Microvascular obstruction: underlying pathophysiology and clinical diagnosis

Coronary microvascular obstruction and dysfunction in patients with acute myocardial infarction

Despite prompt epicardial recanalization in patients presenting with ST-segment elevation myocardial infarction (STEMI), coronary microvascular obstruction and dysfunction (CMVO) is still fairly common and is associated with poor prognosis. Various pharmacological and mechanical strategies to treat CMVO have been proposed, but the positive results reported in preclinical and small proof-of-concept studies have not translated into benefits in large clinical trials conducted in the modern treatment setting of patients with STEMI. Therefore, the optimal management of these patients remains a topic of debate. In this Review, we appraise the pathophysiological mechanisms of CMVO, explore the evidence and provide future perspectives on strategies to be implemented to reduce the incidence of CMVO and improve prognosis in patients with STEMI.

Prehospital crushed versus integral prasugrel loading dose in STEMI patients with a large myocardial area

BACKGROUND

The effect of administering a crushed prasugrel loading dose is uncertain in patients presenting with a large myocardial infarction and ST-segment elevation myocardial infarction (STEMI).

AIMS

The aim of this study was to investigate if patients with a large myocardial infarction may benefit from prehospital administration of a crushed prasugrel loading dose.

METHODS

Patients from the CompareCrush trial with an available ambulance electrocardiography (ECG) were included in the study. An independent core laboratory confirmed a prehospital large myocardial area. We compared pre- and postprocedural angiographic markers, including Thrombolysis in Myocardial Infarction (TIMI) 3 flow in the infarct-related artery, high thrombus burden, and myocardial blush grade 3, in STEMI patients with and without a prehospital large myocardial area.

RESULTS

Ambulance ECG was available for 532 patients, of whom 331 patients were identified with a prehospital large myocardial area at risk. Crushed prasugrel significantly improved postprocedural TIMI 3 flow rates in STEMI patients with a prehospital large myocardial area at risk (92% vs 79%, odds ratio [OR] 3.00, 95% confidence interval [CI]: 1.50-6.00) but not in STEMI patients without a prehospital large myocardial area at risk (91% vs 95%, OR 0.47, 95% CI: 0.14-1.57; pinteraction=0.009).

CONCLUSIONS

Administration of crushed prasugrel may improve postprocedural TIMI 3 flow in STEMI patients with signs of a large myocardial area at risk on the ambulance ECG. The practice of crushing tablets of prasugrel loading dose might, therefore, represent a safe, fast and cost-effective strategy to improve myocardial reperfusion in this high-risk STEMI subgroup undergoing primary percutaneous coronary intervention.

Automatic detection of myocardial ischaemia using generalisable spatio-temporal hierarchical Bayesian modelling of DCE-MRI

Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) can be used as a non-invasive method for the assessment of myocardial perfusion. The acquired images can be utilised to analyse the spatial extent and severity of myocardial ischaemia (regions with impaired microvascular blood flow). In the present paper, we propose a novel generalisable spatio-temporal hierarchical Bayesian model (GST-HBM) to automate the detection of ischaemic lesions and improve the in silico prediction accuracy by systematically integrating spatio-temporal context information. We present a computational inference procedure with an adequate trade-off between accuracy and computational efficiency, whereby model parameters are sampled from the posterior distribution with Gibbs sampling, while lower-level hyperparameters are selected using model selection strategies based on the Watanabe Akaike information criterion (WAIC). We have assessed our method on both synthetic (in silico) data with known gold-standard and 12 sets of clinical first-pass myocardial perfusion DCE-MRI datasets. We have also carried out a comparative performance evaluation with four established alternative methods: Gaussian mixture model (GMM), opening and closing operations based on Gaussian mixture model (GMMC&Omax), Markov random field constrained Gaussian mixture model (GMM-MRF) and model-based hierarchical Bayesian model (M-HBM). Our results show that the proposed GST-HBM method achieves much higher in silico prediction accuracy than the established alternative methods. Furthermore, this method appears to provide a more robust delineation of ischaemic lesions in datasets affected by spatially variant noise.

Efficacy of catheter-based drug delivery in a hybrid in vitro model of cardiac microvascular obstruction with porcine microthrombi

Microvascular obstruction (MVO) often occurs in ST-elevation myocardial infarction (STEMI) patients after percutaneous coronary intervention (PCI). Diagnosis and treatment of MVO lack appropriate and established procedures. This study focused on two major points by using an in vitro multiscale flow model, which comprised an aortic root model with physiological blood flow and a microfluidic model of the microcirculation with vessel diameters down to 50 μm. First, the influence of porcine microthrombi (MT), injected into the fluidic microchip, on perfusion was investigated. We found that only 43 % of all injected MT were fully occlusive. Second, it could also be shown that the maximal concentration of a dye (representing therapeutic agent) during intracoronary infusion could be increased on average by 58 % , when proximally occluding the coronary artery by a balloon during drug infusion. The obtained results and insights enhance the understanding of perfusion in MVO-affected microcirculation and could lead to improved treatment methods for MVO patients.

Diagnosis, toxicological mechanism, and detoxification for hepatotoxicity induced by pyrrolizidine alkaloids from herbal medicines or other plants

Pyrrolizidine alkaloids (PAs) are one type of phytotoxins distributed in various plants, including many medicinal herbs. Many organs might suffer injuries from the intake of PAs, and the liver is the most susceptible one. The diagnosis, toxicological mechanism, and detoxification of PAs-induced hepatotoxicity have been studied for several decades, which is of great significance for its prevention, diagnosis, and therapy. When the liver was exposed to PAs, liver sinusoidal endothelial cells (LSECs) loss, hemorrhage, liver parenchymal cells death, nodular regeneration, Kupffer cells activation, and fibrogenesis occurred. These pathological changes classified the PAs-induced liver injury as acute, sub-acute, and chronic type. PAs metabolic activation, mitochondria injury, glutathione (GSH) depletion, inflammation, and LSECs damage-induced activation of the coagulation system were well recognized to play critical roles in the pathological process of PAs-induced hepatotoxicity. A lot of natural compounds like glycyrrhizic acid, (-)-epicatechin, quercetin, baicalein, chlorogenic acid, and so on were demonstrated to be effective in alleviating PAs-induced liver injury, which rendered them huge potential to be developed into therapeutic drugs for PAs poisoning in clinics. This review presents updated information about the diagnosis, toxicological mechanism, and detoxification studies on PAs-induced hepatotoxicity.

Index of Microcirculatory Resistance to predict microvascular obstruction in STEMI: A systematic review and meta-analysis

BACKGROUND

Microvascular obstruction (MVO) is an independent predictor of adverse cardiac events after ST-elevation myocardial infarction (STEMI). The Index of Microcirculatory Resistance (IMR) may be a useful marker of MVO, which could simplify the care pathway without the need for Cardiac Magnetic Resonance (CMR). We assessed whether the IMR can predict MVO in STEMI patients.

METHODS AND RESULTS

We conducted a systematic review and meta-analysis, including articles where invasive IMR was performed post primary percutaneous coronary intervention (PCI) in addition to MVO assessment with cardiac MRI. We searched PubMed, Scopus, Embase, and Cochrane databases from inception until January 2023. Baseline characteristics, coronary physiology and cardiac MRI data were extracted by two independent reviewers. The random-effects model was used to pool the data. Among 15 articles identified, nine articles (n = 728, mean age 61, 81% male) contained IMR data stratified by MVO. Patients with MVO had a mean IMR of 41.2 [95% CI 32.4-50.4], compared to 25.3 [18.3-32.2] for those without. The difference in IMR between those with and without MVO was 15.1 [9.7-20.6]. Meta-regression analyses demonstrated a linear relationship between IMR and TIMI grade (β = 0.69 [0.13-1.26]), as well as infarct size (β = 1.18 [0.24-2.11]) or ejection fraction at 6 months (β = -0.18 [-0.35 to -0.01]).

CONCLUSION

In STEMI, patients with MVO had 15-unit higher IMR than those without. IMR also predicts key prognostic endpoints such as infarct size, MVO, and long-term systolic function.

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

A Comparison of Dynamic SPECT Coronary Flow Reserve with TIMI Frame Count in the Treatment of Non-Obstructive Epicardial Coronary Patients

Background

Microvascular dysfunction in patients with non-obstructive epicardial coronary may aggravate patient's symptoms or lead to various clinical events.

Objective

To investigate the correlation between dynamic single photon emission computed tomography (D-SPECT) derived coronary flow reserve (CFR) and TIMI frame count (TFC) in patients with non-obstructive epicardial coronary patients.

