Distinct Transcriptomic and Proteomic Profile Specifies Patients Who Have Heart Failure With Potential of Myocardial Recovery on Mechanical Unloading and Circulatory Support.

BACKGROUND: Extensive evidence from single-center studies indicates that a subset of patients with chronic advanced heart failure (HF) undergoing left ventricular assist device (LVAD) support show significantly improved heart function and reverse structural remodeling (ie, termed "responders"). Furthermore, we recently published a multicenter prospective study, RESTAGE-HF (Remission from Stage D Heart Failure), demonstrating that LVAD support combined with standard HF medications induced remarkable cardiac structural and functional improvement, leading to high rates of LVAD weaning and excellent long-term outcomes. This intriguing phenomenon provides great translational and clinical promise, although the underlying molecular mechanisms driving this recovery are largely unknown. METHODS: To identify changes in signaling pathways operative in the normal and failing human heart and to molecularly characterize patients who respond favorably to LVAD unloading, we performed global RNA sequencing and phosphopeptide profiling of left ventricular tissue from 93 patients with HF undergoing LVAD implantation (25 responders and 68 nonresponders) and 12 nonfailing donor hearts. Patients were prospectively monitored through echocardiography to characterize their myocardial structure and function and identify responders and nonresponders. RESULTS: These analyses identified 1341 transcripts and 288 phosphopeptides that are differentially regulated in cardiac tissue from nonfailing control samples and patients with HF. In addition, these unbiased molecular profiles identified a unique signature of 29 transcripts and 93 phosphopeptides in patients with HF that distinguished responders after LVAD unloading. Further analyses of these macromolecules highlighted differential regulation in 2 key pathways: cell cycle regulation and extracellular matrix/focal adhesions. CONCLUSIONS: This is the first study to characterize changes in the nonfailing and failing human heart by integrating multiple -omics platforms to identify molecular indices defining patients capable of myocardial recovery. These findings may guide patient selection for advanced HF therapies and identify new HF therapeutic targets.

Exosomes secreted by cardiosphere-derived cells reduce scarring, attenuate adverse remodelling, and improve function in acute and chronic porcine myocardial infarction.

Aims: Naturally secreted nanovesicles known as exosomes are required for the regenerative effects of cardiosphere-derived cells (CDCs), and exosomes mimic the benefits of CDCs in rodents. Nevertheless, exosomes have not been studied in a translationally realistic large-animal model. We sought to optimize delivery and assess the efficacy of CDC-secreted exosomes in pig models of acute (AMI) and convalescent myocardial infarction (CMI). Methods and Results: In AMI, pigs received human CDC exosomes (or vehicle) by intracoronary (IC) or open-chest intramyocardial (IM) delivery 30 min after reperfusion. No-reflow area and infarct size (IS) were assessed histologically at 48 h. Intracoronary exosomes were ineffective, but IM exosomes decreased IS from 80 ± 5% to 61 ± 12% (P= 0.001) and preserved left ventricular ejection fraction (LVEF). In a randomized placebo-controlled study of CMI, pigs 4 weeks post-myocardial infarction (MI) underwent percutaneous IM delivery of vehicle (n = 6) or CDC exosomes (n = 6). Magnetic resonance imaging (MRI) performed before and 1 month after treatment revealed that exosomes (but not vehicle) preserved LV volumes and LVEF (−0.1 ± 2.2% vs. −5.4 ± 3.6%, P= 0.01) while decreasing scar size. Histologically, exosomes decreased LV collagen content and cardiomyocyte hypertrophy while increasing vessel density. Conclusion: Cardiosphere-derived cell exosomes delivered IM decrease scarring, halt adverse remodelling and improve LVEF in porcine AMI and CMI. While conceptually attractive as cell-free therapeutic agents for myocardial infarction, exosomes have the disadvantage that IM delivery is necessary.

Therapeutic efficacy of cardiosphere-derived cells in a transgenic mouse model of non-ischaemic dilated cardiomyopathy.

