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Background. The relevance of neutrophil extracellular traps (NETs) in acute ST-elevation myocardial infarction (STEMI) is unclear. We explored the temporal profile of circulating NET markers and their associations to myocardial injury and function and to adverse clinical events in STEMI patients. Methods and Results. In 259 patients, blood samples were drawn before and after PCI, on day 1, and after 4 months. Double-stranded deoxyribonucleic acid (dsDNA) and myeloperoxidase-DNA (MPO-DNA) were measured in serum by a nucleic acid stain and ELISA. Cardiac magnetic resonance imaging assessed microvascular obstruction (MVO), area at risk, infarct size, myocardial salvage index, left ventricular ejection fraction (LVEF), and change in indexed left ventricular end-diastolic volume (LVEDVi). Clinical events were registered after 12 months. dsDNA and MPO-DNA levels were highest before PCI, with reduced levels thereafter (all p≤0.02). Patients with high vs. low day 1 dsDNA levels (>median; 366 ng/ml) more frequently had MVO, larger area at risk, larger infarct size acutely and after 4 months, and lower myocardial salvage index (all p<0.03). Moreover, they had lower LVEF acutely and after 4 months, and larger change in LVEDVi (all p≤0.014). High day 1 dsDNA levels also associated with risk of having a large infarct size (>75th percentile) and low LVEF (≤49%) after 4 months when adjusted for gender, time from symptoms to PCI, and infarct localization (OR 2.3 and 3.0, both p<0.021), and patients with high day 1 dsDNA levels were more likely to experience an adverse clinical event, also when adjusting for peak troponin T (hazard ratio 5.1, p=0.012). No such observations were encountered for MPO-DNA. Conclusions. High day 1 dsDNA levels after STEMI were associated with myocardial infarct size, adverse left ventricular remodeling, and clinical outcome. Although the origin of dsDNA could be discussed, these observations indicate a potential role for dsDNA in acute myocardial ischemia. This trial is registered with S-08421d, 2008/10614 (Regional Committee for Medical Research Ethics in South-East Norway (2008)).

Plasma concentrations of many cardiovascular and inflammatory proteins are altered after ST-elevation myocardial infarction (STEMI) and may provide prognostic information. We conducted a large-scale proteomic analysis in patients with STEMI, correlating protein levels to infarct size and left ventricular ejection fraction (LVEF) determined with cardiac magnetic resonance imaging. We analysed 131 cardiovascular and inflammatory proteins using a multiplex proximity extension assay and blood samples obtained at baseline, 6, 24, and 96 h from the randomised clinical trial CHILL-MI. Cardiac magnetic resonance imaging data at 4 ± 2 days and 6 months were available as per trial protocol. Using a linear regression model with bootstrap resampling and false discovery rate adjustment we identified five proteins (ST2, interleukin-6, pentraxin-3, interleukin-10, renin, and myoglobin) with elevated values corresponding to larger infarct size or worse LVEF and four proteins (TNF-related apoptosis-inducing ligand, TNF-related activation induced cytokine, interleukin-16, and cystatin B) with values inversely related to LVEF and infarct size, concluding that among 131 circulating inflammatory and cardiovascular proteins in the acute and sub-acute phase of STEMI, nine showed a relationship with infarct size and LVEF post-STEMI, with IL-6 and ST2 exhibiting the strongest association.

Hyperglycemia during myocardial infarction (MI) has a strong and direct association with mortality. In stable patients and experimental models, statins favor the elevation of glycaemia. The present study investigated whether short-course treatment with statins during MI can influence glucose homeostasis and thus the clinical outcome. In this prospective study, euglycemic hyperinsulinemic clamp (EHC) was performed at second (D2) and sixth (D6) day after MI in patients randomized to simvastatin (S)10 or 80 mg/day during hospitalization (n = 27). In addition, patients (n = 550) were treated without (WS) or with simvastatin (S) at 20, 40 or 80 mg/day had HOMA2S on admission (D1) and fifth (D5) day after MI. According to EHC, insulin sensitivity increased by 20 ± 60% in S10 and decreased by −6 ± 28% in S80 (p = 0.025). Consistently, the changes in HOMA2S between D1 and D5 were 40 ± 145% (WS), 22 ± 117% (S20), 16 ± 61% (S40) and −2% ± 88% (S80) (p = 0.001). In conclusion, statin during the acute phase of MI reduces insulin sensitivity in a dose-dependent manner.

