Left ventricular remodeling in heart failure: current concepts in clinical significance and assessment

Comparison of three-dimensional echocardiographic findings to those of magnetic resonance imaging for determination of left ventricular mass in patients with ischemic and non-ischemic cardiomyopathy

The standard echocardiographic evaluation of left ventricular (LV) mass, particularly in ischemic cardiomyopathy (IC) is challenging because it is based on geometric assumptions. The aim of this study was to assess the accuracy of LV mass calculation using echocardiographic modalities compared with cardiac magnetic resonance (CMR) in IC and in nonischemic cardiomyopathy (non-IC). Echocardiography was performed in 104 patients (mean age 55 ± 15 years) referred for CMR: 63 with IC and 41 with non-IC. CMR, M-mode echocardiography, 2-dimensional echocardiography, and 3-dimensional echocardiography (3DE) were analyzed using standard commercial tools to obtain LV mass. LV mass on 3DE showed a higher correlation with CMR than 2-dimensional echocardiography (r = 0.87 vs r = 0.70, p <0.001). M-mode echocardiography overestimated LV mass (bias +30%) and 2-dimensional echocardiography underestimated LV mass (bias -11%), whereas measurements on 3DE showed only minimal bias (-2%). LV mass on 3DE in non-IC showed a significantly higher correlation with CMR than in IC (r = 0.92 vs r = 0.84, z = 2.3, p <0.05). In non-IC, the mean difference was -2 g (-1% of the mean), with 95% limits of agreement of ±33 g (±19% of the mean). In IC, the mean difference was -7 g (-4% of the mean), with limits of agreement of ±56 g (±31% of the mean). There was a correlation between the absolute LV mass differences (3DE derived and CMR derived) and scar percentage (infarcted mass/total LV mass) using delayed-hyperenhancement images (r = 0.40, p <0.05). The net reclassification index with 3DE was +16% for concentric LV hypertrophy. In conclusion, the most accurate and reliable echocardiographic measurement of LV mass is 3DE, but underestimation and variability remain challenges in IC.

Left ventricular mass and hypertrophy by echocardiography and cardiac magnetic resonance: the multi-ethnic study of atherosclerosis

BACKGROUND

Left ventricular mass (LVM) and hypertrophy (LVH) are important parameters, but their use is surrounded by controversies. We compare LVM by echocardiography and cardiac magnetic resonance (CMR), investigating reproducibility aspects and the effect of echocardiography image quality. We also compare indexing methods within and between imaging modalities for classification of LVH and cardiovascular risk.

METHODS

Multi-Ethnic Study of Atherosclerosis enrolled 880 participants in Baltimore city, 146 had echocardiograms and CMR on the same day. LVM was then assessed using standard techniques. Echocardiography image quality was rated (good/limited) according to the parasternal view. LVH was defined after indexing LVM to body surface area, height(1.7) , height(2.7) , or by the predicted LVM from a reference group. Participants were classified for cardiovascular risk according to Framingham score. Pearson's correlation, Bland-Altman plots, percent agreement, and kappa coefficient assessed agreement within and between modalities.

RESULTS

Left ventricular mass by echocardiography (140 ± 40 g) and by CMR were correlated (r = 0.8, P < 0.001) regardless of the echocardiography image quality. The reproducibility profile had strong correlations and agreement for both modalities. Image quality groups had similar characteristics; those with good images compared to CMR slightly superiorly. The prevalence of LVH tended to be higher with higher cardiovascular risk. The agreement for LVH between imaging modalities ranged from 77% to 98% and the kappa coefficient from 0.10 to 0.76.

CONCLUSIONS

Echocardiography has a reliable performance for LVM assessment and classification of LVH, with limited influence of image quality. Echocardiography and CMR differ in the assessment of LVH, and additional differences rise from the indexing methods.

From cell phenotype to epigenetic mechanisms: new insights into regenerating myocardium

The self-regenerating property of the adult myocardium is not a new discovery. Even though we could not confirm that the adult myocardium is a post-mitotic tissue, we should consider that its plasticity is extremely low. Studies are still in progress to decipher the mechanisms underlying the abovementioned potential fetal features of the adult heart. The modest results of several clinical trials based on the transplantation of millions of autologous stem cells into the dysfunctional heart have confirmed that the cross-talk of different signals, such as the microenvironment, promotes the regeneration of adult myocardium. Recent scientific evidence has revealed that cellular cross-talk does not depend on the action of a single cell phenotype. It is conceivable that the limited turnover of cardiomyocytes is ensured by the interplay of adult cardiac cells in response to environmental changes. The epigenetic state of a cell serves as a dynamic interface between the environment and phenotype. The epigenetic modulation of the adult cardiac cells by natural active compounds encourages further studies to improve myocardial plasticity. In this review, we will highlight the most relevant studies demonstrating the epigenetic modulation of myocardial regeneration without the use of stem cell transplantation.

