Microvascular Obstruction and Intramyocardial Hemorrhage in Reperfused Myocardial Infarctions: Pathophysiology and Clinical Insights From Imaging

Microvascular injury immediately following reperfusion therapy in acute myocardial infarction (MI) has emerged as a driving force behind major adverse cardiovascular events in the postinfarction period. Although postmortem investigations and animal models have aided in developing early understanding of microvascular injury following reperfusion, imaging, particularly serial noninvasive imaging, has played a central role in cultivating critical knowledge of progressive damage to the myocardium from the onset of microvascular injury to months and years after in acute MI patients. This review summarizes the pathophysiological features of microvascular injury and downstream consequences, and the contributions noninvasive imaging has imparted in the development of this understanding. It also highlights the interventional trials that aim to mitigate the adverse consequences of microvascular injury based on imaging, identifies potential future directions of investigations to enable improved detection of disease, and demonstrates how imaging stands to play a major role in the development of novel therapies for improved management of acute MI patients.

Deciphering the Enigma of Intramyocardial Hemorrhage Following Reperfusion Therapy in Acute ST-Segment Elevation Myocardial Infarction: A Comprehensive Exploration from Mechanisms to Therapeutic Strategies

Acute ST-segment elevation myocardial infarction (STEMI) is a formidable challenge in cardiovascular medicine, demanding advanced reperfusion strategies such as emergency percutaneous coronary intervention. While successful revascularization is pivotal, the persistent "no-reflow" phenomenon remains a clinical hurdle, often intertwined with microvascular dysfunction. Within this intricate scenario, the emergence of intramyocardial hemorrhage (IMH) has garnered attention as a significant contributor. This review offers a detailed exploration of the multifaceted relationship between IMH and the "no-reflow" phenomenon, delving into the mechanisms governing IMH occurrence, state-of-the-art diagnostic modalities, predictive factors, clinical implications, and the evolving landscape of preventive and therapeutic strategies. The nuanced examination aims to deepen our comprehension of IMH, providing a foundation for the identification of innovative therapeutic avenues and enhanced clinical outcomes for STEMI patients.

Clinical Outcomes Associated With Various Microvascular Injury Patterns Identified by CMR After STEMI

BACKGROUND

The prognostic significance of various microvascular injury (MVI) patterns after ST-segment elevation myocardial infarction (STEMI) is not well known.

OBJECTIVES

This study sought to investigate the prognostic implications of different MVI patterns in STEMI patients.

METHODS

The authors analyzed 1,109 STEMI patients included in 3 prospective studies. Cardiac magnetic resonance (CMR) was performed 3 days (Q1-Q3: 2-5 days) after percutaneous coronary intervention (PCI) and included late gadolinium enhancement imaging for microvascular obstruction (MVO) and T2∗ mapping for intramyocardial hemorrhage (IMH). Patients were categorized into those without MVI (MVO-/IMH-), those with MVO but no IMH (MVO+/IMH-), and those with IMH (IMH+).

RESULTS

MVI occurred in 633 (57%) patients, of whom 274 (25%) had an MVO+/IMH- pattern and 359 (32%) had an IMH+ pattern. Infarct size was larger and ejection fraction lower in IMH+ than in MVO+/IMH- and MVO-/IMH- (infarct size: 27% vs 19% vs 18% [P < 0.001]; ejection fraction: 45% vs 50% vs 54% [P < 0.001]). During a median follow-up of 12 months (Q1-Q3: 12-35 months), a clinical outcome event occurred more frequently in IMH+ than in MVO+/IMH- and MVO-/IMH- subgroups (19.5% vs 3.6% vs 4.4%; P < 0.001). IMH+ was the sole independent MVI parameter predicting major adverse cardiovascular events (HR: 3.88; 95% CI: 1.93-7.80; P < 0.001).

CONCLUSIONS

MVI is associated with future adverse outcomes only in patients with a hemorrhagic phenotype (IMH+). Patients with only MVO (MVO+/IMH-) had a prognosis similar to patients without MVI (MVO-/IMH-). This highlights the independent prognostic importance of IMH in assessing and managing risk after STEMI.

Long-Term Prognostic Value of Infarct Transmurality Determined by Contrast-Enhanced Cardiac Magnetic Resonance after ST-Segment Elevation Myocardial Infarction

The long-term prognostic significance of maximal infarct transmurality evaluated by contrast-enhanced cardiac magnetic resonance (CE-CMR) in ST-segment elevation myocardial infarction (STEMI) patients has yet to be determined. This study aimed to see if maximal infarct transmurality has any additional long-term prognostic value over other CE-CMR predictors in STEMI patients, such as microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH). The study included 112 consecutive patients who underwent CE-CMR after STEMI to assess established parameters of myocardial injury as well as the maximal infarct transmurality. The primary clinical endpoint was the occurrence of major adverse cardiac events (MACE), which included all-cause death, non-fatal reinfarction, and new heart failure hospitalization. The MACE occurred in 10 patients over a median follow-up of 7.9 years (IQR, 5.8 to 9.2 years) (2 deaths, 3 nonfatal MI, and 5 heart failure hospitalization). Patients with MACE had significantly higher rates of transmural extent of infarction, infarct size >5.4 percent, MVO, and IMH compared to patients without MACE. In stepwise multivariable Cox regression analysis, the transmural extent of infarction defined as 75 percent or more of infarct transmurality was an independent predictor of the MACE after correction for MVO and IMH (hazard ratio 8.7, 95% confidence intervals [CIs] 1.1-71; p=0.043). In revascularized STEMI patients, post-infarction CE-CMR-based maximal infarct transmurality is an independent long-term prognosticator. Adding maximal infarct transmurality to CE-CMR parameters like MVO and IMH could thus identify patients at high risk of long-term adverse outcomes in STEMI.

A novel intracoronary hypothermia device reduces myocardial reperfusion injury in pigs

BACKGROUND

Hypothermia therapy has been suggested to attenuate myocardial necrosis; however, the clinical implementation as a valid therapeutic strategy has failed, and new approaches are needed to translate into clinical applications. This study aimed to assess the feasibility, safety, and efficacy of a novel selective intracoronary hypothermia (SICH) device in mitigating myocardial reperfusion injury.

METHODS

This study comprised two phases. The first phase of the SICH was performed in a normal porcine model for 30 minutes ( n = 5) to evaluate its feasibility. The second phase was conducted in a porcine myocardial infarction (MI) model of myocardial ischemia/reperfusion was performed by balloon occlusion of the left anterior descending coronary artery for 60 minutes and maintained for 42 days. Pigs in the hypothermia group ( n = 8) received hypothermia intervention onset reperfusion for 30 minutes and controls ( n = 8) received no intervention. All animals were followed for 42 days. Cardiac magnetic resonance analysis (5 and 42 days post-MI) and a series of biomarkers/histological studies were performed.

RESULTS

The average time to lower temperatures to a steady state was 4.8 ± 0.8 s. SICH had no impact on blood pressure or heart rate and was safely performed without complications by using a 3.9 F catheter. Interleukin-6 (IL-6), tumor necrosis factor-α, C-reactive protein (CRP), and brain natriuretic peptide (BNP) were lower at 60 min post perfusion in pigs that underwent SICH as compared with the control group. On day 5 post MI/R, edema, intramyocardial hemorrhage, and microvascular obstruction were reduced in the hypothermia group. On day 42 post MI/R, the infarct size, IL-6, CRP, BNP, and matrix metalloproteinase-9 were reduced, and the ejection fraction was improved in pigs that underwent SICH.

CONCLUSIONS

The SICH device safely and effectively reduced the infarct size and improved heart function in a pig model of MI/R. These beneficial effects indicate the clinical potential of SICH for treatment of myocardial reperfusion injury.

Control of coronary vascular cell fate in development and regeneration

The coronary vasculature consists of a complex hierarchal network of arteries, veins, and capillaries which collectively function to perfuse the myocardium. However, the pathways controlling the temporally and spatially restricted mechanisms underlying the formation of this vascular network remain poorly understood. In recent years, the increasing use and refinement of transgenic mouse models has played an instrumental role in offering new insights into the cellular origins of the coronary vasculature, as well as identifying a continuum of transitioning cell states preceding the full maturation of the coronary vasculature. Coupled with the emergence of single cell RNA sequencing platforms, these technologies have begun to uncover the key regulatory factors mediating the convergence of distinct cellular origins to ensure the formation of a collectively functional, yet phenotypically diverse, vascular network. Furthermore, improved understanding of the key regulatory factors governing coronary vessel formation in the embryo may provide crucial clues into future therapeutic strategies to reactivate these developmentally functional mechanisms to drive the revascularisation of the ischaemic adult heart.

