Cardiac imaging after myocardial infarction

Utilising pyrophosphate uptake imaging to establish the timing of acute myocardial infarction: An often-forgotten art

INTRODUCTION

While pyrophosphate uptake imaging with Technetium-99 m pyrophosphate (Tc-99 m PYP) is frequently used for cardiac ATTR amyloid imaging, its role in determining the timing of acute myocardial infarction (AMI) is near forgotten. We present a case that demonstrates the clinical benefit of pyrophosphate uptake imaging in differentiating recent from remote infarction as a reminder of the continued utility of pyrophosphate uptake imaging for this indication.

CASE AND OUTCOMES

A 68-year-old male was referred for surgical replacement of his bicuspid aortic valve with severe aortic regurgitation. He was clinically well, but an elective pre-operative electrocardiogram suggested an anteroseptal wall infarct of possibly recent onset. Troponin-I was elevated at 430 ng/L (N < 26 ng/L) but did not change significantly over several days. Coronary angiography confirmed an occluded left anterior descending artery. Tc-99 m PYP uptake imaging was then utilised to determine the age of infarct and demonstrated mild regional tracer uptake in the left ventricular apex, consistent with a recent infarction. As the infarct was recent, elective surgery was postponed.

DISCUSSION

In this case, the age of the patient's AMI had an important bearing on the timing of his elective surgical aortic valve replacement. Given the recommendation to delay elective cardiac surgery in patients with recent myocardial infarction to reduce peri‑operative morbidity and mortality, this now rare use of pyrophosphate uptake imaging was critical in helping determine when cardiac surgery could be performed safely.

CONCLUSION

This case demonstrates the clinical utility of pyrophosphate uptake imaging in establishing the temporal profile of myocardial infarction to help guide appropriate clinical management.

2024 CSANZ Position Statement on Indications, Assessment and Monitoring of Structural and Valvular Heart Disease With Transthoracic Echocardiography in Adults

Transthoracic echocardiography (TTE) is the most widely available and utilised imaging modality for the screening, diagnosis, and serial monitoring of all abnormalities related to cardiac structure or function. The primary objectives of this document are to provide (1) a guiding framework for treating clinicians of the acceptable indications for the initial and serial TTE assessments of the commonly encountered cardiovascular conditions in adults, and (2) the minimum required standard for TTE examinations and reporting for imaging service providers. The main areas covered within this Position Statement pertain to the TTE assessment of the left and right ventricles, valvular heart diseases, pericardial diseases, aortic diseases, infective endocarditis, cardiac masses, pulmonary hypertension, and cardiovascular diseases associated with cancer treatments or cardio-oncology. Facilitating the optimal use and performance of high quality TTEs will prevent the over or under-utilisation of this resource and unnecessary downstream testing due to suboptimal or incomplete studies.

A Microenvironment-responsive small-molecule probe and application in quick acute myocardial infarction imaging

Acute myocardial infarction (AMI) patients are at an elevated risk for life-threatening myocardial ischemia/reperfusion injury. Early-stage nonradioactive and noninvasive diagnosis of AMI is imperative for the subsequent disease treatment, yet it presents substantial challenges. After AMI, the myocardium typically exhibits elevated levels of peroxynitrite (ONOO-), constituting a distinct microenvironmental feature. In this context, the near-infrared imaging probe (BBEB) is employed to precisely delineate the boundaries of AMI lesions with a high level of sensitivity and specificity by monitoring endogenous ONOO-. This probe allows for the early detection of myocardial damage at cellular and animal levels, providing exceptional temporal and spatial resolution. Notably, BBEB enables visualization of ONOO- level alterations during AMI treatment incorporating antioxidant drugs. Overall, BBEB can rapidly and accurately visualize myocardial injury, particularly in the early stages, and can further facilitate antioxidant drug screening.

Considerations on the Management of Acute Postoperative Ischemia After Cardiac Surgery: A Scientific Statement From the American Heart Association

Acute postoperative myocardial ischemia (PMI) after cardiac surgery is an infrequent event that can evolve rapidly and become a potentially life-threatening complication. Multiple factors are associated with acute PMI after cardiac surgery and may vary by the type of surgical procedure performed. Although the criteria defining nonprocedural myocardial ischemia are well established, there are no universally accepted criteria for the diagnosis of acute PMI. In addition, current evidence on the management of acute PMI after cardiac surgery is sparse and generally of low methodological quality. Once acute PMI is suspected, prompt diagnosis and treatment are imperative, and options range from conservative strategies to percutaneous coronary intervention and redo coronary artery bypass grafting. In this document, a multidisciplinary group including experts in cardiac surgery, cardiology, anesthesiology, and postoperative care summarizes the existing evidence on diagnosis and treatment of acute PMI and provides clinical guidance.