Methods

Patients with suspected or known stable CAD who were recommended to undergo invasive coronary angiography were prospectively enrolled in this study. Those who had non-obstructive coronary received TIMI frame count (TFC) and D-SPECT. A cut-off value of >40 was defined as slow flow referred to TFC.

Results

A total of 47 patients diagnosed with non-obstructive coronary were enrolled. The mean age of patients was 66.09 ± 8.36 years, and 46.8% were male. Dynamic SPECT derived coronary flow reserve (CFR) was significantly correlated with TIMI frame count in 3 epicardial coronary (LAD: r=-0.506, P = 0.0003; LCX: r= -0.532, P = 0.0001; RCA: r= -0.657, P < 0.0001). The sensitivity and specificity of CFR in identifying abnormal TIMI frame count < 40 was 100.0% and 57.6% in LAD, 62.5% and 87.0% in LCX, 83.9% and 75.0% in RCA, respectively. The optimal CFR cut-off values were 2.02, 2.47, and 1.96 among the three vessels.

Conclusion

In patients with non-obstructive coronary, CFR derived from D-SPECT was strongly correlated with TFC. This study demonstrates that that CFR may be an alternative non-invasive method for identifying slow flow in non-obstructive coronary.

Blood pressure targets and management during post-cardiac arrest care

Blood pressure is one modifiable physiological target in patients treated in the intensive care unit after cardiac arrest. Current Guidelines recommend targeting a mean arterial pressure (MAP) of higher than 65-70 mmHg using fluid resuscitation and the use of vasopressors. Management strategies will vary based in the setting, i.e. the pre-hospital compared to the in-hospital phase. Epidemiological data suggest that some degree of hypotension requiring vasopressors occur in almost 50% of patients. A higher MAP could theoretically increase coronary blood flow but on the other hand the use of vasopressor may result in an increase in cardiac oxygen demand and arrhythmia. An adequate MAP is paramount for maintaining cerebral blood flow. In some cardiac arrest patients the cerebral autoregulation may be disturbed resulting in the need for higher MAP in order to avoid decreasing cerebral blood flow. Thus far, four studies including little more than 1000 patients have compared a lower and higher MAP target in cardiac arrest patients. The achieved mean difference of MAP between groups has varied from 10-15 mmHg. Based on these studies a Bayesian meta-analysis suggests that the posterior probability that a future study would find treatment effects higher than a 5% difference between groups to be less than 50%. On the other hand, this analysis also suggests, that the likelihood of harm with a higher MAP target is also low. Noteworthy is that all studies to date have focused mainly on patients with a cardiac cause of the arrest with the majority of patients being resuscitated from a shockable initial rhythm. Future studies should aim to include also non-cardiac causes and aim to target a wider separation in MAP between groups.

Sulforaphane protects microvascular endothelial cells in lower limb ischemia/reperfusion injury mice

Background: Microvascular damage is a key pathological factor in acute lower limb ischemia/reperfusion (I/R) injury. Current evidence suggests that sulforaphane (SFN) protects tissue from I/R injury. However, the role of SFN in acute lower limb I/R injury remains elusive. This study aimed to investigate the role and potential mechanism of SFN in I/R-related microvascular damage in the limb. Methods: Limb viability was evaluated by laser Doppler imaging, tissue edema analysis and histological analysis. Western blotting and immunofluorescence were applied to analyze the levels of apoptosis, oxidative stress, autophagy, transcription factor EB (TFEB) activity and mucolipin 1 (MCOLN1)-calcineurin signaling pathway. Results: SFN administration significantly ameliorated I/R-induced hypoperfusion, tissue edema, skeletal muscle fiber injury and endothelial cell (EC) damage in the limb. Pharmacological inhibition of NFE2L2 (nuclear factor, erythroid 2 like 2) reversed the anti-oxidation and anti-apoptosis effects of SFN on ECs. Additionally, silencing of TFEB by interfering RNA abolished the SFN-induced autophagy restoration, anti-oxidant response and anti-apoptosis effects on ECs. Furthermore, silencing of MCOLN1 by interfering RNA and pharmacological inhibition of calcineurin inhibited the activity of TFEB induced by SFN, demonstrating that SFN regulates the activity of TFEB through the MCOLN1-calcineurin signaling pathway. Conclusion: SFN protects microvascular ECs against I/R injury by TFEB-mediated autophagy restoration and anti-oxidant response.

A Review on Adjunctive Therapies for Endovascular Treatment in Acute Ischemic Stroke

Endovascular treatment (EVT) has revolutionized the management of acute ischemic stroke (AIS), but almost half of patients undergoing EVT do not achieve a good outcome. Adjunctive therapies have been proposed to improve the outcomes of EVT in AIS. This review aims to summarize the current evidence on the use of adjunctive therapies in EVT for AIS, including antithrombotic agents, intra-arterial thrombolytics, cerebroprotective agents, normobaric oxygen, and hypothermia. Several adjunctive therapies have shown promise in improving the outcomes of EVT in AIS, but phase 3 clinical trials are needed to establish clinical efficacy. We summarize the advantages and disadvantages of adjunctive EVT treatments and outline the challenges that each of these therapies will face before being adopted in clinical practice.

Automated diagnosis of cardiovascular diseases from cardiac magnetic resonance imaging using deep learning models: A review

In recent years, cardiovascular diseases (CVDs) have become one of the leading causes of mortality globally. At early stages, CVDs appear with minor symptoms and progressively get worse. The majority of people experience symptoms such as exhaustion, shortness of breath, ankle swelling, fluid retention, and other symptoms when starting CVD. Coronary artery disease (CAD), arrhythmia, cardiomyopathy, congenital heart defect (CHD), mitral regurgitation, and angina are the most common CVDs. Clinical methods such as blood tests, electrocardiography (ECG) signals, and medical imaging are the most effective methods used for the detection of CVDs. Among the diagnostic methods, cardiac magnetic resonance imaging (CMRI) is increasingly used to diagnose, monitor the disease, plan treatment and predict CVDs. Coupled with all the advantages of CMR data, CVDs diagnosis is challenging for physicians as each scan has many slices of data, and the contrast of it might be low. To address these issues, deep learning (DL) techniques have been employed in the diagnosis of CVDs using CMR data, and much research is currently being conducted in this field. This review provides an overview of the studies performed in CVDs detection using CMR images and DL techniques. The introduction section examined CVDs types, diagnostic methods, and the most important medical imaging techniques. The following presents research to detect CVDs using CMR images and the most significant DL methods. Another section discussed the challenges in diagnosing CVDs from CMRI data. Next, the discussion section discusses the results of this review, and future work in CVDs diagnosis from CMR images and DL techniques are outlined. Finally, the most important findings of this study are presented in the conclusion section.

Microvascular obstruction identifies a subgroup of patients who benefit from stem cell therapy following ST-elevation myocardial infarction

BACKGROUND

Microvascular obstruction (MVO) is associated with greater infarct size, adverse left-ventricular (LV) remodeling and reduced ejection fraction following ST-elevation myocardial infarction (STEMI). We hypothesized that patients with MVO may constitute a subgroup of patients that would benefit from intracoronary stem cell delivery with bone marrow mononuclear cells (BMCs) given previous findings that BMCs tended to improve LV function only in patients with significant LV dysfunction.

METHODS AND RESULTS

We analyzed the cardiac MRIs of 356 patients (303 M, 53 F) with anterior STEMIs who received autologous BMCs or placebo / control as part of 4 randomized clinical trials that included the Cardiovascular Cell Therapy Research Network (CCTRN) TIME trial and its pilot, the multicenter French BONAMI trial and SWISS-AMI trials. A total of 327 patients had paired imaging data at 1 year. All patients received 100 to 150 million intracoronary autologous BMCs or placebo / control 3 to 7 days following primary PCI and stenting. LV function, volumes, infarct size and MVO were assessed prior to infusion of BMCs and 1 year later. Patients with MVO (n = 210) had reduced LVEF and much greater infarct size and LV volumes compared to patients without MVO (n = 146) (P < .01). At 12 months, patients with MVO who received BMCs had significantly greater recovery of LVEF compared to those patients with MVO who received placebo (absolute difference = 2.7%; P < .05). Similarly, left-ventricular end-diastolic (LVEDVI) and end-systolic volume indices (LVESVI) demonstrated significantly less adverse remodeling in patients with MVO who received BMCs compared to placebo. In contrast, no improvement in LVEF or LV volumes was observed in those patients without MVO who received BMCs compared to placebo.

CONCLUSIONS

The presence of MVO on cardiac MRI following STEMI identifies a subgroup of patients who benefit from intracoronary stem cell therapy.