Culprit Lesion Vessel Size and Risk of Reperfusion Injury in ST-Segment Elevation Myocardial Infarction: A Cardiac Magnetic Resonance Imaging Study

BACKGROUND

Microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH) are well-established imaging biomarkers of failed myocardial tissue reperfusion in patients with ST-segment elevation-myocardial infarction treated with percutaneous coronary intervention. MVO and IMH are associated with an increased risk of adverse outcome independent of infarct size, but whether the size of the culprit lesion vessel plays a role in the occurrence and severity of reperfusion injury is currently unknown. This study aimed to evaluate the association between culprit lesion vessel size and the occurrence and severity of reperfusion injury as determined by cardiac magnetic resonance imaging.

METHODS AND RESULTS

Patients (n=516) with first-time ST-segment-elevation myocardial infarction underwent evaluation with cardiac magnetic resonance at 4 (3-5) days after infarction. MVO was assessed with late gadolinium enhancement imaging and IMH with T2* mapping. Vessel dimensions were determined using catheter-based reference. Median culprit lesion vessel size was 3.1 (2.7-3.6) mm. MVO and IMH were found in 299 (58%) and 182 (35%) patients. Culprit lesion vessel size was associated with body surface area, diabetes, total ischemic time, postinterventional thrombolysis in myocardial infarction flow, and infarct size. There was no association between vessel size and MVO or IMH in univariable and multivariable analysis (P>0.05). These findings were consistent across patient subgroups with left anterior descending artery and non-left anterior descending artery infarctions and those with thrombolysis in myocardial infarction 3 flow post-percutaneous coronary intervention.

CONCLUSIONS

Comprehensive characterization of myocardial tissue reperfusion injury by cardiac magnetic resonance revealed no association between culprit lesion vessel size and the occurrence of MVO and IMH in patients treated with primary percutaneous coronary intervention for ST-segment-elevation myocardial infarction.

Intramyocardial Hemorrhage Leads to Higher MACE Rate by Increasing Myocardial Infarction Volume in Patients with STEMI

Background and Aims

Whether IMH can directly cause persistent myocardial necrosis after reperfusion therapy in STEMI patients is still unclear. We conducted a prospective study to compare the cardiovascular parameters in patients with STEMI with and without IMH to explore the potential correlations between IMH and poor outcomes.

Methods and Results

We prospectively enrolled 65 consecutive patients with newly diagnosed STEMI admitted to the CCU of the Second Xiangya Hospital of Central South University between April 2019 and November 2021, all of whom underwent primary PCI. Of these, 38 (58.5%) and 27 (41.5%) patients were in the IMH-absent and IMH-present groups, respectively. At a mean time of 5-7 days after reperfusion therapy, the volume of MI measured using LGE sequence was larger in STEMI patients with IMH than in patients without IMH (34.2 ± 12.7 cm3 vs 21.1 ± 13.1 cm3, P<0.001). HsTNT levels were significantly higher in the IMH-present group than in the IMH-absent [2500.0 (1681.5-4307.0) pg/mL vs 1710.0 (203.0-3363.5) pg/mL, P=0.021] group during hospitalization. The LVEF measured using CMR in the IMH-present group was lower than that in the IMH-absent group (30.7 ± 9.8% vs 42.3 ± 11.0%, P < 0.001). The rate of MACE at 12 months in IMH-present group was significantly higher than in the IMH-absent group (9/27 VS 2/38, P = 0.012).

Conclusion

IMH can lead to further expansion of MI volumes in patients with STEMI, resulting in lower LVEF and higher MACE rate in the post-discharge follow-up.

Association of dysglycaemia with persistent infarct core iron in patients with acute ST-segment elevation myocardial infarction

BACKGROUND

Dysglycaemia increases the risk of myocardial infarction and subsequent recurrent cardiovascular events. However, the role of dysglycaemia in ischemia/reperfusion injury with development of irreversible myocardial tissue alterations remains poorly understood. In this study we aimed to investigate the association of ongoing dysglycaemia with persistence of infarct core iron and their longitudinal changes over time in patients undergoing primary percutaneous coronary intervention (PCI) for acute ST-segment elevation myocardial infarction (STEMI).

METHODS

We analyzed 348 STEMI patients treated with primary PCI between 2016 and 2021 that were included in the prospective MARINA-STEMI study (NCT04113356). Peripheral venous blood samples for glucose and glycated hemoglobin (HbA1c) measurements were drawn on admission and 4 months after STEMI. Cardiac magnetic resonance (CMR) imaging including T2 * mapping for infarct core iron assessment was performed at both time points. Associations of dysglycaemia with persistent infarct core iron and iron resolution at 4 months were calculated using multivariable regression analysis.

RESULTS

Intramyocardial hemorrhage was observed in 147 (42%) patients at baseline. Of these, 89 (61%) had persistent infarct core iron 4 months after infarction with increasing rates across HbA1c levels (<5.7%: 33%, ≥5.7: 79%). Persistent infarct core iron was independently associated with ongoing dysglycaemia defined by HbA1c at 4 months (OR: 7.87 [95% CI: 2.60-23.78]; p < 0.001), after adjustment for patient characteristics and CMR parameters. The independent association was present even after exclusion of patients with diabetes (pre- and newly diagnosed, n = 16).

CONCLUSIONS

In STEMI patients treated with primary PCI, ongoing dysglycaemia defined by HbA1c is independently associated with persistent infarct core iron and a lower likelihood of iron resolution. These findings suggest a potential association between ongoing dysglycaemia and persistent infarct core iron, which warrants further investigation for therapeutic implications.

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.

The Canadian Cardiovascular Society Classification of Acute Atherothrombotic Myocardial Infarction Based on Stages of Tissue Injury Severity: An Expert Consensus Statement

Myocardial infarction (MI) remains a leading cause of morbidity and mortality. In atherothrombotic MI (ST-elevation MI and type 1 non-ST-elevation MI), coronary artery occlusion leads to ischemia. Subsequent cardiomyocyte necrosis evolves over time as a wavefront within the territory at risk. The spectrum of ischemia and reperfusion injury is wide: it can be minimal in aborted MI or myocardial necrosis can be large and complicated by microvascular obstruction and reperfusion hemorrhage. Established risk scores and infarct classifications help with patient management but do not consider tissue injury characteristics. This document outlines the Canadian Cardiovascular Society classification of acute MI. It is an expert consensus formed on the basis of decades of data on atherothrombotic MI with reperfusion therapy. Four stages of progressively worsening myocardial tissue injury are identified: (1) aborted MI (no/minimal myocardial necrosis); (2) MI with significant cardiomyocyte necrosis, but without microvascular injury; (3) cardiomyocyte necrosis and microvascular dysfunction leading to microvascular obstruction (ie, "no-reflow"); and (4) cardiomyocyte and microvascular necrosis leading to reperfusion hemorrhage. Each stage reflects progression of tissue pathology of myocardial ischemia and reperfusion injury from the previous stage. Clinical studies have shown worse remodeling and increase in adverse clinical outcomes with progressive injury. Notably, microvascular injury is of particular importance, with the most severe form (hemorrhagic MI) leading to infarct expansion and risk of mechanical complications. This classification has the potential to stratify risk in MI patients and lay the groundwork for development of new, injury stage-specific and tissue pathology-based therapies for MI.

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.

Translational large animal model of coronary microvascular embolism: characterization by serial cardiac magnetic resonance and histopathology

This study aimed to construct a large animal model of coronary microvascular embolism, and investigate whether it could mimic the clinical imaging phenotypes of myocardial hypoperfusion in patients with ST-segment elevation myocardial infarction (STEMI). Nine minipigs underwent percutaneous coronary embolization with microspheres, followed by cardiac magnetic resonance (CMR) on week 1, 2 and 4 post operation. Microvascular obstruction (MVO) was defined as the isolated hypointense core within the enhanced area on late gadolinium enhancement images, which evolved during a 4-week follow-up. Fibrotic fraction of the segments was measured by Masson trichrome staining using a panoramic analysis software. Iron deposit and macrophage infiltration were quantified based on Perl's blue and anti-CD163 staining, respectively. Seven out of 9 (77.8%) minipigs survived and completed all of the imaging follow-ups. Four out of 7 (57.1%) minipigs were identified as transmural infarct with MVO. The systolic wall thickening (SWT) of MVO zone was similar to that of infarct zone (P = 0.762). Histopathology revealed transmural deposition of collagen, with microvessels obstructed by microspheres. The fibrotic fraction of infarct with MVO segments was similar to that of infarct without MVO segments (P = 0.954). The fraction of iron deposit in infarct with MVO segments was higher than that of infarct without MVO segments (P < 0.05), but the fraction of macrophage infiltration between these two segments did not show statistical difference (P = 0.723). Large animal model of coronary microvascular embolism could mimic most clinical imaging phenotypes of myocardial hypoperfusion in patients with STEMI, demonstrated by serial CMR and histopathology.