Deep Learning Synthetic Strain: Quantitative Assessment of Regional Myocardial Wall Motion at MRI

Purpose

To assess the feasibility of a newly developed algorithm, called deep learning synthetic strain (DLSS), to infer myocardial velocity from cine steady-state free precession (SSFP) images and detect wall motion abnormalities in patients with ischemic heart disease.

Materials and Methods

In this retrospective study, DLSS was developed by using a data set of 223 cardiac MRI examinations including cine SSFP images and four-dimensional flow velocity data (November 2017 to May 2021). To establish normal ranges, segmental strain was measured in 40 individuals (mean age, 41 years ± 17 [SD]; 30 men) without cardiac disease. Then, DLSS performance in the detection of wall motion abnormalities was assessed in a separate group of patients with coronary artery disease, and these findings were compared with consensus results of four independent cardiothoracic radiologists (ground truth). Algorithm performance was evaluated by using receiver operating characteristic curve analysis.

Results

Median peak segmental radial strain in individuals with normal cardiac MRI findings was 38% (IQR: 30%-48%). Among patients with ischemic heart disease (846 segments in 53 patients; mean age, 61 years ± 12; 41 men), the Cohen κ among four cardiothoracic readers for detecting wall motion abnormalities was 0.60-0.78. DLSS achieved an area under the receiver operating characteristic curve of 0.90. Using a fixed 30% threshold for abnormal peak radial strain, the algorithm achieved a sensitivity, specificity, and accuracy of 86%, 85%, and 86%, respectively.

Conclusion

The deep learning algorithm had comparable performance with subspecialty radiologists in inferring myocardial velocity from cine SSFP images and identifying myocardial wall motion abnormalities at rest in patients with ischemic heart disease.Keywords: Neural Networks, Cardiac, MR Imaging, Ischemia/Infarction Supplemental material is available for this article. © RSNA, 2023.

Contrast-Enhanced Cardiac Magnetic Resonance Imaging With a Manganese-Based Alternative to Gadolinium for Tissue Characterization of Acute Myocardial Infarction

Background Late gadolinium enhancement cardiac magnetic resonance imaging is an effective and reproducible method for characterizing myocardial infarction. However, gadolinium-based contrast agents are contraindicated in patients with acute and chronic renal insufficiency. In addition, several recent studies have noted tissue deposition of free gadolinium in patients who have undergone serial contrast-enhanced magnetic resonance imaging. There is a clinical need for alternative forms of magnetic resonance imaging contrast agents that are acceptable in the setting of renal insufficiency. Methods and Results Three days after 80 minutes of ischemia/reperfusion of the left anterior descending coronary artery, cardiac magnetic resonance imaging was performed to assess myocardial lesion burden using both contrast agents. Late gadolinium enhancement cardiac magnetic resonance imaging was examined 10 and 15 minutes after contrast injection. Contrast agents were administered in alternating manner with a 2- to 3-hour washout period between contrast agent injections. Lesion evaluation and image processing were performed using Segment Medviso software. Mean infarct size and transmurality, measured using RVP-001, were not different compared with those measured using late gadolinium enhancement images. Bland-Altman analysis demonstrated a nominal bias of 0.13 mL (<1% of average total lesion volume) for RVP-001 in terms of gross infarct size measurement. Conclusions The experimental manganese-based contrast agent RVP-001 appears to be an effective agent for assessment of myocardial infarction location, size, and transmurality, and it may be useful as an alternative to gadolinium-based agents.

Myocardial Regional Shortening from 4D Cardiac CT Angiography for the Detection of Left Ventricular Segmental Wall Motion Abnormality

Purpose

To investigate whether endocardial regional shortening computed from four-dimensional (4D) CT angiography (RSCT) can be used as a decision classifier to detect the presence of left ventricular (LV) wall motion abnormalities (WMAs).