The relationship between antiplatelet therapies and the outcome of endovascular treatment for acute ischemic stroke

PURPOSE

We conducted this study to investigate the safety and efficacy of antiplatelet therapies (APT) for acute ischemic patients received endovascular treatment (EVT).

METHODS

The population of our study was derived from a nationwide multicentered registry conducted by 111 centers in China. Patients were divided to groups of no APT, single APT (SAPT) or dual APT (DAPT) according to the APT received at 24 h after EVT. The primary outcome was 90-day functional independence, and the safety outcomes included the symptomatic intracranial hemorrhage (sICH), any type of intracranial hemorrhage, and all-caused death within 90 days. Patient characteristics, procedural data, and outcomes were analyzed.

RESULTS

A total of 1679 patients were included in this study, 71.42% of whom received oral APT at 24 h after EVT, and the initial time was 20.53(13.94-27.17) hours after recanalization or the end of procedure. 90-day functional independence was significantly more observed in patients with DAPT (54.02% vs. 33.64%; adjusted odds ratio [OR] 1.940, 95% CI 1.444-2.606), but not in SAPT (40.75% vs. 33.64%; adjusted OR 1.280, 95% CI 0.907-1.804) compared with patients without APT. APT increased the risk of sICH (1.14% vs. 0, p = 0.036). Both the application of DAPT (adjusted OR 0.264, 95% CI 0.178-0.392, p < 0.001) and SAPT (adjusted OR 0.341, 95% CI 0.213-0.545, p < 0.001) could reduce the 90-day mortality.

CONCLUSIONS

In this uncontrolled series of patients APT at 24 h after EVT showed improvement of the patients' functional independence and reduction of mortality, even though the rate of sICH was increased, especially in the DAPT-group.

Retroperitoneal Hemorrhage Due to Spontaneous Renal Rupture as the First Presentation of Antiphospholipid Syndrome: A Case Report

Spontaneous renal rupture (SRR) with retroperitoneal hemorrhage is an extremely rare medical emergency and is rather challenging for the surgical team. Management of SRR often requires surgical intervention and nephrectomy as it is life-threatening. Antiphospholipid syndrome (APLS) is an autoimmune disease that affects several organs, including kidneys, causing significant abnormalities. Current data suggest that APLS can result in renal artery stenosis, renal vein thrombosis, arterial hypertension, thrombotic microangiopathy, and antiphospholipid syndrome nephropathy where there is renal involvement. Here, we report the case of a 49-year-old man who presented to the Emergency Department with sudden-onset abdominal pain in the context of retroperitoneal bleeding due to SRR. The patient developed hemodynamic instability and underwent a total nephrectomy. The surgical specimen revealed APLS-related lesions. Serological tests confirmed the diagnosis of APLS, which was managed with acenocoumarol and hydroxychloroquine. Since then, he has not experienced any thromboembolic or hemorrhagic episodes. This article aims to present for the first time a case of SRR as the first presentation of APLS as well as to analyze the possible associated mechanisms.

Prognostic significance of non-infarcted myocardium correlated with microvascular impairment evaluated dynamically by native T1 mapping

OBJECTIVES

This study aimed to investigate the influence of microvascular impairment on myocardial characteristic alterations in remote myocardium at multiple time points, and its prognostic significance after acute ST-segment elevation myocardial infarction (STEMI).

METHODS

Patients were enrolled prospectively and performed CMR at baseline, 30 days, and 6 months. The primary endpoint was major adverse cardiac events (MACE): death, myocardial reinfarction, malignant arrhythmia, and hospitalization for heart failure. Cox proportional hazards regression modeling was analyzed to estimate the correlation between T1 mapping of remote myocardium and MACE in patients with and without microvascular obstruction (MVO).

RESULTS

A total of 135 patients (mean age 60.72 years; 12.70% female, median follow-up 510 days) were included, of whom 86 (63.70%) had MVO and 26 (19.26%) with MACE occurred in patients. Native T1 values of remote myocardium changed dynamically. At 1 week and 30 days, T1 values of remote myocardium in the group with MVO were higher than those without MVO (p = 0.030 and p = 0.001, respectively). In multivariable cox regression analysis of 135 patients, native_1w T1 (HR 1.03, 95%CI 1.01-1.04, p = 0.002), native_30D T1 (HR 1.05, 95%CI 1.03-1.07, p < 0.001) and LGE (HR 1.10, 95%CI 1.05-1.15, p < 0.001) were joint independent predictors of MACE. In multivariable cox regression analysis of 86 patients with MVO, native_30D T1 (HR 1.05, 95%CI 1.04-1.07, p < 0.001) and LGE (HR 1.10, 95%CI 1.05-1.15, p < 0.001) were joint independent predictors of MACE.

CONCLUSIONS

The evolution of native T1 in remote myocardium was associated with the extent of microvascular impairment after reperfusion injury. In patients with MVO, native_30D T1 and LGE were joint independent predictors of MACE.

Enhanced Drug Delivery for Cardiac Microvascular Obstruction with an Occlusion-Infusion-Catheter

Microvascular Obstruction (MVO) is a common consequence of acute myocardial infarction. MVO is underdiagnosed and treatment is often nonspecific and ineffective. A multi-scale in-vitro benchtop model was established to investigate drug perfusion in MVO affected microcirculation. The central element of the benchtop model was a fluidic microchip containing channels with diameters between [Formula: see text] and 50 μm representing [Formula: see text] of the microvascular tree fed by the left anterior descending artery (LAD). The outlets of the chip could be closed to mimic MVO. Two methods for intracoronary infusion of pharmacologic agents (simulated by dye) to regions with MVO were investigated using an occlusion-infusion catheter. The first case was a simple, bolus-like infusion into the LAD, whereas the second case consisted of infusion with concomitant proximal occlusion of the LAD phantom with a balloon. Results show that local dye concentration maxima in the chip with MVO were 2.2-3.2 times higher for the case with proximal balloon occlusion than for the conventional infusion method. The cumulated dose could be raised by a factor 4.6-5.2. These results suggest that drug infusion by catheter is more effective if the blood supply to the treated vascular bed is temporarily blocked by a balloon catheter.

Effect of direct stenting on microvascular dysfunction during percutaneous coronary intervention in acute myocardial infarction: a randomized pilot study

Objective

Whether direct stenting (DS) without predilatation during primary percutaneous coronary intervention (PPCI) reduces microvascular dysfunction in patients with ST-elevation myocardial infarction is unclear. We performed a randomized study to assess the effect of DS on microvascular reperfusion.

Methods

Seventy-two patients undergoing PPCI were randomly assigned to the DS or conventional stenting (CS) with predilatation groups. The primary endpoint was the post-PPCI index of microcirculatory resistance (IMR). We compared thrombolysis in myocardial infarction myocardial perfusion (TMP) grades, ST-segment resolution, and long-term clinical outcomes between the groups.

Results

Microvascular reperfusion parameters immediately after PPCI (e.g., the IMR, TMP grade, and ST-segment resolution) were not different between the groups. However, significantly fewer patients in the DS group had the IMR measured because of no-reflow or cardiogenic shock during PPCI than those in the CS group. No differences were found in left ventricular functional recovery or clinical outcomes between the groups.

Conclusions

This trial showed no effect of DS on the IMR. However, our finding should be interpreted with caution because the number of patients who could not have the IMR measured was higher in the CS group than in the DS group. A larger randomized trial is required (Research Registry number: 8079).

miRNA-486-5p: signaling targets and role in non-malignant disease

MicroRNAs (miRNAs) are short non-coding RNAs, highly conserved between species, that are powerful regulators of gene expression. Aberrant expression of miRNAs alters biological processes and pathways linked to human disease. miR-486-5p is a muscle-enriched miRNA localized to the cytoplasm and nucleus, and is highly abundant in human plasma and enriched in small extracellular vesicles. Studies of malignant and non-malignant diseases, including kidney diseases, have found correlations with circulating miR-486-5p levels, supporting its role as a potential biomarker. Pre-clinical studies of non-malignant diseases have identified miR-486-5p targets that regulate major signaling pathways involved in cellular proliferation, migration, angiogenesis, and apoptosis. Validated miR-486-5p targets include phosphatase and tensin homolog (PTEN) and FoXO1, whose suppression activates phosphatidyl inositol-3-kinase (PI3K)/Akt signaling. Targeting of Smad1/2/4 and IGF-1 by miR-486-5p inhibits transforming growth factor (TGF)-β and insulin-like growth factor-1 (IGF-1) signaling, respectively. Other miR-486-5p targets include matrix metalloproteinase-19 (MMP-19), Sp5, histone acetyltransferase 1 (HAT1), and nuclear factor of activated T cells-5 (NFAT5). In this review, we examine the biogenesis, regulation, validated gene targets and biological effects of miR-486-5p in non-malignant diseases.

