectional study. A multivariate logistic regression model was used to evaluate the combined effect of Cys C and dyslipidemia on hypertension.RESULTS: In univariate analysis, Cys C, high-density lipoprotein cholesterol, low-density lipoprotein, total cholesterol, and triglycerides were independently correlated with hypertension (p < 0.001). A concentration-dependent combined effect of serum Cys C and dyslipidemia on hypertension was observed in multivariate regression analysis. When compared with Cys C of <0.82 mg/L, the risk of hypertension in Cys C of <0.82 mg/L with dyslipidemia, Cys C  of 0.82-0.94 mg/L with dyslipidemia, Cys C  of 0.94-1.08 mg/L with dyslipidemia, and Cys C  of ≥1.08 mg/L with dyslipidemia was increased 1.946 (95% confidence interval [CI]: 1.827-2.074), 1.973 (95% CI: 1.864-2.088), 2.047 (95% CI: 1.941-2.158), and 2.038 (95% CI: 1.937-2.143) folds, respectively, after adjustment.CONCLUSION: There was an association between hypertension and the combined effect of Cys C with dyslipidemia.

Identifying and Managing Hibernating Myocardium: What's New and What Remains Unknown?

PURPOSE OF REVIEW

Hibernation is an important and reversible cause of myocardial dysfunction in ischaemic heart failure.

RECENT FINDINGS

Hibernation is an adaptive process that promotes myocyte survival over maintaining contractile function. It is innate to mammalian physiology, sharing features with physiological hibernation in other species. Advanced imaging methods have reasonable accuracy in identifying hibernating myocardium. Novel superior hybrid methods may provide diagnostic potential. New evidence supports the role of surgical revascularisation in ischaemic heart failure, but the role of viability tests in planning such procedures remains unclear. Research to date has exclusively involved patients with ambulatory heart failure: Investigating the role of hibernation in ADHF is a key avenue for the future. Whilst our understanding of hibernation pathophysiology has improved dramatically, the clinical utility of identifying and targeting hibernation remains unclear.

Evaluation of changes in left ventricular structure and function in hypertensive patients with coronary artery disease after PCI using real-time three-dimensional echocardiography

We aimed to evaluate the changes in left ventricular structure and function in hypertensive patients with coronary artery disease before and after percutaneous coronary intervention (PCI) using real-time three-dimensional echocardiography. Two hundred and eighty hypertensive patients with coronary artery disease undergoing PCI and 120 cases who did not receive PCI in our hospital were selected as the subjects of our study. All patients were administered with routine antiplatelet, anticoagulant, lipid-lowering, antihypertensive, dilating coronary artery and other medications. The left ventricular systolic function and systolic synchrony index changes before and after subjects were treated by PCI were analyzed using three-dimensional echocardiography. At 2 days before surgery, there were no significant differences in the left ventricular end-diastolic volume, left ventricular end-systolic volume (LVESV) and ejection fraction (EF) between the two patient groups (P>0.05). At 3 months and 9 months, the two key time points after PCI, the LVESV level in the PCI group was distinctly decreased, while EF was significantly increased (P<0.05). In addition, before treatment, there were no significant differences in the parameters of time from the corresponding segment of the myocardium to the minimal systolic volume in two patient groups, such as Tmsv-16SD, Tmsv-16Dif, Tmsv-12SD, Tmsv-12Dif, Tmsv-6SD and Tmsv-6Dif (P>0.05); however, the parameters of time from the corresponding segment of the myocardium to the minimal systolic volume in patients in the PCI group were significantly reduced at 3 and 9 months after surgery (P<0.05). Three-dimensional echocardiography can evaluate the critical parameters in the prognosis of hypertensive patients with coronary artery disease after PCI accurately and in real-time, which may play a significant role.