Materials and Methods

One hundred electrocardiographically gated cardiac 4D CT studies (mean age, 59 years ± 14 [SD]; 61 male patients) conducted between April 2018 and December 2020 were retrospectively evaluated. Three experts labeled LV wall motion in each of the 16 American Heart Association (AHA) segments as normal or abnormal; they also measured peak RSCT across one heartbeat in each segment. The data set was split evenly into training and validation groups. During training, interchangeability of RSCT thresholding with experts to detect WMA was assessed using the individual equivalence index (γ), and an optimal threshold of the peak RSCT (RSCT*) that achieved maximum agreement was identified. RSCT* was then validated using the validation group, and the effect of AHA segment-specific thresholds was evaluated. Agreement was assessed using κ statistics.

Results

The optimal threshold, RSCT* of -0.19, when applied to all AHA segments, led to high agreement (agreement rate = 92.17%, κ = 0.82) and interchangeability with experts (γ = -2.58%). The same RSCT* also achieved high agreement in the validation group (agreement rate = 90.29%, κ = 0.76, γ = -0.38%). The use of AHA segment-specific thresholds (range: 0.16 to -0.23 across AHA segments) slightly improved agreement (1.79% increase).

Conclusion

RSCT thresholding was interchangeable with expert visual analysis in detecting segmental WMA from 4D CT and may be used as an objective decision classifier.Keywords: CT, Left Ventricle, Regional Endocardial Shortening, Wall Motion Abnormality Supplemental material is available for this article. © RSNA, 2023.

Evidence of the Cardioprotective Effects of Aloysia polystachya in Isoproterenol-Induced Myocardial Infarction in Rats

Aloysia polystachya is a plant species that is widely used in Brazilian folk medicine for the treatment of different disorders that affect the cardiovascular system. The aim of the study was to investigate the cardioprotective effects of an ethanol-soluble fraction of A. polystachya (ESAP) on isoproterenol-induced myocardial infarction in rats. Different groups of rats (n = 8) were orally treated with ESAP (30, 100, and 300 mg/kg), carvedilol (10 mg/kg), or vehicle (filtered water; 1 mL/100 g) for 7 days. Naive rats received no treatment. On the morning of day 6, acute myocardial infarction was induced by the acute oral administration of isoproterenol (100 mg/kg). On the morning of day 8, all rats underwent electrocardiography and transthoracic echocardiography. Blood samples were then collected, and serum levels of creatine kinase-MB fraction (CK-MB) and cardiac troponin T (cTNT) were quantified. ESAP significantly reduced electrocardiographic changes, improved the ventricular ejection fraction, and reduced serum levels of CK-MB and cTNT in infarcted rats. The cardioprotective effects of ESAP could be exploited as an effective tool against isoproterenol-induced myocardial infarction in rats.

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.

Prognostic value of divergent pattern detection by 99mTc-sestamibi gated SPECT in patients with anterior acute myocardial infarction

PURPOSE

In gated myocardial perfusion SPECT, apical remodeling may be identified by the presence of a divergent pattern (DP) of the left ventricle (LV).

METHODS AND RESULTS

We examined 150 anterior ST-elevation myocardial infarction (STEMI) patients, all successfully treated with primary percutaneous coronary interventions (PCI). Perfusion gated-SPECT to measure infarct size, LV end-diastolic (ED) and end-systolic (ES) volumes and ejection fraction (EF) was acquired before hospital discharge and repeated at 6-month follow-up. DP was observed in 26 patients, who had larger infarct size (28 ± 19% vs. 15.7 ± 17%, P < 0.02), and lower EF (33 ± 7% vs. 41 ± 10%, P < 0.001) than patients without DP. At follow-up, DP patients had significantly larger EDV (156 ± 54 vs. 107 ± 44 mL, P < 0.0001), ESV (104 ± 47 vs. 59 ± 36 mL, P < 0.0001) and lower EF (35 ± 12% vs. 48 ± 13%, P < 0.0001). 54% of DP patients developed remodeling at follow-up vs. 12% of those without DP (P < 0.001). During follow up, 7 events in the DP group (27%) and 11 events in patients without DP (9%; P < 0.02) occurred. Kaplan-Meier survival curves showed a worse prognosis for DP patients.

CONCLUSION

In patients with anterior AMI, early DP detection is related to subsequent LV dysfunction, larger infarct size, and worse severity. It is helpful for predicting LV remodeling at short-term follow-up and has prognostic implications.