Antithrombotic therapy is a critical component of the management of ST-elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PCI). Rapid and profound inhibition of platelet reactivity has been shown to mitigate the ischemic risks and improve myocardial salvage. High residual platelet reactivity (HRPR) has been reported up to 4 or 6 h after loading dose of prasugrel or ticagrelor; therefore, multiple alternative strategies, including crushed or chewed oral tables or intravenous agents, have been investigated to provide a more rapid and sustained inhibition of platelet function and bridge the initial treatment gap. The FABOLUS FASTER is the first investigator-initiated, multicentre, open-label, prospective, randomized study to directly compare the pharmacodynamics effects of cangrelor, tirofiban, chewed or integer prasugrel. This study will add new insights in the management of antiplatelet therapy in patients with STEMI undergoing primary PCI and might be hypothesis-generating for future clinical trials in this field. The trial is registered on clinicaltrials.gov NCT02978040, and EudraCT 2017-001065-24.

ObjectiveMaladaptive repair contributes towards the development of heart failure following myocardial infarction (MI). The αvβ3 integrin receptor is a key mediator and determinant of cardiac repair. We aimed to establish whether αvβ3 integrin expression determines myocardial recovery following MI.Methods18F-Fluciclatide (a novel αvβ3-selective radiotracer) positron emission tomography (PET) and CT imaging and gadolinium-enhanced MRI (CMR) were performed in 21 patients 2 weeks after ST-segment elevation MI (anterior, n=16; lateral, n=4; inferior, n=1). CMR was repeated 9 months after MI. 7 stable patients with chronic total occlusion (CTO) of a major coronary vessel and nine healthy volunteers underwent a single PET/CT and CMR.Results18F-Fluciclatide uptake was increased at sites of acute infarction compared with remote myocardium (tissue-to-background ratio (TBRmean) 1.34±0.22 vs 0.85±0.17; p<0.001) and myocardium of healthy volunteers (TBRmean 1.34±0.22 vs 0.70±0.03; p<0.001). There was no 18F-fluciclatide uptake at sites of established prior infarction in patients with CTO, with activity similar to the myocardium of healthy volunteers (TBRmean 0.71±0.06 vs 0.70±0.03, p=0.83). 18F-Fluciclatide uptake occurred at sites of regional wall hypokinesia (wall motion index≥1 vs 0; TBRmean 0.93±0.31 vs 0.80±0.26 respectively, p<0.001) and subendocardial infarction. Importantly, although there was no correlation with infarct size (r=0.03, p=0.90) or inflammation (C reactive protein, r=−0.20, p=0.38), 18F-fluciclatide uptake was increased in segments displaying functional recovery (TBRmean 0.95±0.33 vs 0.81±0.27, p=0.002) and associated with increase in probability of regional recovery.Conclusion18F-Fluciclatide uptake is increased at sites of recent MI acting as a biomarker of cardiac repair and predicting regions of recovery.Trial registration numberNCT01813045; Post-results.

Background Post-infarction cardiovascular remodeling and heart failure are the leading cause of myocardial infarction (MI)-driven death during the past decades. Experimental observations have involved intestinal microbiota in the susceptibility to MI in mice; however, in humans, identifying whether translocation of gut bacteria to systemic circulation contributes to cardiovascular events post-MI remains a major challenge. Results Here, we carried out a metagenomic analysis to characterize the systemic bacteria in a cohort of 49 healthy control individuals, 50 stable coronary heart disease (CHD) subjects, and 100 ST-segment elevation myocardial infarction (STEMI) patients. We report for the first time higher microbial richness and diversity in the systemic microbiome of STEMI patients. More than 12% of post-STEMI blood bacteria were dominated by intestinal microbiota ( Lactobacillus , Bacteroides , and Streptococcus ). The significantly increased product of gut bacterial translocation (LPS and d -lactate) was correlated with systemic inflammation and predicted adverse cardiovascular events. Following experimental MI, compromised left ventricle (LV) function and intestinal hypoperfusion drove gut permeability elevation through tight junction protein suppression and intestinal mucosal injury. Upon abrogation of gut bacterial translocation by antibiotic treatment, both systemic inflammation and cardiomyocyte injury in MI mice were alleviated. Conclusions Our results provide the first evidence that cardiovascular outcomes post-MI are driven by intestinal microbiota translocation into systemic circulation. New therapeutic strategies targeting to protect the gut barrier and eliminate gut bacteria translocation may reduce or even prevent cardiovascular events post-MI.

Tyro3, AXL, and MerTK (TAM) receptors are activated in macrophages in response to tissue injury and as such have been proposed as therapeutic targets to promote inflammation resolution during sterile wound healing, including myocardial infarction. Although the role of MerTK in cardioprotection is well characterized, the unique role of the other structurally similar TAMs, and particularly AXL, in clinically relevant models of myocardial ischemia/reperfusion infarction (IRI) is comparatively unknown. Utilizing complementary approaches, validated by flow cytometric analysis of human and murine macrophage subsets and conditional genetic loss and gain of function, we uncover a maladaptive role for myeloid AXL during IRI in the heart. Cross signaling between AXL and TLR4 in cardiac macrophages directed a switch to glycolytic metabolism and secretion of proinflammatory IL-1β, leading to increased intramyocardial inflammation, adverse ventricular remodeling, and impaired contractile function. AXL functioned independently of cardioprotective MerTK to reduce the efficacy of cardiac repair, but like MerTK, was proteolytically cleaved. Administration of a selective small molecule AXL inhibitor alone improved cardiac healing, which was further enhanced in combination with blockade of MerTK cleavage. These data support further exploration of macrophage TAM receptors as therapeutic targets for myocardial infarction.

