Cardiovascular magnetic resonance-derived left atrioventricular coupling index and major adverse cardiac events in patients following acute myocardial infarction.

BACKGROUND: Recently, a novel left atrioventricular coupling index (LACI) has been introduced providing prognostic value to predict cardiovascular events beyond common risk factors in patients without cardiovascular disease. Since data on cardiovascular magnetic resonance (CMR)-derived LACI in patients following acute myocardial infarction (AMI) are scarce, we aimed to assess the diagnostic and prognostic implications of LACI in a large AMI patient cohort. METHODS: In total, 1046 patients following AMI were included. After primary percutaneous coronary intervention CMR imaging and subsequent functional analyses were performed. LACI was defined by the ratio of the left atrial end-diastolic volume divided by the left ventricular (LV) end-diastolic volume. Major adverse cardiac events (MACE) including death, reinfarction or heart failure within 12 months after the index event were defined as primary clinical endpoint. RESULTS: LACI was significantly higher in patients with MACE compared to those without MACE (p < 0.001). Youden Index identified an optimal LACI cut-off at 34.7% to classify patients at high-risk (p < 0.001 on log-rank testing). Greater LACI was associated with MACE on univariate regression modeling (HR 8.1, 95% CI 3.4-14.9, p < 0.001) and after adjusting for baseline confounders and LV ejection fraction (LVEF) on multivariate regression analyses (HR 3.1 95% CI 1.0-9, p = 0.049). Furthermore, LACI assessment enabled further risk stratification in high-risk patients with impaired LV systolic function (LVEF ≤ 35%; p < 0.001 on log-rank testing). CONCLUSION: Atrial-ventricular interaction using CMR-derived LACI is a superior measure of outcome beyond LVEF especially in high-risk patients following AMI. Trial registration ClinicalTrials.gov, NCT00712101 and NCT01612312.

Imaging coronary plaques using 3D motion-compensated [18F]NaF PET/MR.

BACKGROUND: Cardiac PET has recently found novel applications in coronary atherosclerosis imaging using [18F]NaF as a radiotracer, highlighting vulnerable plaques. However, the resulting uptakes are relatively small, and cardiac motion and respiration-induced movement of the heart can impair the reconstructed images due to motion blurring and attenuation correction mismatches. This study aimed to apply an MR-based motion compensation framework to [18F]NaF data yielding high-resolution motion-compensated PET and MR images. METHODS: Free-breathing 3-dimensional Dixon MR data were acquired, retrospectively binned into multiple respiratory and cardiac motion states, and split into fat and water fraction using a model-based reconstruction framework. From the dynamic MR reconstructions, both a non-rigid cardiorespiratory motion model and a motion-resolved attenuation map were generated and applied to the PET data to improve image quality. The approach was tested in 10 patients and focal tracer hotspots were evaluated concerning their target-to-background ratio, contrast-to-background ratio, and their diameter. RESULTS: MR-based motion models were successfully applied to compensate for physiological motion in both PET and MR. Target-to-background ratios of identified plaques improved by 7 ± 7%, contrast-to-background ratios by 26 ± 38%, and the plaque diameter decreased by -22 ± 18%. MR-based dynamic attenuation correction strongly reduced attenuation correction artefacts and was not affected by stent-related signal voids in the underlying MR reconstructions. CONCLUSIONS: The MR-based motion correction framework presented here can improve the target-to-background, contrast-to-background, and width of focal tracer hotspots in the coronary system. The dynamic attenuation correction could effectively mitigate the risk of attenuation correction artefacts in the coronaries at the lung-soft tissue boundary. In combination, this could enable a more reproducible and reliable plaque localisation.

Defining the optimal temporal and spatial resolution for cardiovascular magnetic resonance imaging feature tracking.