Guidelines for experimental models of myocardial ischemia and infarction

Myocardial infarction is a prevalent major cardiovascular event that arises from myocardial ischemia with or without reperfusion, and basic and translational research is needed to better understand its underlying mechanisms and consequences for cardiac structure and function. Ischemia underlies a broad range of clinical scenarios ranging from angina to hibernation to permanent occlusion, and while reperfusion is mandatory for salvage from ischemic injury, reperfusion also inflicts injury on its own. In this consensus statement, we present recommendations for animal models of myocardial ischemia and infarction. With increasing awareness of the need for rigor and reproducibility in designing and performing scientific research to ensure validation of results, the goal of this review is to provide best practice information regarding myocardial ischemia-reperfusion and infarction models.

Listen to this article’s corresponding podcast at ajpheart.podbean.com/e/guidelines-for-experimental-models-of-myocardial-ischemia-and-infarction/.

Proteomic footprint of myocardial ischemia/reperfusion injury: Longitudinal study of the at-risk and remote regions in the pig model

Reperfusion alters post-myocardial infarction (MI) healing; however, very few systematic studies report the early molecular changes following ischemia/reperfusion (I/R). Alterations in the remote myocardium have also been neglected, disregarding its contribution to post-MI heart failure (HF) development. This study characterizes protein dynamics and contractile abnormalities in the ischemic and remote myocardium during one week after MI. Closed-chest 40 min I/R was performed in 20 pigs sacrificed at 120 min, 24 hours, 4days, and 7days after reperfusion (n = 5 per group). Myocardial contractility was followed up by cardiac magnetic resonance (CMR) and tissue samples were analyzed by multiplexed quantitative proteomics. At early reperfusion (120 min), the ischemic area showed a coordinated upregulation of inflammatory processes, whereas interstitial proteins, angiogenesis and cardio-renal signaling processes increased at later reperfusion (day 4 and 7). Remote myocardium showed decreased contractility at 120 min- and 24 h-CMR accompanied by transient alterations in contractile and mitochondrial proteins. Subsequent recovery of regional contractility was associated with edema formation on CMR and increases in inflammation and wound healing proteins on post-MI day 7. Our results establish for the first time the altered protein signatures in the ischemic and remote myocardium early after I/R and might have implications for new therapeutic targets to improve early post-MI remodeling.

Myocardial Viability: Survival Mechanisms and Molecular Imaging Targets in Acute and Chronic Ischemia

Myocardial responses to acute ischemia/reperfusion and to chronic ischemic conditions have been studied extensively at all levels of organization. These include subcellular (eg, mitochondria in vitro); intact, large animal models (eg, swine with chronic coronary stenosis); as well as human subjects. Investigations in humans have used positron emission tomographic metabolic and myocardial blood flow measurements, assessment of gene expression and anatomic description of myocardium obtained at the time of coronary artery revascularization, ventricular assist device placement, or heart transplantation. A multitude of genetic, molecular, and metabolic pathways have been identified, which may promote either myocyte survival or death or, most interestingly, both. Many of these potential mediators in both acute ischemia/reperfusion and adaptations to chronic ischemic conditions involve the mitochondria, which play a central role in cellular energy production and homeostasis. The present review is focused on operative survival mechanisms and potential myocardial viability molecular imaging targets in acute and chronic ischemia, especially those which impact mitochondrial function.

Baseline subendocardial viability ratio influences left ventricular systolic improvement with cardiac rehabilitation

OBJECTIVE

Subendocardial viability ratio (SEVR), defined as diastolic to systolic pressure-time integral ratio, is a useful tool reflecting the balance between coronary perfusion and arterial load. Suboptimal SEVR creating a supply-demand imbalance may limit favorable cardiac response to cardiac rehabilitation (CR). To explore this hypothesis, we designed a study to analyze the relationship between baseline SEVR and response to CR in patients with coronary artery disease (CAD).

METHODS

In this prospectively study, after baseline arterial tonometry, echocardiography, and cardiopulmonary exercise tests (CPETs), patients undergone 20 sessions of CR. Post-CR echocardiographic and CPET measurements were obtained for comparison.

