Optimized Treatment of ST-Elevation Myocardial Infarction

Intracoronary Versus Intravenous Low-Dose Tirofiban in Patients With ST-Elevation Myocardial Infarction: A Meta-Analysis of Randomised Controlled Trials

BACKGROUND

This meta-analysis aimed to evaluate the effects of intracoronary (IC) low-dose tirofiban versus intravenous (IV) administration on clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

All published randomised controlled trials (RCTs) comparing the effects of IC low-dose tirofiban (a bolus of ≤10 ug/kg) versus IV administration in patients with STEMI were identified by searching PubMed, EMBASE, Cochrane Library, and ISI Web of Science from inception to June 2023, with no language restriction. The risk ratio (RR) with 95% confidence intervals (CI) and the weighted mean difference (WMD) with 95% CI were calculated.

RESULTS

Eleven RCTs involving 1,802 patients were included. Compared with the IV group, IC low-dose tirofiban was associated with improved major adverse cardiac events rate (RR 0.595, 95% CI 0.442-0.802; p=0.001), left ventricular ejection fraction (WMD 1.982, 95% CI 0.565-3.398; p=0.006), thrombolysis in myocardial infarction (TIMI) flow grade (RR 1.065, 95% CI 1.004-1.131; p=0.037), and TIMI myocardial perfusion grade (RR 1.194, 95% CI 1.001-1.425; p=0.049). The two groups had no significant difference in bleeding events (RR 0.952, 95% CI 0.709-1.279; p=0.745).

CONCLUSIONS

Intracoronary low-dose tirofiban administration may be a safe and effective alternative to IV administration in STEMI patients.

Invasive assessment of coronary microvascular dysfunction and cardiovascular outcomes across the full spectrum of CHD: a meta-analysis

INTRODUCTION AND OBJECTIVES

Coronary microvascular dysfunction (CMD) is highly prevalent and is recognized as an important clinical entity in patients with coronary heart disease (CHD). Nevertheless, the association of CMD with adverse cardiovascular events in the spectrum of CHD has not been systemically quantified.

METHODS

We searched electronic databases for studies on patients with CHD in whom coronary microvascular function was measured invasively, and clinical events were recorded. The primary endpoint was major adverse cardiac events (MACE), and the secondary endpoint was all-cause death. Estimates of effect were calculated using a random-effects model from published risk ratios.

RESULTS

We included 27 studies with 11 404 patients. Patients with CMD assessed by invasive methods had a higher risk of MACE (RR, 2.18; 95%CI, 1.80-2.64; P<.01) and all-cause death (RR, 1.88; 95%CI, 1.55-2.27; P<.01) than those without CMD. There was no significant difference in the impact of CMD on MACE (interaction P value=.95) among different invasive measurement modalities. The magnitude of risk of CMD assessed by invasive measurements for MACE was greater in acute coronary syndrome patients (RR, 2.84, 95%CI, 2.26-3.57; P<.01) than in chronic coronary syndrome patients (RR, 1.77, 95%CI, 1.44-2.18; P<.01) (interaction P value<.01).

CONCLUSIONS

CMD based on invasive measurements was associated with a high incidence of MACE and all-cause death in patients with CHD. The magnitude of risk for cardiovascular events in CMD as assessed by invasive measurements was similar among different methods but varied among CHD populations.

N-terminal pro-B-type natriuretic peptide and pulmonary echography are predictors of acute heart failure needing early mechanical ventilation in acute coronary syndrome

AIM

The aim of this study was to determine the best clinical predictors of acute heart failure needing mechanical ventilation (MV) in the first 48 h of evolution of patients admitted because of acute coronary syndrome (ACS).

METHODS

We analyzed a cohort of patients admitted for ACS between February 2017 and February 2018. A pulmonary ultrasound was performed on admission and was considered positive (PE+) when there were three or more B-lines in two quadrants or more of each hemithorax. It was compared with N-terminal pro-B-type natriuretic peptide (NT-proBNP), peak troponin T-us value GRACE (Global Registry of Acute Coronary Events), CRUSADE (Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the American College of Cardiology and American Heart Association guidelines - Bleeding Score), CACS (Canada Acute Coronary Syndrome risk score), and HAMIOT (Heart Failure after Acute Myocardial Infarction with Optimal Treatment score) scores, shock index, ejection fraction, chest X-ray, and Killip class at admission as predictors of MV in the first 48 h of admission.

RESULTS

A total of 119 patients were included: 54.6% with ST elevation and 45.4% without ST elevation. Twelve patients (10.1%) required MV in the first 48 h of evolution. The sensitivity of PE+ was 100% (73.5-100%), specificity 91.6% (84.6-96.1%), and area under the curve was 0.96 (0.93-0.96). The sensitivity of an NT-proBNP value more than 3647 was 88.9% (51.9-99.7%), specificity 92.1% (84.5-96.8%), and area under the curve was 0.905 (0.793-1). The κ statistic between both predictors was 0.579. All the other scores were significantly worse than PE + .

CONCLUSION

Lung ultrasound and a high NT-proBNP (3647 ng/L in our series) on admission are the best predictors of acute heart failure needing MV in the first 48 h of ACS. The agreement between both tests was only moderate.

Injury minimization after myocardial infarction: focus on extracellular vesicles

Despite improvements in clinical outcomes following acute myocardial infarction, mortality remains high, especially in patients with severely reduced left ventricular ejection fraction (LVEF <30%), emphasizing the need for effective cardioprotective strategies adjunctive to recanalization. Traditional cell therapy has shown equivocal success, shifting the focus to innovative cardioactive biologicals and cell mimetic therapies, particularly extracellular vesicles (EVs). EVs, as carriers of non-coding RNAs and other essential biomolecules, influence neighbouring and remote cell function in a paracrine manner. Compared to cell therapy, EVs possess several clinically advantageous traits, including stability, ease of storage (enabling off-the-shelf clinical readiness), and decreased immunogenicity. Allogeneic EVs from mesenchymal and/or cardiac stromal progenitor cells demonstrate safety and potential efficacy in preclinical settings. This review delves into the translational potential of EV-based therapeutic approaches, specifically highlighting findings from large-animal studies, and offers a synopsis of ongoing early-stage clinical trials in this domain.

Recombinant human soluble domain of CD39L3 and ticagrelor: cardioprotective effects in experimental myocardial infarction

BACKGROUND AND AIMS

The ecto-nucleoside triphosphate diphosphohydrolases of the CD39 family degrade ATP and ADP into AMP, which is converted into adenosine by the extracellular CD73/ecto-5-nucleotidase. This pathway has been explored in antithrombotic treatments but little in myocardial protection. We have investigated whether the administration of solCD39L3 (AZD3366) confers additional cardioprotection to that of ticagrelor alone in a pre-clinical model of myocardial infarction (MI).

METHODS

Ticagrelor-treated pigs underwent balloon-induced MI (90 min) and, before reperfusion, received intravenously either vehicle, 1 mg/kg AZD3366 or 3 mg/kg AZD3366. All animals received ticagrelor twice daily for 42 days. A non-treated MI group was run as a control. Serial cardiac magnetic resonance (baseline, Day 3 and Day 42 post-MI), light transmittance aggregometry, bleeding time, and histological and molecular analyses were performed.

RESULTS

Ticagrelor reduced oedema formation and infarct size at Day 3 post-MI vs. controls. A 3 mg/kg AZD3366 provided an additional 45% reduction in oedema and infarct size compared with ticagrelor and a 70% reduction vs. controls (P < .05). At Day 42, infarct size declined in all ticagrelor-administered pigs, particularly in 3 mg/kg AZD3366-treated pigs (P < .05). Left ventricular ejection fraction was diminished at Day 3 in placebo pigs and worsened at Day 42, whereas it remained unaltered in ticagrelor ± AZD3366-administered animals. Pigs administered with 3 mg/kg AZD3366 displayed higher left ventricular ejection fraction upon dobutamine stress at Day 3 and minimal dysfunctional segmental contraction at Day 42 (χ2P < .05 vs. all). Cardiac and systemic molecular readouts supported these benefits. Interestingly, AZD3366 abolished ADP-induced light transmittance aggregometry without affecting bleeding time.

CONCLUSIONS

Infusion of AZD3366 on top of ticagrelor leads to enhanced cardioprotection compared with ticagrelor alone.

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.

Spatial genomics: mapping human steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as non-alcoholic fatty liver disease) is a leading cause of chronic liver disease worldwide. MASLD can progress to metabolic dysfunction-associated steatohepatitis (MASH, formerly known as non-alcoholic steatohepatitis) with subsequent liver cirrhosis and hepatocellular carcinoma formation. The advent of current technologies such as single-cell and single-nuclei RNA sequencing have transformed our understanding of the liver in homeostasis and disease. The next frontier is contextualizing this single-cell information in its native spatial orientation. This understanding will markedly accelerate discovery science in hepatology, resulting in a further step-change in our knowledge of liver biology and pathobiology. In this Review, we discuss up-to-date knowledge of MASLD development and progression and how the burgeoning field of spatial genomics is driving exciting new developments in our understanding of human liver disease pathogenesis and therapeutic target identification.