Left Ventricular Thrombus Following Acute Myocardial Infarction: JACC State-of-the-Art Review

The incidence of left ventricular (LV) thrombus following acute myocardial infarction has markedly declined in recent decades caused by advancements in reperfusion and antithrombotic therapies. Despite this, embolic events remain the most feared complication of LV thrombus necessitating systemic anticoagulation. Mechanistically, LV thrombus development depends on Virchow's triad (ie, endothelial injury from myocardial infarction, blood stasis from LV dysfunction, and hypercoagulability triggered by inflammation, with each of these elements representing potential therapeutic targets). Diagnostic modalities include transthoracic echocardiography with or without ultrasound-enhancing agents and cardiac magnetic resonance. Most LV thrombi develop within the first 2 weeks post-acute myocardial infarction, and the role of surveillance imaging appears limited. Vitamin K antagonists remain the mainstay of therapy because the efficacy of direct oral anticoagulants is less well established. Only meager data support the routine use of prophylactic anticoagulation, even in high-risk patients.

Cardiac biomarkers and detection methods for myocardial infarction

Background

A significant heart attack known as a myocardial infarction (MI) occurs when the blood supply to the heart is suddenly interrupted, harming the heart muscles due to a lack of oxygen. The incidence of myocardial infarction is increasing worldwide. A relationship between COVID-19 and myocardial infarction due to the recent COVID-19 pandemic has also been revealed.

Objective

We propose a biomarker and a method that can be used for the diagnosis of myocardial infarction, and an aptamer-based approach.

Results

For the diagnosis of myocardial infarction, an algorithm-based diagnosis method was developed using electrocardiogram data. A diagnosis method through biomarker detection was then developed.

Conclusion

Myocardial infarction is a disease that is difficult to diagnose based on the aspect of a single factor. For this reason, it is necessary to use a combination of various methods to diagnose myocardial infarction quickly and accurately. In addition, new materials such as aptamers must be grafted and integrated into new ways.

Purpose of Review

The incidence of myocardial infarction is increasing worldwide, and some studies are being conducted on the association between COVID-19 and myocardial infarction. The key to properly treating myocardial infarction is early detection, thus we aim to do this by offering both tools and techniques as well as the most recent diagnostic techniques.

Recent Findings

Myocardial infarction is diagnosed using an electrocardiogram and echocardiogram, which utilize cardiac signals. It is required to identify biomarkers of myocardial infarction and use biomarker-based ELISA, SPR, gold nanoparticle, and aptamer technologies in order to correctly diagnose myocardial infarction.

Incremental Value of Global Longitudinal Strain in the Long-Term Prediction of Heart Failure among Patients with Coronary Artery Disease

BACKGROUND

Heart failure (HF) remains a common complication for patients with coronary artery disease (CAD), especially after acute myocardial infarction. Although left ventricular ejection fraction (LVEF) is conventionally used to assess cardiac function for risk stratification, it has been shown in other settings to underestimate the risk of HF compared with global longitudinal strain (GLS). Moreover, most evidence pertains to early-onset HF. We sought the clinical and myocardial predictors for late-onset HF in patients with CAD.

METHODS

We analyzed echocardiograms (including GLS) in 334 patients with CAD (ages 65 ± 11 years, 77% male) who were enrolled in the Nurse-Led Intervention for Less Chronic Heart Failure trial, a prospective, randomized controlled trial that compared standard care with nurse-led intervention to prevent HF in individuals at risk of incident HF. Long-term (9 years) follow-up was obtained via data linkage. Analysis was performed using a competing-risk model.

RESULTS

Baseline LVEF values were normal or mildly impaired (LVEF ≥ 40%) in all subjects. After a median of 9 years of follow-up, 50 (15%) of the 334 patients had new HF admissions, and 68 (20%) died. In a competing-risk model, HF was associated with GLS (hazard ratio = 1.15 [1.05-1.25], P = .001), independent of estimated glomerular filtration rate (hazard ratio = 0.98 [0.97-0.99], P = .045), Charlson comorbidity score (hazard ratio = 1.64 [1.25-2.15], P < .001), or E/e' (hazard ratio = 1.08 [1.02-1.14], P = .01). Global longitudinal strain-but not conventional echocardiographic measures-added incremental value to a clinical model based on age, gender, and Charlson score (area under the curve, 0.78-0.83, P = .01). Global longitudinal strain was still associated with HF development in patients taking baseline angiotensin convertase enzyme inhibitors (hazard ratio = 1.21 [1.11-1.31], P < .01) and baseline beta-blockers (1.17 [1.09, 1.26]; P < .01). Mortality was associated with older men, risk factors (hypertension or diabetes), and comorbidities (AF and chronic kidney disease).