BACKGROUND: Myocardial deformation analyses using cardiovascular magnetic resonance (CMR) feature tracking (CMR-FT) have incremental value in the assessment of cardiac function beyond volumetric analyses. Since guidelines do not recommend specific imaging parameters, we aimed to define optimal spatial and temporal resolutions for CMR cine images to enable reliable post-processing. METHODS: Intra- and inter-observer reproducibility was assessed in 12 healthy subjects and 9 heart failure (HF) patients. Cine images were acquired with different temporal (20, 30, 40 and 50 frames/cardiac cycle) and spatial resolutions (high in-plane 1.5 × 1.5 mm through-plane 5 mm, standard 1.8 × 1.8 x 8mm and low 3.0 × 3.0 x 10mm). CMR-FT comprised left ventricular (LV) global and segmental longitudinal/circumferential strain (GLS/GCS) and associated systolic strain rates (SR), and right ventricular (RV) GLS. RESULTS: Temporal but not spatial resolution did impact absolute strain and SR. Maximum absolute changes between lowest and highest temporal resolution were as follows: 1.8% and 0.3%/s for LV GLS and SR, 2.5% and 0.6%/s for GCS and SR as well as 1.4% for RV GLS. Changes of strain values occurred comparing 20 and 30 frames/cardiac cycle including LV and RV GLS and GCS (p < 0.001-0.046). In contrast, SR values (LV GLS/GCS SR) changed significantly comparing all successive temporal resolutions (p < 0.001-0.013). LV strain and SR reproducibility was not affected by either temporal or spatial resolution, whilst RV strain variability decreased with augmentation of temporal resolution. CONCLUSION: Temporal but not spatial resolution significantly affects strain and SR in CMR-FT deformation analyses. Strain analyses require lower temporal resolution and 30 frames/cardiac cycle offer consistent strain assessments, whilst SR measurements gain from further increases in temporal resolution.

Meta-analysis on the immunohistological detection of inflammatory cardiomyopathy in endomyocardial biopsies.

Meta-analysis on immunohistological (IHC) concepts for the detection of inflammatory cardiomyopathy (InfCM) in endomyocardial biopsies (EMB). We included 61 publications, with 10,491 patients (mean age 47.1 years; men 66%) who underwent EMB and IHC evaluation. The 460 control patients were devoid of IHC proof of InfCM. The mean IHC detection rate of InfCM was 50.8% (95% CI 47.7-53.8%; range 18.4-91.7%). A publication bias was excluded (Funnel Plot p = 0.4264). This IHC detection rate was significantly (p < 0.0001) higher compared to the histological detection of myocarditis according to the Dallas criteria (mean 8.04%; 95% CI 5.08-12.5%; subset of 3274 patients in 30 publications). However, 13 different diagnostic IHC criteria were described in the publications, with various thresholds of diverse phenotypes of quantified infiltrates, and endothelial expression of diverse cell adhesion molecules (CAM), quantified either visually or by digital image analysis (DIA). The comparison of IHC with cardiac magnetic resonance (CMR) data available in a subset of 13 publications with 1185 patients revealed a sensitivity for CMR of 69% (95% CI 58-79%), a specificity of 73% (95% CI 59-84%), and a ROC-AUC of 0.77 (95% CI 0.73-0.81). This meta-analysis encompassing 10,491 patients confirms a mean detection rate of InfCM in 50.8% of EMB, being significantly more sensitive compared to the histological Dallas criteria. IHC cannot be fully substituted by CMR. However, standardization of the diverse IHC markers and protocols seems pertinent, especially considering the published adverse prognostic impact of IHC-confirmed InfCM and its published suitability for the selection of candidates responding favorably to immunosuppression.

Advancements in the diagnostic workup, prognostic evaluation, and treatment of takotsubo syndrome.

Takotsubo syndrome (TTS) is an acute and mostly reversible cardiomyopathy that mimics an acute coronary syndrome with left ventricular (LV) systolic dysfunction without relevant obstructive coronary artery disease. Its prevalence is probably underestimated and reaches 1.2-2% in patients with acute coronary syndrome undergoing coronary catheterization. Although supraphysiological epinephrine levels have been associated with TTS, the detailed pathophysiology is incompletely understood. Chest pain is the most common clinical presentation; however, cardiac decompensation, cardiogenic shock, and sudden cardiac death due to ventricular fibrillation may also be the first clinical manifestations. Patients are mostly postmenopausal women, in whom the condition is commonly associated with emotional triggers; however, men have a higher prevalence of TTS being associated with physical triggers, which has a worse prognosis compared with TTS associated with emotional triggers. As a diagnosis of exclusion, TTS has no single definitive diagnostic test. According to the distribution of LV wall motion abnormalities, various morphological subtypes have been identified. The final diagnosis depends on cardiac imaging with left ventricular angiography during acute heart catheterization, as well as on echocardiography and cardiac magnetic resonance. Most patients recover completely, albeit several factors have been associated with worse prognosis. Management is based on observational data, while randomized multicenter studies are still lacking. This review provides a general overview of TTS and focuses on the hypothesized pathophysiology, and especially on current practices in diagnosis, prognosis, and treatment.