Qihuang Zhuyu formula alleviates coronary microthrombosis by inhibiting PI3K/Akt/αIIbβ3-mediated platelet activation

BACKGROUND

Coronary microembolism (CME) is commonly seen in the peri-procedural period of Percutaneous Coronary Intervention (PCI), where local platelet activation and endothelial cell inflammation crosstalk may lead to micro thrombus erosion and rupture, with serious consequences. Qihuang Zhuyu Formula (QHZYF) is a Chinese herbal compound with high efficacy against coronary artery disease, but its antiplatelet mechanism is unclear.

HYPOTHESIS/PURPOSE

This study aimed to elucidate the effects and mechanisms of QHZYF on sodium laurate-induced CME using network pharmacology and in vitro and in vivo experiments.

METHODS

We employed high-performance liquid chromatography mass spectrometry to identify the main components of QHZYF. Network pharmacology analysis, molecular docking and surface plasmon resonance (SPR) were utilized to predict the primary active components, potential therapeutic targets, and intervention pathways mediating the effects of QHZYF on platelet activation. Next, we pretreated a sodium laurate-induced minimally invasive CME rat model with QHZYF. In vivo experiments were performed to examine cardiac function in rats, to locate coronary arteries on heart sections to observe internal microthrombi, to extract rat Platelet-rich plasma (PRP) for adhesion assays and CD62p and PAC-1 (ITGB3/ITGA2B) flow assays, and to measure platelet-associated protein expression in PRP. In vitro clot retraction and Co-culture of HUVECs with PRP were performed and the gene pathway was validated through flow cytometry and immunofluorescence.

RESULTS

Combining UPLC-Q-TOF/MS technology and database mining, 78 compounds were finally screened as the putative and representative compounds of QHZYF, with 75 crossover genes associated with CME. QHZYF prevents CME mainly by regulating key pathways of the inflammation and platelets, including Lipid and atherosclerosis, Fluid shear stress, platelet activation, and PI3K-Akt signaling pathways. Five molecules including Calyson, Oroxin A, Protosappanin A,Kaempferol and Geniposide were screened and subjected to molecular docking and SPR validation in combination with Lipinski rules (Rule of 5, Ro5). In vivo experiments showed that QHZYF not only improved myocardial injury but also inhibited formation of coronary microthrombi. QHZYF inhibited platelet activation by downregulating expression of CD62p receptor and platelet membrane protein αIIbβ3 and reduced the release of von Willebrand Factor (vWF), Ca2+ particles and inflammatory factor IL-6. Further analysis revealed that QHZYF inhibited the activation of integrin αIIbβ3, via modulating the PI3K/Akt pathways. In in vitro experiments, QHZYF independently inhibited platelet clot retraction. Upon LPS induction, the activation of platelet membrane protein ITGB3 was inhibited via the PI3K/Akt pathway, revealing an important mechanism for attenuating coronary microthrombosis. We performed mechanistic validation using PI3K inhibitor LY294002 and Akt inhibitor MK-2206 to show that QHZYF inhibited platelet membrane protein activation and inflammation to improved coronary microvessel embolism by regulating PI3K/Akt/αIIbβ3 pathways, mainly by inhibiting PI3K and Akt phosphorylation.

CONCLUSION

QHZYF interferes with coronary microthrombosis through inhibition of platelet adhesion, activation and inflammatory crosstalk, thus has potential in clinical anti-platelet applications. Calyson, Oroxin A, Protosappanin A, Kaempferol and Geniposide may be the major active ingredient groups of QHZYF that alleviate coronary microthrombosis.

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.

Determinants and Prognoses of Visual-Functional Mismatches After Mechanical Reperfusion in ST-Elevation Myocardial Infarction

Background

Discordance between the anatomy and physiology of the coronary has important implications for managing patients with stable coronary disease, but its significance in ST-elevation myocardial infarction has not been fully elucidated.

Methods

The retrospective study involved patients diagnosed with ST-elevation myocardial infarction (STEMI) who underwent percutaneous coronary intervention (PCI), along with quantitative coronary angiography (QCA) and quantitative flow ratio (QFR) assessments. Patients were stratified into four groups regarding the severity of the culprit vessel, both visually and functionally: concordantly negative (QCA-diameter stenosis [DS] ≤ 50% and QFR > 0.80), mismatch (QCA-DS > 50% and QFR > 0.80), reverse mismatch (QCA-DS ≤ 50% and QFR ≤ 0.80), and concordantly positive (QCA-DS > 50% and QFR ≤ 0.80). Multivariable logistic regression analyses were conducted to identify the clinical factors linked to visual-functional mismatches. Kaplan‒Meier analysis was conducted to estimate the 18-month adverse cardiovascular events (MACE)-free survival between the four groups.

Results

The study involved 310 patients, with 68 presenting visual-functional mismatch, and 51 exhibiting reverse mismatch. The mismatch was associated with higher angiography-derived microcirculatory resistance (AMR) (adjusted odds ratio [aOR]=1.016, 95% CI: 1.010-1.022, P<0.001). Reverse mismatch was associated with larger area stenosis (aOR=1.044, 95% CI: 1.004-1.086, P=0.032), lower coronary flow velocity (aOR=0.690, 95% CI: 0.567-0.970, P<0.001) and lower AMR (aOR=0.947, 95% CI: 0.924-0.970, P<0.001). Additionally, the mismatch group showed the worst 18-month MACE-free survival among the four groups (Log rank test p = 0.013).

Conclusion

AMR plays a significant role in the occurrence of visual-functional mismatches between QCA-DS and QFR, and the mismatch group showed the worst prognosis.

Pinacidil ameliorates cardiac microvascular ischemia-reperfusion injury by inhibiting chaperone-mediated autophagy of calreticulin

Calcium overload is the key trigger in cardiac microvascular ischemia-reperfusion (I/R) injury, and calreticulin (CRT) is a calcium buffering protein located in the endoplasmic reticulum (ER). Additionally, the role of pinacidil, an antihypertensive drug, in protecting cardiac microcirculation against I/R injury has not been investigated. Hence, this study aimed to explore the benefits of pinacidil on cardiac microvascular I/R injury with a focus on endothelial calcium homeostasis and CRT signaling. Cardiac vascular perfusion and no-reflow area were assessed using FITC-lectin perfusion assay and Thioflavin-S staining. Endothelial calcium homeostasis, CRT-IP3Rs-MCU signaling expression, and apoptosis were assessed by real-time calcium signal reporter GCaMP8, western blotting, and fluorescence staining. Drug affinity-responsive target stability (DARTS) assay was adopted to detect proteins that directly bind to pinacidil. The present study found pinacidil treatment improved capillary density and perfusion, reduced no-reflow and infraction areas, and improved cardiac function and hemodynamics after I/R injury. These benefits were attributed to the ability of pinacidil to alleviate calcium overload and mitochondria-dependent apoptosis in cardiac microvascular endothelial cells (CMECs). Moreover, the DARTS assay showed that pinacidil directly binds to HSP90, through which it inhibits chaperone-mediated autophagy (CMA) degradation of CRT. CRT overexpression inhibited IP3Rs and MCU expression, reduced mitochondrial calcium inflow and mitochondrial injury, and suppressed endothelial apoptosis. Importantly, endothelial-specific overexpression of CRT shared similar benefits with pinacidil on cardiovascular protection against I/R injury. In conclusion, our data indicate that pinacidil attenuated microvascular I/R injury potentially through improving CRT degradation and endothelial calcium overload.

Application of AMR in evaluating microvascular dysfunction after ST-elevation myocardial infarction

BACKGROUND

A guidewire-free angiography-derived microcirculatory resistance (AMR) derived from Quantitative flow ratio (QFR) exhibits good diagnostic accuracy for assessing coronary microvascular dysfunction (CMD), but there are no relevant studies supporting the specific application of AMR in patients with ST-elevation myocardial infarction (STEMI). The study aims to evaluate CMD in patients with STEMI using the AMR index.

METHODS

This study included patients with STEMI who underwent percutaneous coronary intervention (PCI) from June 1, 2020 to September 28, 2021. All patients were divided into two groups: the CMD (n = 215) and non-CMD (n = 291) groups. After matching, there were 382 patients in both groups.1-year follow-up major adverse cardiac events (MACEs) were evaluated.