Role of Cardiovascular Imaging in Risk Assessment: Recent Advances, Gaps in Evidence, and Future Directions

Optimal risk assessment for primary prevention remains highly challenging. Recent registries have highlighted major discrepancies between guidelines and daily practice. Although guidelines have improved over time and provide updated risk scores, they still fail to identify a significant proportion of at-risk individuals, who then miss out on effective prevention measures until their initial ischemic events. Cardiovascular imaging is progressively assuming an increasingly pivotal role, playing a crucial part in enhancing the meticulous categorization of individuals according to their risk profiles, thus enabling the customization of precise therapeutic strategies for patients with increased cardiovascular risks. For the most part, the current approach to patients with atherosclerotic cardiovascular disease (ASCVD) is homogeneous. However, data from registries (e.g., REACH, CORONOR) and randomized clinical trials (e.g., COMPASS, FOURIER, and ODYSSEY outcomes) highlight heterogeneity in the risks of recurrent ischemic events, which are especially higher in patients with poly-vascular disease and/or multivessel coronary disease. This indicates the need for a more individualized strategy and further research to improve definitions of individual residual risk, with a view of intensifying treatments in the subgroups with very high residual risk. In this narrative review, we discuss advances in cardiovascular imaging, its current place in the guidelines, the gaps in evidence, and perspectives for primary and secondary prevention to improve risk assessment and therapeutic strategies using cardiovascular imaging.

Nomograms referenced by cardiac magnetic resonance in the prediction of cardiac injuries in patients with ST-elevation myocardial infarction

BACKGROUND

Evaluation of cardiac injuries is essential in patients with ST-elevation myocardial infarction (STEMI). Cardiac magnetic resonance (CMR) has become the gold standard for quantifying cardiac injuries; however, its routine application is limited. A nomogram is a useful tool for prognostic prediction based on the comprehensive utilization of clinical data. We presumed that the nomogram models established using CMR as a reference could precisely predict cardiac injuries.

METHODS

This analysis included 584 patients with acute STEMI from a CMR registry study for STEMI (NCT03768453). The patients were divided into training (n = 408) and testing (n = 176) datasets. The least absolute shrinkage and selection operator method and multivariate logistic regression were used to construct nomograms for predicting left ventricular ejection fraction (LVEF) ≤40%, infarction size (IS) ≥ 20% on the LV mass, and microvascular dysfunction.

RESULTS

The nomogram for predicting LVEF≤40%, IS≥20%, and microvascular dysfunction comprised 14, 10, and 15 predictors, respectively. With the nomograms, the individual risk probability of developing specific outcomes could be calculated, and the weight of each risk factor was demonstrated. The C-index of the nomograms in the training dataset were 0.901, 0.831, and 0.814, respectively, and were comparable in the testing set, showing good nomogram discrimination and calibration. The decision curve analysis demonstrated good clinical effectiveness. Online calculators were also constructed.

CONCLUSIONS

With the CMR results as the reference standard, the established nomograms demonstrated good effectiveness in predicting cardiac injuries after STEMI and could provide physicians with a new option for individual risk stratification.

Temporal Trends in Infarct Severity Outcomes in ST-Segment-Elevation Myocardial Infarction: A Cardiac Magnetic Resonance Imaging Study

Background Severity of myocardial tissue injury is a main determinant of morbidity and death related to ST-segment-elevation myocardial infarction (STEMI). Temporal trends of infarct characteristics at the myocardial tissue level have not been described. This study sought to assess temporal trends in infarct characteristics through a comprehensive assessment by cardiac magnetic resonance imaging at a standardized time point early after STEMI. Methods and Results We analyzed patients with STEMI treated with percutaneous coronary intervention at the University Hospital of Innsbruck who underwent cardiac magnetic resonance imaging between 2005 and 2021. The study period was divided into terciles. Myocardial damage characteristics were assessed using a multiparametric cardiac magnetic resonance imaging protocol within the first week after STEMI and compared between groups. A total of 843 patients with STEMI (17% women) with a median age of 57 (interquartile range, 51-66) years were analyzed. While age, sex, and the clinical risk profile expressed as thrombolysis in myocardial infarction risk score were comparable across the study period, there were differences in guideline-recommended therapies. At the same time, there was no significant change in infarct size (P=0.25), microvascular obstruction (P=0.50), and intramyocardial hemorrhage (P=0.34). Left ventricular remodeling indices and left ventricular ejection fraction remained virtually unchanged (all P>0.05). Major adverse cardiovascular events at 4 (interquartile range, 4-5) months were similar between groups (P=0.36). Conclusions In this magnetic resonance imaging study investigating patients with STEMI treated with primary percutaneous coronary intervention over the past 15 years, no change in infarct severity at the myocardial level has been observed. Clinical research on novel therapeutic approaches to reduce myocardial tissue injury should be a priority.

Prospects for Precision Medicine in Acute Myocardial Infarction: Patient-Level Insights into Myocardial Injury and Repair

The past decade has seen a marked expansion in the understanding of the pathobiology of acute myocardial infarction and the systemic inflammatory response that it elicits. At the same time, a portfolio of tools has emerged to characterise some of these processes in vivo. However, in clinical practice, key decision making still largely relies on assessment built around the timing of the onset of chest pain, features on electrocardiograms and measurements of plasma troponin. Better understanding the heterogeneity of myocardial injury and patient-level responses should provide new opportunities for diagnostic stratification to enable the delivery of more rational therapies. Characterisation of the myocardium using emerging imaging techniques such as the T1, T2 and T2* mapping techniques can provide enhanced assessments of myocardial statuses. Physiological measures, which include microcirculatory resistance and coronary flow reserve, have been shown to predict outcomes in AMI and can be used to inform treatment selection. Functionally informative blood biomarkers, including cellular transcriptomics; microRNAs; extracellular vesicle analyses and soluble markers, all give insights into the nature and timing of the innate immune response and its regulation in acute MI. The integration of these and other emerging tools will be key to developing a fuller understanding of the patient-level processes of myocardial injury and repair and should fuel new possibilities for rational therapeutic intervention.

Association of GSDMD with microvascular-ischemia reperfusion injury after ST-elevation myocardial infarction

Objectives

Little is known about the clinical prognosis of gasdermin D (GSDMD) in patients with ST-elevation myocardial infarction (STEMI). The purpose of this study was to investigate the association of GSDMD with microvascular injury, infarction size (IS), left ventricular ejection fraction (LVEF), and major adverse cardiac events (MACEs), in STEMI patients with primary percutaneous coronary intervention (pPCI).

Methods

We retrospectively analyzed 120 prospectively enrolled STEMI patients (median age 53 years, 80% men) treated with pPCI between 2020 and 2021 who underwent serum GSDMD assessment and cardiac magnetic resonance (CMR) within 48 h post-reperfusion; CMR was also performed at one year follow-up.

Results

Microvascular obstruction was observed in 37 patients (31%). GSDMD concentrations ≧ median (13 ng/L) in patients were associated with a higher risk of microvascular obstruction and IMH (46% vs. 19%, P = 0.003; 31% vs. 13%, P = 0.02, respectively), as well as with a lower LVEF both in the acute phase after infarction (35% vs. 54%, P < 0.001) and in the chronic phase (42% vs. 56%, P < 0.001), larger IS in the acute (32% vs. 15%, P < 0.001) and in the chronic phases (26% vs. 11%, P < 0.001), and larger left ventricular volumes (119 ± 20 vs. 98 ± 14, P = 0.003) by CMR. Univariable and multivariable Cox regression analysis results showed that patients with GSDMD concentrations ≧ median (13 ng/L) had a higher incidence of MACE (P < 0.05).