Systematic review on left atrial appendage closure with the LAmbre device in patients with non-valvular atrial fibrillation.

BACKGROUND: Percutaneous closure (LAAC) of the left atrial appendage (LAA) is an efficacious preventive procedure for patients with non-valvular atrial fibrillation (NVAF) and considerable bleeding risk. We sought to systematically review the available LAAC data on the novel occluder device LAmbre™. METHODS: For this systematic review, a search of the literature was conducted by 3 independent reviewers, reporting the safety and therapeutic success of LAAC in patients being treated with a LAmbre™. Publications reporting the safety and therapeutic success of LAAC using LAmbre™ in n > 5 patients were included. RESULTS: The literature search retrieved n = 10 publications, encompassing n = 403 NVAF patients treated with a LAmbre™ LAAC, with relevant data regarding safety and therapeutic success of the procedure. The mean CHA2DS2-VASc Score was 4.0 + 0.9, and the mean HAS-BLED score was 3.4 + 0.5. The implantation success was 99.7%, with a mean procedure time of 45.4 ± 18.7 min, and a fluoroscopy time of 9.6 ± 5.9 min, and a contrast agent volume of 96.7 ± 0.7 ml. The anticoagulation regimen was switched to DAPT post procedure in the majority of the patients (96.8%). Partial and full recapture were done in 45.5% and in 25.6%, respectively. Major complications were reported in 2.9%, with 0.3% mortality, 1.7% pericardial tamponade, 0.3% stroke, and 0.6% major bleeding complications; no device embolization was observed. During follow up at 6 or 12 months, major adverse cardiovascular events were reported in 3.3%: Stroke or TIA in 1.7%, thrombus formation on the device in 0.7%, and residual flow > 5 mm in 1.0%. In some publications, the favorable implantion properties of the LAmbre™ for difficult anatomies such as shallow or multilobular LAA anatomies were described. CONCLUSIONS: This systematic review on the LAmbre™ LAA-occluder including n = 403 NVAF patients demonstrates an excellent implantion success rate, promising follow-up clinical data, and favorable properties for also challenging LAA anatomies,. While its design seems to be helpful in preventing device embolization, pericardial tamponade may not be substantially reduced by the LAmbre™ as compared with other established LAAC devices. Further larger prospective multicenter registries and randomized trials are needed to scrutinize the value of the LAmbre™ compared with established LAAC devices.

Left Atrial Function with MRI Enables Prediction of Cardiovascular Events after Myocardial Infarction: Insights from the AIDA STEMI and TATORT NSTEMI Trials.

Background The role of left atrial (LA) performance in acute myocardial infarction (AMI) remains controversial. Cardiac MRI myocardial feature tracking (hereafter, MRI-FT) is a method used to quantify myocardial function that enables reliable assessment of atrial function. Purpose To assess the relationship between LA function assessed with MRI-FT and major adverse cardiovascular events (MACE) after AMI. Materials and Methods This secondary analysis of two prospective multicenter cardiac MRI studies (AIDA STEMI [NCT00712101] and TATORT NSTEMI [NCT01612312]) included 1235 study participants with ST-elevation myocardial infarction (n = 795) or non-ST-elevation myocardial infarction (n = 440) between July 2008 and June 2013. All study participants underwent primary percutaneous coronary intervention. MRI-FT analyses were performed in a core laboratory by researchers blinded to clinical status to determine LA performance using LA reservoir function peak systolic strain (εs), LA conduit strain (εe), and LA booster pump function active strain (εa). The relationship of LA performance to a MACE within 12 months after AMI was evaluated by using Cox proportional hazards models and area under the receiver operating characteristic curve (AUC). Results Study participants with MACE had worse LA performance parameters compared with study participants without MACE (εs = 21.2% vs 16.2%, εe = 8.8% vs 6.9%, εa = 11.8% vs 10%; P < .001 for all). All atrial parameters were strongly associated with MACE (hazard ratio [HR], εs = 0.9, εe = 0.88, εa = 0.89; P < .001 for all). For εs, a cutoff of 18.8% was identified as the only independent atrial parameter with which to predict MACE after accounting for confounders and established prognostic markers in adjusted analysis (HR, 0.95; P = .02). The εs yielded incremental prognostic value above left ventricular ejection fraction, global longitudinal strain, microvascular obstruction, and infarct size (AUC comparisons, P < .04 for all). Conclusion Feature tracking of cardiac MRI to derive left atrial peak reservoir strain provided incremental prognostic value for major adverse cardiovascular events prediction versus established cardiac risk factors after acute myocardial infarction. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Almeida in this issue.