RESULTS

After matching, the primary endpoint was achieved in 41 patients (10.7%), with 27 and 14 patients in the CMD and non-CMD groups, respectively (HR 1.954 [95% CI 1.025-3.726]; 14.1% versus 7.3%, p = .042). Subgroup analysis revealed that 18 patients (4.7%) were readmitted for heart failure, with 15 and 3 in the CMD and non-CMD groups, respectively (HR 5.082 [95% CI 1.471-17.554]; 7.9% versus 1.6%, p = .010). Post-PCI AMR ≥ 250 was significantly associated with a higher risk of the primary endpoint and was its independent predictor (HR 2.265 [95% CI 1.136-4.515], p = .020).

CONCLUSION

The retrospective use of AMR with a cutoff value of ≥250 after PCI in patients with STEMI can predict a significant difference in the 1-year MACE rates when compared with a propensity score-matched group with normal AMR.

Myocardial ischemia/reperfusion: Translational pathophysiology of ischemic heart disease

Ischemic heart disease is the greatest health burden and most frequent cause of death worldwide. Myocardial ischemia/reperfusion is the pathophysiological substrate of ischemic heart disease. Improvements in prevention and treatment of ischemic heart disease have reduced mortality in developed countries over the last decades, but further progress is now stagnant, and morbidity and mortality from ischemic heart disease in developing countries are increasing. Significant problems remain to be resolved and require a better pathophysiological understanding. The present review attempts to briefly summarize the state of the art in myocardial ischemia/reperfusion research, with a view on both its coronary vascular and myocardial aspects, and to define the cutting edges where further mechanistic knowledge is needed to facilitate translation to clinical practice.

HbA1c/C-Peptide Ratio Is a Potential Biomarker Used to Predict No-Reflow Phenomenon in Patients With ST-Elevation Myocardial Infarction

In this letter, we discussed that HbA1c/C-peptide ratio is a potential biomarker used to predict no-reflow phenomenon in patients with ST-elevation myocardial infarction.

Chinese expert consensus on the diagnosis and treatment of coronary microvascular diseases (2023 Edition)

Since the four working groups of the Chinese Society of Cardiology issued first expert consensus on coronary microvascular diseases (CMVD) in 2017, international consensus documents on CMVD have increased rapidly. Although some of these documents made preliminary recommendations for the diagnosis and treatment of CMVD, they did not provide classification of recommendations and levels of evidence. In order to summarize recent progress in the field of CMVD, standardize the methods and procedures of diagnosis and treatment, and identify the scientific questions for future research, the four working groups of the Chinese Society of Cardiology updated the 2017 version of the Chinese expert consensus on CMVD and adopted a series of measures to ensure the quality of this document. The current consensus has raised a new classification of CMVD, summarized new epidemiological findings for different types of CMVD, analyzed key pathological and molecular mechanisms, evaluated classical and novel diagnostic technologies, recommended diagnostic pathways and criteria, and therapeutic strategies and medications, for patients with CMVD. In view of the current progress and knowledge gaps of CMVD, future directions were proposed. It is hoped that this expert consensus will further expedite the research progress of CMVD in both basic and clinical scenarios.

The prognostic value of myocardial salvage index by cardiac magnetic resonance in ST-segment elevation myocardial infarction patients: a systematic review and meta-analysis

OBJECTIVE

To assess the prognostic value of myocardial salvage index (MSI) by cardiac magnetic resonance (CMR) in ST-segment elevation myocardial infarction (STEMI) patients.

METHODS

We systematically searched PubMed, Embase, Web of Science, Cochrane Central, China National Knowledge Infrastructure, and Wanfang Data to identify primary studies reporting MSI in STEMI patients with major adverse cardiovascular events (MACE) comprised of death, myocardial reinfarction, and congestive heart failure. The MSI and MACE rates were pooled. The bias of risk was assessed using the Quality In Prognosis Studies tool. The evidence level was rated based on the meta-analysis of hazard ratio (HR) and 95% confidence interval (CI) of MSI for predicting MACE.

RESULTS

Eighteen studies were included covering twelve unique cohorts. Eleven cohorts measured MSI using T2-weighted imaging and T1-weighted late gadolinium enhancement, while one cohort applied T2-mapping and T1-mapping. The pooled MSI (95% CI) was 44% (39 to 49%; 11 studies, 2946 patients), and the pooled MACE rate (95% CI) was 10% (7 to 14%; 12 studies, 311/3011 events/patients). Seven prognostic studies overall showed low risk of bias. The HR (95% CI) per 1% increase of MSI for MACE was 0.95 (0.92 to 0.98; 5 studies, 150/885 events/patients), and HR (95% CI) of MSI < median versus MSI > median for MACE was 5.62 (3.74 to 8.43; 6 studies, 166/1570 events/patients), both rated as weak evidence.

CONCLUSIONS

MSI presents potential in predicting MACE in STEMI patients. The prognostic value of MSI using advanced CMR techniques for adverse cardiovascular events needs further investigation.

CLINICAL RELEVANCE STATEMENT

Seven studies supported the MSI to serve as a predictor for MACE in STEMI patients, indicating its potential as a risk stratification tool to help manage expectations for these patients in clinical practice.

KEY POINTS

• The pooled infarct size (95% CI) and area at risk (95% CI) were 21% (18 to 23%; 11 studies, 2783 patients) and 38% (34 to 43%; 10 studies, 2022 patients), respectively. • The pooled rates (95% CI) of cardiac mortality, myocardial reinfarction, and congestive heart failure were 2% (1 to 3%; 11 studies, 86/2907 events/patients), 4% (3 to 6%; 12 studies, 127/3011 events/patients), and 3% (1 to 5%; 12 studies, 94/3011 events/patients), respectively. • The HRs (95% CI) per 1% increase of MSI for cardiac mortality and congestive heart failure were 0.93 (0.91 to 0.96; 1 study, 14/202 events/patients) and 0.96 (0.93 to 0.99; 1 study, 11/104 events/patients), respectively, but the prognostic value of MSI for myocardial re-infraction has not been measured.

Cellular Membrane-Engineered Nanovesicles as a Three-Stage Booster to Target the Lesion Core

The lesion core is the area with the most serious injury and vigorous repair. Existing nanocarriers are difficult to break through the targeted delivery to the lesion core for precise treatment in the intracellular and extracellular microenvironment. Herein, a cellular membrane-engineered nanovesicle (CMEV) with a hierarchical structure is constructed using the double emulsion-extrusion method by integrating a neutrophil membrane, functional antibody, and gelled drug-loaded core as a three-stage booster to target the lesion core and deliver catestatin (CST), a small therapeutic peptide, for ischemic cardiomyopathy therapy. By coating the neutrophil membrane outside the shell, CMEV is endowed with the function of neutrophil-like migration to achieve the first stage of tissue targeting. Based on the specific anchoring to injured myocardium, a myosin light chain 3 (MLC3) antibody is embedded to fulfill the second stage of CMEV accumulation in the lesion core. The gelled core containing CST-sodium alginate (NaAlg) with a pH-responsive shell is prepared by ionic cross-linking to accomplish the third stage of precise CST administration. Triggered by the microenvironment, NaAlg electrostatically adheres to the lesion core for sustained release, enhancing the efficacy of CST in improving cardiomyocyte apoptosis, excessive fibrosis, macrophage polarization, and angiogenesis. Thus, the "three-stage booster" nanovesicle significantly ameliorates cardiac function and adverse remodeling to treat ischemic cardiomyopathy.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

The role and mechanisms of microvascular damage in the ischemic myocardium

Following myocardial ischemic injury, the most effective clinical intervention is timely restoration of blood perfusion to ischemic but viable myocardium to reduce irreversible myocardial necrosis, limit infarct size, and prevent cardiac insufficiency. However, reperfusion itself may exacerbate cell death and myocardial injury, a process commonly referred to as ischemia/reperfusion (I/R) injury, which primarily involves cardiomyocytes and cardiac microvascular endothelial cells (CMECs) and is characterized by myocardial stunning, microvascular damage (MVD), reperfusion arrhythmia, and lethal reperfusion injury. MVD caused by I/R has been a neglected problem compared to myocardial injury. Clinically, the incidence of microvascular angina and/or no-reflow due to ineffective coronary perfusion accounts for 5-50% in patients after acute revascularization. MVD limiting drug diffusion into injured myocardium, is strongly associated with the development of heart failure. CMECs account for > 60% of the cardiac cellular components, and their role in myocardial I/R injury cannot be ignored. There are many studies on microvascular obstruction, but few studies on microvascular leakage, which may be mainly due to the lack of corresponding detection methods. In this review, we summarize the clinical manifestations, related mechanisms of MVD during myocardial I/R, laboratory and clinical examination means, as well as the research progress on potential therapies for MVD in recent years. Better understanding the characteristics and risk factors of MVD in patients after hemodynamic reconstruction is of great significance for managing MVD, preventing heart failure and improving patient prognosis.