Conclusions

High GSDMD concentrations in STEMI patients are associated with microvascular injury (including MVO and IMH), which is a powerful MACE predictor. Nevertheless, the therapeutic implications of this relation need further research.

SGLT2 inhibitor dapagliflozin alleviates intramyocardial hemorrhage and adverse ventricular remodeling via suppressing hepcidin in myocardial ischemia-reperfusion injury

Intramyocardial hemorrhage (IMH), a reperfusion therapy-associated complication, is the extravasation of red blood cells caused by severe microvascular injury. IMH is an independent predictor of adverse ventricular remodeling (AVR) after acute myocardial infarction (AMI). Hepcidin, a major regulator of iron uptake and systemic distribution, is a key factor affecting AVR. However, the role of cardiac hepcidin in the development of IMH has not been completely elucidated. This study aimed to explore if sodium-dependent glucose co-transporter 2 inhibitor (SGLT2i) exerts therapeutic effects on IMH and AVR by suppressing hepcidin and to elucidate the underlying mechanisms. SGLT2i alleviated IMH and AVR in the ischemia-reperfusion injury (IRI) mouse model. Additionally, SGLT2i downregulated the cardiac levels of hepcidin in IRI mice, suppressed M1-type macrophage polarization, and promoted M2-type macrophage polarization. The effects of hepcidin knockdown on macrophage polarization were similar to those of SGLT2i in RAW264.7 cells. SGLT2i treatment or hepcidin knockdown inhibited the expression of MMP9, an inducer of IMH and AVR, in RAW264.7 cells. Regulation of macrophage polarization and reduction of MMP9 expression by SGLT2i and hepcidin knockdown is achieved through activation of pSTAT3. In conclusion, this study demonstrated that SGLT2i alleviated IMH and AVR by regulating macrophage polarization. The potential mechanism through which SGLT2i exerted its therapeutic effect seems to involve the downregulation of MMP9 via the hepcidin-STAT3 pathway.

Global trend and future landscape of coronary microcirculation: A bibliometric and visualized analysis from 1990 to 2021

Background

Coronary microcirculation has a fundamental role in the regulation of coronary blood flow in response to cardiac requirements, which has aroused wide concerns in basic science and clinical cardiovascular research. We aimed to analyze coronary microcirculation-associated literatures over 30 years and provide insightful information on the evolutionary path, frontier research hotspots, and future developmental trends.

Methods

Publications were retrieved from the Web of Science Core Collection (WoSCC). VOSviewer was used to perform co-occurrence analyses for countries, institutions, authors, and keywords and to generate visualized collaboration maps. CiteSpace was used to visualize the knowledge map derived from reference co-citation analysis, burst references, and keywords detection.

Results

This analysis was performed based on 11,702 publications including 9981 articles and 1721 reviews. The United States and Harvard University ranked at the top among all the countries and institutions. The majority of articles were published in Circulation, and it also was the most co-cited journal. Thematic hotspots and frontiers were focused on coronary microvascular dysfunction, magnetic resonance imaging, fractional flow reserve, STEMI, and heart failure. Additionally, keywords burst and co-occurrence cluster analysis showed that management, microvascular dysfunction, microvascular obstruction, prognostic value, outcomes, and guidelines were current knowledge gaps and future directions.

Conclusions

Coronary microcirculation presented a research hotspot relevant wide spectrum of cardiovascular diseases. Definite diagnostics and prognostics are particularly valued. The protection of cardiovascular events that influence clinical outcomes should be an insightful concern in the future. Multidisciplinary collaborations will provide significant advances for the development of coronary microcirculation.

Interaction of Cardiovascular Nonmodifiable Risk Factors, Comorbidities and Comedications With Ischemia/Reperfusion Injury and Cardioprotection by Pharmacological Treatments and Ischemic Conditioning

Preconditioning, postconditioning, and remote conditioning of the myocardium enhance the ability of the heart to withstand a prolonged ischemia/reperfusion insult and the potential to provide novel therapeutic paradigms for cardioprotection. While many signaling pathways leading to endogenous cardioprotection have been elucidated in experimental studies over the past 30 years, no cardioprotective drug is on the market yet for that indication. One likely major reason for this failure to translate cardioprotection into patient benefit is the lack of rigorous and systematic preclinical evaluation of promising cardioprotective therapies prior to their clinical evaluation, since ischemic heart disease in humans is a complex disorder caused by or associated with cardiovascular risk factors and comorbidities. These risk factors and comorbidities induce fundamental alterations in cellular signaling cascades that affect the development of ischemia/reperfusion injury and responses to cardioprotective interventions. Moreover, some of the medications used to treat these comorbidities may impact on cardioprotection by again modifying cellular signaling pathways. The aim of this article is to review the recent evidence that cardiovascular risk factors as well as comorbidities and their medications may modify the response to cardioprotective interventions. We emphasize the critical need for taking into account the presence of cardiovascular risk factors as well as comorbidities and their concomitant medications when designing preclinical studies for the identification and validation of cardioprotective drug targets and clinical studies. This will hopefully maximize the success rate of developing rational approaches to effective cardioprotective therapies for the majority of patients with multiple comorbidities. SIGNIFICANCE STATEMENT: Ischemic heart disease is a major cause of mortality; however, there are still no cardioprotective drugs on the market. Most studies on cardioprotection have been undertaken in animal models of ischemia/reperfusion in the absence of comorbidities; however, ischemic heart disease develops with other systemic disorders (e.g., hypertension, hyperlipidemia, diabetes, atherosclerosis). Here we focus on the preclinical and clinical evidence showing how these comorbidities and their routine medications affect ischemia/reperfusion injury and interfere with cardioprotective strategies.

Screening for Biomarkers Associated with Left Ventricular Function During Follow-up After Acute Coronary Syndrome

A proportion of patients with the acute coronary syndrome (ACS) will suffer progressive remodeling of the left ventricular (LV). The aim was to screen for important biomarkers from a large-scale protein profiling in 420 ACS patients and define biomarkers associated with reduced LV function early and 1 year after the ACS. Transferrin receptor protein 1 and NT-proBNP were associated with LV function early and after 1 year, whereas osteopontin and soluble ST2 were associated with LV function in the early phase and, tissue-type plasminogen activator after 1 year. Fatty-acid-binding protein and galectin 3 were related to worse GLS but not to LVEF 1 year after the ACS. Proteins involved in remodeling and iron transport in cardiomyocytes were related to worse LV function after ACS. Biomarkers for energy metabolism and fibrosis were exclusively related to worse LV function by GLS. Studies on the functions of these proteins might add knowledge to the biological processes involved in heart failure in long term after ACS.

Heart failure as a complication of myocardial infarction: rational therapy. Case report

Heart failure (HF) is still a frequent complication of myocardial infarction. Timely identification of subjects at risk for HF development and early initiation of guideline-directed HF therapy in these patients, can decrease the HF burden. This article aims at summarizing clinical data on established pharmacological therapies in treating post-MI patients with left ventricular systolic dysfunction and signs and symptoms of HF.

Successful visible thrombus aspiration in ST-segment elevation myocardial infarction: associated factors and the clinical impact

BACKGROUND

Thrombus aspiration (TA) has been considered a procedure for controlling distal emboli and improving microvascular perfusion. However, current guidelines classify routine TA as class III recommendation, and it has been reported that the efficacy of TA is limited because of the relatively high incidence of failure in retrieval of thrombotic material. The aim of this study was to explore patient characteristics and procedural factors associated with successful TA in ST-elevation myocardial infarction (STEMI) and to assess the clinical impact of successful TA.

METHODS

This single-center retrospective study enrolled 158 STEMI patients who underwent TA as initial recanalization. Factors associated with successful TA, which was defined as retrieving any visible material by aspiration catheter, were explored, and angiographical and short-term outcomes were assessed.

RESULTS

In 146 cases (92.4%), the aspiration catheter reached the culprit lesion. Successful TA was achieved in 72 cases (45.6%). The single angiographical characteristic of successful TA was a higher Thrombolysis in Myocardial Infarction grade before TA. Among the procedural characteristics, the rate of successful TA was higher with a 7-French aspiration catheter compared with the rate with a 6-French catheter (57.1% vs. 29.9%, P  = 0.01). Thrombolysis in Myocardial Infarction grade 3 flow was more frequent in patients with successful TA immediately after TA (36.1% vs. 16.3%, P  = 0.006) and at final angiography (91.7% vs 79.1%, P  = 0.04) compared with the grade in patients without successful TA, respectively.