Optimizing benefit from CRT: role of speckle tracking echocardiography, the importance of LV lead position and scar

Cardiac resynchronization therapy is demonstrated to be effective in patients with advanced heart failure. Correcting mechanical dyssynchrony is proposed as the predominant mechanism of response. Achieving optimum left ventricular lead position, at the site of maximal mechanical dyssynchrony but away from transmural scar, is identified as one of the main determinants of both symptomatic and prognostic benefit. Strategies employing multimodality cardiac imaging techniques have been used to identify this optimal pacing site, in addition to any potential anatomical limitations to successful implantation. Speckle tracking echocardiography offers prospective lead targeting, incorporating pathophysiological determinants of cardiac resynchronization therapy response. This review considers the key factors in defining optimum left ventricular lead location, emphasizing the role of myocardial scar. The use of speckle tracking echocardiography and the potential for this technique to be incorporated into routine practice to guide the implant strategy in an individual patient is discussed.

Durable scar size reduction due to allogeneic mesenchymal stem cell therapy regulates whole-chamber remodeling

BACKGROUND

Intramyocardial injection of mesenchymal stem cells (MSCs) in chronic ischemic cardiomyopathy is associated with reverse remodeling in experimental models and humans. Here, we tested the hypothesis that allogeneic MSC therapy drives ventricular remodeling by producing durable and progressive scar size reduction in ischemic cardiomyopathy.

METHODS AND RESULTS

Gottingen swine (n=12) underwent left anterior descending coronary artery myocardial infarction (MI), and 3 months post-MI animals received either intramyocardial allogeneic MSC injection (200 mol/L cells; n=6) or left ventricle (LV) catheterization without injection (n=6). Swine were followed with serial cardiac magnetic resonance imaging for 9 months to assess structural and functional changes of the LV. Intramyocardial injection was performed using an integrated imaging platform combining electroanatomical mapping unipolar voltage and 3-dimensional cardiac magnetic resonance imaging angiography-derived anatomy to accurately target infarct border zone injections. MSC-treated animals had a 19.62 ± 2.86% reduction in scar size at 3 months postinjection, which progressed to 28.09 ± 2.31% from 3 to 6 months postinjection (P<0.0001). MSC-treated animals had unchanged end-diastolic volume (EDV; P=0.08) and end-systolic volume (ESV; P=0.28) from preinjection to 6 months postinjection, whereas controls had progressive dilatation in both EDV (P=0.0002) and ESV (P=0.0002). In addition, MSC-treated animals had improved LV sphericity index. Percentage change in infarct size correlated with percentage change in EDV (r=0.68; P=0.01) and ESV (r=0.77; P=0.001). Ejection fraction increased from 29.69 ± 1.68% to 35.85 ± 2.74% at 3 months post-MSC injection and progressed to 39.02 ± 2.42% 6 months postinjection (P=0.0001), whereas controls had a persistently depressed ejection fraction during follow-up (P=0.33).

CONCLUSION

Intramyocardial injection of allogeneic MSCs leads to a sustained and progressive reduction in infarct size, which in turn drives reverse remodeling and increases in ejection fraction. These findings support ongoing biological activity of cell therapy for substantial periods and suggest optimal end points for future clinical trials.

Heart failure: what does ejection fraction have to do with it?

Heart failure (HF) occurs across the entire range of left ventricular (LV) ejection fractions (EF), not just reduced EF. Nearly half or more patients presenting with HF have a preserved EF>0.50 (HFpEF). Diastolic dysfunction is apparent in all patients with HF, regardless of EF. A preserved EF indicates that the end-diastolic volume is appropriate for the stroke volume, and a reduced EF indicates that the end-diastolic volume is enlarged relative to stroke volume (i.e. the LV is dilated). Most therapies proven to be effective in HF with a reduced EF (ACE-inhibitors, angiotensin receptor blockers, beta-blockers, and cardiac resynchronization) reverse LV dilation. These therapies have not been proven to be effective in HFpEF. Increasing c-GMP may be a treatment target in HFpEF, and potential ways of increasing c-GMP are being studied. Finally, comorbidities are important in HFpEF and are additional targets for therapy.

High-sensitivity troponin T and C-reactive protein to identify patients without cardiac structural and functional abnormalities as assessed by cardiac CT and SPECT imaging: can biomarkers predict cardiac health?

While high-sensitivity troponin-T (hsTnT) and C-reactive protein (hsCRP) are associated with structural heart disease, we thought to determine whether biomarkers can predict which heart is healthy based on multimodality imaging. Patients from the emergency department with acute chest pain suggestive of acute coronary syndrome undergoing contrast enhanced cardiac CT and stress single photon emission computed tomography (SPECT) myocardial perfusion imaging were included. HsTnT and hsCRP were assessed at time of CT. Imaging data were assessed for coronary atherosclerosis, left ventricular hypertrophy/dysfunction and myocardial perfusion abnormalities. Patients were stratified into those with or without any cardiac findings, who were considered as cardiac healthy. For biomarkers, low cut-off corresponding to good specificity and high cut-off corresponding to good sensitivity for cardiac health were derived. Among 117 patients (52 years, 55 % male), 42 (36 %) were cardiac healthy based on cardiac CT and SPECT imaging. These patients had significantly lower hsTnT and hsCRP levels as compared to those with functional or structural abnormalities (3.58 vs. 5.63 ng/L, p = 0.002; 0.82 vs. 1.93 mg/L, p = 0.0005; respectively). Patients with both low hsTnT (<3.00 ng/L) and hsCRP (<0.45 mg/L) had a probability of 85 % for being cardiac healthy. In contrast, patients with high hsTnT (>7.00 ng/L) and hsCRP (>2.00 mg/L) had 8 % probability for being cardiac healthy. Discriminative capacity of a dual-biomarker strategy was significantly improved as compared to hsTnT or hsCRP alone or to Framingham Risk score (AUC: 0.781 vs. 0.691; vs. 0.678; vs. 0.649; all p ≤ 0.02, respectively). A dual-biomarker strategy of hsTnT and hsCRP is highly discriminative for patients with normal cardiac structure and function and provides incremental value beyond the Framingham risk score.