Optical Coherence Tomography Assessment of Coronary Lesions Associated With Microvascular Dysfunction in ST-Segment Elevation Myocardial Infarction

BACKGROUND

Microvascular reperfusion following percutaneous coronary intervention (PCI) is associated with the prognosis of patients with ST-segment elevation myocardial infarction (STEMI). We investigated how plaque characteristics detected by optical coherence tomography (OCT) in STEMI patients affect the status of the microcirculation during PCI.Methods and Results: This retrospective, single-center study was a post hoc analysis basedon the multicenter SALVAGE randomized control trial (NCT03581513) that enrolled 629 STEMI patients, and finally we enrolled 235 patients who underwent PCI and pre-intervention OCT. Microvascular perfusion was evaluated using the Thrombolysis in Myocardial Infarction (TIMI) myocardial perfusion frame count (TMPFC). Patients were divided into 3 groups based on the change in TMPFC from before to after PCI: improving TMPFC (n=11; 4.7%), stable TMPFC (n=182; 77.4%), and worsening TMPFC group (n=42; 17.9%). The proportion of patients with a microcirculation dysfunction before reperfusion was 11.9%, which increased significantly by (P=0.079) 8.5% to 20.4% after reperfusion. Compared with plaque characteristics in the stable and worsening TMPFC groups, the improving TMPFC group had fewer thrombi (90.7% and 90.5% vs. 89.4%, respectively; P=0.018), a lower proportion of plaque rupture (66.5% and 66.3% vs. 54.5%, respectively; P=0.029), and a lower proportion of lipid-rich plaques (89.6% and 88.1% vs. 63.6%, respectively; P=0.036).

CONCLUSIONS

PCI may not always achieve complete myocardial reperfusion. Thrombi, plaque rupture, and lipid-rich plaques detected by OCT can indicate microcirculation dysfunction during the reperfusion period.

Changes in the extracellular matrix at microvascular obstruction area after reperfused myocardial infarction: A morphometric study

BACKGROUND

Extracellular matrix (ECM) suffers substantial alterations after myocardial infarction (MI), including the invasion of leukocyte subtypes. Despite a complete reopening at epicardial level, hypoperfusion within the infarcted myocardium, known as microvascular obstruction (MVO), occurs and exerts a negative impact on ventricular remodeling. In this study, ECM composition at MVO regions was described using a morphometric analysis.

METHODS

MI was induced in female swine (n = 10) by transitory 90-minute coronary occlusion followed by seven days of reperfusion. Prior to euthanasia, intracoronary thioflavin-S was infused. Within the infarcted myocardium, regions displaying MVO (thioflavin-S-) or no MVO (thioflavin-S+) were isolated and stained to morphometrically compare ECM composition.

RESULTS

As reflected by cell invasion through ECM, areas with MVO displayed an enlarged presence of neutrophils and lymphocytes, whilst no differences in the amount of macrophages and myofibroblasts were detected compared to infarcted myocardium without MVO. Indeed, those regions with macroscopic MVO showed lower capillary density than areas without MVO. Lastly, a significant reduction in the extension of total collagen, type I, but not type III, collagen, laminin, and fibronectin together with an augmentation of polysaccharides were noted in areas showing MVO compared to those without microvascular injury.

CONCLUSIONS

ECM composition in infarcted regions with MVO isolated from female swine displays a higher presence of inflammatory infiltrate and polysaccharides as well as reduced number of microvessels and collagen content compared to those areas without microvascular hypoperfusion. These characteristics might underlie the development of adverse ventricular remodeling in MI patients with extensive MVO.

Endothelial ILK induces cardioprotection by preventing coronary microvascular dysfunction and endothelial-to-mesenchymal transition

Endothelial dysfunction is an early event in coronary microvascular disease. Integrin-linked kinase (ILK) prevents endothelial nitric oxide synthase (eNOS) uncoupling and, thus, endothelial dysfunction. However, the specific role of endothelial ILK in cardiac function remains to be fully elucidated. We hypothesised that endothelial ILK plays a crucial role in maintaining coronary microvascular function and contractile performance in the heart. We generated an endothelial cell-specific ILK conditional knock-out mouse (ecILK cKO) and investigated cardiovascular function. Coronary endothelial ILK deletion significantly impaired cardiac function: ejection fraction, fractional shortening and cardiac output decreased, whilst left ventricle diastolic internal diameter decreased and E/A and E/E' ratios increased, indicating not only systolic but also diastolic dysfunction. The functional data correlated with extensive extracellular matrix remodelling and perivascular fibrosis, indicative of adverse cardiac remodelling. Mice with endothelial ILK deletion suffered early ischaemic-like events with ST elevation and transient increases in cardiac troponins, which correlated with fibrotic remodelling. In addition, ecILK cKO mice exhibited many features of coronary microvascular disease: reduced cardiac perfusion, impaired coronary flow reserve and arterial remodelling with patent epicardial coronary arteries. Moreover, endothelial ILK deletion induced a moderate increase in blood pressure, but the antihypertensive drug Losartan did not affect microvascular remodelling whilst only partially ameliorated fibrotic remodelling. The plasma miRNA profile reveals endothelial-to-mesenchymal transition (endMT) as an upregulated pathway in endothelial ILK conditional KO mice. Our results show that endothelial cells in the microvasculature in endothelial ILK conditional KO mice underwent endMT. Moreover, endothelial cells isolated from these mice and ILK-silenced human microvascular endothelial cells underwent endMT, indicating that decreased endothelial ILK contributes directly to this endothelial phenotype shift. Our results identify ILK as a crucial regulator of microvascular endothelial homeostasis. Endothelial ILK prevents microvascular dysfunction and cardiac remodelling, contributing to the maintenance of the endothelial cell phenotype.

No robust reduction of infarct size and no-reflow by metoprolol pretreatment in adult Göttingen minipigs

Whereas prior experiments in juvenile pigs had reported infarct size reduction by intravenous metoprolol early during myocardial ischaemia, two major clinical trials in patients with reperfused acute myocardial infarction were equivocal. We, therefore, went back and tested the translational robustness of infarct size reduction by metoprolol in minipigs. Using a power analysis-based prospective design, we pretreated 20 anaesthetised adult Göttingen minipigs with 1 mg kg-1 metoprolol or placebo and subjected them to 60-min coronary occlusion and 180-min reperfusion. Primary endpoint was infarct size (triphenyl tetrazolium chloride staining) as a fraction of area at risk; no-reflow area (thioflavin-S staining) was a secondary endpoint. There was no significant reduction in infarct size (46 ± 8% of area at risk with metoprolol vs. 42 ± 8% with placebo) or area of no-reflow (19 ± 21% of infarct size with metoprolol vs. 15 ± 23% with placebo). However, the inverse relationship between infarct size and ischaemic regional myocardial blood flow was modestly, but significantly shifted downwards with metoprolol, whereas ischaemic blood flow tended to be reduced by metoprolol. With an additional dose of 1 mg kg-1 metoprolol after 30-min ischaemia in 4 additional pigs, infarct size was also not reduced (54 ± 9% vs. 46 ± 8% in 3 contemporary placebo, n.s.), and area of no-reflow tended to be increased (59 ± 20% vs. 29 ± 12%, n.s.).Infarct size reduction by metoprolol in pigs is not robust, and this result reflects the equivocal clinical trials. The lack of infarct size reduction may be the result of opposite effects of reduced infarct size at any given blood flow and reduced blood flow, possibly through unopposed alpha-adrenergic coronary vasoconstriction.

SYSTEMI - systemic organ communication in STEMI: design and rationale of a cohort study of patients with ST-segment elevation myocardial infarction

BACKGROUND

ST-segment elevation myocardial infarction (STEMI) still causes significant mortality and morbidity despite best-practice revascularization and adjunct medical strategies. Within the STEMI population, there is a spectrum of higher and lower risk patients with respect to major adverse cardiovascular and cerebral events (MACCE) or re-hospitalization due to heart failure. Myocardial and systemic metabolic disorders modulate patient risk in STEMI. Systematic cardiocirculatory and metabolic phenotyping to assess the bidirectional interaction of cardiac and systemic metabolism in myocardial ischemia is lacking.