CONCLUSIONS

Global longitudinal strain is independently associated with risk of incident HF in patients admitted with CAD and provides incremental prognostic value to standard markers. Identifying an at-risk subgroup using GLS may be the focus of future randomized controlled trails to enable targeted therapeutic intervention.

Prognostically relevant periprocedural myocardial injury and infarction associated with percutaneous coronary interventions: a Consensus Document of the ESC Working Group on Cellular Biology of the Heart and European Association of Percutaneous Cardiovascular Interventions (EAPCI)

A substantial number of chronic coronary syndrome (CCS) patients undergoing percutaneous coronary intervention (PCI) experience periprocedural myocardial injury or infarction. Accurate diagnosis of these PCI-related complications is required to guide further management given that their occurrence may be associated with increased risk of major adverse cardiac events (MACE). Due to lack of scientific data, the cut-off thresholds of post-PCI cardiac troponin (cTn) elevation used for defining periprocedural myocardial injury and infarction, have been selected based on expert consensus opinions, and their prognostic relevance remains unclear. In this Consensus Document from the ESC Working Group on Cellular Biology of the Heart and European Association of Percutaneous Cardiovascular Interventions (EAPCI), we recommend, whenever possible, the measurement of baseline (pre-PCI) cTn and post-PCI cTn values in all CCS patients undergoing PCI. We confirm the prognostic relevance of the post-PCI cTn elevation >5× 99th percentile URL threshold used to define type 4a myocardial infarction (MI). In the absence of periprocedural angiographic flow-limiting complications or electrocardiogram (ECG) and imaging evidence of new myocardial ischaemia, we propose the same post-PCI cTn cut-off threshold (>5× 99th percentile URL) be used to define prognostically relevant ‘major’ periprocedural myocardial injury. As both type 4a MI and major periprocedural myocardial injury are strong independent predictors of all-cause mortality at 1 year post-PCI, they may be used as quality metrics and surrogate endpoints for clinical trials. Further research is needed to evaluate treatment strategies for reducing the risk of major periprocedural myocardial injury, type 4a MI, and MACE in CCS patients undergoing PCI.

Prognostic Value of Vasodilator Stress Perfusion Cardiovascular Magnetic Resonance in Patients With Prior Myocardial Infarction

OBJECTIVES

This study sought to assess the incremental prognostic value of vasodilator stress cardiovascular magnetic resonance (CMR) in patients with prior myocardial infarction (MI).

BACKGROUND

Recurrent MI is a major cause of mortality and morbidity among MI survivors.

METHODS

Between 2008 and 2019, consecutive patients with prior MI referred for stress CMR were followed up for the occurrence of major adverse cardiovascular events (MACE), defined by cardiovascular mortality or recurrent nonfatal MI. Uni- and multivariable Cox regressions were performed to determine the prognostic value of inducible ischemia and the extent of myocardial scar.

RESULTS

Among 1,594 patients with prior MI and myocardial scar on CMR, 1,401 (92%) (68.2 ± 11.0 years; 61.4% men) completed the follow-up (median: 6.2 years), and 205 had MACE (14.6%). Patients without inducible ischemia experienced a lower annual rate of MACE (3.1%) than those with 1-2 (4.9%), 3-5 (21.5%), or ≥6 segments of ischemia (45.7%) (all p < 0.01). Using Kaplan-Meier analysis, the presence of inducible ischemia and the extent of scar were associated with MACE (hazard ratio [HR]:3.52; 95% confidence interval [CI]: 2.67 to 4.65 and HR: 1.66; 95% CI: 1.53 to 2.18, respectively; both p < 0.001). In multivariable stepwise Cox regression, the presence of ischemia and the extent of scar were independent predictors of MACE (HR: 2.84; 95% CI: 2.14 to 3.78 and HR: 1.57; 95% CI: 1.44 to 1.72, respectively; both p < 0.001). These findings were significant in both symptomatic and asymptomatic patients. The addition of CMR parameters to the model including traditional risk factors resulted in a better discrimination for MACE (C-statistic: 0.76 vs. 0.62).