The PARACHUTE IV trial design and rationale: percutaneous ventricular restoration using the parachute device in patients with ischemic heart failure and dilated left ventricles

BACKGROUND

Left ventricle (LV) remodeling after anterior wall myocardial infarction leads to increased LV volumes, myocardial stress, and, ultimately, heart failure (HF). Patients have high morbidity and mortality risk, and treatment remains limited. Percutaneous ventricular restoration (PVR) therapy using the Parachute device, a fluoropolymer membrane stretched over a nitinol conical frame, is a novel approach to partition off the damaged myocardium. In the European and United States PARACHUTE feasibility trials, the observed rates of death or rehospitalization for HF were <17% at 12 months. These data compare favorably with historical data and support the need of a randomized trial to determine the clinical efficacy of PVR on outcomes for patients with ischemic HF.

OBJECTIVE

To determine the safety and efficacy of PVR utilizing a LV partitioning device, Parachute, in a randomized clinical trial compared with optimal medical therapy.

METHODS

This US pivotal trial is approved by the Food and Drug Administration (ClinicalTrials.gov Identifier: NCT01286116) and will randomly assign (1:1) 478 patients with New York Heart Association class III-IV ischemic HF, akinetic or dyskinetic LV wall abnormality, and ejection fraction between 15% and 35% to optimal medical therapy (control) versus Parachute device implantation in approximately 65 hospitals. The primary endpoint is death or rehospitalization for worsening HF. Sample size calculation assumes constant hazards and follow-up ≥12 months using an event-driven trial design.

CONCLUSIONS

We reported the rational and design of the first multicenter randomized trial to test the efficacy of PVR using the Parachute device to treat patients with ischemic HF and dilated LV.

Membrane-associated matrix proteolysis and heart failure

The extracellular matrix (ECM) is a complex entity containing a large portfolio of structural proteins, signaling molecules, and proteases. Changes in the overall integrity and activational state of these ECM constituents can contribute to tissue structure and function, which is certainly true of the myocardium. Changes in the expression patterns and activational states of a family of ECM proteolytic enzymes, the matrix metalloproteinases (MMPs), have been identified in all forms of left ventricle remodeling and can be a contributory factor in the progression to heart failure. However, new clinical and basic research has identified some surprising and unpredicted changes in MMP profiles in left ventricle remodeling processes, such as with pressure or volume overload, as well as with myocardial infarction. From these studies, it has become recognized that proteolytic processing of signaling molecules by certain MMP types, particularly the transmembrane MMPs, actually may facilitate ECM accumulation and modulate fibroblast transdifferentiation; both are critical events in adverse left ventricle remodeling. Based on the ever-increasing substrates and diversity of biological actions of MMPs, it is likely that continued research about the relationship of left ventricle remodeling in this family of proteases will yield new insights into the ECM remodeling process and new therapeutic targets.

Left ventricular reverse remodeling in long-term (>12 years) survivors with idiopathic dilated cardiomyopathy

Little is known about left ventricular (LV) reverse remodeling (LVRR) in long-term survivors with idiopathic dilated cardiomyopathy. We studied 59 patients with idiopathic dilated cardiomyopathy who had a potential clinical and echocardiographic follow-up period of >12 years. LVRR was defined as LV end-diastolic dimension ≤ 55 mm and fractional shortening ≥ 25% on the last echocardiogram. Of the 59 patients, 38 died (heart failure in 20, sudden death in 11, and other causes in 7), 2 underwent transplantation, and 19 survived. In the survivors, the LV size had significantly decreased and LV fractional shortening had significantly increased on the last echocardiogram. LVRR occurred in 37% of the survivors. The remaining 63% of the survivors still had LV dysfunction, but the LV end-systolic dimension had decreased significantly. In patients who died or underwent transplantation, the LV size significantly increased. No patient who died or underwent transplantation had LVRR. In conclusion, >60% of the long-term (>12 years) survivors with idiopathic dilated cardiomyopathy still had LV systolic dysfunction, but the LV end-systolic dimension had decreased significantly. In contrast, patients who died or underwent transplantation had significant LV enlargement. These results suggest that LVRR, even if it is not marked, is associated with a favorable prognosis.