METHODS

Systemic organ communication in STEMI (SYSTEMI) is an all-comer open-end prospective study in STEMI patients > 18 years of age to assess the interaction of cardiac and systemic metabolism in STEMI by systematically collecting data on a regional and systemic level. Primary endpoint will be myocardial function, left ventricular remodelling, myocardial texture and coronary patency at 6 month after STEMI. Secondary endpoint will be all-cause death, MACCE, and re-hospitalisation due to heart failure or revascularisation assessed 12 month after STEMI. The objective of SYSTEMI is to identify metabolic systemic and myocardial master switches that determine primary and secondary endpoints. In SYSTEMI 150-200 patients are expected to be recruited per year. Patient data will be collected at the index event, within 24 h, 5 days as well as 6 and 12 months after STEMI. Data acquisition will be performed in multilayer approaches. Myocardial function will be assessed by using serial cardiac imaging with cineventriculography, echocardiography and cardiovascular magnetic resonance. Myocardial metabolism will be analysed by multi-nuclei magnetic resonance spectroscopy. Systemic metabolism will be approached by serial liquid biopsies and analysed with respect to glucose and lipid metabolism as well as oxygen transport. In summary, SYSTEMI enables a comprehensive data analysis on the levels of organ structure and function alongside hemodynamic, genomic and transcriptomic information to assess cardiac and systemic metabolism.

DISCUSSION

SYSTEMI aims to identify novel metabolic patterns and master-switches in the interaction of cardiac and systemic metabolism to improve diagnostic and therapeutic algorithms in myocardial ischemia for patient-risk assessment and tailored therapy.

TRIAL REGISTRATION

Trial Registration Number: NCT03539133.

Coronary microcirculation in nonculprit vessel territory in reperfused acute myocardial infarction

BACKGROUND

There is an ongoing debate on the extension of reperfusion-related microvascular damage (MVD) throughout the remote noninfarcted myocardial regions in patients with ST-elevation myocardial infarction (STEMI) that undergo primary percutaneous intervention (pPCI). The aim of this study was to elucidate the impact of reperfusion on remote microcirculatory territory by analyzing hemodynamic alterations in the nonculprit-vessel in relation to reperfusion.

METHODS

A total of 20 patients with STEMI undergoing pPCI were included. Peri-reperfusion temporal changes in hemodynamic parameters were obtained in angiographically normal nonculprit vessels before and 1-h after reopening of the culprit vessel. Intracoronary pressure and flow velocity data were compared using pairwise analyses (before and 1-h after reperfusion).

RESULTS

In the non-culprit vessel, compared to the pre-reperfusion state, mean resting average peak velocity (33.4 ± 9.4 to 25.0 ± 4.9 cm/s, P < 0.001) and mean hyperemic average peak velocity (53.5 ± 14.4 to 42.1 ± 10.66 cm/s, P = 0.001) significantly decreased; whereas baseline (3.2 ± 1.0 to 4.0 ± 1.0 mmHg.cm^-1.s, P < 0.001) and hyperemic microvascular resistance (HMR) (1.9 ± 0.6 to 2.4 ± 0.7 mmHg.cm^-1.s, P < 0.001) and mean zero flow pressure (Pzf) values (32.5 ± 6.9 to 37.6 ± 8.3 mmHg, P = 0.003) significantly increased 1-h after reperfusion. In particular, the magnitude of changes in HMR and Pzf values following reperfusion were more prominent in patients with larger infarct size and with higher extent of MVD in the culprit vessel territory.

CONCLUSION

Reperfusion-related microvascular injury extends to involve remote myocardial territory in relation to the magnitude of the adjacent infarction and infarct-zone MVD. (GUARD Clinical TrialsNCT02732080).

Impact of Persistent Microvascular Obstruction Late After STEMI on Adverse LV Remodeling: A CMR Study

BACKGROUND

Little is known about the occurrence and implications of persistent microvascular obstruction (MVO) after reperfused ST-segment elevation myocardial infarction (STEMI).

OBJECTIVES

The authors used cardiac magnetic resonance (CMR) to characterize the impact of persistent MVO on adverse left ventricular remodeling (ALVR).

METHODS

A prospective registry of 471 STEMI patients underwent CMR 7 (IQR: 5-10) days and 198 (IQR: 167-231) days after infarction. MVO (≥1 segment) and ALVR (relative increase >15% at follow-up CMR) of left ventricular end-diastolic index (LVEDVI) and left ventricular end-systolic volume index (LVESVI) were determined.

RESULTS

One-week MVO occurred in 209 patients (44%) and persisted in 30 (6%). Extent of MVO (P = 0.026) and intramyocardial hemorrhage (P = 0.001) at 1 week were independently associated with the magnitude of MVO at follow-up CMR. Compared with patients without MVO (n = 262, 56%) or with MVO only at 1 week (n = 179, 38%), those with persistent MVO at follow-up (n = 30, 6%) showed higher rates of ALVR-LVEDVI (22%, 27%, 50%; P = 0.003) and ALVR-LVESVI (20%, 21%, 53%; P < 0.001). After adjustment, persistent MVO at follow-up (≥1 segment) was independently associated with ΔLVEDVI (relative increase, %) (P < 0.001) and ΔLVESVI (P < 0.001). Compared with a 1:1 propensity score-matched population on CMR variables made up of 30 patients with MVO only at 1 week, patients with persistent MVO more frequently displayed ALVR-LVEDVI (12% vs 50%; P = 0.003) and ALVR-LVESVI (12% vs 53%; P = 0.001).

CONCLUSIONS

MVO persists in a small percentage of patients in chronic phase after STEMI and exerts deleterious effects in terms of LV remodeling. These findings fuel the need for further research on microvascular injury repair.

Coronary Microcirculation: The Next Frontier in the Management of STEMI

Although the widespread adoption of timely invasive reperfusion strategies over the last two decades has significantly improved the prognosis of patients with ST-segment elevation myocardial infarction (STEMI), up to half of patients after angiographically successful primary percutaneous coronary intervention (PCI) still have signs of inadequate reperfusion at the level of coronary microcirculation. This phenomenon, termed coronary microvascular dysfunction (CMD), has been associated with impaired prognosis. The aim of the present review is to describe the collected evidence on the occurrence of CMD following primary PCI, means of assessment and its association with the infarct size and clinical outcomes. Therefore, the practical role of invasive assessment of CMD in the catheterization laboratory, at the end of primary PCI, is emphasized, with an overview of available technologies including thermodilution- and Doppler-based methods, as well as recently developing functional coronary angiography. In this regard, we review the conceptual background and the prognostic value of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), hyperemic microvascular resistance (HMR), pressure at zero flow (PzF) and angiography-derived IMR. Finally, the so-far investigated therapeutic strategies targeting coronary microcirculation after STEMI are revisited.

Adenosine as adjunctive therapy in acute coronary syndrome: a meta-analysis of randomized controlled trials

AIMS

Adenosine has been tested in several randomized controlled trials (RCTs) to minimize the incidence of coronary microvascular obstruction (CMVO). The aim of this study was to pool all the RCTs comparing intracoronary or intravenous adenosine versus placebo in patients with acute coronary syndrome (ACS) undergoing myocardial revascularization.

METHODS AND RESULTS

PubMed and Scopus electronic databases were scanned for eligible studies up to 5th June 2022. A total of 26 RCTs with 5843 patients were included. Efficacy endpoints were major adverse cardiac events (MACE), all-cause death, non-fatal myocardial infarction, and heart failure. Atrioventricular blocks and ventricular fibrillation/sustained ventricular tachycardia (VF/SVT) were the safety endpoints. Myocardial blush grade, thrombolysis in myocardial infarction (TIMI) flow grade, left ventricular ejection fraction (LVEF), infarct size, and ST-segment resolution were also assessed. Adenosine administration was not associated with any clinical benefit in terms of MACE, all-cause death, non-fatal myocardial infarction, and heart failure. However, adenosine was associated with an increased rate of advanced atrioventricular blocks and of VF/SVT in studies with total mean ischaemic time >3 h, compared to placebo. Remarkably, among patients undergoing percutaneous coronary intervention, adenosine was associated with reduced myocardial blush grade 0-1 and TIMI flow grade 0-2, compared to placebo. Furthermore, adenosine did not show favourable effects on LVEF and infarct size.

CONCLUSION

Adenosine infusion, as adjunctive therapy in ACS, was associated with an increased risk of advanced atrioventricular blocks and increased rates of adenosine-triggered ventricular arrhythmias in patients with long ischaemic time, without providing any clinical benefit compared to placebo.

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.