CONCLUSIONS

The use of a larger aspiration catheter may be effective in retrieving visible thrombus material, and successful TA led to better angiographical results.

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.

Myocardial extracellular volume quantified by cardiac magnetic resonance predicts left ventricular aneurysm following acute myocardial infarction

OBJECTIVE

This study aimed to investigate the correlation between increased extracellular matrix estimated by cardiac magnetic resonance (CMR) and left ventricular aneurysm after acute myocardial infarction.

METHODS

A total of 175 patients from 3 centers with an isolated left anterior descending culprit vessel underwent CMR examinations within 1 week and at a 6-month follow-up. Of these, 92 were identified to have left ventricular aneurysms (LVAs): 74 with functional aneurysm and 18 with anatomical aneurysm. The predictive significance of acute extracellular volume (ECV), left gadolinium enhancement (LGE), and other characteristics were analyzed using binary logistic regression analysis.

RESULTS

Patients with LVA were more likely to present with left ventricular adverse remodeling (LVAR) than those without (p = 0.009). With optimal cutoff values of 30.90% for LGE and 33% for ECV to discriminate LVA from non-LVA, the area under the curve (AUC) by receiver operator characteristic curve (ROC) analysis was 0.92 (95% CI: 0.87-0.96; p < 0.001) and 0.93 (95% CI: 0.88-0.96; p < 0.001), respectively. ECV was significantly better than LGE at discriminating between functional and anatomical LVA (p < 0.001). Both acute LGE and ECV were predictors of LVA, with an odds ratio of 1.35 (95% CI: 1.21-1.52, p < 0.001) and 1.23 (95% CI: 1.13-1.33, p < 0.001), respectively, by multivariable logistic regression analysis.

CONCLUSIONS

Acute LGE and ECV of the myocardium provided predictive significance for LVA. The discriminative significance of ECV for functional versus anatomical LVA was better than the discriminative significance of LGE.

KEY POINTS

• Patients with LVA were more likely to present with LVAR. • Acute LGE and ECV of the myocardium provided the strongest predictive significance for LVA. • The discriminative significance of ECV for functional versus anatomical LVA was better than that of LGE.

Red blood cell eNOS is cardioprotective in acute myocardial infarction

Red blood cells (RBCs) were shown to transport and release nitric oxide (NO) bioactivity and carry an endothelial NO synthase (eNOS). However, the pathophysiological significance of RBC eNOS for cardioprotection in vivo is unknown. Here we aimed to analyze the role of RBC eNOS in the regulation of coronary blood flow, cardiac performance, and acute myocardial infarction (AMI) in vivo. To specifically distinguish the role of RBC eNOS from the endothelial cell (EC) eNOS, we generated RBC- and EC-specific knock-out (KO) and knock-in (KI) mice by Cre-induced inactivation or reactivation of eNOS. We found that RBC eNOS KO mice had fully preserved coronary dilatory responses and LV function. Instead, EC eNOS KO mice had a decreased coronary flow response in isolated perfused hearts and an increased LV developed pressure in response to elevated arterial pressure, while stroke volume was preserved. Interestingly, RBC eNOS KO showed a significantly increased infarct size and aggravated LV dysfunction with decreased stroke volume and cardiac output. This is consistent with reduced NO bioavailability and oxygen delivery capacity in RBC eNOS KOs. Crucially, RBC eNOS KI mice had decreased infarct size and preserved LV function after AMI. In contrast, EC eNOS KO and EC eNOS KI had no differences in infarct size or LV dysfunction after AMI, as compared to the controls. These data demonstrate that EC eNOS controls coronary vasodilator function, but does not directly affect infarct size, while RBC eNOS limits infarct size in AMI. Therefore, RBC eNOS signaling may represent a novel target for interventions in ischemia/reperfusion after myocardial infarction.

Prevalence and prognostic impact of mitral annular disjunction in patients with STEMI - A cardiac magnetic resonance study

BACKGROUND

Mitral annular disjunction (MAD) represents the detachment of the mitral leaflet hinge-point from the ventricular myocardium. Its role in patients with ST-segment-elevation myocardial infarction (STEMI) is unknown. This study aims to investigate the prevalence of MAD by cardiac magnetic resonance imaging (CMR) in STEMI-patients and its association with serious adverse events.

METHODS

STEMI-patients (n = 621) underwent CMR 4 days [interquartile range (IQR) 2-5] after percutaneous coronary intervention. Presence and longitudinal extent of MAD were obtained in long-axis cine-images, infarct characteristics in late gadolinium enhancement-images. During a median follow-up time of 366 days (IQR 136-454), patients were observed for the occurrence of major adverse cardiac events (MACE), comprising death, myocardial reinfarction, and congestive heart failure.

RESULTS

Overall, 307 patients (49 %) had MAD. Longitudinal MAD-distance was 4.6 ± 1.7 mm and the P3-segment was affected most frequently (n = 262, 85 % of MAD-patients). MAD-patients had a significantly smaller infarct size, lower prevalence of microvascular obstruction, and intramyocardial hemorrhage as well as a higher ejection fraction (all p < 0.03). During follow-up period, MACE occurred in 52 patients (8 %) and did not show significant difference between patients with and without MAD (7 % vs. 9 %, p = 0.424). Cardiovascular death occurred significantly more often in patients without MAD (n = 10, 3.2 % vs. n = 2, 0.7 %, p = 0.021).

CONCLUSION

MAD is a rather common finding in patients presenting with STEMI. Patients with MAD had less severe infarct characteristics, however, they were not more commonly affected by MACE. Further confirmation and longer follow-up intervals are necessary to define the exact role of MAD in STEMI patients.

Evolution of Myocardial Tissue Injury: A CMR Study Over a Decade After STEMI

BACKGROUND

In patients with a first ST-segment elevation myocardial infarction (STEMI), the multi-annual evolution of myocardial tissue injury parameters, as assessed by cardiac magnetic resonance (CMR), has not yet been described.

OBJECTIVES

This study examined myocardial tissue injury dynamics over a decade after STEMI.

METHODS

Sequential CMR examinations (within the first week after STEMI, and at 4, 12, months, and 9 years thereafter) were conducted in 74 patients with STEMI treated with primary percutaneous coronary intervention. Left ventricular function, infarct size (IS), and microvascular obstruction (MVO) were assessed at all time points. T2∗, T2, and T1 mapping (n = 59) were added at 9-year scan to evaluate the presence of iron and edema within the infarct core, respectively.

RESULTS

IS decreased progressively and significantly between all CMR time points (all P < 0.001), with an average reduction rate of 5.8% per year (IQR: 3.5%-8.8%) and a relative reduction of 49% (IQR: 39%-76%) over a decade. MVO was present in 61% of patients at baseline, but was not present at the follow-up examinations. At 9-year CMR, 17 of 59 (29%) patients showed iron deposition within the infarct core, whereas 82% had persistent edema. Persistent iron and edema were associated with greater IS on any occasion (all P < 0.001), as well as the presence of MVO (P < 0.001). Patients with persistent iron and edema showed a lower relative regression of IS (P = 0.005 and P = 0.032, respectively) and greater end-systolic volumes over a decade (all P < 0.012 and P > 0.023, respectively). A T1 hypointense infarct core without evidence of T2∗ iron deposition (14 of 59 [24%] patients) was attributed to lipomatous metaplasia of the infarct.

CONCLUSIONS

The evolution of IS is a dynamic process that extends well beyond the first few months after STEMI. Persistence of iron and edema within the infarct core occurs up to a decade after STEMI and is associated with initial infarct severity and poor infarct healing.

A Noncontrast CMR Risk Score for Long-Term Risk Stratification in Reperfused ST-Segment Elevation Myocardial Infarction

OBJECTIVES

This study compared the prognostic value of a noncontrast CMR risk score for the composite of all-cause death, nonfatal myocardial infarction, and new congestive heart failure.

BACKGROUND

A cardiovascular magnetic resonance (CMR) risk score including left ventricular ejection fraction (LVEF), myocardial infarct (MI) size, and microvascular obstruction (MVO) was recently proposed to risk-stratify patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

The Eitel CMR risk score and GRACE (Global Registry of Acute Coronary Events) score were used as a reference (Score 1: acute MI size ≥19% LV, LVEF ≤47%, MVO >1.4% LV and GRACE score). MVO was replaced by intramyocardial hemorrhage (IMH) in Score 2 (acute MI size ≥19% LV, LVEF ≤47%, IMH, and GRACE score). Score 3 included only LVEF ≤45%, IMH, and GRACE score.