Targeting Wnt signaling to improve wound healing after myocardial infarction

Myocardial infarction is one of the major causes of left ventricular dilatation, frequently leading to heart failure. In the last decade, the wound healing process that takes place in the infarct area after infarction has been recognized as a novel therapeutic target to attenuate left ventricular dilatation and preserve an adequate cardiac function. In this chapter, we discuss the role of Wnt signaling in the wound healing process after infarction, with a specific focus on its modulating effect on myofibroblast characteristics.

Postmyocardial infarction left ventricular dysfunction - assessment and follow up of patients undergoing surgical ventricular restoration by the endoventricular patchplasty

BACKGROUND

Surgical ventricular restoration with endoventricular patchplasty improves left ventricular function and restores left ventricular shape.

METHOD

The study included patients who presented with transmural anterior myocardial infarctions between June 2007 and May 2008. Briefly the technique included - coronary revascularization, resection of the endocardial scar, left ventricular reconstruction using an endoventricular synthetic patch. Left ventricular geometric parameters were studied preoperatively, early postoperatively, at 3 and 6 months and statistically analyzed by SPSS 14 software package.

RESULTS

The ejection fraction increased from 33.5 ± 5.02 to 37.77 ± 7.17 immediate postoperatively. The preoperative left ventricular ejection fraction - a mean of 33.25% (±5.02%), increased by 10.3%-11% at the third and fourth follow up respectively after surgical ventricular restoration (p ≤ 0.001). The left ventricular end systolic volume index improved from a mean of 48.84 ± 11.37 preoperatively to 24.66 ± 5.92 postoperatively (p ≤ 0.001).

CONCLUSIONS

Surgical ventricular restoration in our study has clearly demonstrated a positive effect on LV geometry.

Injection of vessel-derived stem cells prevents dilated cardiomyopathy and promotes angiogenesis and endogenous cardiac stem cell proliferation in mdx/utrn-/- but not aged mdx mouse models for duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy. DMD patients lack dystrophin protein and develop skeletal muscle pathology and dilated cardiomyopathy (DCM). Approximately 20% succumb to cardiac involvement. We hypothesized that mesoangioblast stem cells (aorta-derived mesoangioblasts [ADMs]) would restore dystrophin and alleviate or prevent DCM in animal models of DMD. ADMs can be induced to express cardiac markers, including Nkx2.5, cardiac tropomyosin, cardiac troponin I, and α-actinin, and adopt cardiomyocyte morphology. Transplantation of ADMs into the heart of mdx/utrn(-/-) mice prior to development of DCM prevented onset of cardiomyopathy, as measured by echocardiography, and resulted in significantly higher CD31 expression, consistent with new vessel formation. Dystrophin-positive cardiomyocytes and increased proliferation of endogenous Nestin(+) cardiac stem cells were detected in ADM-injected heart. Nestin(+) striated cells were also detected in four of five mdx/utrn(-/-) hearts injected with ADMs. In contrast, when ADMs were injected into the heart of aged mdx mice with advanced fibrosis, no functional improvement was detected by echocardiography. Instead, ADMs exacerbated some features of DCM. No dystrophin protein, increase in CD31 expression, or increase in Nestin(+) cell proliferation was detected following ADM injection in aged mdx heart. Dystrophin was observed following transplantation of ADMs into the hearts of young mdx mice, however, suggesting that pathology in aged mdx heart may alter the fate of donor stem cells. In summary, ADMs delay or prevent development of DCM in dystrophin-deficient heart, but timing of stem cell transplantation may be critical for achieving benefit with cell therapy in DMD cardiac muscle.

Improvement in structural and functional echocardiographic parameters during chronic heart failure therapy guided by natriuretic peptides: mechanistic insights from the ProBNP Outpatient Tailored Chronic Heart Failure (PROTECT) study

AIMS

We sought to determine if heart failure (HF) care with a goal to lower N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations, compared with standard of care (SOC) management, is associated with improvement in echocardiographic parameters of cardiac structure and function.

METHODS AND RESULTS

Of 151 subjects with HF due to left ventricular systolic dysfunction (LVSD) prospectively randomized to NT-proBNP-guided vs. SOC HF care, 116 had serial echocardiographic data. Endpoints in this echocardiographic study included the relationship between change in NT-proBNP and LV reverse remodelling, as well as associations between biomarker-guided therapy and measures of diastolic function, right ventricular (RV) size and function, estimates of LV filling pressure and RV systolic pressure (RVSP), and the degree of mitral regurgitation (MR). After a mean of 10 months of study procedures, in adjusted analyses, final NT-proBNP concentrations predicted risk of remodelling [hazard ratio (HR) ↑LV end-diastolic volume index = 1.43, 95% confidence interval (CI) 1.10-1.86, P = 0.007; HR ↑LV end-systolic volume index = 1.54, 95% CI 1.10-1.91, P = 0.01; HR ↓LV ejection fraction (LVEF) = 1.53, 905% CI 1.12-1.89, P = 0.02]. In addition to greater improvement in LVEF and reductions in LV volume, compared with SOC, NT-proBNP-guided patients showed significant decreases in the ratio of early transmitral peak velocity to early diastolic peak annular velocity (E/E'), pulmonary vein peak S velocity, RV fractional area change, RVSP, and MR severity.