Implication of IGF1R signaling in the protective effect of Astragaloside IV on ischemia and reperfusion-induced cardiac microvascular endothelial hyperpermeability

BACKGROUND

Myocardial ischemia-reperfusion (I/R) causes damage to coronary capillary endothelial barrier and microvascular leakage (MVL), aggravating tissue injury and heart dysfunction. However, the effective strategy for protecting endothelium barrier of cardiac vasculature remains limited.

PURPOSE

This study aimed to explore the effect of Astragaloside IV (ASIV) on coronary MVL after cardiac I/R and the underlying mechanism.

STUDY DESIGN

Sprague-Dawley (SD) rats were used for assessment of the efficacy of Astragaloside IV in protection of myocardial I/R injury, while human cardiac microvascular endothelial cells were applied to gain more insight into the underlying mechanism.

METHODS

Sprague-Dawley rats with or without pretreatment by ASIV at 10 mg/kg were subjected to occlusion of left coronary anterior descending artery followed by reperfusion. Endothelial cells were exposed to hypoxia and re-oxygenation (H/R). The distribution of junction proteins was detected by immunofluorescence staining and confocal microscope, the content of junction proteins was detected by Western blot, the level of adenosine triphosphate (ATP) was detected by ELISA, and the signal pathway related to permeability was detected by siRNA infection. The fluorescence intensity of FITC-albumin and FITC-Dextran was measured to evaluate the permeability of endothelial cells.

RESULTS

ASIV exhibited protective effects on capillary damage, myocardium edema, albumin leakage, leucocyte infiltration, and the downregulated expression of endothelial junction proteins after I/R. Moreover, ASIV displayed ability to protect ATP from depletion after I/R or H/R, and the effect of ASIV on regulating vascular permeability and junction proteins was abolished once ATP synthase was inhibited. Notably, ASIV activated the insulin-like growth factor 1 receptor (IGF1R) and downstream signaling after reoxygenation. Knocking IGF1R down abolished the effect of ASIV on restoration of ATP, junction proteins and endothelial barrier after H/R.

CONCLUSION

ASIV was potential to prevent MVL after I/R in heart. Moreover, the study for the first time demonstrated that the beneficial role of ASIV depended on promoting production of ATP through activating IGF1R signaling pathway. This result provided novel insight for better understanding the mechanism underlying the potential of ASIV to cope with cardiac I/R injury.

Simultaneous measurements of myocardial glucose metabolism and extracellular volumes with hybrid PET/MRI using concurrent injections of Gd-DTPA and [18F]FDG

BACKGROUND

The aims of this study were to investigate the application of a constant infusion (CI) to mitigate the issue of constantly changing Gd-DTPA contrast levels in a bolus injection for extracellular volume (ECV) measurements by (a) comparing a CI alone to a bolus alone and a bolus followed by CI in healthy myocardium, (b) evaluating the impact of glucose suppression using heparin on ECV.

METHODS

Five healthy canine subjects were imaged to compare three different protocols for injecting Gd-DTPA and FDG: bolus alone, CI alone, bolus followed by CI. Suppression of myocardial glucose uptake was induced using a continuous infusion of 20% lipid at a rate of 0.25 mL·min-1·kg-1 as well as 2000 units of intravenous heparin injected 20 minutes prior to FDG/Gd-DTPA injection.

RESULTS

There was no significant effect on ECV measurement when heparin was used for glucose suppression at equilibrium irrespective of infusion protocol). Measurements of ECV in myocardium, regardless of infusion protocol showed no significant difference at all time points (P = 0.21) prior to washout.

CONCLUSIONS

The suppression of myocardial uptake of [18F]FDG with heparin did not alter the determination of myocardial ECV though a larger sample size may show differences. Further, the infusion protocol (bolus or constant infusion) had no effect on the calculated ECV.

Tracking the progress of inflammation with PET/MRI in a canine model of myocardial infarction

BACKGROUND

Following myocardial infarction, tissue undergoes pathophysiological changes involving inflammation and scar tissue formation. However, little is known about the pathophysiology and prognostic significance of any corresponding changes in remote myocardium. The aim of this study was to investigate the potential application of a combined constant infusion of 18F-FDG and Gd-DTPA to quantitate inflammation and extracellular volume (ECV) from 3 to 40 days after myocardial infarction.

METHODS

Eight canine subjects were imaged at multiple time points following induction of an MI with a 60-minute concurrent constant infusion of Gd-DTPA and 18F-FDG using a hybrid PET/MRI scanner.

RESULTS

There was a significant increase in ECV in remote myocardium on day 14 post-MI (P = .034) and day 21 (P = .021) compared to the baseline. ECV was significantly elevated in the infarcted myocardium compared to remote myocardium at all time points post-MI (days 3, 7, 14, 21, and 40) (P < .001) while glucose uptake was also increased within the infarct on days 3, 7, 14, and 21 but not 40.

CONCLUSIONS

The significant increase in ECV in remote tissue may be due to an ongoing inflammatory process in the early weeks post-infarct.

Effect of Collateral Flow on Catheter-Based Assessment of Cardiac Microvascular Obstruction

Cardiac microvascular obstruction (MVO) associated with acute myocardial infarction (heart attack) is characterized by partial or complete elimination of perfusion in the myocardial microcirculation. A new catheter-based method (CoFI, Controlled Flow Infusion) has recently been developed to diagnose MVO in the catheterization laboratory during acute therapy of the heart attack. A porcine MVO model demonstrates that CoFI can accurately identify the increased hydraulic resistance of the affected microvascular bed. A benchtop microcirculation model was developed and tuned to reproduce in vivo MVO characteristics. The tuned benchtop model was then used to systematically study the effect of different levels of collateral flow. These experiments showed that measurements obtained in the catheter-based method were adversely affected such that collateral flow may be misinterpreted as MVO. Based on further analysis of the measured data, concepts to mitigate the adverse effects were formulated which allow discrimination between collateral flow and MVO.

Controlled-Level EVERolimus in Acute Coronary Syndrome (CLEVER-ACS) - A phase II, randomized, double-blind, multi-center, placebo-controlled trial

BACKGROUND

Activation of inflammatory pathways during acute myocardial infarction contributes to infarct size and left ventricular (LV) remodeling. The present prospective randomized clinical trial was designed to test the efficacy and safety of broad-spectrum anti-inflammatory therapy with a mammalian target of rapamycin (mTOR) inhibitor to reduce infarct size.

DESIGN

Controlled-Level EVERolimus in Acute Coronary Syndrome (CLEVER-ACS, clinicaltrials.gov NCT01529554) is a phase II randomized, double-blind, multi-center, placebo-controlled trial on the effects of a 5-day course of oral everolimus on infarct size, LV remodeling, and inflammation in patients with acute ST-elevation myocardial infarction (STEMI). Within 5 days of successful primary percutaneous coronary intervention (pPCI), patients are randomly assigned to everolimus (first 3 days: 7.5 mg every day; days 4 and 5: 5.0 mg every day) or placebo, respectively. The primary efficacy outcome is the change from baseline (defined as 12 hours to 5 days after pPCI) to 30-day follow-up in myocardial infarct size as measured by cardiac magnetic resonance imaging (CMRI). Secondary endpoints comprise corresponding changes in cardiac and inflammatory biomarkers as well as microvascular obstruction and LV volumes assessed by CMRI. Clinical events, laboratory parameters, and blood cell counts are reported as safety endpoints at 30 days.

CONCLUSION

The CLEVER-ACS trial tests the hypothesis whether mTOR inhibition using everolimus at the time of an acute STEMI affects LV infarct size following successful pPCI.

Rare Coronary Embolism Secondary to Cardioversion of Atrial Fibrillation

The diagnosis and management of myocardial infarction with nonobstructive coronary arteries (MINOCA) are difficult due to its variable presentations, different causes, and challenging diagnostic approaches. Cardiac imaging modalities including cardiac magnetic resonance (CMR) are very useful tools for diagnosing and managing MINOCA. Myocardial infarction (MI) can be caused by coronary emboli that can be contributed to atrial fibrillation (AF). Rarely, coronary embolism with resultant MINOCA can occur after direct current cardioversion (DCCV) even in fully anticoagulated patients. We present a rare case of a coronary embolism following DCCV as well as a CMR finding of microvascular obstruction (MVO), which has not previously been reported after DCCV. This case also emphasizes the value of obtaining a CMR for patients with MINOCA.