Review on sudden death risk reduction after septal reduction therapies in hypertrophic obstructive cardiomyopathy.

Treatment of left ventricular outflow tract (LVOT) obstruction in hypertrophic obstructive cardiomyopathy (HOCM) with septal reduction, either with myectomy or alcohol septal ablation, is aiming to reduce the LVOT gradient and improve symptoms in patients who are refractory to or do not tolerate medical treatment. Apart from contributing to the evolution to heart failure, LVOT obstruction is considered a risk factor for sudden cardiac death (SCD). Both septal reduction treatments have been proven effective in reducing symptoms and seem to improve survival, which has been shown equal to the expected in the normal population. SCD is probably reduced after septal reduction, implying that LVOT obstruction is a major factor predisposing to ventricular tachyarrhythmias. Although available algorithms for SCD stratification have not been tested in patients after septal reduction treatments, effective treatment improves SCD risk profile substantially. Furthermore, high-risk patients with already implanted implantable cardioverter defibrillators (ICDs) before septal reduction show very low appropriate ICD shock rate after effective treatment. It should be noted, however, that the best outcomes for septal myectomy or ablation have been reported in HOCM patients treated in high-volume centres, which substantiates the need to refer patients to centres with high procedural expertise.

Advances in the diagnosis and treatment of transthyretin amyloidosis with cardiac involvement.

Amyloidosis is caused by extracellular deposition of insoluble abnormal fibrils constituted by misfolded proteins, which can modify tissue anatomy and hinder the function of multiple organs including the heart. Amyloidosis that can affect the heart includes mostly systemic amyloidosis (amyloid light chain, AL) and transthyretin amyloidosis (ATTR). The latter can be acquired in elderly patients (ATTRwt), or be inherited in younger individuals (ATTRm). The diagnosis is demanding given the high phenotypic heterogeneity of the disease. Therefore, "red flags," which are suggestive features giving support to diagnostic suspicion, are extremely valuable. However, the lack of broad awareness among clinicians represents a major obstacle for early diagnosis and treatment of ATTR. Furthermore, recent implementation of noninvasive diagnostic techniques has revisited the need for endomyocardial biopsy (EMB). In fact, unlike AL amyloidosis, which requires tissue confirmation and typing for diagnosis, ATTR can now be diagnosed noninvasively with the combination of bone scintigraphy and the absence of a monoclonal protein. Securing the correct diagnosis is pivotal for the newly available therapeutic options targeting both ATTRm and ATTRwt, and are directed to either stabilization of the abnormal protein or the reduction of the production of transthyretin. The purpose of this article is to review the contemporary aspects of diagnosis and management of transthyretin amyloidosis with cardiac involvement, summarizing also the recent therapeutic advances with tafamidis, patisiran, and inotersen.

Transplantation in patients with iron overload: is there a place for magnetic resonance imaging? : Transplantation in iron overload.

In iron overload diseases (thalassemia, sickle cell, and myelodysplastic syndrome), iron is deposited in all internal organs, leading to functional abnormalities. Hematopoietic stem cell transplantation (HSCT) is the only treatment offering a potential cure in these diseases. Our aim was to describe the experience in the field and the role of magnetic resonance imaging in the evaluation of iron overload before and after HSCT. Magnetic resonance imaging (MRI), using T2*, is the most commonly used tool to diagnose myocardial-liver iron overload and guide tailored treatment. Currently, HSCT offers complete cure in thalassemia major, after overcoming the immunologic barrier, and should be considered for all patients who have a suitable donor. The overall thalassemia-free survival of low-risk, HLA-matched sibling stem cell transplantation patients is 85-90%, with a 95% overall survival. The problems of rejection and engraftment are improving with the use of adequate immunosuppression. However, a detailed iron assessment of both heart and liver is necessary for pre- and post-transplant evaluation. In iron overload diseases, heart and liver iron evaluation is indispensable not only for the patients' survival, but also for evaluation before and after HSCT.

The MOGE(S) classification for cardiomyopathies: current status and future outlook.