CONCLUSION

NT-proBNP concentrations may serve as a non-invasive indicator of the state of cardiac structure and function in HF due to LVSD. Multiple, prognostically meaningful echocardiographic variables improved more significantly in patients treated with NT-proBNP-guided care vs. SOC.

Pressure overload induces early morphological changes in the heart

Cardiac hypertrophy, whether pathological or physiological, induces a variety of additional morphological and physiological changes in the heart, including altered contractility and hemodynamics. Events exacerbating these changes are documented during later stages of hypertrophy (usually termed pathological hypertrophy). Few studies document the morphological and physiological changes during early physiological hypertrophy. We define acute cardiac remodeling events in response to transverse aortic constriction (TAC), including temporal changes in hypertrophy, collagen deposition, capillary density, and the cell populations responsible for these changes. Cardiac hypertrophy induced by TAC in mice was detected 2 days after surgery (as measured by heart weight, myocyte width, and wall thickness) and peaked by day 7. Picrosirius staining revealed increased collagen deposition 7 days after TAC; immunostaining and flow cytometry indicated a concurrent increase in fibroblasts. The findings correlated with angiogenesis in TAC hearts; a decrease in capillary density was observed at day 2, with recovery to sham-surgery levels by day 7. Increased pericyte levels, which were observed 2 days after TAC, may mediate this angiogenic transition. Gene expression suggests a coordinated response in growth, extracellular matrix, and angiogenic factors to mediate the observed morphological changes. Our data demonstrate that morphological changes in response to cardiovascular injury occur rapidly, and the present findings allow correlation of specific events that facilitate these changes.

Gene targeting in ischemic heart disease and failure: translational and clinical studies

Alternative and innovative targeted strategies hold relevance in improving the current treatments for ischemic heart disease (IHD). One potential treatment modality, gene targeting, may provide a unique alternative to current IHD therapies. The principal function of gene targeting in IHD is to augment the expression of an endogenous gene through amplification of an exogenous gene, delivered by a plasmid or a viral vector to enhance myocardial perfusion, and limit the long-term sequelae. The initial clinical studies of gene targeting in IHD were focused upon induction of angiogenic factors and the outcomes were equivocal. Nevertheless, significant advancements have been made in viral vectors, mode of delivery, and potentially relevant targets for IHD. Several of these advancements, particularly with a focus on translational large animal studies, are the focus of this review. The development of novel vectors with prolonged transduction efficiency and minimal inflammation, coupled with hybrid perfusion-mapping delivery devices, and improving the safety of vector use and efficacy of gene systems are but a few of the exciting progresses that are likely to proceed to clinical studies in the near future.

Toll-like receptor (TLR) 2 and TLR4 differentially regulate doxorubicin induced cardiomyopathy in mice

Recent evidence indicates that toll-like receptor (TLR) 2 and 4 are involved in the pathogenesis of dilated cardiomyopathy (DCM), but the exact mechanisms of their actions have not been elucidated. We explored the therapeutic potential of blocking TLRs in mice with established cardiomyopathy. Cardiomyopathy was generated by a single intraperitoneal injection of doxorubicin (10 mg/kg). Two weeks later, the mice were treated with TLR2 or TLR4 neutralizing antibody. Blocking TLR2, but not TLR4, activity not only reduced mortality, but also attenuated doxorubicin-induced cardiac dysfunction by 20% and inhibited myocardial fibrosis. To determine the differential effects of blocking TLR2 and TLR4 in chronic cardiomyopathy, mice were injected with doxorubicin (3.5 mg/kg) once a week for 8 weeks, followed by treatment with TLR2 or TLR4 neutralizing antibody for 40 days. Blocking TLR2 activity blunted cardiac dysfunction by 13% and inhibited cardiac fibrosis, which was associated with a significant suppression of myocardial inflammation. The underlying mechanism involved interrupting the interaction of TLR2 with its endogenous ligands, resulting in attenuation of inflammation and fibrosis. In contrast, blocking TLR4 exacerbated cardiac dysfunction and fibrosis by amplifying inflammation and suppressing autophagy. Our studies demonstrate that TLR2 and TLR4 play distinct roles in the progression of doxorubicin-induced DCM. TLR4 activity is crucial for the resolution of inflammation and cardiac fibrosis, while blocking TLR2 activity has therapeutic potential for the treatment of DCM.

Remodeling after acute myocardial infarction: mapping ventricular dilatation using three dimensional CMR image registration

BACKGROUND

Progressive heart failure due to remodeling is a major cause of morbidity and mortality following myocardial infarction. Conventional clinical imaging measures global volume changes, and currently there is no means of assessing regional myocardial dilatation in relation to ischemic burden. Here we use 3D co-registration of Cardiovascular Magnetic Resonance (CMR) images to assess the long-term effects of ischemia-reperfusion injury on left ventricular structure after acute ST-elevation myocardial infarction (STEMI).