AIM: Cardiosphere-derived cells (CDCs) produce regenerative effects in the post-infarct setting. However, it is unclear whether CDCs are beneficial in non-ischaemic dilated cardiomyopathy (DCM). We tested the effects of CDC transplantation in mice with cardiac-specific Gαq overexpression, which predictably develop progressive cardiac dilation and failure, with accelerated mortality. METHODS AND RESULTS: Wild-type mouse CDCs (10(5) cells) or vehicle only were injected intramyocardially in 6-, 8-, and 11-week-old Gαq mice. Cardiac function deteriorated in vehicle-treated mice over 3 months of follow-up, accompanied by oxidative stress, inflammation and adverse ventricular remodelling. In contrast, CDCs preserved cardiac function and volumes, improved survival, and promoted cardiomyogenesis while blunting Gαq-induced oxidative stress and inflammation in the heart. The mechanism of benefit is indirect, as long-term engraftment of transplanted cells is vanishingly low. CONCLUSIONS: Cardiosphere-derived cells reverse fundamental abnormalities in cell signalling, prevent adverse remodelling, and improve survival in a mouse model of DCM. The ability to impact favourably on disease progression in non-ischaemic heart failure heralds new potential therapeutic applications of CDCs.

Angiopoietins 1 and 2 in sputum supernatant of optimally treated asthmatics: the effect of smoking.

BACKGROUND: Angiopoietin-1 (Ang-1) is an essential mediator of angiogenesis by establishing vascular integrity, whereas angiopoietin-2 (Ang-2) acts as its natural inhibitor. OBJECTIVE: We aimed to determine the levels of angiopoietins in sputum supernatants of patients with optimally treated asthma and to investigate whether smoking represents a significant covariate on the above possible processes. METHODS: Eighty-seven patients with asthma (42 smokers) and 28 healthy subjects (14 smokers) were studied. All subjects underwent lung function tests, bronchial hyper-responsiveness assessment and sputum induction for cell count identification and measurement of Ang-1, Ang-2, vascular endothelial growth factor, TGF-ß1, MMP-2, IL-13, Eosinophilic cationic protein and IL-8 in supernatants. Airway vascular permeability (AVP) index was also assessed. RESULTS: Ang-1 (ng/mL) levels were significantly higher in patients with asthma compared to normal subjects. Smoking significantly increased Ang-1 levels [median, interquartile ranges 24 (13-37) in smoking asthmatics vs 10 (7-14) in nonsmoking asthmatics vs 5·3 (3·7-6·5) and 4·6 (3·8-5·7) in healthy smokers and nonsmokers, respectively, P < 0·001]. Similar results were observed for Ang-2 (pg/mL) [168 (132-203) vs 124 (82-152) vs 94 (78-113) vs 100 (96-108), respectively, P < 0·001]. Regression analysis in the whole study population showed a significant negative association for Ang-1, with AVP index, and MMP-2. Smoking was a significant covariate for both Ang-1 and Ang-2 in asthmatic patients. CONCLUSIONS: Ang-1 and Ang-2 levels are upregulated in patients with optimally treated asthma. Our data support a possible role for smoking in the angiogenetic process in asthma.

Afterload-induced left ventricular diastolic dysfunction during myocardial ischaemia and reperfusion.