Imatinib attenuates reperfusion injury in a rat model of acute myocardial infarction

Following an acute myocardial infarction, reperfusion of an occluded coronary artery is often accompanied by microvascular injury, leading to worse long-term prognosis. Experimental studies have revealed the potential of tyrosine-kinase inhibitor imatinib to reduce vascular leakage in various organs. Here, we examined the potential of imatinib to attenuate microvascular injury in a rat model of myocardial reperfusion injury. Isolated male Wistar rat hearts (n = 20) in a Langendorff system and male Wistar rats (n = 37) in an in vivo model were randomly assigned to imatinib or placebo and subjected to ischaemia and reperfusion. Evans-blue/Thioflavin-S/TTC staining and Cardiac Magnetic Resonance Imaging were performed to assess the extent of reperfusion injury. Subsequently, in vivo hearts were perfused ex vivo with a vascular leakage tracer and fluorescence and electron microscopy were performed. In isolated rat hearts, imatinib reduced global infarct size, improved end-diastolic pressure, and improved rate pressure product recovery compared to placebo. In vivo, imatinib reduced no-reflow and infarct size with no difference between imatinib and placebo for global cardiac function. In addition, imatinib showed lower vascular resistance, higher coronary flow, and less microvascular leakage in the affected myocardium. At the ultrastructural level, imatinib showed higher preserved microvascular integrity compared to placebo. We provide evidence that low-dose imatinib can reduce microvascular injury and accompanying myocardial infarct size in a rat model of acute myocardial infarction. These data warrant future work to examine the potential of imatinib to reduce reperfusion injury in patients with acute myocardial infarction.

Insights into research on myocardial ischemia/reperfusion injury from 2012 to 2021: a bibliometric analysis

BACKGROUND

Numerous studies on myocardial ischemia/reperfusion (MI/R) injury have been undertaken in recent years. Hotspots and developmental trends in MI/R research are being rapidly updated. However, there has been no bibliometric analysis that systematically evaluates existing literature on MI/R injury. Our study explores developments in MI/R research over the past decade, and provides a reference for future research.

MATERIALS AND METHODS

Both experimental and clinical publications on MI/R injury from 2012 to 2021 were retrieved from the Web of Science Core Collection database. The CiteSpace and VOSviewer tools were used to perform a bibliometric analysis.

RESULTS

A total of 8419 papers were analyzed. The number of annual publications demonstrated an overall upward trend, rising from 629 publications in 2012 to 1024 publications in 2021. China, the USA, Germany, England, and Italy were the top five contributors to MI/R studies. The Fourth Military Medical University in China contributed the most publications (188, 2.23%), while the University College London in England cooperated the most with relevant research institutions. Derek J Hausenloy (University College London), Derek M Yellon (University College London), and Gerd Heusch (University of Essen Medical School) were the top three most active and influential scholars according to the H-index. Among the top 10 journals with the most publications, Basic Research in Cardiology had the highest impact factors. The top three co-cited journals were Circulation, Circulation Research, and Cardiovascular Research. According to a co-cited reference analysis, MI/R research can be divided across 10 major subfields of mitophagy, cardioprotection, inflammation, remote ischemic preconditioning, long non-coding RNA, melatonin, postconditioning, mitochondria, microvascular obstruction, and ferroptosis. After 2018, the keywords with strongest citation bursts included extracellular vesicles, long non-coding RNA, cell proliferation, microRNA, mitochondrial quality control, mitophagy, biomarker, and mitochondrial biogenesis.

CONCLUSIONS

The present study reveals the influential authors, cooperating institutions, and main research foci in the field of MI/R injury in the past decade. The latest hotspots are a more in-depth insight into the molecular mechanisms underlying MI/R injury, such as mitochondrial quality control, non-coding RNAs, cell proliferation, and extracellular vesicles.

Trends in outcomes of women with myocardial infarction undergoing primary angioplasty-Analysis of randomized trials

Background

Sex- and gender-associated differences determine the disease response to treatment.

Aim

The study aimed to explore the hypothesis that progress in the management of STE-myocardial infarction (STEMI) overcomes the worse outcome in women.

Methods and results

We performed an analysis of three randomized trials enrolling patients treated with primary PCI more than 10 years apart. PRAGUE-1,-2 validated the preference of transport for primary PCI over on-site fibrinolysis. PRAGUE-18 enrollment was ongoing at the time of the functional network of 24/7PCI centers, and the intervention was supported by intensive antiplatelets. The proportion of patients with an initial Killip ≥ 3 was substantially higher in the more recent study (0.6 vs. 6.7%, p = 0.004). Median time from symptom onset to the door of the PCI center shortened from 3.8 to 3.0 h, p < 0.001. The proportion of women having total ischemic time ≤3 h was higher in the PRAGUE-18 (OR [95% C.I.] 2.65 [2.03-3.47]). However, the percentage of patients with time-to-reperfusion >6 h was still significant (22.3 vs. 27.2% in PRAGUE-18). There was an increase in probability for an initial TIMI flow >0 in the later study (1.49 [1.0-2.23]), and also for an optimal procedural result (4.24 [2.12-8.49], p < 0.001). The risk of 30-day mortality decreased by 61% (0.39 [0.17-0.91], p = 0.029).

Conclusion

The prognosis of women with MI treated with primary PCI improved substantially with 24/7 regional availability of mechanical reperfusion, performance-enhancing technical progress, and intensive adjuvant antithrombotic therapy. A major modifiable hindrance to achieving this benefit in a broad population of women is the timely diagnosis by health professional services.

A comprehensive and longitudinal cardiac magnetic resonance imaging study of the impact of coronary ischemia duration on myocardial damage in a highly translatable animal model

OBJECTIVES

We performed a comprehensive assessment of the effect of myocardial ischemia duration on cardiac structural and functional parameters by serial cardiac magnetic resonance (CMR) and characterized the evolving scar.

BACKGROUND

CMR follow-up on the cardiac impact of time of ischemia in a closed-chest animal model of myocardial infarction with human resemblance is missing.

METHODS

Pigs underwent MI induction by occlusion of the left anterior descending (LAD) coronary artery for 30, 60, 90 or 120 min and then revascularized. Serial CMR was performed on day 3 and day 42 post-MI. CMR measurements were also run in a sham-operated group. Cellular and molecular changes were investigated.

RESULTS

On day 3, cardiac damage and function were similar in sham and pigs subjected to 30 min of ischemia. Cardiac damage (oedema and necrosis) significantly increased from 60 min onwards. Microvascular obstruction was extensively seen in animals with ≥90 min of ischemia and correlated with cardiac damage. A drop in global systolic function and wall motion of the jeopardized segments was seen in pigs subjected to ≥60 min of ischemia. On day 42, scar size and cardiac dysfunction followed the same pattern in the animals subjected to ≥60 min of ischemia. Adverse left ventricular remodelling (worsening of both LV volumes) was only present in animals subjected to 120 min of ischemia. Cardiac fibrosis, myocyte hypertrophy and vessel rarefaction were similar in the infarcted myocardium of pigs subjected to ≥60 min of ischemia. No changes were observed in the remote myocardium.

CONCLUSION

Sixty-minute LAD coronary occlusion already induces cardiac structural and functional alterations with longer ischemic time (120 min) causing adverse LV remodelling.

The Importance of Integrated Regulation Mechanism of Coronary Microvascular Function for Maintaining the Stability of Coronary Microcirculation: An Easily Overlooked Perspective

Coronary microvascular dysfunction (CMD) refers to a group of disorders affecting the structure and function of coronary microcirculation and is associated with an increased risk of major adverse cardiovascular events. At present, great progress has been made in the diagnosis of CMD, but there is no specific treatment for it because of the complexity of CMD pathogenesis. Vascular dysfunction is one of the important causes of CMD, but previous reviews mostly considered microvascular dysfunction as a whole abnormality so the obtained conclusions are skewed. The coronary microvascular function is co-regulated by multiple mechanisms, and the mechanisms by which microvessels of different luminal diameters are regulated vary. The main purpose of this review is to revisit the mechanisms by which coronary microvessels at different diameters regulate coronary microcirculation through integrated sequential activation and briefly discuss the pathogenesis, diagnosis, and treatment progress of CMD from this perspective.

Reduction in mitochondrial ROS improves oxidative phosphorylation and provides resilience to coronary endothelium in non-reperfused myocardial infarction

Recent studies demonstrated that mitochondrial antioxidant MnSOD that reduces mitochondrial (mito) reactive oxygen species (ROS) helps maintain an optimal balance between sub-cellular ROS levels in coronary vascular endothelial cells (ECs). However, it is not known whether EC-specific mito-ROS modulation provides resilience to coronary ECs after a non-reperfused acute myocardial infarction (MI). This study examined whether a reduction in endothelium-specific mito-ROS improves the survival and proliferation of coronary ECs in vivo. We generated a novel conditional binary transgenic animal model that overexpresses (OE) mitochondrial antioxidant MnSOD in an EC-specific manner (MnSOD-OE). EC-specific MnSOD-OE was validated in heart sections and mouse heart ECs (MHECs). Mitosox and mito-roGFP assays demonstrated that MnSOD-OE resulted in a 50% reduction in mito-ROS in MHEC. Control and MnSOD-OE mice were subject to non-reperfusion MI surgery, echocardiography, and heart harvest. In post-MI hearts, MnSOD-OE promoted EC proliferation (by 2.4 ± 0.9 fold) and coronary angiogenesis (by 3.4 ± 0.9 fold), reduced myocardial infarct size (by 27%), and improved left ventricle ejection fraction (by 16%) and fractional shortening (by 20%). Interestingly, proteomic and Western blot analyses demonstrated upregulation in mitochondrial complex I and oxidative phosphorylation (OXPHOS) proteins in MnSOD-OE MHECs. These MHECs also showed increased mitochondrial oxygen consumption rate (OCR) and membrane potential. These findings suggest that mito-ROS reduction in EC improves coronary angiogenesis and cardiac function in non-reperfused MI, which are associated with increased activation of OXPHOS in EC-mitochondria. Activation of an energy-efficient mechanism in EC may be a novel mechanism to confer resilience to coronary EC during MI.