METHODS

Forty six patients (age range 33-77 years) underwent CMR imaging within 7 days following primary percutaneous coronary intervention (PPCI) for acute STEMI with follow-up at one year. Functional cine imaging and Late Gadolinium Enhancement (LGE) were segmented and co-registered. Local left ventricular wall dilatation was assessed by using intensity-based similarities to track the structural changes in the heart between baseline and follow-up. Results are expressed as means, standard errors and 95% confidence interval (CI) of the difference.

RESULTS

Local left ventricular remodeling within infarcted myocardium was greater than in non-infarcted myocardium (1.6%±1.0 vs 0.3%±0.9, 95% CI: -2.4% - -0.2%, P=0.02). One-way ANOVA revealed that transmural infarct thickness had a significant effect on the degree of local remodeling at one year (P<0.0001) with greatest wall dilatation observed when infarct transmurality exceeded 50%. Infarct remodeling was more severe when microvascular obstruction (MVO) was present (3.8%±1.3 vs -1.6%±1.4, 95% CI: -9.1% - -1.5%, P=0.007) and when end-diastolic volume had increased by >20% (4.8%±1.4 vs -0.15%±1.2, 95% CI: -8.9% - -0.9%, P=0.017).

CONCLUSIONS

The severity of ischemic injury has a significant effect on local ventricular wall remodeling with only modest dilatation observed within non-ischemic myocardium. Limitation of chronic remodeling may therefore depend on therapies directed at modulating ischemia-reperfusion injury. CMR co-registration has potential for assessing dynamic changes in ventricular structure in relation to therapeutic interventions.

Influence of baseline left ventricular function on the clinical outcome of surgical ventricular reconstruction in patients with ischaemic cardiomyopathy

AIMS

The Surgical Treatment for Ischemic Heart Failure (STICH) trial demonstrated no overall benefit when surgical ventricular reconstruction (SVR) was added to coronary artery bypass grafting (CABG) in patients with ischaemic cardiomyopathy. The present analysis was to determine whether, based on baseline left ventricular (LV) function parameters, any subgroups could be identified that benefited from SVR.

METHODS AND RESULTS

Among the 1000 patients enrolled, Core Lab measures of baseline LV function with adequate quality were obtained in 710 patients using echocardiography, in 352 using cardiovascular magnetic resonance, and in 344 using radionuclide imaging. The relationship between LV end-systolic volume index (ESVI), end-diastolic volume index, ejection fraction (EF), regional wall motion abnormalities, and outcome were first assessed only by echocardiographic measures, and then by 13 algorithms using a different hierarchy of imaging modalities and their quality. The median ESVI and EF were 78.0 (range: 22.8-283.8) mL/m2 and 28.0%, respectively. Hazard ratios comparing the randomized arms by subgroups of LVESVI and LVEF measured by echocardiography found that patients with smaller ventricles (LVESVI <60 mL/m2) and better LVEF (≥33%) may have benefitted by SVR, while those with larger ventricles (LVESVI >90 mL/m(2)) and lower LVEF (≤25%) did worse with SVR. Algorithms using all three imaging modalities found a weaker relationship between LV global function and the effects of SVR. The extent of regional wall motion abnormality did not influence the effects of SVR.

CONCLUSIONS

Subgroup analyses of the STICH trial suggest that patients with less dilated LV and better LVEF may benefit from SVR, while those with larger LV and poorer LVEF may do worse. Clinical Trial Registration #: NCT00023595.

Implications of acute left ventricular remodeling during squatting stress echocardiography

BACKGROUND

We previously demonstrated that squatting induces left ventricular (LV) wall motion abnormalities (WMA) in areas subtended by stenotic coronary arteries. In addition, it was observed that some subjects developed acute changes in LV shape (acute left ventricular remodeling [ALVRM]) during squatting.

OBJECTIVE

This study tested the hypothesis that patients with ALVRM during squatting echocardiography have higher incidences of severe coronary artery disease (CAD).

METHODS

Echocardiography was performed in all standard views during standing and squatting. End-systolic frames in the apical four-chamber view were analyzed.

RESULTS

The subjects were divided into three groups. Group 1 consisted of 12 subjects who developed squatting-induced ALVRM with apical and distal posterior septal akinesis, dilation of the apex and marked LV shape change at end-systole. Group 2 consisted of 20 subjects with distal posterior septal and apical akinesis without ALVRM, during squatting. Group 3 consisted of 64 subjects who developed WMA in areas other than the apex (n = 49), or normal wall motion (n = 15) during squatting. Coronary angiography in group 1 revealed that 6 subjects had left main coronary artery stenosis (LMCAS ≥ 50%), two had severe three vessel disease (≥ 90% stenosis), and one had 100% left anterior descending coronary artery occlusion. Severe CAD was defined for purpose of this study as the presence of LMCAS, or severe three vessel disease (≥ 90% stenosis). Six subjects in group 2 had LMCAS and none had severe three vessel disease (P < 0.05 vs. group 1 for LMCAS and/or three vessel disease). In group 3, eight had LMCAS and none had severe three vessel disease (P < 0.0001 vs. group 1).

CONCLUSION

Patients with ALVRM have severe CAD. Therefore, patients who develop ALVRM during squatting require urgent evaluation for revascularization therapy.