CONCLUSIONS

In patients with prior MI, vasodilator stress CMR has independent and incremental prognostic value over traditional risk factors.

Ischemic Heart Disease: Noninvasive Imaging Techniques and Findings

Ischemic heart disease is a leading cause of death worldwide and comprises a large proportion of annual health care expenditure. Management of ischemic heart disease is now best guided by the physiologic significance of coronary artery stenosis. Invasive coronary angiography is the standard for diagnosing coronary artery stenosis. However, it is expensive and has risks including vascular access site complications and contrast material–induced nephropathy. Invasive coronary angiography requires fractional flow reserve (FFR) measurement to determine the physiologic significance of a coronary artery stenosis. Multiple noninvasive cardiac imaging modalities can also anatomically delineate or functionally assess for significant coronary artery stenosis, as well as detect the presence of myocardial infarction (MI). While coronary CT angiography can help assess the degree of anatomic stenosis, its inability to assess the physiologic significance of lesions limits its specificity. Physiologic significance of coronary artery stenosis can be determined by cardiac MR vasodilator or dobutamine stress imaging, CT stress perfusion imaging, FFR CT, PET myocardial perfusion imaging (MPI), SPECT MPI, and stress echocardiography. Clinically unrecognized MI, another clear indicator of physiologically significant coronary artery disease, is relatively common and is best evaluated with cardiac MRI. The authors illustrate the spectrum of imaging findings of ischemic heart disease (coronary artery disease, myocardial ischemia, and MI); highlight the advantages and disadvantages of the various noninvasive imaging methods used to assess ischemic heart disease, as illustrated by recent clinical trials; and summarize current indications and contraindications for noninvasive imaging techniques for detection of ischemic heart disease.

Online supplemental material is available for this article.

Published under a CC BY 4.0 license.

Modeling Left Ventricle Perfusion in Healthy and Stenotic Conditions

A theoretical fluid mechanical model is proposed for the investigation of myocardial perfusion in healthy and stenotic conditions. The model hinges on Terzaghi’s consolidation theory and reformulates the related unsteady flow equation for the simulation of the swelling–drainage alternation characterizing the diastolic–systolic phases. When compared with the outcome of experimental in vivo observations in terms of left ventricle transmural perfusion ratio (T.P.R.), the analytical solution provided by the present study for the time-dependent blood pressure and flow rate across the ventricle wall proves to consistently reproduce the basic mechanisms of both healthy and ischemic perfusion. Therefore, it could constitute a useful interpretative support to improve the comprehension of the basic hemodynamic mechanisms leading to the most common cardiac diseases. Additionally, it could represent the mathematical basis for the application of inverse methods aimed at estimating the characteristic parameters of ischemic perfusion (i.e., location and severity of coronary stenoses) via downstream ventricular measurements, possibly inspiring their assessment via non-invasive myocardial imaging techniques.

Machine Learning Quantitation of Cardiovascular and Cerebrovascular Disease: A Systematic Review of Clinical Applications

Research into machine learning (ML) for clinical vascular analysis, such as those useful for stroke and coronary artery disease, varies greatly between imaging modalities and vascular regions. Limited accessibility to large diverse patient imaging datasets, as well as a lack of transparency in specific methods, are obstacles to further development. This paper reviews the current status of quantitative vascular ML, identifying advantages and disadvantages common to all imaging modalities. Literature from the past 8 years was systematically collected from MEDLINE^® and Scopus database searches in January 2021. Papers satisfying all search criteria, including a minimum of 50 patients, were further analysed and extracted of relevant data, for a total of 47 publications. Current ML image segmentation, disease risk prediction, and pathology quantitation methods have shown sensitivities and specificities over 70%, compared to expert manual analysis or invasive quantitation. Despite this, inconsistencies in methodology and the reporting of results have prevented inter-model comparison, impeding the identification of approaches with the greatest potential. The clinical potential of this technology has been well demonstrated in Computed Tomography of coronary artery disease, but remains practically limited in other modalities and body regions, particularly due to a lack of routine invasive reference measurements and patient datasets.