NEW FINDINGS: What is the central question of this study? While the load dependence of the diastolic function is established for the normal heart, little is known about the response of the acutely ischaemic and reperfused myocardium to alterations in afterload. What is the main finding and its importance? Using a model that simulates the clinical scenario of acute ischaemia-reperfusion, we show that increased afterload aggravates diastolic dysfunction during both acute ischaemia and reperfusion. In addition, increased afterload induces diastolic dyssynchrony, which might be the underlying mechanism of the diastolic dysfunction of the ischaemic myocardium. These findings provide us with new information regarding how better to manage patients who undergo revascularization therapy after acute myocardial infarction. The effects of changes in left ventricular (LV) afterload on diastolic function of acutely ischaemic and reperfused myocardium have not been studied in depth. We examined the following factors: (i) the consequences of increasing the LV afterload on LV diastolic function during acute ischaemia and reperfusion; (ii) whether the myocardial response to afterload elevation is stable throughout a 2 h reperfusion period; and (iii) the role of LV wall synchrony in the development of afterload-induced diastolic dysfunction. We instrumented 12 anaesthetized, open-chest pigs with Millar pressure catheters and piezoelectric crystals before ligating mid-left anterior descending coronary artery for 1 h, followed by reperfusion for 2 h. Six of the animals survived throughout the 2 h of reperfusion, and their data were used for comparisons across the different experimental phases. Left ventricular afterload was increased by inflating an intra-aortic balloon. Data were recorded at baseline, after 20 min of coronary occlusion and at 30 and 90 min of myocardial reperfusion. The increased afterload for 2 min lengthened the isovolumic relaxation during ischaemia and during early and late reperfusion but had no significant effect on isovolumic relaxation before coronary artery occlusion. Increasing the afterload aggravated LV diastolic dyssynchrony during coronary artery occlusion, but not during reperfusion. The afterload-induced prolongation of isovolumic relaxation was positively correlated with afterload-induced diastolic dyssynchrony. These observations indicate that, during myocardial ischaemia and throughout reperfusion, LV diastolic function is afterload dependent. Afterload-induced diastolic dyssynchrony might be an underlying mechanism of diastolic dysfunction during acute ischaemia.

Validation of contrast-enhanced magnetic resonance imaging to monitor regenerative efficacy after cell therapy in a porcine model of convalescent myocardial infarction.

BACKGROUND: Magnetic resonance imaging (MRI) in the CArdiosphere-Derived aUtologous stem CElls to reverse ventricUlar dySfunction (CADUCEUS) trial revealed that cardiosphere-derived cells (CDCs) decrease scar size and increase viable myocardium after myocardial infarction (MI), but MRI has not been validated as an index of regeneration after cell therapy. We tested the validity of contrast-enhanced MRI in quantifying scarred and viable myocardium after cell therapy in a porcine model of convalescent MI. METHODS AND RESULTS: Yucatan minipigs underwent induction of MI and 2-3 weeks later were randomized to receive intracoronary infusion of 12.5×10(6) mismatched allogeneic CDCs or vehicle. Allogeneic CDCs induced mild local mononuclear infiltration but no systemic immunogenicity. MRI revealed that allogeneic CDCs attenuated remodeling, improved global and regional function, decreased scar size, and increased viable myocardium compared with placebo 2 months post-treatment. Extensive histological analysis validated quantitatively the MRI measurements of scar size, scar mass, and viable mass. CDCs neither altered gadolinium contrast myocardial kinetics nor induced changes in vascular density or architecture in viable and scarred myocardium. Histology demonstrated that CDCs lead to cardiomyocyte hyperplasia in the border zone, consistent with the observed stimulation of endogenous regenerative mechanisms (cardiomyocyte cycling, upregulation of endogenous progenitors, angiogenesis). CONCLUSIONS: Contrast-enhanced MRI accurately measures scarred and viable myocardium after cell therapy in a porcine model of convalescent MI. MRI represents a useful tool for assessing dynamic changes in the infarct and monitoring regenerative efficacy.

Cardiospheres reverse adverse remodeling in chronic rat myocardial infarction: roles of soluble endoglin and Tgf-ß signaling.

Self-assembling heart-derived stem cell clusters named cardiospheres (CSps) improve function and attenuate remodeling in rodent models of acute myocardial infarction. The effects of CSps in chronically remodeled myocardium post-MI, and the underlying mechanisms, remain unknown. One month after permanent coronary ligation, rats were randomly assigned to injection of vehicle (controls) or CSps in the peri-infarct area. One month post-injection, CSps increased left ventricular function, reduced scar mass and collagen density, and enhanced vascularity within the infarct zone compared to controls. Immunoblots revealed Tgfß-1/smad cascade downregulation and an increase in soluble endoglin post-CSp injection. Six months post-transplantation, left ventricular function further improved and cardiomyocyte hypertrophy was attenuated in the CSp-treated group. In vitro, co-culture of CSps with fibroblasts recapitulated the suppression of the Tgf-ß1/smad pathway changes, responses which were blunted by neutralizing antibody against endoglin. Thus, cardiosphere transplantation enhances angiogenesis and reduces fibrosis in chronically infarcted myocardium, leading to partial reversal of cardiac dysfunction. The underlying mechanism involves inhibition of Tgf-ß1/smad signaling by CSp-secreted soluble endoglin.