Cardiomyopathies are complex diseases of multifactorial pathogenesis and have a high morbidity and mortality. Over the past decades, several revisions of classifications and definitions of cardiomyopathies have been proposed, primarily focusing on the phenotypic characterization of cardiomyopathies. The MOGE(S) classification system published in 2013 encompasses the classification of rapidly growing knowledge on genetic mutations, acquired causes (i.e., intramyocardial inflammation, viral infections), and further conditions involved in the induction of cardiomyopathies (e.g., storage diseases, toxicity). It is based on five attributes, including morphofunctional characteristics (M), organ involvement (O), genetic or familial inheritance pattern (G), etiological annotation (E), and optional information about the heart failure functional status (S). This review summarizes the development, the cornerstones of the MOGE(S) classification, and the published data on the clinical relevance of the MOGE(S) classification. We furthermore discuss new issues which might be considered for future updates of the MOGE(S) classification of cardiomyopathies.

Takotsubo syndrome - adding pieces to a complex puzzle.

Takotsubo syndrome, a form of acutely decompensated heart failure, has drawn interest because of its intriguing pathophysiology and therapeutic dilemmas. In their recent work in BMC Cardiovascular Disorders, Abanador-Kamper et al. describe the therapy management in these patients and add valuable information on cardiovascular magnetic resonance imaging evolution.

Expression of stromal cell-derived factor-1 receptors CXCR4 and CXCR7 on circulating platelets of patients with acute coronary syndrome and association with left ventricular functional recovery.

BACKGROUND: Surface expression of stromal cell-derived factor-1 (SDF-1) on platelets is enhanced during ischaemic events and might play an important role in peripheral homing and myocardial repair. As SDF-1 effects are mediated through CXCR4/CXCR7, we investigated platelet expression of SDF-1/CXCR4/CXCR7 in patients with coronary artery disease (CAD). METHODS AND RESULTS: Expression of SDF-1, CXCR4, and CXCR7 in platelets was investigated by western blot analysis, immunofluorescence confocal microscopy, and flow cytometry among healthy subjects and patients with acute coronary syndrome (ACS) and stable CAD. In a cohort study, platelet surface expression of CXCR4, CXCR7, and SDF-1 was measured in 215 patients with symptomatic CAD (stable CAD = 112, ACS = 103) at the time of percutaneous coronary intervention. Course of left ventricular ejection fraction (LVEF) was followed up during intrahospital stay and at 3 months. Both CXCR4 and CXCR7 are surface expressed on human platelets and to a higher degree in CAD patients when compared with healthy controls. Platelet surface expression of CXCR7 but not CXCR4 was enhanced in patients with ACS when compared with patients with stable CAD (mean fluorescence intensity 17.8 vs. 15.3, P = 0.004 and 29.0 vs. 26.3, P = 0.122, respectively). CXCR4 and CXCR7 significantly correlated with their ligand SDF-1 on platelets (ρ = 0.273, P < 0.001 and ρ = 0.454, P < 0.001, respectively). Additionally, high CXCR7 expression above the median correlated with the absolute improvement of LVEF% after 5 days and 3 months (46.2, 49.8, 53.7; P = 0.003). CONCLUSION: These findings indicate that platelet surface expression of CXCR4 and CXCR7 might differentially contribute to SDF-1-mediated effects on regenerative mechanisms following ACS. Studies are warranted to further evaluate the regulatory mechanisms of CXCR4/-7 expression and its prognostic impact on CAD.

Quantitative assessment of magnetic resonance derived myocardial perfusion measurements using advanced techniques: microsphere validation in an explanted pig heart system.