Meta-Analysis of Extracellular Matrix Dynamics after Myocardial Infarction Using RNA-Sequencing Transcriptomic Database

Extracellular matrix (ECM) changes after myocardial infarction (MI) need precise regulation, and next-generation sequencing technologies provide omics data that can be used in this context. We performed a meta-analysis using RNA-sequencing transcriptomic datasets to identify genes involved in post-MI ECM turnover. Eight studies available in Gene Expression Omnibus were selected following the inclusion criteria. We compare RNA-sequencing data from 92 mice submitted to permanent coronary ligation or sham, identifying differentially expressed genes (p-value < 0.05 and Log2FoldChange ≥ 2). Functional enrichment analysis was performed based on Gene Ontology biological processes (BPs). BPs implicated in response to extracellular stimulus, regulation of ECM organization, and ECM disassembly were detected soon after ischemia onset. ECM disassembly occurred between days one to seven post-MI, compared with ECM assembly from day seven onwards. We identified altered mRNA expression of 19 matrix metalloproteinases and four tissue inhibitors of metalloproteinases at post-infarcted ECM remodeling and altered transcriptomic expression of 42 genes encoding 26 collagen subunits at the fibrotic stage. To our knowledge, this is the first meta-analysis using RNA-sequencing datasets to evaluate post-infarcted cardiac interstitium healing, revealing previously unknown mechanisms and molecules actively implicated in ECM remodeling post-MI, which warrant further validation.

Microcirculation function assessment in acute myocardial infarction: A systematic review of microcirculatory resistance indices

Background

Up to 50% of acute myocardial infarction (MI) patients present with microvascular dysfunction, after a successful percutaneous coronary intervention (PCI), which leads to worse clinical outcomes. The main purpose of this study is to provide a critical appraisal of the emerging role of invasive microvascular resistance indices in the MI setting, using the index of microcirculatory resistance (IMR), hyperemic microvascular resistance (HMR) and zero-flow pressure (Pzf).

Methods

We systematically explored relevant studies in the context of MI that correlated microcirculation resistance indices with microvascular dysfunction on cardiac magnetic resonance (CMR), microvascular dysfunction occurring in infarct related arteries (IRA) and non-IRA and its relation to clinical outcomes.

Results

The microcirculation resistance indices correlated significantly with microvascular obstruction (MVO) and infarct size (IS) on CMR. Although HMR and Pzf seem to have better diagnostic accuracy for MVO and IS, IMR has more validation data. Although, both IMR and HMR were independent predictors of adverse cardiovascular events, HMR has no validated cut-off value and data is limited to small observational studies. The presence of microvascular dysfunction in non-IRA does not impact prognosis.

Conclusion

Microvascular resistance indices are valuable means to evaluate microcirculation function following MI. Microvascular dysfunction relates to the extent of myocardial damage and clinical outcomes after MI.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021228432], identifier [CRD42021228432].

The protective effect of remote ischemic conditioning is lost in patients with hypercholesterolemia

Remote ischemic conditioning (RIC), brief repetitive cycles of ischemia and reperfusion in remote tissues, is known to induce robust protection against myocardial ischemia-reperfusion (I/R) injury in preclinical studies. However, translation of the beneficial effects to the clinical setting has been challenging. A possibility is that comorbidities, including hypercholesterolemia, interfere with the protective mechanisms of RIC. The aim of this study was to test if hypercholesterolemia attenuates the efficacy of RIC in patients with hypercholesterolemia. Patients with familial hypercholesterolemia (FH) with high (≥5.5 mmol/L) low-density lipoprotein cholesterol (LDL-C), FH with low (≤2.5 mmol/L) and healthy control subjects (n = 12 in each group) were included. Flow-mediated vasodilatation (FMD) of the brachial artery was evaluated, before and after a 20-min period of forearm ischemia and 20 min reperfusion (I/R) as a measure of endothelial function. Study subjects were randomized to a RIC protocol consisting of four cycles of 5 min of leg ischemia or sham using a crossover design. Forearm I/R induced significant reduction in FMD in all three groups during the sham procedure. RIC protected from endothelial dysfunction induced by forearm ischemia-reperfusion in healthy controls [FMD baseline 2.8 ± 2.3 vs. FMD after I/R + RIC 4.5 ± 4.0%; means (SD)] and in patients with FH with low LDL-C (4.5 ± 3.5 vs. 4.4 ± 4.2%). By contrast, RIC fails to protect against I/R-induced endothelial dysfunction in patients with FH and high LDL-C (3.9 ± 3.0 vs. 1.1 ± 1.5%; P < 0.01). These findings provide the first evidence in humans that the protective effect of RIC is lost in patients with elevated cholesterol.NEW & NOTEWORTHY We investigated the impact of hypercholesterolemia on the protective effect of RIC on ischemia-reperfusion injury in a well-characterized patient population with isolated hypercholesterolemia. The results show that the protective effect of RIC is absent in patients with hypercholesterolemia but is apparent in patients with hypercholesterolemic following treatment with lipid-lowering drugs. The results are of importance for the understanding of how comorbidities affect the therapeutic potential of RIC.

Myocardial infarction size as an independent predictor of intramyocardial haemorrhage in acute reperfused myocardial ischaemic rats

Background

In previous studies, haemorrhage occurred only with large infarct sizes, and studies found a moderate correlation between the extent of necrosis and haemorrhage, but the extent of infarction size in these studies was limited. This study aimed to find the correlations between intramyocardial haemorrhage (IMH), myocardial infarction (MI), and myocardial oedema (ME) from small to large sizes of MI in a 7.0-T MR scanner.

Methods

Different sizes of myocardial infarction were induced by occluding different sections of the proximal left anterior descending coronary artery (1–3 mm under the left auricle). T2*-mapping, T2-mapping and late gadolinium enhancement (LGE) sequences were performed on a 7.0 T MR system at Days 2 and 7. T2*- and T2-maps were calculated using custom-made software. All areas were expressed as a percentage of the entire myocardial tissue of the left ventricle. The rats were divided into two groups based on the T2* results and pathological findings; MI with IMH was referred to as the + IMH group, while MI without IMH was referred to as the –IMH group.

Results

The final experimental sample consisted of 25 rats in the + IMH group and 10 rats in the –IMH group. For the + IMH group on Day 2, there was a significant positive correlation between IMH size and MI size (r = 0.677, P < 0.01) and a positive correlation between IMH size and ME size (r = 0.552, P < 0.01). On Day 7, there was a significant positive correlation between IMH size and MI size (r = 0.711, P < 0.01), while no correlation was found between IMH size and ME size (r = 0.429, P = 0.097). The MI sizes of the + IMH group were larger than those of the –IMH group (P < 0.01).

Conclusions

Infarction size prior to reperfusion is a critical factor in determining IMH size in rats.

The predictive value of eosinophil levels on no-reflow in patients with STEMI following PCI: a retrospective cohort study

In patients with acute ST-elevation myocardial infarction (STEMI), it is essential to restore myocardial perfusion as soon as possible. However, a considerable proportion of patients have no-reflow. No-reflow increases the risk of major adverse cardiac events and even death. The role of blood eosinophil count in predicting no-reflow in STEMI patients has not been determined, particularly after primary percutaneous coronary intervention (pPCI). The present study aimed to evaluate the predictive value of eosinophil counts for no-reflow in patients with STEMI who underwent pPCI. A total of 674 STEMI patients who underwent pPCI were enrolled. The subjects were divided into two groups according to eosinophil counts for primary analysis and with or without T₂DM for secondary analysis. Logistic regression analysis was used to determine whether eosinophil count was an independent predictor of no-reflow in the entire cohort, and subgroup and receiver operating characteristic (ROC) curves were explored to evaluate its predictive value. DeLong's test was used to compare the area under curves of the three ROC curves. The low eosinophil count was an independent predictor for no-reflow in whole cohort (adjusted OR: 2.012, 95% CI 1.242-3.259, p = 0.004) and in patients with T₂DM (adjusted OR: 4.312, 95% CI 1.878-9.900, p = 0.001). In patients without T₂DM, hemoglobin, but not low eosinophil count, was an independent predictor of no-reflow. The results of the ROC curve analysis revealed that a low eosinophil count had moderate predictive efficiency for predicting no-reflow in patients with T₂DM, and the power was superior to all populations and patients without T₂DM. Our data suggest that decreased eosinophil count was an independent risk factor for no-reflow in patients with STEMI who underwent pPCI, especially in T₂DM patients, which provides guidance for clinicians to identify patients at a higher risk of developing no-reflow and lowering their risk.