In vivo contrast free chronic myocardial infarction characterization using diffusion-weighted cardiovascular magnetic resonance.

BACKGROUND: Despite the established role of late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in characterizing chronic myocardial infarction (MI), a significant portion of chronic MI patients are contraindicative for the use of contrast agents. One promising alternative contrast free technique is diffusion weighted CMR (dwCMR), which has been shown ex vivo to be sensitive to myocardial fibrosis. We used a recently developed in vivo dwCMR in chronic MI pigs to compare apparent diffusion coefficient (ADC) maps with LGE imaging for infarct characterization. METHODS: In eleven mini pigs, chronic MI was induced by complete occlusion of the left anterior descending artery for 150 minutes. LGE, cine, and dwCMR imaging was performed 8 weeks post MI. ADC maps were derived from three orthogonal diffusion directions (b = 400 s/mm2) and one non-diffusion weighted image. Two semi-automatic infarct classification methods, threshold and full width half max (FWHM), were performed in both LGE and ADC maps. Regional wall motion (RWM) analysis was performed and compared to ADC maps to determine if any observed ADC change was significantly influenced by bulk motion. RESULTS: ADC of chronic MI territories was significantly increased (threshold: 2.4 ± 0.3 µm2/ms, FWHM: 2.4 ± 0.2 µm2/ms) compared to remote myocardium (1.4 ± 0.3 µm2/ms). RWM was significantly reduced (threshold: 1.0 ± 0.4 mm, FWHM: 0.9 ± 0.4 mm) in infarcted regions delineated by ADC compared to remote myocardium (8.3 ± 0.1 mm). ADC-derived infarct volume and location had excellent agreement with LGE. Both LGE and ADC were in complete agreement when identifying transmural infarcts. Additionally, ADC was able to detect LGE-delineated infarcted segments with high sensitivity, specificity, PPV, and NPV. (threshold: 0.88, 0.93, 0.87, and 0.94, FWHM: 0.98, 0.97, 0.93, and 0.99, respectively). CONCLUSIONS: In vivo diffusion weighted CMR has potential as a contrast free alternative for LGE in characterizing chronic MI.

Cardiac Reverse Remodeling Mediated by HeartMate 3 Left Ventricular Assist Device: Comparison to Older Generation Devices.

Currently, the fully magnetically levitated left ventricular assist device (LVAD) HeartMate 3 (HM3) is the only commercially available device for advanced heart failure (HF) patients. However, the left ventricular (LV) functional and structural changes following mechanical unloading and circulatory support (MCS) with the HM3 have not been investigated. We compared the reverse remodeling induced by the HM3 to older generation continuous-flow LVADs. Chronic HF patients (n = 405) undergoing MCS with HeartWare Ventricular Assist Device (HVAD, n = 115), HM3 (n = 186), and HeartMate II (HM2, n = 104) at four programs were included. Echocardiograms were obtained preimplant and at 1, 3, 6, and 12 months following LVAD implantation. There were no differences in the postimplant serial LV ejection fraction (LVEF) between the devices. The postimplant LV internal diastolic diameter (LVIDd) was significantly lower for HM2 at 3 and 6 months compared with HVAD and HM3. The proportion of patients achieving "cardiac reverse remodeling responder" status (defined as LVEF improvement to ≥40% and LVIDD ≤5.9 cm) was 11.9%, and was similar between devices. HeartMate 3 appears to result in similar cardiac reverse remodeling as older generation CF-LVADs, suggesting that the fully magnetically levitated device technology could provide an effective platform to further study and promote cardiac reverse remodeling.

Clinical Characteristics and Outcomes of Patients Suffering Acute Decompensated Heart Failure Complicated by Cardiogenic Shock.