A Narrative Review of the Classical and Modern Diagnostic Methods of the No-Reflow Phenomenon

The incidence of the no-reflow (NR) phenomenon varies depending on the diagnostic criteria used. If just the angiographic criteria are considered (i.e., a degree of thrombolysis in myocardial infarction ≤2), it will be found that the incidence of NR is quite low; on the other hand, when the myocardial NR is taken into account (i.e., a decrease in the quality of myocardial reperfusion expressed by the degree of myocardial blush), the real incidence is higher. Thus, the early establishment of a diagnosis of NR and the administration of specific treatment can lead to its reversibility. Otherwise, regardless of the follow-up period, patients with NR have a poor prognosis. In the present work, we offer a comprehensive perspective on diagnostic tools for NR detection, for improving the global management of patients with arterial microvasculature damage, which is a topic of major interest in the cardiology field, due to its complexity and its link with severe clinical outcomes.

Prediction of Myocardial Infarction From Patient Features With Machine Learning

This study proposes machine learning-based models to automatically evaluate the severity of myocardial infarction (MI) from physiological, clinical, and paraclinical features. Two types of machine learning models are investigated for the MI assessment: the classification models classify the presence of the infarct and the persistent microvascular obstruction (PMO), and the regression models quantify the Percentage of Infarcted Myocardium (PIM) of patients suspected of having an acute MI during their reception in the emergency department. The ground truth labels for these supervised models are derived from the corresponding Delayed Enhancement MRI (DE-MRI) exams and manual annotations of the myocardium and scar tissues. Experiments were conducted on 150 cases and evaluated with cross-validation. Results showed that for the MI (PMO inclusive) and the PMO (infarct exclusive), the best models obtained respectively a mean error of 0.056 and 0.012 for the quantification, and 88.67 and 77.33% for the classification accuracy of the state of the myocardium. The study of the features' importance also revealed that the troponin value had the strongest correlation to the severity of the MI among the 12 selected features. For the proposal's translational perspective, in cardiac emergencies, qualitative and quantitative analysis can be obtained prior to the achievement of MRI by relying only on conventional tests and patient features, thus, providing an objective reference for further treatment by physicians.

Combined Approach to Eptifibatide and Thrombectomy in Acute Ischemic Stroke Because of Large Vessel Occlusion: A Matched-Control Analysis

BACKGROUND

In patients undergoing mechanical thrombectomy (MT), adjunctive antithrombotic might improve angiographic reperfusion, reduce the risk of distal emboli and reocclusion but possibly expose patients to a higher intracranial hemorrhage risk. This study evaluated the safety and efficacy of combined MT plus eptifibatide for acute ischemic stroke.

METHODS

This was a propensity-matched analysis of data from 2 prospective trials in Chinese populations: the ANGEL-ACT trial (Endovascular Treatment Key Technique and Emergency Workflow Improvement of Acute Ischemic Stroke) in 111 hospitals between November 2017 and March 2019, and the EPOCH trial (Eptifibatide in Endovascular Treatment of Acute Ischemic Stroke) in 15 hospitals between April 2019 and March 2020. The primary efficacy outcome was good outcome (modified Rankin Scale score 0-2) at 3 months. Secondary efficacy outcomes included the distribution of 3-month modified Rankin Scale scores and poor outcome (modified Rankin Scale score 5-6) and successful recanalization. The safety outcomes included any intracranial hemorrhage, symptomatic intracranial hemorrhage, and 3-month mortality. Mixed-effects logistic regression models were used to account for within-hospital clustering in adjusted analyses.

RESULTS

Eighty-one combination arm EPOCH subjects were matched with 81 ANGEL-ACT noneptifibatide patients. Compared with the no eptifibatide group, the eptifibatide group had significantly higher rates of successful recanalization (91.3% versus 81.5%; P=0.043) and 3-month good outcomes (53.1% versus 33.3%; P=0.016). No significant difference was found in the remaining outcome measures between the 2 groups. All outcome measures of propensity score matching were consistent with mixed-effects logistic regression models in the total population.

CONCLUSIONS

This matched-control study demonstrated that MT combined with eptifibatide did not raise major safety concerns and showed a trend of better efficacy outcomes compared with MT alone. Overall, eptifibatide shows potential as a periprocedural adjunctive antithrombotic therapy when combined with MT. Further randomized controlled trials of MT plus eptifibatide should be prioritized.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03844594 (EPOCH), NCT03370939 (ANGEL-ACT).

Post-ST-Segment-Elevation Myocardial Infarction Platelet Reactivity Is Associated With the Extent of Microvascular Obstruction and Infarct Size as Determined by Cardiac Magnetic Resonance Imaging

Background

Despite optimized medical management and techniques of primary percutaneous coronary intervention, a substantial proportion of patients with ST‐segment–elevation myocardial infarction (STEMI) display significant microvascular damage. Thrombotic microvascular obstruction (MVO) has been implicated in the pathogenesis of microvascular and subsequent myocardial damage attributed to distal embolization and microvascular platelet plugging. However, there are only scarce data regarding the effect of platelet reactivity on MVO.

Methods and Results

We prospectively evaluated 105 patients in 2 distinct periods (2012–2013 and 2016–2018) who presented with first ST‐segment–elevation myocardial infarction and underwent primary percutaneous coronary intervention. All patients were treated with dual antiplatelet therapy (DAPT). Blood samples were analyzed for platelet reactivity, and cardiac magnetic resonance imaging scans were evaluated for late gadolinium enhancement and MVO. DAPT suboptimal response was defined as hyporesponsiveness to either aspirin or P2Y12 receptor inhibitor agents and demonstrated in 31 patients (29.5%) of the current cohort. Suboptimal platelet response to DAPT was associated with a significantly greater extent of MVO when expressed as a percentage of the left ventricular mass, left ventricular scar, and the number of myocardial left ventricular segments showing MVO (P<0.01 for each). Adjusted multivariable logistic regression model revealed that suboptimal response to DAPT is significantly associated with both greater late gadolinium enhancement (P<0.01) and MVO extent (odds ratio, 3.7 [95% CI, 1.3–10.5]; P=0.01). Patients with a greater extent of MVO were more likely to sustain major adverse cardiovascular events at a 1‐year follow‐up (37% versus 11%; P<0.01).

Conclusions

In patients undergoing primary percutaneous coronary intervention for ST‐segment–elevation myocardial infarction, platelet reactivity in response to DAPT is a key predictor of the extent of both myocardial and microvascular damage.

HMGB1-Mediated Activation of the Inflammatory-Reparative Response Following Myocardial Infarction

Different cell types belonging to the innate and adaptive immune system play mutually non-exclusive roles during the different phases of the inflammatory-reparative response that occurs following myocardial infarction. A timely and finely regulation of their action is fundamental for the process to properly proceed. The high-mobility group box 1 (HMGB1), a highly conserved nuclear protein that in the extracellular space can act as a damage-associated molecular pattern (DAMP) involved in a large variety of different processes, such as inflammation, migration, invasion, proliferation, differentiation, and tissue regeneration, has recently emerged as a possible regulator of the activity of different immune cell types in the distinct phases of the inflammatory reparative process. Moreover, by activating endogenous stem cells, inducing endothelial cells, and by modulating cardiac fibroblast activity, HMGB1 could represent a master regulator of the inflammatory and reparative responses following MI. In this review, we will provide an overview of cellular effectors involved in these processes and how HMGB1 intervenes in regulating each of them. Moreover, we will summarize HMGB1 roles in regulating other cell types that are involved in the different phases of the inflammatory-reparative response, discussing how its redox status could affect its activity.

Lipid nitroalkene nanoparticles for the focal treatment of ischemia reperfusion

Rationale: The treatment of microvascular obstruction (MVO) using ultrasound-targeted LNP cavitation (UTC) therapy mechanically relieves the physical obstruction in the microcirculation but does not specifically target the associated inflammatory milieu. Electrophilic fatty acid nitroalkene derivatives (nitro-fatty acids), that display pleiotropic anti-inflammatory signaling and transcriptional regulatory actions, offer strong therapeutic potential but lack a means of rapid targeted delivery. The objective of this study was to develop nitro-fatty acid-containing lipid nanoparticles (LNP) that retain the mechanical efficacy of standard LNP and can rapidly target delivery of a tissue-protective payload that reduces inflammation and improves vascular function following ischemia-reperfusion. Methods: The stability and acoustic behavior of nitro-fatty acid LNP (NO₂-FA-LNP) were characterized by HPLC-MS/MS and ultra-high-speed microscopy. The LNP were then used in a rat hindlimb model of ischemia-reperfusion injury with ultrasound-targeted cavitation. Results: Intravenous administration of NO₂-FA-LNP followed by ultrasound-targeted LNP cavitation (UTC) in both healthy rat hindlimb and following ischemia-reperfusion injury showed enhanced NO₂-FA tissue delivery and microvascular perfusion. In addition, vascular inflammatory mediator expression and lipid peroxidation were decreased in tissues following ischemia-reperfusion revealed NO₂-FA-LNP protected against inflammatory injury. Conclusions: Vascular targeting of NO₂-FA-LNP with UTC offers a rapid method of focal anti-inflammatory therapy at sites of ischemia-reperfusion injury.