BACKGROUND: Cardiovascular Magnetic Resonance (CMR) myocardial perfusion imaging has the potential to evolve into a method allowing full quantification of myocardial blood flow (MBF) in clinical routine. Multiple quantification pathways have been proposed. However at present it remains unclear which algorithm is the most accurate. An isolated perfused, magnetic resonance (MR) compatible pig heart model allows very accurate titration of MBF and in combination with high-resolution assessment of fluorescently-labeled microspheres represents a near optimal platform for validation. We sought to investigate which algorithm is most suited to quantify myocardial perfusion by CMR at 1.5 and 3 Tesla using state of the art CMR perfusion techniques and quantification algorithms. METHODS: First-pass perfusion CMR was performed in an MR compatible blood perfused pig heart model. We acquired perfusion images at physiological flow ("rest"), reduced flow ("ischaemia") and during adenosine-induced hyperaemia ("hyperaemia") as well as during coronary occlusion. Perfusion CMR was performed at 1.5 Tesla (n = 4 animals) and at 3 Tesla (n = 4 animals). Fluorescently-labeled microspheres and externally controlled coronary blood flow served as reference standards for comparison of different quantification strategies, namely Fermi function deconvolution (Fermi), autoregressive moving average modelling (ARMA), exponential basis deconvolution (Exponential) and B-spline basis deconvolution (B-spline). RESULTS: All CMR derived MBF estimates significantly correlated with microsphere results. The best correlation was achieved with Fermi function deconvolution both at 1.5 Tesla (r = 0.93, p < 0.001) and at 3 Tesla (r = 0.9, p < 0.001). Fermi correlated significantly better with the microspheres than all other methods at 3 Tesla (p < 0.002). B-spline performed worse than Fermi and Exponential at 1.5 Tesla and showed the weakest correlation to microspheres (r = 0.74, p < 0.001). All other comparisons were not significant. At 3 Tesla exponential deconvolution performed worst (r = 0.49, p < 0.001). CONCLUSIONS: CMR derived quantitative blood flow estimates correlate with true myocardial blood flow in a controlled animal model. Amongst the different techniques, Fermi function deconvolution was the most accurate technique at both field strengths. Perfusion CMR based on Fermi function deconvolution may therefore emerge as a useful clinical tool providing accurate quantitative blood flow assessment.

Expression of platelet-bound stromal-cell derived factor-1 (SDF-1) and number of CD34(+) progenitor cells in patients with congestive heart failure.

Platelet-bound stromal cell-derived factor-1 (SDF-1) plays a crucial role in attachment of circulating CD34(+) progenitor cells to the vascular wall, facilitating tissue healing after injury. However there is no evidence about expression of platelet-bound SDF-1 in patients with congestive heart failure (CHF). The aim of our study was to evaluate expression of platelet-bound SDF-1 and number of CD34(+) progenitor cells in patients with CHF. Forty-eight patients with idiopathic dilated cardiomyopathy (DCM) and 61 patients with ischaemic cardiomyopathy (ICM) were consecutively enrolled into the study. Blood taken from 109 consecutive patients was studied for surface expression of platelet-bound SDF-1 and number of CD34(+) progenitor cells by flow cytometry. The highest expression of platelet-bound SDF-1 was observed in patients with severe impairment of left ventricular systolic function compared with patients with mild or moderate impairment of left ventricular systolic function (mild vs. moderate vs. severe impairment of left ventricular systolic function: MFI ± SD: 35.6 ± 34 vs. 101.45 ± 73 vs. 124.86 ± 86.7, Kruskal-Wallis p < 0.001). Similar to platelet-bound SDF-1 number of CD34(+) progenitor cells was the highest in severe impairment of left ventricular systolic function (mild vs. moderate vs. severe impairment of left ventricular systolic function: mean ± SD: 260.4 ± 177.5 vs. 580.7 ± 340.5 vs. 640.82 ± 370.6, Kruskal-Wallis p < 0.001). Platelet-bound SDF-1 expression was associated with number of circulating CD34(+) progenitor cells (r = 0.454, p < 0.001) in patients with CHF. Expression of platelet-bound SDF-1 and number of CD34(+) cells were higher in patients with DCM compared with patients with ICM (p < 0.001 for both) and inversely correlated with age and aspirin therapy. Platelet-bound SDF-1 and CD34(+) progenitor cells are especially increased in patients with severe impairment of left ventricular systolic function in CHF.

Circulating platelet-progenitor cell coaggregate formation is increased in patients with acute coronary syndromes and augments recruitment of CD34+ cells in the ischaemic microcirculation.