Sacubitril/valsartan attenuates myocardial ischemia/reperfusion injury via inhibition of the GSK3β/NF-κB pathway in cardiomyocytes

In ischemia/reperfusion (I/R) injury, both inflammation and apoptosis play a vital role, and the inhibition of excessive inflammation and apoptosis show substantial clinical potential in the treatment of I/R disease. The role of sacubitril/valsartan (SAC/VAL)-a first-in-class angiotensin receptor-neprilysin inhibitor (ARNI)-in inflammation regulation and apoptosis in the context of I/R injury needs to be further explored. In this study, we investigate the short- and long-term effects of SAC/VAL administration in treating adult murine I/R injury both in vivo and in vitro. Our results verified that the application of SAC/VAL could reduce infarct size and suppress apoptosis and the inflammatory response in the acute phase post I/R. Long-term application of SAC/VAL for four weeks significantly improved ventricular function and reversed pathological ventricular remodeling. Mechanistically, SAC/VAL treatment induces the inhibition of the GSK3β-mediated NF-κB pathway through synergistically blocking angiotensin 1 receptor (AT1R) and activating natriuretic peptide receptor (NPR). In summary, we reported the therapeutic role of SAC/VAL in regulating the GSK3β/NF-κB signaling pathway to suppress the inflammatory response and apoptosis, thereby reducing cardiac dysfunction and remodeling post I/R.

Comparison of Diagnostic Value Between STE+LDDSE and CMR-FT for Evaluating Coronary Microvascular Obstruction in Post-PCI Patients for STEMI

Background

Coronary microvascular obstruction (CMVO) is closely associated with poor prognosis of ST-segment elevation myocardial infarction (STEMI) patients. However, data showing the comparison between cardiac magnetic resonance feature tracking (CMR-FT) and speckle tracking echocardiography (STE) combined with low-dose dobutamine stress echocardiography (LDDSE) in evaluating CMVO was scarcely available. We aimed to explore and compare the predictive value between CMR-FT and STE+LDDSE in detecting CMVO.

Methods

Sixty-one STEMI patients were executed cardiac magnetic resonance and echocardiography within the first 5–7 days after primary percutaneous coronary intervention (PCI). The myocardial strain analysis was performed in STE, STE+LDDSE, and CMR-FT, and strain parameters included radial strain (RS), circumferential strain (CS), and longitudinal strain (LS). ROC curves were performed to predict infarcted myocardium segments with CMVO.

Results

Finally, 324 infarcted myocardium segments were analyzed, including 100 infarcted segments with CMVO and 224 segments without CMVO by the gold standard assessment of late gadolinium-enhancement cardiac magnetic resonance imaging (LGE-CMR). The results showed that CS was generally superior to RS and LS in identifying CMVO. CS in CMR-FT facilitated the detection of CMVO, with a sensitivity, specificity, and accuracy of 78.00%, 81.25%, and 80.25%, respectively. The sensitivity, specificity, and accuracy of CS in STE combined with LDDSE were better than STE alone (76.00% vs 60.00%, 79.91% vs 64.29%, and 78.70% vs 62.96%, P < 0.05). In addition, CMR-FT is not superior to STE+LDDSE for detection of CMVO (P > 0.05).

Conclusion

Low-dose dobutamine can improve the clinical value of STE for evaluating CMVO in STEMI patients. Compared with CMR-FT, STE+LDDSE might be a better choice for STEMI patients because of its safety, convenience, and low-cost.

Preclinical multi-target strategies for myocardial ischemia-reperfusion injury

Despite promising breakthroughs in diagnosing and treating acute coronary syndromes, cardiovascular disease’s high global mortality rate remains indisputable. Nearly half of these patients died of ischemic heart disease. Primary percutaneous coronary intervention (PCI) and coronary artery bypass grafting can rapidly restore interrupted blood flow and become the most effective method for salvaging viable myocardium. However, restoring blood flow could increase the risk of other complications and myocardial cell death attributed to myocardial ischemia-reperfusion injury (IRI). How to reduce the damage of blood reperfusion to ischemic myocardium has become an urgent problem to be solved. In preclinical experiments, many treatments have substantial cardioprotective effects against myocardial IRI. However, the transition from these cardioprotective therapies to clinically beneficial therapies for patients with acute myocardial infarction remains elusive. The reasons for the failure of the clinical translation may be multi-faceted, and three points are summarized here: (1) Our understanding of the complex pathophysiological mechanisms of myocardial IRI is far from enough, and the classification of specific therapeutic targets is not rigorous, and not clear enough; (2) Most of the clinical patients have comorbidities, and single cardioprotective strategies including ischemia regulation strategies cannot exert their due cardioprotective effects under conditions of hyperglycemia, hypertension, hyperlipidemia, and aging; (3) Most preclinical experimental results are based on adult, healthy animal models. However, most clinical patients had comorbidities and received multiple drug treatments before reperfusion therapy. In 2019, COST Action proposed a multi-target drug combination initiative for prospective myocardial IRI; the optimal cardioprotective strategy may be a combination of additive or synergistic multi-target therapy, which we support. By establishing more reasonable preclinical models, screening multi-target drug combinations more in line with clinical practice will benefit the translation of clinical treatment strategies.

Ischemic Cardiomyopathy and Heart Failure After Acute Myocardial Infarction

Purpose of Review

Ischemic cardiomyopathy refers to systolic left ventricular dysfunction in the setting of obstructive coronary artery disease and represents the most common cause of heart failure worldwide. It is often the combination of an irreversible loss of viable mass following an acute myocardial infarction (AMI) with a dysfunctional, but still viable, myocardium in the context of a chronically reduced myocardial blood flow and reduced coronary reserve. Medical treatments aiming at modulating neurohumoral response and restoring blood flow to the ischemic cardiomyocytes were shown to dramatically abate the occurrence of ventricular dysfunction and adverse remodeling in ischemic cardiomyopathy.

Recent Findings

Novel therapeutic approaches, such as mechanical unloading and modulation of the inflammatory response, appear to be promising. Furthermore, the understanding of the mechanisms by which, despite optimal treatment, heart failure ensues after AMI, with or without adverse remodeling and systolic dysfunction, is a critical step in the search for novel ways to tackle heart failure risk beyond preservation of left ventricular volumes and systolic function.

Summary

In this review article, we explore the principal pathophysiological mechanisms and pathways of heart failure in ischemic cardiomyopathy, therapeutic opportunities, and knowledge gaps in this area.

Prognostic value of myocardial salvage index assessed by cardiovascular magnetic resonance in reperfused ST-segment elevation myocardial infarction

Aims

Cardiovascular magnetic resonance (CMR) is a powerful tool to quantify the myocardial area at risk (AAR) and infarct size (IS), and evaluate the extent of myocardial salvage in acute ST-segment elevation myocardial infarction (STEMI). This study aimed to assess the prognostic value of myocardial salvage index (MSI) assessed by CMR in reperfused STEMI and investigate whether MSI could improve the predictive efficacy of the Global Registry of Acute Coronary Events (GRACE) risk score.

Methods and results:

About 104 consecutive patients who were hospitalized with first-time STEMI and received reperfusion therapy were prospectively enrolled. The primary endpoint was the incident of major adverse cardiovascular event (MACE) including all-cause mortality, non-fatal myocardial reinfarction and congestive heart failure within 36 months after the index event. Cox regression analysis was used to evaluate the prognostic association of MSI with MACE risk. About 21 (20.2%) patients developed MACE during the 3-year follow-up period, and patients with MSI &lt; median had a higher incidence of MACE than those with MSI ≥ median [16 (30.8%) vs. 5 (9.6%), P = 0.007]. After adjusting all the parameters associated with MACE in univariate Cox analysis, MSI assessed by CMR remained independently significant as a predictor of MACE in multivariate Cox analysis (hazard ratio 0.963, 95% CI: 0.943–0.983; P &lt; 0.001). Adding MSI to the GRACE risk score significantly increased the prognostic accuracy of the GRACE risk score (area under the curve: 0.833 vs. 0.773; P = 0.044), with a net reclassification improvement of 0.635 (P = 0.009) and an integrated discrimination improvement of 0.101 (P = 0.002).

Conclusion

This study confirmed that MSI assessed by CMR had a good long-term prognostic value in reperfused STEMI and improve the prognostic performance of the GRACE risk score.