Predictive value of C-reactive protein/albumin ratio for no-reflow in patients with non-ST-elevation myocardial infarction

Introduction: The focus of this research was to explore the link between CRP (C-reactive protein) /albumin ratio (CAR), a novel inflammatory response marker, and no-reflow (NR) phenomena in non-ST elevation myocardial infarction (non-STEMI) patients during percutaneous coronary intervention (PCI). Methods: The current study recruited 209 non-STEMI participants who underwent PCI. The patients were divided into two groups based on their post-intervention Thrombolysis in Myocardial Infarction (TIMI) flow grade; those with and without NR. Results: In all, 30 non-STEMI patients (6.9%) had NR after PCI. CAR values were substantially greater in the NR group. The CAR was identified to be a determinant of the NR (OR: 1.250, 95% CI: 1.033-1.513, P=0.02), although CRP and albumin were not independently related with NR in the multivariate analysis. In our investigation, low density lipoprotein-cholesterol levels and high thrombus burden were also predictors of the occurrence of NR. According to receiver operating characteristic curve evaluation, the optimal value of CAR was>1.4 with 60% sensitivity and 47% specificity in detecting NR in non-STEMI patients following PCI. Conclusion: To the best of knowledge, this is the first investigation to demonstrate that the CAR, a new and useful inflammatory marker, can be utilized as a predictor of NR in patients with non-STEMI prior to PCI.

Near-infrared spectroscopy to predict microvascular obstruction after primary percutaneous coronary intervention

BACKGROUND

Successful restoration of epicardial coronary artery patency by primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction (STEMI) does not always lead to adequate reperfusion at the microvascular level.

AIMS

This study sought to investigate the association between lipid-rich coronary plaque identified by near-infrared spectroscopy combined with intravascular ultrasound (NIRS-IVUS) and microvascular obstruction (MVO) detected by cardiac magnetic resonance imaging (MRI) after PPCI for STEMI.

METHODS

We investigated 120 patients with STEMI undergoing PPCI. NIRS-IVUS was used to measure the maximum lipid core burden index in 4 mm (maxLCBI4 mm) in the infarct-related lesions before PPCI. Delayed contrast-enhanced cardiac MRI was performed to evaluate MVO one week after PPCI.

RESULTS

MVO was identified in 40 (33%) patients. MaxLCBI4 mm in the infarct-related lesion was significantly larger in the MVO group compared with the no-MVO group (median [interquartile range]: 745 [522-853] vs 515 [349-698], p<0.001). A multivariable logistic regression model showed that maxLCBI4 mm was an independent predictor of MVO (odds ratio: 24.7 [95% confidence interval: 2.5-248.0], p=0.006). Receiver operating characteristic curve analysis demonstrated that maxLCBI4 mm >600 was the optimal cut-off value to predict MVO (Youden index=0.44 and area under the curve=0.71) with a sensitivity of 75% and a specificity of 69%.

CONCLUSIONS

Lipid content measured by NIRS in the infarct-related lesions was associated with the occurrence of MVO after PPCI in STEMI.

The effectiveness of alprostadil in treating coronary microcirculation dysfunction following ST-segment elevation myocardial infarction in a pig model

Though alprostadil has been reported to improve the impaired microcirculation of patients with pulmonary arterial hypertension, its effectiveness as a treatment for coronary microvasculature dysfunction (CMD) following ST-segment elevation myocardial infarction (STEMI) is unknown. A total of 18 miniature pigs with CMD following STEMI were randomized into three groups that received an intracoronary injection of 5 ml of normal saline, 2 mg of nicorandil or 10 µg of alprostadil immediately after measurement of the index of microcirculatory resistance (IMR) and then an intravenous drip containing 5 ml of normal saline, 2 mg of nicorandil or 10 µg of alprostadil once a day for 6 days. The IMR, cardiac function using ultrasound, infarct areas and heparanase levels in infarct areas were measured and compared between the three groups. The IMR decreased markedly 10 min after alprostadil or nicorandil intracoronary injection (both P<0.05) but not following saline injection (P>0.05). After 7 days, the IMR was substantially lower in the alprostadil and nicorandil groups compared with the saline group (both P<0.05) and the ejection fraction was considerably higher in the alprostadil and nicorandil groups compared with the saline group (both P<0.05). Differences in infarct areas and the relative heparanase expression levels among the 3 groups were similar to the differences in the ejection fraction. No significant differences in the above assessment indexes were identified in the alprostadil and nicorandil groups. Alprostadil infusion improved coronary microcirculation function, reduced the infarct area and limited left ventricular dilatation in a pig coronary microvasculature dysfunction model following STEMI.

Vitamin D level predicts angiographic no-reflow phenomenon after percutaneous coronary intervention in patients with ST segment elevation myocardial infarction

Aim: No-reflow phenomenon (NRP) is an undesirable result of coronary interventions, and usually occurred during the primary percutaneous coronary intervention (PPCI). On the other hand, there is growing evidence of epidemiological studies suggest that serum 25 hydroxy-vitamin D (25(OH)D3) level is significantly associated with cardiovascular mortality and morbidity. Objective: To investigate whether there is a relationship between admission serum 25(OH)D3 levels and NRP in patients with ST elevation myocardial infarction (STEMI). Methods: This study consisted of 496 consecutive acute STEMI patients who underwent PPCI. After the restoration of antegrade flow, the patients were divided into the normal flow and no-reflow groups. No-reflow defined as; thrombosis in myocardial infarction (TIMI) flow grade ≤2, or a TIMI flow grade = 3 with a myocardial perfusion grade ≤1. Results: Angiographic no-reflow occurred 18.2% of all study patients. Serum 25(OH)D3 levels were significantly lower when compared with the normal flow group (14.6 ± 7.3 vs 22.6 ± 9.6 ng/ml; p < 0.001). 25(OH)D3 level was significantly negatively correlated with Neutrophil/lymphocyte (N/L) ratio. In multivariate analysis, 25(OH)D3 level on admission (OR: 0.738; 95% CI: 0.584-0.878; p = 0.001) was found an independent predictor of NRP together with N/L ratio, N-Terminal-proBNP, balloon pre dilatation and syntax score I. On receiver operating curve analysis (ROC), the cut-off value of admission 25(OH)D3 level was 10.5 ng/ml for the prediction of NRP with a sensitivity of 93% and specificity of 68%. The area under the ROC curve (AUC) was 0.772 (95% CI: 0.697-0.846; p < 0.001). Conclusion: We have shown that lower 25(OH)D3 level on admission is associated with higher NRP frequency and may be used as a predictor for NRP in STEMI patients undergoing PPCI.

Controlling Reperfusion Injury With Controlled Reperfusion: Historical Perspectives and New Paradigms

Cardiac reperfusion injury is a well-established outcome following treatment of acute myocardial infarction and other types of ischemic heart conditions. Numerous cardioprotection protocols and therapies have been pursued with success in pre-clinical models. Unfortunately, there has been lack of successful large-scale clinical translation, perhaps in part due to the multiple pathways that reperfusion can contribute to cell death. The search continues for new cardioprotection protocols based on what has been learned from past results. One class of cardioprotection protocols that remain under active investigation is that of controlled reperfusion. This class consists of those approaches that modify, in a controlled manner, the content of the reperfusate or the mechanical properties of the reperfusate (e.g., pressure and flow). This review article first provides a basic overview of the primary pathways to cell death that have the potential to be addressed by various forms of controlled reperfusion, including no-reflow phenomenon, ion imbalances (particularly calcium overload), and oxidative stress. Descriptions of various controlled reperfusion approaches are described, along with summaries of both mechanistic and outcome-oriented studies at the pre-clinical and clinical phases. This review will constrain itself to approaches that modify endogenously-occurring blood components. These approaches include ischemic postconditioning, gentle reperfusion, controlled hypoxic reperfusion, controlled hyperoxic reperfusion, controlled acidotic reperfusion, and controlled ionic reperfusion. This review concludes with a discussion of the limitations of past approaches and how they point to potential directions of investigation for the future.