BACKGROUND: Cardiogenic shock (CS) can stem from multiple causes and portends poor prognosis. Prior studies have focused on acute myocardial infarction-CS; however, acute decompensated heart failure (ADHF)-CS accounts for most cases. We studied patients suffering ADHF-CS to identify clinical factors, early in their trajectory, associated with a higher probability of successful outcomes. METHODS: Consecutive patients with CS were evaluated (N=1162). We studied patients who developed ADHF-CS at our hospital (N=562). Primary end point was native heart survival (NHS), defined as survival to discharge without receiving advanced HF therapies. Secondary end points were adverse events, survival, major cardiac interventions, and hospital readmissions within 1 year following index hospitalization discharge. Association of clinical data with NHS was analyzed using logistic regression. RESULTS: Overall, 357 (63.5%) patients achieved NHS, 165 (29.2%) died, and 41 (7.3%) were discharged post advanced HF therapies. Of 398 discharged patients (70.8%), 303 (53.9%) were alive at 1 year. Patients with NHS less commonly suffered cardiac arrest, underwent intubation or pulmonary artery catheter placement, or received temporary mechanical circulatory support, had better hemodynamic and echocardiographic profiles, and had a lower vasoactive-inotropic score at shock onset. Bleeding, hemorrhagic stroke, hemolysis in patients with mechanical circulatory support, and acute kidney injury requiring renal replacement therapy were less common compared with patients who died or received advanced HF therapies. After multivariable adjustments, clinical variables associated with NHS likelihood included younger age, history of systemic hypertension, absence of cardiac arrest or acute kidney injury requiring renal replacement therapy, lower pulmonary capillary wedge pressure and vasoactive-inotropic score, and higher tricuspid annular plane systolic excursion at shock onset (all P<0.05). CONCLUSIONS: By studying contemporary patients with ADHF-CS, we identified clinical factors that can inform clinical management and provide future research targets. Right ventricular function, renal function, pulmonary artery catheter placement, and type and timing of temporary mechanical circulatory support warrant further investigation to improve outcomes of this devastating condition.

Enhancing mitochondrial pyruvate metabolism ameliorates myocardial ischemic reperfusion injury.

The established clinical therapy for the treatment of acute myocardial infarction is primary percutaneous coronary intervention (PPCI) to restore blood flow to the ischemic myocardium. PPCI is effective at reperfusing the ischemic myocardium, however the rapid re-introduction of oxygenated blood also can cause ischemia-reperfusion (I/R) injury. Reperfusion injury is the culprit for up to half of the final myocardial damage, but there are no clinical interventions to reduce I/R injury. We previously demonstrated that inhibiting the lactate exporter, monocarboxylate transporter 4 (MCT4), and re-directing pyruvate towards oxidation can blunt isoproterenol-induced hypertrophy. Based on this finding, we hypothesized that the same pathway might be important during I/R. Here, we establish that the pyruvate-lactate metabolic axis plays a critical role in determining myocardial salvage following injury. Post-I/R injury, the mitochondrial pyruvate carrier (MPC), required for pyruvate oxidation, is upregulated in the surviving myocardium following I/R injury. MPC loss in cardiomyocytes caused more cell death with less myocardial salvage, which was associated with an upregulation of MCT4 in the myocardium at risk of injury. We deployed a pharmacological strategy of MCT4 inhibition with a highly selective compound (VB124) at the time of reperfusion. This strategy normalized reactive oxygen species (ROS), mitochondrial membrane potential (Δψ), and Ca 2+ , increased pyruvate entry to TCA cycle, and improved myocardial salvage and functional outcomes following I/R injury. Altogether, our data suggest that normalizing the pyruvate-lactate metabolic axis via MCT4 inhibition is a promising pharmacological strategy to mitigate I/R injury.

Enhancing mitochondrial pyruvate metabolism ameliorates ischemic reperfusion injury in the heart.