RESULTS

Final study population was comprised of fifty subjects. Study population was divided into two subgroups by median SEVR value (1.45, interquartile range 0.38). Although both groups showed significant improvements in peak VO2, significant improvements in oxygen pulse (πO2) (from 16.1±3.4 to 19.1±4.8 mL O2.kg-1.beat-1; p<0.001) and stroke volume index (from 31±5 to 35±6 mL; p=0.008) were observed in only the patients in the above-median subgroup. The change in πO2 was also significantly higher in the above-median SEVR subgroup (2.9±3.3 vs. 0.5±2.4; p=0.007).

CONCLUSION

Our study shows that baseline supply-demand imbalance may limit systolic improvement response to CR in patients with CAD.

Comparative Efficacy of Intracoronary Allogeneic Mesenchymal Stem Cells and Cardiosphere-Derived Cells in Swine with Hibernating Myocardium

RATIONALE

Allogeneic bone marrow-derived mesenchymal stem cells (MSCs) and cardiosphere-derived cells (CDCs) have each entered clinical trials, but a direct comparison of these cell types has not been performed in a large animal model of hibernating myocardium.

OBJECTIVE

Using completely blinded methodology, we compared the efficacy of global intracoronary allogeneic MSCs (icMSCs, ≈35×10(6)) and CDCs (icCDCs, ≈35×10(6)) versus vehicle in cyclosporine-immunosuppressed swine with a chronic left anterior descending coronary artery stenosis (n=26).

METHODS AND RESULTS

Studies began 3 months after instrumentation when wall thickening was reduced (left anterior descending coronary artery % wall thickening [mean±SD], 38±11% versus 83±26% in remote; P<0.01) and similar among groups. Four weeks after treatment, left anterior descending coronary artery % wall thickening increased similarly after icCDCs and icMSCs, whereas it remained depressed in vehicle-treated controls (icMSCs, 51±13%; icCDCs, 51±17%; vehicle, 34±3%, treatments P<0.05 versus vehicle). There was no change in myocardial perfusion. Both icMSCs and icCDCs increased left anterior descending coronary artery myocyte nuclear density (icMSCs, 1601±279 nuclei/mm(2); icCDCs, 1569±294 nuclei/mm(2); vehicle, 973±181 nuclei/mm(2); treatments P<0.05 versus vehicle) and reduced myocyte diameter (icMSCs, 16.4±1.5 μm; icCDCs, 16.8±1.2 μm; vehicle, 20.2±3.7 μm; treatments P<0.05 versus vehicle) to the same extent. Similar changes in myocyte nuclear density and diameter were observed in the remote region of cell-treated animals. Cell fate analysis using Y-chromosome fluorescent in situ hybridization demonstrated rare cells from sex-mismatched donors.

CONCLUSIONS

Allogeneic icMSCs and icCDCs exhibit comparable therapeutic efficacy in a large animal model of hibernating myocardium. Both cell types produced equivalent increases in regional function and stimulated myocyte regeneration in ischemic and remote myocardium. The activation of endogenous myocyte proliferation and regression of myocyte cellular hypertrophy support a common mechanism of cardiac repair.

Cardiomyocyte Remodeling in Atrial Fibrillation and Hibernating Myocardium: Shared Pathophysiologic Traits Identify Novel Treatment Strategies?

Atrial fibrillation (AF) is the most common arrhythmia and is associated with a high risk of morbidity and mortality. However, there are limited treatment strategies for prevention of disease onset and progression. Development of novel therapies for primary and secondary prevention of AF is critical and requires improved understanding of the cellular and molecular mechanisms underlying the AF disease process. Translational and clinical studies conducted over the past twenty years have revealed that atrial remodeling in AF shares several important pathophysiologic traits with the remodeling processes exhibited by hibernating myocardium that develop in response to chronic ischemia. These shared features, which include an array of structural, metabolic, and electrophysiologic changes, appear to represent a conserved adaptive myocyte response to chronic stress that involves dedifferentiation towards a fetal phenotype to promote survival. In this review, we discuss the pathophysiology of AF, summarize studies supporting a common remodeling program in AF and hibernating myocardium, and propose future therapeutic implications of this emerging paradigm. Ultimately, better understanding of the molecular mechanisms of atrial myocyte remodeling during the onset of AF and the transition from paroxysmal to persistent stages of the disease may facilitate discovery of new therapeutic targets.