Severe obstructive sleep apnea is associated with coronary microvascular dysfunction and obstruction in patients with ST-elevation myocardial infarction

BACKGROUND

Coronary microvascular dysfunction and obstruction (CMVO) is a strong predictor of a poor prognosis in patients with ST-segment elevation myocardial infarction (STEMI). Although research has suggested that obstructive sleep apnea (OSA) exacerbates CMVO after primary percutaneous coronary intervention, data supporting a correlation between OSA and CMVO are limited. This study was performed to investigate whether OSA is associated with CMVO, detected as microvascular obstruction on cardiovascular magnetic resonance images, in patients with STEMI.

METHODS

Patients (N = 249) with a first STEMI underwent primary percutaneous coronary intervention. CMVO was evaluated on cardiovascular magnetic resonance images based on the presence of microvascular obstruction. OSA was classified into four levels of severity based on the respiratory event index (REI): absent (REI of <5), mild (REI of ≥5 to <15), moderate (REI of ≥15 to <30) and severe (REI of ≥30).

RESULTS

The REI was significantly higher in the presence of microvascular obstruction (n = 139) than in its absence (n = 110) (REI of 12.8 vs. 10.7, respectively; p = 0.023). Microvascular obstruction was observed in 42%, 58%, 57% and 70% of patients in the absent, mild, moderate and severe OSA groups, respectively. Multiple logistic regression analysis showed that severe OSA was associated with increased odds of microvascular obstruction (odds ratio (OR), 5.10; 95% confidence interval (CI),1.61-16.2; p = 0.006). Mild and moderate OSA were also associated with increased odds of microvascular obstruction (mild OSA: OR, 2.88; 95% CI, 1.19-7.00; p = 0.019 and moderate OSA: OR, 3.79; 95% CI, 1.43-10.1; p = 0.008).

CONCLUSION

Severe OSA was associated with CMVO after primary percutaneous coronary intervention in patients with STEMI.

Effects of deferred versus immediate stenting on left ventricular function in patients with ST elevation myocardial infarction

BACKGROUND

Previous studies have shown conflicting results on the benefits of deferred stenting (DS) in infarct size and the incidence of microvascular obstruction in patients with ST elevation myocardial infarction (STEMI). However, effect of DS on left ventricular (LV) function was not known. We aimed to evaluate whether DS improve LV function and relevant clinical outcomes after STEMI, using follow-up data from the INNOVATION study (NCT02324348).

METHODS

In total, 114 patients were randomly assigned to DS group or immediate stenting (IS) group at a 1:1 ratio. LV functional remodeling indices and MACE (major adverse cardiac events: a composite of death, non-fatal MI, unplanned target vessel revascularization, or hospitalization due to heart failure) were compared between DS and IS groups.

RESULTS

Serial echocardiographic analyses were completed in 89 subjects (78%). There were no significant changes in LV volume in either group. While LV ejection fraction and wall motion score index (WMSI) improved in both groups during follow-up, the increments were not statistically different between the 2 groups (4.3 ± 8.2 vs 3.2 ± 7.1, P = .504 for ΔLV ejection fraction; -0.16 ± 0.25 vs -0.16 ± 0.25, P = .99 for ΔWMSI). However, E/e'' was decreased and e' was increased only in the DS group (-3.31 ± 5.60 vs -0.46 ± 3.10, P = .005 for ΔE/e'; 0.77 ± 1.71 vs -0.22 ± 1.64, P = .009 for Δe'). The incidence of major adverse cardiac events was numerically lower in the DS group than in the IS group without a statistical significance at 1-year follow-up.

CONCLUSIONS

Routine DS improved LV diastolic function but not systolic function compared with IS in patients with STEMI.

Protective Effect of Nicorandil on Cardiac Microvascular Injury: Role of Mitochondrial Integrity

A major shortcoming of postischemic therapy for myocardial infarction is the no-reflow phenomenon due to impaired cardiac microvascular function including microcirculatory barrier function, loss of endothelial activity, local inflammatory cell accumulation, and increased oxidative stress. Consequently, inadequate reperfusion of the microcirculation causes secondary ischemia, aggravating the myocardial reperfusion injury. ATP-sensitive potassium ion (KATP) channels regulate the coronary blood flow and protect cardiomyocytes from ischemia-reperfusion injury. Studies in animal models of myocardial ischemia-reperfusion have illustrated that the opening of mitochondrial KATP (mito-KATP) channels alleviates endothelial dysfunction and reduces myocardial necrosis. By contrast, blocking mito-KATP channels aggravates microvascular necrosis and no-reflow phenomenon following ischemia-reperfusion injury. Nicorandil, as an antianginal drug, has been used for ischemic preconditioning (IPC) due to its mito-KATP channel-opening effect, thereby limiting infarct size and subsequent severe ischemic insult. In this review, we analyze the protective actions of nicorandil against microcirculation reperfusion injury with a focus on improving mitochondrial integrity. In addition, we discuss the function of mitochondria in the pathogenesis of myocardial ischemia.

Development and Validation of a Random Forest Diagnostic Model of Acute Myocardial Infarction Based on Ferroptosis-Related Genes in Circulating Endothelial Cells

The high incidence and mortality of acute myocardial infarction (MI) drastically threaten human life and health. In the past few decades, the rise of reperfusion therapy has significantly reduced the mortality rate, but the MI diagnosis is still by means of the identification of myocardial injury markers without highly specific biomarkers of microcirculation disorders. Ferroptosis is a novel reported type of programmed cell death, which plays an important role in cancer development. Maintaining iron homeostasis in cells is essential for heart function, and its role in the pathological process of ischemic organ damages remains unclear. Being quickly detected through blood tests, circulating endothelial cells (CECs) have the potential for early judgment of early microcirculation disorders. In order to explore the role of ferroptosis-related genes in the early diagnosis of acute MI, we relied on two data sets from the GEO database to first detect eight ferroptosis-related genes differentially expressed in CECs between the MI and healthy groups in this study. After comparing different supervised learning algorithms, we constructed a random forest diagnosis model for acute MI based on these ferroptosis-related genes with a compelling diagnostic performance in both the validation (AUC = 0.8550) and test set (AUC = 0.7308), respectively. These results suggest that the ferroptosis-related genes might play an important role in the early stage of MI and have the potential as specific diagnostic biomarkers for MI.

Oral pre-treatment with thiocyanate (SCN-) protects against myocardial ischaemia-reperfusion injury in rats

Despite improvements in revascularization after a myocardial infarction, coronary disease remains a major contributor to global mortality. Neutrophil infiltration and activation contributes to tissue damage, via the release of myeloperoxidase (MPO) and formation of the damaging oxidant hypochlorous acid. We hypothesized that elevation of thiocyanate ions (SCN⁻), a competitive MPO substrate, would modulate tissue damage. Oral dosing of rats with SCN⁻, before acute ischemia–reperfusion injury (30 min occlusion, 24 h or 4 week recovery), significantly reduced the infarct size as a percentage of the total reperfused area (54% versus 74%), and increased the salvageable area (46% versus 26%) as determined by MRI imaging. No difference was observed in fractional shortening, but supplementation resulted in both left-ventricle end diastolic and left-ventricle end systolic areas returning to control levels, as determined by echocardiography. Supplementation also decreased antibody recognition of HOCl-damaged myocardial proteins. SCN⁻ supplementation did not modulate serum markers of damage/inflammation (ANP, BNP, galectin-3, CRP), but returned metabolomic abnormalities (reductions in histidine, creatine and leucine by 0.83-, 0.84- and 0.89-fold, respectively), determined by NMR, to control levels. These data indicate that elevated levels of the MPO substrate SCN⁻, which can be readily modulated by dietary means, can protect against acute ischemia–reperfusion injury.

EpCAM and microvascular obstruction in patients with STEMI: a cardiac magnetic resonance study

INTRODUCTION AND OBJECTIVES

Microvascular obstruction (MVO) is negatively associated with cardiac structure and worse prognosis after ST-segment elevation myocardial infarction (STEMI). Epithelial cell adhesion molecule (EpCAM), involved in epithelium adhesion, is an understudied area in the MVO setting. We aimed to determine whether EpCAM is associated with the appearance of cardiac magnetic resonance (CMR)-derived MVO and long-term systolic function in reperfused STEMI.

METHODS

We prospectively included 106 patients with a first STEMI treated with percutaneous coronary intervention, quantifying serum levels of EpCAM 24hours postreperfusion. All patients underwent CMR imaging 1 week and 6 months post-STEMI. The independent correlation of EpCAM with MVO, systolic volume indices, and left ventricular ejection fraction was evaluated.