Purpose Complete and rapid recanalization of blood flow by percutaneous coronary intervention (PCI) is the most effective intervention for patients with ST-segment elevation myocardial infarction (STEMI). However, myocardial ischemia/reperfusion (I/R) injury leads to microvascular obstruction (MVO), limiting its efficacy. Colchicine can reduce myocardial I/R injury, but its effect on MVO is unclear. Hence, this study aimed to assess the role and mechanism of colchicine on MVO. Methods Clinical data on STEMI patients with PCI were collected and risk factors related to MVO were analyzed. The rat myocardial I/R model was established to evaluate the MVO by thioflavin S staining. The myocardial I/R model of mice was treated with PBS or colchicine at the reperfusion. The effect of colchicine on cardiomyocyte apoptosis after I/R was evaluated by TUNEL and expression of cleaved caspase-3. ROS levels were detected in H9c2 cells to evaluate the colchicine effect on myocardial oxidative stress. Moreover, the mechanism through which colchicine attenuated MVO was examined using flow cytometry, WB, ELISA, immunohistochemistry, bioinformatics analysis, and immunofluorescence. Results Multivariate analysis showed that elevated neutrophils were associated with extensive MVO. Colchicine could attenuate MVO and reduce neutrophil recruitment and NETs formation after myocardial I/R. In addition, colchicine inhibited cardiomyocyte apoptosis in vivo and ROS levels in vitro. Furthermore, colchicine inhibited neutrophil proliferation in the bone marrow (BM) by inhibiting the S100A8/A9 inflammatory signaling pathway. Conclusions Colchicine attenuated MVO after myocardial I/R injury by inhibiting the proliferation of neutrophils in BM through the neutrophil-derived S100A8/A9 inflammatory signaling pathway.

Neutrophils release their chromatin into the extracellular space upon activation. These web-like structures are called neutrophil extracellular traps (NETs) and have potent prothrombotic and proinflammatory properties. In ST-elevation myocardial infarction (STEMI), NETs correlate with increased infarct size. The interplay of neutrophils and monocytes impacts cardiac remodeling. Monocyte subsets are classified as classical, intermediate and non-classical monocytes. In the present study, in vitro stimulation with NETs led to an increase of intermediate monocytes and reduced expression of CX3CR1 in all subsets. Intermediate monocytes have been associated with poor outcome, while non-classical CX3CR1-positive monocytes could have reparative function after STEMI. We characterized monocyte subsets and NET markers at the culprit lesion site of STEMI patients (n = 91). NET surrogate markers were increased and correlated with larger infarct size and with fewer non-classical monocytes. Intermediate and especially non-classical monocytes were increased at the culprit site compared to the femoral site. Low CX3CR1 expression of monocytes correlated with high NET markers and increased infarct size. In this translational system, causality cannot be proven. However, our data suggest that NETs interfere with monocytic differentiation and receptor expression, presumably promoting a subset shift at the culprit lesion site. Reduced monocyte CX3CR1 expression may compromise myocardial salvage.

Pericardial fluid (PF) has been suggested as a reservoir of molecular targets that can be modulated for efficient repair after myocardial infarction (MI). Here, we set out to address the content of this biofluid after MI, namely in terms of microRNAs (miRs) that are important modulators of the cardiac pathological response. PF was collected during coronary artery bypass grafting (CABG) from two MI cohorts, patients with non-ST-segment elevation MI (NSTEMI) and patients with ST-segment elevation MI (STEMI), and a control group composed of patients with stable angina and without previous history of MI. The PF miR content was analyzed by small RNA sequencing, and its biological effect was assessed on human cardiac fibroblasts. PF accumulates fibrotic and inflammatory molecules in STEMI patients, namely causing the soluble suppression of tumorigenicity 2 (ST-2), which inversely correlates with the left ventricle ejection fraction. Although the PF of the three patient groups induce similar levels of fibroblast-to-myofibroblast activation in vitro, RNA sequencing revealed that PF from STEMI patients is particularly enriched not only in pro-fibrotic miRs but also anti-fibrotic miRs. Among those, miR-22-3p was herein found to inhibit TGF-β-induced human cardiac fibroblast activation in vitro. PF constitutes an attractive source for screening diagnostic/prognostic miRs and for unveiling novel therapeutic targets in cardiac fibrosis.