Presence of extensive LV remodeling limits the benefits of CRT in patients with intraventricular dyssynchrony

OBJECTIVES

The aim of this study was to evaluate whether, in patients with evidence of both electrical and mechanical left ventricular (LV) dyssynchrony, extensive LV dilation would affect response to cardiac resynchronization therapy (CRT).

BACKGROUND

Cardiac resynchronization therapy is effective in heart failure patients with LV dysfunction and wide QRS complex. However, many patients still fail to respond. We hypothesized that presence of extensive LV dilation might prevent response to CRT, despite LV mechanical dyssynchrony.

METHODS

We studied 78 heart failure patients (68 ± 9 years of age, 77% men) with both electrical (QRS width >120 ms) and mechanical intraventricular dyssynchrony (by tissue Doppler imaging and/or left lateral wall post-systolic contraction). Echocardiographic evaluation was performed at baseline and 6 to 8 months after CRT. As an indication of LV remodeling, end-diastolic volume index and end-systolic volume index (ESVI) and sphericity index were measured. Long-term (40 ± 23 months) clinical follow-up (events: cardiac death and hospital admission for heart failure) was also obtained.

RESULTS

At follow-up after CRT, in the overall population, ejection fraction increased from 26 ± 6% to 35 ± 11% (p < 0.0001), whereas end-diastolic volume index (from 144 ± 43 ml/m(2) to 119 ± 55 ml/m(2)), ESVI (from 108 ± 37 ml/m(2) to 82 ± 49 ml/m(2), p < 0.0001 for both), and sphericity index (from 0.60 ± 0.22 to 0.53 ± 0.15, p = 0.0036) all significantly decreased. By multiple linear regression analysis, after controlling for confounding factors, change in LV ejection fraction at follow-up resulted independently and negatively associated with baseline ESVI (p = 0.001), with much lower improvement after implant in the highest tertile of baseline ESVI. During follow-up, 31 patients (39.7%) had a cardiac event. By Cox regression model, baseline ESVI was the most powerful predictor of events, with event-rate/year increasing with increasing tertiles of ESVI (6.3%, 10.1%, and 23.8%, respectively, p < 0.05).

CONCLUSIONS

In this nonrandomized, open-label clinical study, despite intraventricular electrical and mechanical dyssynchrony, extensive LV remodeling at baseline negatively impacted CRT results in terms of LV function improvement and incidence of cardiac events at follow-up.

Novel therapeutic approaches to post-infarction remodelling

Adverse cardiac remodelling is a major cause of morbidity and mortality following acute myocardial infarction (MI). Mechanical and neurohumoral factors involved in structural and molecular post-infarction remodelling were important targets in research and treatment for years. More recently, therapeutic strategies that address myocardial regeneration and pathophysiological mechanisms of infarct wound healing appear to be useful novel tools to prevent progressive ventricular dilation, functional deterioration, life-threatening arrhythmia, and heart failure. This review provides an overview of future and emerging therapies for cardiac wound healing and remodelling after MI.

A long road for stem cells to cure sick hearts: update on recent clinical trials

The contribution of stem cells to cure damaged hearts has finally been unraveled. A large number of preclinical and clinical studies have showed beneficial outcomes after myocardial infarction. In this review, the current understanding of stem cell therapy in preclinical and clinical experiences is summarized. Stem cells from bone marrow have shown a potential to improve cardiac performance after myocardial infarction in animal and early clinical studies. Clinical trials from all over the world have provided safety assessments of stem cell therapy with marginal improvement of clinical outcomes. Thus, further investigations should be encouraged to resolve the discrepancies between studies, clinical issues, and unclear translational findings. This review provides information and commentary on key trials for stem cell-based treat-ment of cardiovascular disease.

Use of cardiac radionuclide imaging to identify patients at risk for arrhythmic sudden cardiac death

Sudden cardiac death (SCD) accounts for about ½ of all cardiovascular deaths, in most cases the result of a lethal ventricular arrhythmia. Patients considered at risk are often treated with an implantable cardiac defibrillator (ICD), but current criteria for device use, based largely on left ventricular ejection fraction (LVEF), leads to many patients receiving ICDs that they do not use, and many others not receiving ICDs but who suffer SCD. Thus, better methods of identifying patients at risk for SCD are needed, and radionuclide imaging offers much potential. Recent work has focused on imaging of cardiac autonomic innervation. (123)I-mIBG, a norepinephrine analog, is the tracer most studied, and a variety of positron emission tomographic tracers are also under investigation. Radionuclide autonomic imaging may identify at-risk patients with ischemic coronary artery disease, particularly following myocardial infarction and in the setting of hibernating myocardium. Most studies have been done in the setting of congestive heart failure (CHF), with a recent large multicenter study of patients with advanced disease, typically at high risk of SCD, showing that (123)I-mIBG can identify a low risk subgroup with an extremely low incidence of lethal ventricular arrhythmias and cardiac death, therefore, perhaps not requiring an ICD. Cardiac neuronal imaging has been shown to be better predictive of lethal arrhythmias/cardiac death than LVEF and New York Heart Association class, as well as various ECG parameters. Autonomic imaging will likely play an important role in the advancement of cardiac molecular imaging.