AIMS: The aim of the present study was to evaluate the levels of platelet interaction with circulating CD34+ cells in patients with stable angina pectoris (SAP) and acute coronary syndromes (ACS) and to study the functional consequence of coaggregates formation in vitro and in vivo. METHODS AND RESULTS: Platelet binding to circulating progenitor cells was defined by the presence of the platelet-specific marker glycoprotein Ib (CD42b) on the surface of CD34+ cells using flow cytometry. The percentage of CD34+/CD42b+ cell coaggregates was increased in patients with ACS (n = 162), and especially in patients with ST-elevation myocardial infarction (STEMI) (n = 44), compared with patients with SAP (n = 116; P < 0.001). In the ANCOVA analysis, platelet/CD34+ cell coaggregates were independently increased in ACS after adjustment for possible confounders. In a subgroup of our cohort, we also evaluated the levels of CD34+/CD133+/CD42b+ cell coaggregates, which were also significantly increased in ACS, and especially in STEMI (P < 0.05). Platelet/CD34+ cell coaggregates formation correlated with platelet activation (P = 0.001). In a prospective pilot study of patients with AMI (n = 40) using cardiac MRI, patients with increased baseline platelet/CD34+ cell coaggregates presented with a less myocardial infarct size and better left ventricular function at a 3-month follow-up compared with patients with lower coaggregates (P < 0.05 for all). The adhesion of platelet/CD34+ cell coaggregates onto the extracellular matrix and to endothelial monolayer was enhanced compared with CD34+ under high shear rates in vitro (P < 0.05) and within the microcirculation in mice after ischaemia/reperfusion injury as assessed by intravital microscopy (P < 0.05). CONCLUSIONS: These findings imply that circulating platelet/CD34+ cell coaggregate levels are increased in ACS, especially in STEMI, which may be a novel mechanism of domiciliation of CD34+ progenitor cells to the injured microvasculature after acute myocardial infarction.

Skepinone-L, a novel potent and highly selective inhibitor of p38 MAP kinase, effectively impairs platelet activation and thrombus formation.

BACKGROUND/AIMS: Platelets are critically important for primary haemostasis and the major players in thrombotic vascular occlusion. Platelets are activated by agonists, such as thrombin and collagen-related peptide as well as second-wave mediators including thromboxane A2 via different intracellular signaling pathways resulting in degranulation, aggregation and thrombus formation. Platelet activation is paralleled by phosphorylation and activation of p38 MAPK. The limited specificity of hitherto known p38 MAPK inhibitors precluded safe conclusions on the precise role of p38 MAPK in the regulation of platelet function. The present study examined the impact of Skepinone-L, a novel and highly selective inhibitor of p38 mitogen-activated protein kinase (p38 MAPK), on platelet activation and thrombus formation. METHODS: Experiments were performed in freshly isolated human platelets. Protein phosphorylation was quantified by Western blotting, thromboxane B2 synthesis by enzyme immunoassay, ATP release by ChronoLume luciferin assay, cytosolic Ca(2+) concentration by Fura-2 fluorescence-measurements, platelet aggregation by a light transmissions measurement and in vitro thrombus formation by a flow chamber. RESULTS: Skepinone-L (1 µM) virtually abrogated the phosphorylation of platelet p38 MAPK substrate Hsp27 following stimulation with CRP (1 µg/ml), thrombin (5 mU/ml) or thromboxane A2 analogue U-46619 (1 µM). Furthermore, Skepinone-L significantly blunted activation-dependent platelet secretion and aggregation following threshold concentrations of CRP, thrombin and thromboxane A2 analogue U-46619. Skepinone-L did not impair platelet Ca(2+) signaling but prevented agonist-induced thromboxane A2 synthesis through abrogation of p38 MAPK-dependent phosphorylation of platelet cytosolic phospholipase A2 (cPLA2). Skepinone-L further markedly blunted thrombus formation under low (500-s) and high (1700-s) arterial shear rates. CONCLUSIONS: The present study discloses a powerful inhibiting effect of p38 MAPK-blocker Skepinone-L on platelet activation and thrombus formation.

Binding of oxidized low-density lipoprotein on circulating platelets is increased in patients with acute coronary syndromes and induces platelet adhesion to vascular wall in vivo--brief report.

OBJECTIVE: Hyperlipidemia is associated with platelet hyperactivity. In the present study, we evaluated the binding of oxidized low-density lipoprotein (oxLDL) on the surface of circulating platelets in patients with stable coronary artery disease and acute coronary syndromes and its possible association with platelet activation. Furthermore, the role of oxLDL binding on platelet adhesion to collagen and endothelial cells in vitro as well as after carotid ligation in mice was investigated. METHODS AND RESULTS: Using flow cytometry, patients with acute coronary syndromes (n=174) showed significantly enhanced oxLDL binding compared with patients with stable coronary artery disease (n=182; P=0.007). Platelet-bound oxLDL positively correlated with the degree of platelet activation (expression of P-selectin and activated fibrinogen receptor; P<0.001 for both). Plasma oxLDL was increased in patients with acute coronary syndromes compared with stable angina pectoris patients. Preincubation of isolated platelets with oxLDL, but not with native LDL, resulted in enhanced platelet adhesion to collagen and activated endothelial cells under high shear stress in vitro, as well as after carotid ligation in C57BL/6J mice and apolipoprotein E(-/-) mice fed a high cholesterol diet. CONCLUSIONS: Increased platelet-bound oxLDL in patients with acute coronary syndromes may play an important role in atherothrombosis, thus providing a potential future therapeutic target.