The clinical therapy for treating acute myocardial infarction is primary percutaneous coronary intervention (PPCI). PPCI is effective at reperfusing the heart; however, the rapid reintroduction of blood can cause ischemia-reperfusion (I/R). Reperfusion injury is responsible for up to half of the total myocardial damage, but there are no pharmacological interventions to reduce I/R. We previously demonstrated that inhibiting monocarboxylate transporter 4 (MCT4) and redirecting pyruvate toward oxidation can blunt hypertrophy. We hypothesized that this pathway might be important during I/R. Here, we establish that the pyruvate-lactate axis plays a role in determining myocardial salvage following injury. After I/R, the mitochondrial pyruvate carrier (MPC), required for pyruvate oxidation, is upregulated in the surviving myocardium. In cardiomyocytes lacking the MPC, there was increased cell death and less salvage after I/R, which was associated with an upregulation of MCT4. To determine the importance of pyruvate oxidation, we inhibited MCT4 with a small-molecule drug (VB124) at reperfusion. This strategy normalized reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨ), and Ca2+, increased pyruvate entry to the TCA cycle, increased oxygen consumption, and improved myocardial salvage and functional outcomes following I/R. Our data suggest normalizing pyruvate-lactate metabolism by inhibiting MCT4 is a promising therapy to mitigate I/R injury.

Impact of Diabetes and Glycemia on Cardiac Improvement and Adverse Events Following Mechanical Circulatory Support.

BACKGROUND: Type 2 diabetes is prevalent in cardiovascular disease and contributes to excess morbidity and mortality. We sought to investigate the effect of glycemia on functional cardiac improvement, morbidity, and mortality in durable left ventricular assist device (LVAD) recipients. METHODS AND RESULTS: Consecutive patients with an LVAD were prospectively evaluated (n=531). After excluding patients missing pre-LVAD glycated hemoglobin (HbA1c) measurements or having inadequate post-LVAD follow-up, 375 patients were studied. To assess functional cardiac improvement, we used absolute left ventricular ejection fraction change (ΔLVEF: LVEF post-LVAD-LVEF pre-LVAD). We quantified the association of pre-LVAD HbA1c with ΔLVEF as the primary outcome, and all-cause mortality and LVAD-related adverse event rates (ischemic stroke/transient ischemic attack, intracerebral hemorrhage, gastrointestinal bleeding, LVAD-related infection, device thrombosis) as secondary outcomes. Last, we assessed HbA1c differences pre- and post-LVAD. Patients with type 2 diabetes were older, more likely men suffering ischemic cardiomyopathy, and had longer heart failure duration. Pre-LVAD HbA1c was inversely associated with ΔLVEF in patients with nonischemic cardiomyopathy but not in those with ischemic cardiomyopathy, after adjusting for age, sex, heart failure duration, and left ventricular end-diastolic diameter. Pre-LVAD HbA1c was not associated with all-cause mortality, but higher pre-LVAD HbA1c was shown to increase the risk of intracerebral hemorrhage, LVAD-related infection, and device thrombosis by 3 years on LVAD support (P<0.05 for all). HbA1c decreased from 6.68±1.52% pre-LVAD to 6.11±1.33% post-LVAD (P<0.001). CONCLUSIONS: Type 2 diabetes and pre-LVAD glycemia modify the potential for functional cardiac improvement and the risk for adverse events on LVAD support. The degree and duration of pre-LVAD glycemic control optimization to favorably affect these outcomes warrants further investigation.

Integrating molecular and clinical variables to predict myocardial recovery.

Mechanical unloading and circulatory support with left ventricular assist devices (LVADs) mediate significant myocardial improvement in a subset of advanced heart failure (HF) patients. The clinical and biological phenomena associated with cardiac recovery are under intensive investigation. Left ventricular (LV) apical tissue, alongside clinical data, were collected from HF patients at the time of LVAD implantation (n=208). RNA was isolated and mRNA transcripts were identified through RNA sequencing and confirmed with RT-qPCR. To our knowledge this is the first study to combine transcriptomic and clinical data to derive predictors of myocardial recovery. We used a bioinformatic approach to integrate 59 clinical variables and 22,373 mRNA transcripts at the time of LVAD implantation for the prediction of post-LVAD myocardial recovery defined as LV ejection fraction (LVEF) ≥40% and LV end-diastolic diameter (LVEDD) ≤5.9cm, as well as functional and structural LV improvement independently by using LVEF and LVEDD as continuous variables, respectively. To substantiate the predicted variables, we used a multi-model approach with logistic and linear regressions. Combining RNA and clinical data resulted in a gradient boosted model with 80 features achieving an AUC of 0.731±0.15 for predicting myocardial recovery. Variables associated with myocardial recovery from a clinical standpoint included HF duration, pre-LVAD LVEF, LVEDD, and HF pharmacologic therapy, and LRRN4CL (ligand binding and programmed cell death) from a biological standpoint. Our findings could have diagnostic, prognostic, and therapeutic implications for advanced HF patients, and inform the care of the broader HF population.