RESULTS

There were 370 patients in the derivation cohort and 234 patients in the validation cohort. In the derivation cohort, the 3 scores performed similarly and better than GRACE score to predict the 1-year composite endpoint with C-statistics of 0.83, 0.83, 0.82, and 0.74, respectively. In the validation cohort, there was good discrimination and calibration of score 3, with a C-statistic of 0.87 and P = 0.71 in a Hosmer-Lemeshow test for goodness of fit, on the 1-year composite outcome. Kaplan-Meier curves for 5-year composite outcome showed that those with LVEF ≤45% (high-risk) and LVEF >45% and IMH (intermediate-risk) had significantly higher cumulative events than those with LVEF >45% and no IMH (low-risk), log-rank tests: P = 0.02 and P = 0.03, respectively. The HR for the high-risk group was 2.3 (95% CI: 1.1-4.7) and for the intermediate-risk group was 2.0 (95% CI: 1.0-3.8), and these remained significant after adjusting for the GRACE score.

CONCLUSIONS

This noncontrast CMR risk score has performance comparable to an established risk score, and patients with STEMI could be stratified into low risk (LVEF >45% and no IMH), intermediate risk (LVEF >45% and IMH), and high risk (LVEF ≤45%). (A Trial of Low-dose Adjunctive alTeplase During prIMary PCI [T-TIME]; NCT02257294) (Detection and Significance of Heart Injury in ST Elevation Myocardial Infarction [BHF MR-MI]; NCT02072850).

Association of plasma interleukin-6 with infarct size, reperfusion injury, and adverse remodelling after ST-elevation myocardial infarction

AIMS

Little is known about the clinical relevance of interleukin (IL)-6 in patients with acute ST-elevation myocardial infarction (STEMI). This study examined the possible associations of plasma IL-6 concentrations with infarct size (IS), reperfusion injury and adverse left ventricular remodelling (LVR), in STEMI patients treated with primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

We prospectively included 170 consecutive STEMI patients (median age 57 years, 14% women) treated with primary PCI between 2017 and 2019. Blood samples for biomarker analyses including IL-6 were collected on Day 2. Left ventricular ejection fraction (LVEF), IS, and reperfusion injury [microvascular obstruction (MVO) and intramyocardial haemorrhage (IMH)] were determined using cardiac magnetic resonance (CMR) imaging on Day 4. Left ventricular remodelling was defined as ≥10% increase in left ventricular end-diastolic volume from baseline to 4 months CMR follow-up. Patients with IL-6 concentrations ≥median (17 ng/L) showed a significantly lower LVEF (43% vs. 52%, P < 0.001), larger IS (22% vs. 13%, P < 0.001), larger MVO (1.9% vs. 0.0%, P < 0.001), and more frequent IMH (52% vs. 18%, P < 0.001). Left ventricular remodelling was more common in patients with IL-6 ≥ median (24% vs. 9%, P = 0.005). In both linear and binary multivariable regression analyses, IL-6 remained independently associated with lower LVEF [odds ratio (OR): 0.10, 95% confidence interval (CI) 0.02-0.42, P = 0.002], larger IS (OR: 5.29, 95% CI 1.52-18.40, P = 0.009), larger MVO (OR: 5.20, 95% CI 1.30-20.85, P = 0.020), with presence of IMH (OR: 3.73, 95% CI 1.27-10.99, P = 0.017), and adverse LVR (OR: 2.72, 95% 1.06-6.98, P = 0.038).

CONCLUSIONS

High concentrations of circulating plasma IL-6 on Day 2 after STEMI were independently associated with worse myocardial function, larger infarct extent, more severe reperfusion injury, and a higher likelihood for LVR, suggesting IL-6 as a useful biomarker of more serious outcome and potential therapeutic target.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT04113356;NCT04113356.

Prognostic relevance of peri-infarct zone measured by cardiovascular magnetic resonance in patients with ST-segment elevation myocardial infarction

BACKGROUND

Cardiac magnetic resonance (CMR) imaging provides valuable prognostic information in patients with ST-elevation myocardial infarction (STEMI). The peri-infarct zone (PIZ) is a potential marker for post-infarction risk stratification. The aim of this study was to assess the prognostic impact of PIZ in a large multicenter STEMI-trial.

METHODS

The study population consisted of 704 consecutive patients undergoing CMR within 10 days after STEMI to assess established parameters of myocardial injury and additionally the extent of PIZ. The primary clinical endpoint was major adverse cardiac events (MACE) consisting of death, re-infarction and new congestive heart failure within 1 year after infarction.

RESULTS

The median heterogeneous PIZ-volume in the overall population was 14 ml (interquartile range [IQR] 7 to 24 ml). Male sex, infarct size, and left ventricular ejection fraction were identified as independent predictors of larger PIZ alterations. Patients with MACE had a significantly larger PIZ volume compared to patients without adverse events (21 ml [IQR 12 to 35 ml] versus 14 ml [IQR 7 to 23 ml]; p = 0.001). In stepwise multivariable Cox regression analysis, PIZ > median (>14 ml) emerged as an independent predictor of MACE (hazard ratio [HR] 2.84; 95% confidence interval [CI] 1.34 to 6.00; p = 0.006) in addition to the Thrombolysis In Myocardial Infarction (TIMI) risk score (HR 1.53; 95% CI 1.19 to 1.53; p < 0.001). Addition of PIZ to a CMR risk model comprising LVEF, infarct size and microvascular obstruction resulted in net reclassification improvement of 0.46 (0.19-0.73, p < 0.001).

CONCLUSION

In this currently largest prospective, multicenter CMR study assessing PIZ, the extent of PIZ emerged as an independent predictor of MACE and a potential novel marker for optimized risk stratification in STEMI patients. ClinicalTrials.gov: NCT00712101.

Coronary blood flow in heart failure: cause, consequence and bystander

Heart failure is a clinical syndrome where cardiac output is not sufficient to sustain adequate perfusion and normal bodily functions, initially during exercise and in more severe forms also at rest. The two most frequent forms are heart failure of ischemic origin and of non-ischemic origin. In heart failure of ischemic origin, reduced coronary blood flow is causal to cardiac contractile dysfunction, and this is true for stunned and hibernating myocardium, coronary microembolization, myocardial infarction and post-infarct remodeling, possibly also for the takotsubo syndrome. The most frequent form of non-ischemic heart failure is dilated cardiomyopathy, caused by genetic mutations, myocarditis, toxic agents or sustained tachyarrhythmias, where alterations in coronary blood flow result from and contribute to cardiac contractile dysfunction. Hypertrophic cardiomyopathy is caused by genetic mutations but can also result from increased pressure and volume overload (hypertension, valve disease). Heart failure with preserved ejection fraction is characterized by pronounced coronary microvascular dysfunction, the causal contribution of which is however not clear. The present review characterizes the alterations of coronary blood flow which are causes or consequences of heart failure in its different manifestations. Apart from any potentially accompanying coronary atherosclerosis, all heart failure entities share common features of impaired coronary blood flow, but to a different extent: enhanced extravascular compression, impaired nitric oxide-mediated, endothelium-dependent vasodilation and enhanced vasoconstriction to mediators of neurohumoral activation. Impaired coronary blood flow contributes to the progression of heart failure and is thus a valid target for established and novel treatment regimens.