Value of serum pregnancy-associated plasma protein A for predicting cardiovascular events among patients presenting with cardiac chest pain.

BACKGROUND: Pregnancy-associated plasma protein A (PAPP-A) has been suggested as a candidate marker for the identification of unstable plaques in coronary arteries. We assessed the value of PAPP-A for predicting short-term cardiovascular events in a large cohort of patients presenting with cardiac chest pain. METHODS: We included consecutive patients who presented to a teaching hospital in Germany with chest pain of cardiac origin confirmed by coronary angiography. We analyzed PAPP-A levels from serum samples drawn within 30 minutes after arrival in the emergency department or in the catheterization laboratory. Patients were followed for 90 days or until death for major adverse cardiovascular events, defined as the combined outcome of stent thrombosis, myocardial (re)infarction, ischemic stroke or cardiovascular-related death. RESULTS: A total of 2568 patients (mean age [± standard deviation (SD)] 68 ± 11 years; 74% male) presented with cardiac chest pain: 55% had stable angina and 45% had acute coronary syndrome. The PAPP-A levels ranged from 4 to 2154 mIU/L (median 14.0 mIU/L, interquartile range 9.3-25.2 mIU/L). Major adverse cardiovascular events occurred in 203 patients (7.9%). The mean PAPP-A level was higher among patients who had an event than among those who did not (62 ± 156 v. 21 ± 23 mIU/L, p < 0.001). In a multivariable analysis, PAPP-A remained a significant independent predictor of the primary outcome within 90 days (hazard ratio per 1 SD increase in PAPP-A level 1.96, 95% confidence interval 1.74-2.21). The optimal prognostic cutoff value was a PAPP-A level of 34.6 mIU/L. INTERPRETATION: Higher levels of serum PAPP-A were independently associated with an increased short-term risk of cardiovascular events in patients presenting with cardiac chest pain. Further studies are required to validate the use of PAPP-A in routine clinical practice to predict future cardiovascular events.

Plasma levels of soluble glycoprotein VI (sGPVI) are associated with ischemic stroke.

Platelet collagen receptor glycoprotein VI (pGPVI) is elevated in patients with acute coronary syndrome (ACS) and ischemic stroke. Recently, we developed a novel bead-based sandwich immunoassay to determine soluble GPVI (sGPVI), which has been validated in ACS patients. This study aimed to evaluate the plasma levels of sGPVI and pGPVI expression in patients with suspected stroke. We consecutively evaluated 176 patients, who were admitted to the stroke unit. Surface expression of pGPVI was determined by flow cytometry, sGPVI concentrations were determined using our sandwich immunoassay. Unlike patients with TIA, patients with stroke showed significantly decreased plasma levels of sGPVI compared to patients with non-ischemic (NI) events (TIA: mean [µg/L] ± standard deviation): 6.1 ± 2.1 vs. NI: 8 ± 4; p = 0.192; stroke: 5.9 ± 2.3 vs. NI; p = 0.013), whereas for pGPVI, patients with TIA and ischemic stroke revealed a significantly increased platelet surface expression compared to NI patients (TIA: mean fluorescence intensity [MFI] ± standard deviation): 20.9 ± 5.4 vs. NI: 17.6 ± 5.2; p = 0.021; stroke: 20.3 ± 6.2 vs. NI; p = 0.016). Using logistic regression analysis, both sGPVI (p = 0.002) and pGPVI (p = 0.012) are independently associated with ischemic stroke compared to other laboratory markers. To predict the individual risk for ischemic stroke using the plasma levels of sGPVI, receiver operating characteristic (ROC) analysis determined an optimal cutoff value of sGPVI at 6.5 µg/l, thus, patients with decreased plasma levels (<6.5 µg/l) have a 1.5-fold adjusted odds ratio (95%confidence interval, 1.4-2.7). Lower plasma levels of sGPVI are associated with the slightly elevated risk of stroke and may be a promising novel biomarker.