RESULTS

The mean age of the sample was 59±13 years and 76% were male. Patients were dichotomized according to median EpCAM (4.48 pg/mL). At 1-week CMR, lower EpCAM was related to extensive MVO (P=.021) and larger infarct size (P=.019). At presentation, EpCAM values were significantly associated with the presence of MVO in univariate (OR, 0.58; 95%CI, 0.38-0.88; P=.011) and multivariate logistic regression models (OR, 0.55; 95%CI, 0.35-0.87; P=.010). Although MVO tends to resolve at chronic phases, decreased EpCAM was associated with worse systolic function: reduced left ventricular ejection fraction (P=.009) and higher left ventricular end-systolic volume (P=.043).

CONCLUSIONS

EpCAM is associated with the occurrence of CMR-derived MVO at acute phases and long-term adverse ventricular remodeling post-STEMI.

Optimum Blood Pressure in Patients With Shock After Acute Myocardial Infarction and Cardiac Arrest

BACKGROUND

In patients with shock after acute myocardial infarction (AMI), the optimal level of pharmacologic support is unknown. Whereas higher doses may increase myocardial oxygen consumption and induce arrhythmias, diastolic hypotension may reduce coronary perfusion and increase infarct size.

OBJECTIVES

This study aimed to determine the optimal mean arterial pressure (MAP) in patients with AMI and shock after cardiac arrest.

METHODS

This study used patient-level pooled analysis of post-cardiac arrest patients with shock after AMI randomized in the Neuroprotect (Neuroprotective Goal Directed Hemodynamic Optimization in Post-cardiac Arrest Patients; NCT02541591) and COMACARE (Carbon Dioxide, Oxygen and Mean Arterial Pressure After Cardiac Arrest and Resuscitation; NCT02698917) trials who were randomized to MAP 65 mm Hg or MAP 80/85 to 100 mm Hg targets during the first 36 h after admission. The primary endpoint was the area under the 72-h high-sensitivity troponin-T curve.

RESULTS

Of 235 patients originally randomized, 120 patients had AMI with shock. Patients assigned to the higher MAP target (n = 58) received higher doses of norepinephrine (p = 0.004) and dobutamine (p = 0.01) and reached higher MAPs (86 ± 9 mm Hg vs. 72 ± 10 mm Hg, p < 0.001). Whereas admission hemodynamics and angiographic findings were all well-balanced and revascularization was performed equally effective, the area under the 72-h high-sensitivity troponin-T curve was lower in patients assigned to the higher MAP target (median: 1.14 μg.72 h/l [interquartile range: 0.35 to 2.31 μg.72 h/l] vs. median: 1.56 μg.72 h/l [interquartile range: 0.61 to 4.72 μg. 72 h/l]; p = 0.04). Additional pharmacologic support did not increase the risk of a new cardiac arrest (p = 0.88) or atrial fibrillation (p = 0.94). Survival with good neurologic outcome at 180 days was not different between both groups (64% vs. 53%, odds ratio: 1.55; 95% confidence interval: 0.74 to 3.22).

CONCLUSIONS

In post-cardiac arrest patients with shock after AMI, targeting MAP between 80/85 and 100 mm Hg with additional use of inotropes and vasopressors was associated with smaller myocardial injury.

Colchicine Inhibits Neutrophil Extracellular Trap Formation in Patients With Acute Coronary Syndrome After Percutaneous Coronary Intervention

Background

Release of neutrophil extracellular traps (NETs) after percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) is associated with periprocedural myocardial infarction, as a result of microvascular obstruction via pro‐inflammatory and prothrombotic pathways. Colchicine is a well‐established anti‐inflammatory agent with growing evidence to support use in patients with coronary disease. However, its effects on post‐PCI NET formation in ACS have not been explored.

Methods and Results

Sixty patients (40 ACS; 20 stable angina pectoris) were prospectively recruited and allocated to colchicine or no treatment. Within 24 hours of treatment, serial coronary sinus blood samples were collected during PCI. Isolated neutrophils from 10 patients with ACS post‐PCI and 4 healthy controls were treated in vitro with colchicine (25 nmol/L) and stimulated with either ionomycin (5 μmol/L) or phorbol 12‐myristate 13‐acetate (50 nmol/L). Extracellular DNA was quantified using Sytox Green and fixed cells were stained with Hoechst 3342 and anti‐alpha tubulin. Baseline characteristics were similar across both treatment and control arms. Patients with ACS had higher NET release versus patients with stable angina pectoris (P<0.001), which was reduced with colchicine treatment (area under the curve: 0.58 versus 4.29; P<0.001). In vitro, colchicine suppressed unstimulated (P<0.001), phorbol 12‐myristate 13‐acetate–induced (P=0.009) and ionomycin‐induced (P=0.002) NET formation in neutrophils isolated from patients with ACS post‐PCI, but not healthy controls. Tubulin organization was impaired in neutrophils from patients with ACS but was restored by colchicine treatment.

Conclusions

Colchicine suppresses NET formation in patients with ACS post‐PCI by restoring cytoskeletal dynamics. These findings warrant further investigation in randomized trials powered for clinical end points.

Registration

URL: https://anzctr.org.au; Unique identifier: ACTRN12619001231134.

Prognostic value of microvascular occlusion MRI quantification in assessment of reperfused myocardial infarction

Background

Reperfusion therapy in patients with acute myocardial infarction (AMI) can salvage the myocardium; however, successful restoration of the coronary artery patency is not always associated with adequate perfusion at the level of microvasculature, known as the no-reflow or microvascular occlusion (MVO). The primary objective of our prospective study was to assess, by cardiac magnetic resonance (CMR), the prognostic value of MVO size, and its impact on left ventricular (LV) remodeling in cases of reperfused AMI.

Thirty-three patients with AMI underwent cardiac MRI at 1.5-T scanner within 7 days (baseline) and 3 months (follow-up) after reperfusion. Patients with MVO were included where early gadolinium enhancement (EGE), late gadolinium enhancement (LGE), and cine sequences were acquired. The impact of MVO size on LV ejection fraction (EF%) and LV volumes was quantitively analyzed.

Results

There was a significant inverse correlation between the MVO size % of the LV mass (LVM) and the EF% values measured at follow-up with a P value of 0.000, while a significant positive correlation was encountered between the MVO% of LVM and both indexed end-systolic volume (ESVI) and indexed end-diastolic volume (EDVI) values measured at follow-up with P values of 0.438 and 0.389, respectively. MVO size was found to be a significant factor affecting the patient’s outcome (P = 0.000) where MVO size of > 10% of the total LVM can be a predictor of a worse outcome and reduced EF% at follow-up.

Conclusion

The prognostic value of MVO could be statistically determined with a cut off value to predict a possible good outcome using CMR.

Neuropeptide-Y causes coronary microvascular constriction and is associated with reduced ejection fraction following ST-elevation myocardial infarction

Aims

The co-transmitter neuropeptide-Y (NPY) is released during high sympathetic drive, including ST-elevation myocardial infarction (STEMI), and can be a potent vasoconstrictor. We hypothesized that myocardial NPY levels correlate with reperfusion and subsequent recovery following primary percutaneous coronary intervention (PPCI), and sought to determine if and how NPY constricts the coronary microvasculature.

Methods and results

Peripheral venous NPY levels were significantly higher in patients with STEMI (n = 45) compared to acute coronary syndromes/stable angina ( n = 48) or with normal coronary arteries (NC, n = 16). Overall coronary sinus (CS) and peripheral venous NPY levels were significantly positively correlated (r = 0.79). STEMI patients with the highest CS NPY levels had significantly lower coronary flow reserve, and higher index of microvascular resistance measured with a coronary flow wire. After 2 days they also had significantly higher levels of myocardial oedema and microvascular obstruction on cardiac magnetic resonance imaging, and significantly lower ejection fractions and ventricular dilatation 6 months later. NPY (100–250 nM) caused significant vasoconstriction of rat microvascular coronary arteries via increasing vascular smooth muscle calcium waves, and also significantly increased coronary vascular resistance and infarct size in Langendorff hearts. These effects were blocked by the Y₁ receptor antagonist BIBO3304 (1 μM). Immunohistochemistry of the human coronary microvasculature demonstrated the presence of vascular smooth muscle Y₁ receptors.

Conclusion

High CS NPY levels immediately after reperfusion correlate with microvascular dysfunction, greater myocardial injury, and reduced ejection fraction 6 months after STEMI. NPY constricts the coronary microcirculation via the Y₁ receptor, and antagonists may be a useful PPCI adjunct therapy.