Regional analysis of inflammation and contractile function in reperfused acute myocardial infarction by in vivo 19F cardiovascular magnetic resonance in pigs

Inflammatory cell infiltration is central to healing after acute myocardial infarction (AMI). The relation of regional inflammation to edema, infarct size (IS), microvascular obstruction (MVO), intramyocardial hemorrhage (IMH), and regional and global LV function is not clear. Here we noninvasively characterized regional inflammation and contractile function in reperfused AMI in pigs using fluorine (¹⁹F) cardiovascular magnetic resonance (CMR). Adult anesthetized pigs underwent left anterior descending coronary artery instrumentation with either 90 min occlusion (n = 17) or without occlusion (sham, n = 5). After 3 days, in surviving animals a perfluorooctyl bromide nanoemulsion was infused intravenously to label monocytes/macrophages. At day 6, in vivo ¹H-CMR was performed with cine, T2 and T2* weighted imaging, T2 and T1 mapping, perfusion and late gadolinium enhancement followed by ¹⁹F-CMR. Pigs were sacrificed for subsequent ex vivo scans and histology. Edema extent was 35 ± 8% and IS was 22 ± 6% of LV mass. Six of ten surviving AMI animals displayed both MVO and IMH (3.3 ± 1.6% and 1.9 ± 0.8% of LV mass). The ¹⁹F signal, reflecting the presence and density of monocytes/macrophages, was consistently smaller than edema volume or IS and not apparent in remote areas. The ¹⁹F signal-to-noise ratio (SNR) > 8 in the infarct border zone was associated with impaired remote systolic wall thickening. A whole heart value of ¹⁹F integral (¹⁹F SNR × milliliter) > 200 was related to initial LV remodeling independently of edema, IS, MVO, and IMH. Thus, ¹⁹F-CMR quantitatively characterizes regional inflammation after AMI and its relation to edema, IS, MVO, IMH and regional and global LV function and remodeling.

Cardiac magnetic resonance imaging improves prognostic stratification of patients with ST-elevation myocardial infarction and preserved ejection fraction

Aims

To evaluate the prognostic validity of clinical risk factors as well as infarct characterization and myocardial deformation by cardiac magnetic resonance (CMR) in ST-elevation myocardial infarction (STEMI) patients with preserved left ventricular ejection fraction (LVEF) following primary percutaneous coronary intervention (PCI).

Methods and results

This multicentre, individual patient-data analysis from two large CMR trials included 1247 STEMI patients. Cardiac magnetic resonance examinations were conducted 3 [interquartile range (IQR) 2–4] days after PCI. LVEF, infarct size, microvascular obstruction (MVO), and myocardial strain values were measured. Primary endpoint was defined as composite of major adverse cardiovascular events (MACE) including death, re-infarction, and congestive heart failure. A preserved LVEF (defined as LVEF ≥50%) was observed in 724 patients (=58%). In the overall cohort, 97 patients experienced a MACE event [follow-up time 12 (IQR 12–13) months], and 34 MACE events occurred in the group with preserved LVEF (5% vs. 12% incidence rate in patients with LVEF < 50%). TIMI risk score [hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.02–1.59; P = 0.03] and female gender (HR 2.24, 95% CI 1.10–4.57; P = 0.03) emerged as independent clinical determinants of MACE in the patient group with preserved LVEF. Among CMR parameters, the presence of MVO (HR 2.39, 95% CI 1.05–5.46; P = 0.04) and reduced global longitudinal strain (GLS; HR 1.12, 95% CI 1.02–1.23; P = 0.02) independently predicted MACE in the LVEF-preserved population. The addition of MVO and GLS to the clinical prognostic markers (TIMI risk score, female gender) increased (P = 0.02) the prognostic validity [AUC 0.76 (95% CI 0.73–0.79)] compared to the clinical markers alone [AUC 0.65 (0.62–0.69)].

Conclusion

In contemporary treated STEMI patients showing preserved LVEF, a CMR-based risk prediction approach assessing MVO and GLS provided strong prognostic value that was incremental to clinical outcome parameters.

Prognostic value of depressed cardiac index after STEMI: a phase-contrast magnetic resonance study

AIMS 

An invasively measured cardiac index (CI) of ≤2.2 L/min/m2 is one of the strongest prognostic indicators after ST-elevation myocardial infarction (STEMI), however, knowledge is mainly based on invasive evaluations performed in the pre-stent era. Velocity-encoded phase-contrast cardiac magnetic resonance (PC-CMR) allows non-invasive determination of CI.

METHODS AND RESULTS 

In this prospective study, CMR was performed in 406 stable and contemporarily revascularized patients a median of 3 days after STEMI. Forward stroke volume was assessed at the level of the ascending aorta by PC-CMR. Left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) were determined by cine CMR. Major adverse cardiac events (MACE) were defined as the composite of death, myocardial infarction, or hospitalization for heart failure. Median CI was 2.52 L/min/m2 and 27% of patients had ≤2.2 L/min/m2. Median LVEF was 53% and median GLS was -12.2%. During a median follow-up of 14.2 [95% confidence interval (95% CI) 13.6-14.7] months, 41 patients (10.1%) experienced a MACE. A depressed CI was significantly associated with MACE after adjustment for LVEF, GLS, Thrombolysis in Myocardial Infarction (TIMI) risk score, and infarct size [hazard ratio = 3.15 (95% CI 1.53-6.47); P = 0.002] and led to significant discrimination improvement [net reclassification improvement 0.61 (95% CI 0.25-0.97); P < 0.001].

CONCLUSIONS 

A CI of 2.2 L/min/m2 or less as measured by PC-CMR was present in 27% of clinically stable patients after STEMI and strongly and independently predicted medium-term MACE. The prognostic value of a depressed CI was superior and incremental to LVEF, GLS, TIMI risk score, and infarct size.

Impact of COVID-19 pandemic restrictions on ST-elevation myocardial infarction: a cardiac magnetic resonance imaging study

AIMS

The severity of myocardial tissue damage following ST-elevation myocardial infarction (STEMI) strongly determines short- and long-term prognosis. This study explored the impact of the coronavirus disease 2019 (COVID-19) pandemic and associated public health restrictions on infarct severity.

METHODS AND RESULTS

STEMI patients treated with primary percutaneous coronary intervention (PCI) and included in the prospective Magnetic Resonance Imaging in Acute ST-Elevation Myocardial Infarction (MARINA-STEMI) cohort study from 2015- 2020 (n = 474) were categorized according to (i) timeframes with and without major public health restrictions in 2020, and (ii) timeframes of major public health restrictions during 2020 and during the corresponding timeframes between 2015-2019. Myocardial damage was evaluated by cardiac magnetic resonance imaging. During major public health restrictions in 2020 (n = 48), there was an increase in infarct size (22 [IQR 12-29] vs. 14 [IQR 6-23]%, P < 0.01), a higher frequency (77% vs. 52%, P < 0.01) and larger extent of microvascular obstruction (1.5 [IQR 0.1-11.4] vs. 0.2 [IQR 0.0-2.6]%, P < 0.01) and a higher rate of intramyocardial haemorrhage (56% vs. 34%, P = 0.02) as compared to the phases without major restrictions in 2020 (n = 101). These findings were confirmed in adjusted analysis and were consistent when comparing patients admitted in 2020 versus patients admitted in the "pre-pandemic" era (2015-2019). Patient characteristics were comparable between groups, except for a significantly longer total ischemia time (P < 0.01) and higher frequency of pre-PCI Thrombolysis in Myocardial Infarction (TIMI) flow 0 during times of major restrictions (P = 0.03).

CONCLUSION

This study provides novel mechanistic insights demonstrating a significant increase in myocardial damage in STEMI patients admitted during the COVID-19 pandemic with a temporal relation to major public health restrictions.

Global longitudinal strain improves risk assessment after ST-segment elevation myocardial infarction: a comparative prognostic evaluation of left ventricular functional parameters

AIM

We aimed to investigate the comparative prognostic value of left ventricular ejection fraction (LVEF), mitral annular plane systolic excursion (MAPSE), fast manual long-axis strain (LAS) and global longitudinal strain (GLS) determined by cardiac magnetic resonance (CMR) in patients after ST-segment elevation myocardial infarction (STEMI).

METHODS AND RESULTS

This observational cohort study included 445 acute STEMI patients treated with primary percutaneous coronary intervention (pPCI). Comprehensive CMR examinations were performed 3 [interquartile range (IQR): 2-4] days after pPCI for the determination of left ventricular (LV) functional parameters and infarct characteristics. Primary endpoint was the occurrence of major adverse cardiac events (MACE) defined as composite of death, re-infarction and congestive heart failure. During a follow-up of 16 [IQR: 12-49] months, 48 (11%) patients experienced a MACE. LVEF (p = 0.023), MAPSE (p < 0.001), LAS (p < 0.001) and GLS (p < 0.001) were significantly related to MACE. According to receiver operating characteristic analyses, only the area under the curve (AUC) of GLS was significantly higher compared to LVEF (0.69, 95% confidence interval (CI) 0.64-0.73; p < 0.001 vs. 0.60, 95% CI 0.55-0.65; p = 0.031. AUC difference: 0.09, p = 0.020). After multivariable analysis, GLS emerged as independent predictor of MACE even after adjustment for LV function, infarct size and microvascular obstruction (hazard ratio (HR): 1.13, 95% CI 1.01-1.27; p = 0.030), as well as angiographical (HR: 1.13, 95% CI 1.01-1.28; p = 0.037) and clinical parameters (HR: 1.16, 95% CI 1.05-1.29; p = 0.003).