Biology of myocardial recovery in advanced heart failure with long-term mechanical support.

Cardiac remodeling is an adaptive, compensatory biological process following an initial insult to the myocardium that gradually becomes maladaptive and causes clinical deterioration and chronic heart failure (HF). This biological process involves several pathophysiological adaptations at the genetic, molecular, cellular, and tissue levels. A growing body of clinical and translational investigations demonstrated that cardiac remodeling and chronic HF does not invariably result in a static, end-stage phenotype but can be at least partially reversed. One of the paradigms which shed some additional light on the breadth and limits of myocardial elasticity and plasticity is long term mechanical circulatory support (MCS) in advanced HF pediatric and adult patients. MCS by providing (a) ventricular mechanical unloading and (b) effective hemodynamic support to the periphery results in functional, structural, cellular and molecular changes, known as cardiac reverse remodeling. Herein, we analyze and synthesize the advances in our understanding of the biology of MCS-mediated reverse remodeling and myocardial recovery. The MCS investigational setting offers access to human tissue, providing an unparalleled opportunity in cardiovascular medicine to perform in-depth characterizations of myocardial biology and the associated molecular, cellular, and structural recovery signatures. These human tissue findings have triggered and effectively fueled a "bedside to bench and back" approach through a variety of knockout, inhibition or overexpression mechanistic investigations in vitro and in vivo using small animal models. These follow-up translational and basic science studies leveraging human tissue findings have unveiled mechanistic myocardial recovery pathways which are currently undergoing further testing for potential therapeutic drug development. Essentially, the field is advancing by extending the lessons learned from the MCS cardiac recovery investigational setting to develop therapies applicable to the greater, not end-stage, HF population. This review article focuses on the biological aspects of the MCS-mediated myocardial recovery and together with its companion review article, focused on the clinical aspects, they aim to provide a useful framework for clinicians and investigators.

Baseline QRS duration associates with cardiac recovery in patients with continuous-flow left ventricular assist device implantation.

Objective: In chronic heart failure (HF) patients supported with continuous-flow left ventricular assist device (CF-LVAD), we aimed to assess the clinical association of pre-LVAD QRS duration (QRSd) with post-LVAD cardiac recovery, and its correlation with pre- to post-LVAD change in left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD). Methods: Chronic HF patients (n = 402) undergoing CF-LVAD implantation were prospectively enrolled, at one of the centers comprising the U.T.A.H. (Utah Transplant Affiliated Hospitals) consortium. After excluding patients with acute HF etiologies, hypertrophic or infiltrative cardiomyopathy, and/or inadequate post-LVAD follow up (<3 months), 315 patients were included in the study. Cardiac recovery was defined as LVEF ≥ 40 % and LVEDD < 6 cm within 12 months post-LVAD implantation. Patients fulfilling this condition were termed as responders (R) and results were compared with non-responders (NR). Results: Thirty-five patients (11 %) achieved 'R' criteria, and exhibited a 15 % shorter QRSd compared to 'NR' (123 ± 37 ms vs 145 ± 36 ms; p < 0.001). A univariate analysis identified association of baseline QRSd with post-LVAD cardiac recovery (OR: 0.986, 95 % CI: 0.976-0.996, p < 0.001). In a multivariate logistic regression model, after adjusting for duration of HF (OR: 0.990, 95 % CI: 0.983-0.997, p = 0.006) and gender (OR: 0.388, 95 % CI: 0.160-0.943, p = 0.037), pre-LVAD QRSd exhibited a significant association with post-LVAD cardiac structural and functional improvement (OR: 0.987, 95 % CI: 0.977-0.998, p = 0.027) and the predictive model showed a c-statistic of 0.73 with p < 0.001. The correlations for baseline QRSd with pre- to post-LVAD change in LVEF and LVEDD were also investigated in 'R' and 'NR' groups. Conclusion: Chronic advanced HF patients with a shorter baseline QRSd exhibit an increased potential for cardiac recovery after LVAD support.