Myofibroblasts in the infarct area: concepts and challenges

Myofibroblasts are differentiated fibroblasts that hold a key role in wound healing and remodeling following myocardial infarction (MI). A large repertoire of stimuli, such as mechanical stretch, growth factors, cytokines, and vasoactive peptides, induces myofibroblast differentiation. Myofibroblasts are responsible for the production and deposition of collagen, leading to the establishment of a dense extracellular matrix that strengthens the infarcted tissue and minimizes dilatation of the infarct area. In addition, cells contributing to fibrosis act on sites distal from the infarct area and promote collagen deposition in noninfarcted tissue, thus contributing to adverse remodeling and consequently to the development of congestive heart failure (CHF). Current drugs that are used to treat post-MI CHF do influence fibroblasts and myofibroblasts; however, their therapeutic efficacy is far from being regarded as ideal. Novel therapeutic agents targeting (myo)fibroblasts are being developed to successfully prevent the cardiac remodeling of sites remote from the infarct area and therefore hinder the establishment of CHF. The purpose of this review article is to discuss the basic concepts of the myofibroblasts' actions in cardiac wound healing processes, factors that influence them, currently available pharmacological agents, and future challenges in this area.

10 years of intracoronary and intramyocardial bone marrow stem cell therapy of the heart: from the methodological origin to clinical practice

Intracoronary and intramyocardial stem cell therapy aim at the repair of compromised myocardium thereby--as a causal treatment--preventing ventricular remodeling and improving overall performance. Since the first-in-human use of bone marrow stem cells (BMCs) after acute myocardial infarction in 2001, a large number of clinical studies have demonstrated their clinical benefit: BMC therapy can be performed with usual cardiac catheterization techniques in the conscious patient as well as also easily during cardiosurgical interventions. New York Heart Association severity degree of patients as well as physical activity improve in addition to ("on top" of) all other therapeutic regimens. Stem cell therapy also represents an ultimate approach in advanced cardiac failure. For acute myocardial infarction and chronic ischemia, long-term mortality after 1 and 5 years, respectively, is significantly reduced. A few studies also indicate beneficial effects for chronic dilated cardiomyopathy. The clinical use of autologous BMC therapy implies no ethical problems, when unmodified primary cells are used. With the use of primary BMCs, there are no major stem cell-related side effects, especially no cardiac arrhythmias and inflammation. Various mechanisms of the stem cell action in the human heart are discussed, for example, cell transdifferentiation, cell fusion, activation of intrinsic cardiac stem cells, and cytokine-mediated effects. New techniques allow point-of-care cell preparations, for example, within the cardiac intervention or operation theater, thereby providing short preparation time, facilitated logistics of cell transport, and reasonable cost effectiveness of the whole procedure. The 3 main indications are acute infarction, chronic ischemic heart failure, and dilated cardiomyopathy. Future studies are desirable to further elucidate the mechanisms of stem cell action and to extend the current use of intracoronary and/or intramyocardial stem cell therapy by larger and presumably multicenter and randomized trials.

Chronic social stress induces cardiomyocyte contractile dysfunction and intracellular Ca2+ derangement in rats

Chronic psychosocial stress triggers cardiovascular diseases although underlying mechanisms are still elusive. This study examined the effect of social stress on cardiomyocyte contractile function and pathological changes in myocardium using the visible burrow system (VBS) model. Chronic social stress was induced using a mixed-sex VBS housing in adult Sprague-Dawley (SD) rats. Contractile and intracellular Ca(2+) properties were evaluated in isolated cardiomyocytes including peak shortening (PS), time-to-PS (TPS), time-to-90% relengthening (TR(90)), maximal velocity of shortening/relengthening (± dL/dt), Fura-2 fluorescence intensity, and intracellular Ca(2+) decay. Myocardial histology was evaluated using Masson trichrome staining. Social stress led to depressed PS, ± dL/dt, shortened TPS and prolonged TR(90) compared with the unstressed controls. Baseline and electrically-stimulated rise in Ca(2+) were reduced whereas intracellular Ca(2+) decay was delayed in stressed rats. Histological analyses exhibited overt interstitial fibrosis and cardiomyocyte hypertrophy in stressed rats. The GSH/GSSG ratio (indicative of oxidative stress status) was reduced whereas oxidative protein carbonyl formation was elevated in stressed rats. Western blot analysis showed unchanged expression of superoxide dismutase 1 (SOD1), β(1)-adrenoceptor (β(1)-AR) levels, reduced sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a) levels, and elevated phosphorylation of the stress signaling protein kinase JNK but not ERK in myocardium from stressed rats. Short-term in vitro treatment of cardiomyocytes with the stress inducer phenylephrine mimicked cell damage and intracellular Ca(2+) mishandling, the effects of which were mitigated by antioxidant, JNK inhibition, carvedilol and SERCA2a adenovirus. These findings indicate that chronic social stress is detrimental to cardiac structure and function possibly via mechanisms associated with oxidative injury and intracellular Ca(2+) mishandling.