CONCLUSION

GLS emerged as independent predictor of MACE after adjustment for parameters of LV function and myocardial damage as well as angiographical and clinical characteristics with superior prognostic validity compared to LVEF.

Cardiac Magnetic Resonance Tissue Characterization in Ischemic Cardiomyopathy

Ischemic cardiomyopathy (ICM) is one of the most common causes of congestive heart failure. In patients with ICM, tissue characterization with cardiac magnetic resonance imaging (CMR) allows for evaluation of myocardial abnormalities in acute and chronic settings. Myocardial edema, microvascular obstruction (MVO), intracardiac thrombus, intramyocardial hemorrhage, and late gadolinium enhancement of the myocardium are easily depicted using standard CMR sequences. In the acute setting, tissue characterization is mainly focused on assessment of ventricular thrombus and MVO, which are associated with poor prognosis. Conversely, in chronic ICM, it is important to depict late gadolinium enhancement and myocardial ischemia using stress perfusion sequences. Overall, with CMR's ability to accurately characterize myocardial tissue in acute and chronic ICM, it represents a valuable diagnostic and prognostic imaging method for treatment planning. In particular, tissue characterization abnormalities in the acute setting can provide information regarding the patients that may develop major adverse cardiac event and show the presence of ventricular thrombus; in the chronic setting, evaluation of viable myocardium can be fundamental for planning myocardial revascularization. In this review, the main findings on tissue characterization are illustrated in acute and chronic settings using qualitative and quantitative tissue characterization.

Early or deferred cardiovascular magnetic resonance after ST-segment-elevation myocardial infarction for effective risk stratification

AIMS

In ST-segment-elevation myocardial infarction (STEMI), cardiovascular magnetic resonance (CMR) holds the potentiality to improve risk stratification in addition to Thrombolysis in Myocardial Infarction (TIMI) risk score. Nevertheless, the optimal timing for CMR after STEMI remains poorly defined. We aim at comparing the prognostic performance of three stratification strategies according to the timing of CMR after STEMI.

METHODS AND RESULTS

The population of this prospective registry-based study included 492 reperfused STEMI patients. All patients underwent post-reperfusion (median: 4 days post-STEMI) and follow-up (median: 4.8 months post-STEMI) CMR. Left ventricular (LV) volumes, function, infarct size, and microvascular obstruction extent were quantified. Primary endpoint was a composite of all-death and heart failure (HF) hospitalization. Baseline-to-follow-up percentage increase of LV end-diastolic (EDV; ΔLV-EDV) ≥20% or end-systolic volumes (ESV; ΔLV-ESV) ≥15% were tested against outcome. Three multivariate models were developed including TIMI risk score plus early post-STEMI (early-CMR) or follow-up CMR (deferred-CMR) or both CMRs parameters along with adverse LV remodelling (paired-CMRs). During a median follow-up of 8.3 years, the primary endpoint occurred in 84 patients (47 deaths; 37 HF hospitalizations). Early-CMR, deferred-CMR, and paired-CMR demonstrated similar predictive value for the primary endpoint (C-statistic: 0.726, 0.728, and 0.738, respectively; P = 0.663). ΔLV-EDV ≥20% or ΔLV-ESV ≥15% were unadjusted outcome predictors (hazard ratio: 2.020 and 2.032, respectively; P = 0.002 for both) but lost their predictive value when corrected for other covariates in paired-CMR model.

CONCLUSION

In STEMI patients, early-, deferred-, or paired-CMR were equivalent stratification strategies for outcome prediction. Adverse LV remodelling parameters were not independent prognosticators.

C-reactive protein velocity predicts microvascular pathology after acute ST-elevation myocardial infarction

BACKGROUND

The role of C-reactive protein velocity (CRPv) as an early and sensitive marker of an excessive inflammatory response in the setting of acute ST-elevation myocardial infarction (STEMI) is only poorly understood. The aim of this study was to investigate, in patients with STEMI treated with primary percutaneous coronary intervention (PCI), the association of CRPv with microvascular infarct pathology.

METHODS AND RESULTS

This prospective cohort study included a total of 316 patients with STEMI undergoing PCI. CRPv was defined as the difference between CRP 24 ± 8 h and CRP at hospital admission, divided by the time (in h) that have passed during the two examinations. The association of biomarker levels with cardiac magnetic resonance (CMR)-determined microvascular obstruction (MVO) was evaluated. CMR was performed at a median of 3 [interquartile range 2-4] days after PCI. After adjustment for cardiac troponin T (cTnT), anterior infarction and TIMI flow pre and post-PCI, CRPv (odds ratio 2.70, 95% confidence interval (CI) 1.54-4.73; p = 0.001) remained significantly associated with the occurrence of MVO. CRPv (area under the curve [AUC] 0.76, 95% CI 0.71-0.81; p < 0.001) was a better predictor for MVO compared to 24 h CRP (AUC difference: 0.03, p = 0.002). The addition of CRPv to peak cTnT resulted in a higher AUC for MVO prediction than peak cTnT alone (AUC 0.86, 95% CI 0.82-0.90; p < 0.001 vs. AUC 0.84, 95% CI 0.79-0.88; p < 0.001. AUC difference: 0.02, p = 0.042).

CONCLUSIONS

In patients with STEMI treated with primary PCI, CRPv was associated with microvascular infarct pathology with a predictive value incremental to cTnT, suggesting CRPv as an early and sensitive biomarker for more severe infarct pathology and outcome.

Impact of microvascular injury various types on function of left ventricular in patients with primary myocardial infarction with ST segment elevation

AIM

To analyze the long-term effect of microvascular injury various types on the structural and functional parameters of the left ventricle assessed by echocardiography in patients with primary ST-segment elevation myocardial infarction (STEMI).

MATERIALS AND METHODS

The study included 60 patients with primary STEMI admitted within the first 12 hours after the onset of disease who underwent stenting of the infarct-associated coronary artery. Each patient included in the study underwent CMR imaging on the second day post-STEMI. MVO and IMH were assessed using late gadolinium enhancement and T2-weighted CMR imaging. Subsequently, all patients underwent the standard echocardiographic protocol on the 7th day and 3 months after MI.

RESULTS

We divided all patients into 4 groups: the 1st group didn't have any phenomena of IMH and MVO, the 2nd group had only MVO, patients of the 3rd group had only IMH and in the 4th group there was a combination of MVO and IMH. LV ejection fraction was significantly lower in patients with combination of MVO and IMH, if compared to those without it. Correlation analysis showed a moderate inverse correlation between the MVO area and LV contractile function: the larger the area, the lower the LVEF (R=-0,60; p=0,000002).

CONCLUSIONS

The combination of IMH and MVO is a predictor of a reduction in LVEF and an increase of volumetric measurements within 3 months after MI. In comparison with patients without microvascular injury isolated MVO is associated with lower LVEF. The size of MVO is directly correlated with the LV contractile function decrease. Isolated IMH was not associated with deterioration of left ventricular function.

Translational Block in Stroke: A Constructive and "Out-of-the-Box" Reappraisal

Why can we still not translate preclinical research to clinical treatments for acute strokes? Despite > 1000 successful preclinical studies, drugs, and concepts for acute stroke, only two have reached clinical translation. This is the translational block. Yet, we continue to routinely model strokes using almost the same concepts we have used for over 30 years. Methodological improvements and criteria from the last decade have shed some light but have not solved the problem. In this conceptual analysis, we review the current status and reappraise it by thinking "out-of-the-box" and over the edges. As such, we query why other scientific fields have also faced the same translational failures, to find common denominators. In parallel, we query how migraine, multiple sclerosis, and hypothermia in hypoxic encephalopathy have achieved significant translation successes. Should we view ischemic stroke as a "chronic, relapsing, vascular" disease, then secondary prevention strategies are also a successful translation. Finally, based on the lessons learned, we propose how stroke should be modeled, and how preclinical and clinical scientists, editors, grant reviewers, and industry should reconsider their routine way of conducting research. Translational success for stroke treatments may eventually require a bold change with solutions that are outside of the box.