Chronotropic incompetence and abnormal heart rate recovery early after left ventricular assist device implantation.

BACKGROUND: Chronotropic response to exercise and heart rate recovery immediately after exercise (HRR(1) ) are valid prognostic markers in patients with chronic heart failure (CHF). The aim of this study was to evaluate heart rate profile during and after exercise in CHF patients early after left ventricular assist device (LVAD) implantation. METHODS: We enrolled seven stable consecutive CHF patients (five males, mean age: 45 ± 16 years) after 1 month of LVAD (HeartMate II; Thoratec Corp, Pleasanton, CA, USA) implantation, seven healthy subjects, and 14 patients with advanced HF (HF control group) who performed an incremental symptom-limited cardiopulmonary exercise testing (CPET). CHF patients performed CPET at 1 and 3 months after LVAD. HRR(1) was defined as the HR difference from peak to 1 minute after exercise and chronotropic response to exercise as the chronotropic reserve ([CR, %]=[peak HR-resting HR/220-age-resting HR]× 100). RESULTS: LVAD patients 3 months after implantation had a significantly different HR profile during exercise compared to healthy controls, with significantly lower CR (57 ± 31 vs 90 ± 14, %, P < 0.001) and HRR(1) (14 ± 6 vs 28 ± 8, bpm, P < 0.01). HR profile during exercise did not significantly change 1 and 3 months after LVAD implantation. There was no statistical difference compared to HF control group and LVAD group regarding cardiopulmonary parameters. CONCLUSIONS: LVAD patients present an impaired CR and an abnormal HRR(1) after implantation, indicating significant cardiac autonomic abnormalities. These alterations seem to remain unaltered 3 months after LVAD implantation.

Increased levels of osteopontin in sputum supernatant in severe refractory asthma.

BACKGROUND: Osteopontin (OPN) is a glycoprotein that has been associated with inflammation and fibrosis. Severe refractory asthma (SRA) is characterised by an intense inflammatory and remodelling process. The aim of this study was to investigate the levels of OPN in sputum supernatants of patients with SRA, to compare them with milder forms of the disease and to investigate their possible association with mediators and cells involved in the inflammatory and remodelling process. METHODS: 33 patients with SRA, 29 with moderate asthma, 21 with steroid-naïve asthma and 20 healthy subjects were studied. All subjects underwent lung function tests, bronchial hyper-responsiveness assessment and sputum induction for cell count identification and measurement of OPN, vascular endothelial growth factor, transforming growth factor beta1 (TGF-beta1), cysteinyl leukotrienes, interleukin 13 (IL-13), eosinophilic cationic protein (ECP) and IL-8 in sputum supernatants. RESULTS: Median (IQR) OPN levels (pg/ml) were significantly higher in patients with SRA than in those with moderate asthma, steroid-naive asthma and healthy control subjects (1840 (1125-11000) vs 130 (100-210) vs 100 (67-130) vs 50 (42-70), respectively, p<0.001). Regression analysis showed a significant association between log OPN and sputum eosinophils, cysteinyl leukotrienes, IL-13, TGF-beta1 and ECP. TGF-beta1 represented the strongest association with OPN. The above associations were not observed in milder forms of the disease or in healthy subjects. CONCLUSIONS: The results indicate that OPN levels are higher in SRA than in less severe forms of the disease. Moreover, OPN is associated with mediators involved in both the inflammatory and remodelling process such as TGF-beta1, IL-13 and cysteinyl leukotrienes only in SRA.