Plasma Concentrations of Extracellular Vesicles Are Decreased in Patients with Post-Infarct Cardiac Remodelling

Simple Summary

A heart attack may lead to the remodelling of the cardiac muscle, which negatively affects patient’s prognosis. At present, the mechanisms of cardiac remodelling remain unclear. In patients with heart attack, many body cells become activated and release small particles, called extracellular vesicles, which can either aggravate cardiac injury, or contribute to healing of heart muscle. In our study, we hypothesized that the concentrations of these small particles in plasma allow to determine which patients will experience remodelling of the cardiac muscle after the heart attach. We found that concentrations of extracellular vesicles from endothelial cells, erythrocytes and platelets, measured directly the heart attack, were lower in patients who developed cardiac remodelling 6 months later, compared to patients who had no remodelling. Vesicles from endothelial cells and erythrocytes allowed to determine remodelling independently of other clinical features. Hence, decreased concentrations of these vesicles may on one hand be a sign of inappropriate cardiac repair mechanisms, and on the other hand may allow to identify patients, who will develop cardiac remodelling after the heart attack.

Abstract

Background, the mechanisms underlying left ventricular remodelling (LVR) after acute myocardial infarction (AMI) remain obscure. In the course of AMI, blood cells and endothelial cells release extracellular vesicles (EVs). We hypothesized that changes in EV concentrations after AMI may underlie LVR. Methods, plasma concentrations of EVs from endothelial cells (CD146+), erythrocytes (CD235a+), leukocytes (CD45+), platelets (CD61+), activated platelets (P-selectin+), and EVs exposing phosphatidylserine after AMI were determined by flow cytometry in 55 patients with the first AMI. LVR was defined as an increase in left ventricular end-diastolic volume by 20% at 6 months after AMI, compared to baseline. Results, baseline concentrations of EVs from endothelial cells, erythrocytes and platelets were lower in patients who developed LVR (p ≤ 0.02 for all). Concentrations of EVs from endothelial cells and erythrocytes were independent LVR predictors (OR 8.2, CI 1.3–54.2 and OR 17.8, CI 2.3–138.6, respectively) in multivariate analysis. Combining the three EV subtypes allowed to predict LVR with 83% sensitivity and 87% specificity. Conclusions, decreased plasma concentrations of EVs from endothelial cells, erythrocytes and platelets predict LVR after AMI. Since EV release EVs contributes to cellular homeostasis by waste removal, decreased concentrations of EVs may indicate dysfunctional cardiac homeostasis after AMI, thus promoting LVR.

Heart failure after myocardial infarction: incidence and predictors

Aims

The aim of the present paper was to provide an up‐to‐date view on epidemiology and risk factors of heart failure (HF) development after myocardial infarction.

Methods and results

Based on literature review, several clinical risk factors and biochemical, genetic, and imaging biomarkers were identified to predict the risk of HF development after myocardial infarction.

Conclusions

Heart failure is still a frequent complication of myocardial infarction. Timely identification of subjects at risk for HF development using a multimodality approach, and early initiation of guideline‐directed HF therapy in these patients, can decrease the HF burden.

In-depth proteomics approach reveals novel biomarkers of cardiac remodelling after myocardial infarction: An exploratory analysis

Cardiac remodelling following myocardial infarction (MI) is a maladaptive change associated with progressive heart failure and compromises long‐term clinical outcome. A substantial proportion of patients afflicted by MI still develop adverse outcomes associated with cardiac remodelling. Therefore, it is crucial to identify biomarkers for the early prediction of cardiac remodelling. An in‐depth proteomics approach, including both semi‐quantitative and quantitative antibody arrays, was used to identify circulating biomarkers that may be associated with detrimental cardiac remodelling. Furthermore, statistical correlation analysis was performed between the candidate biomarkers and clinical cardiac remodelling data to demonstrate their clinical utility. A systematic proteomics approach revealed that sclerostin (SOST), growth differentiation factor‐15 (GDF‐15), urokinase‐type plasminogen activator (uPA), and midkine (MK) were increased, while monocyte chemotactic protein‐3 (MCP‐3) was uniquely decreased in MI patients who developed cardiac remodelling, compared to MI patients who did not develop cardiac remodelling and healthy humen. Moreover, correlation analyses between serum proteomes and cardiac remodelling echocardiographic parameters demonstrated a moderate positive association between left ventricular end‐diastolic volume index (LVEDVi) and the three serum proteins, uPA, MK and GDF‐15 (P < .05, respectively), and a moderate negative correlation between LV ejection fraction (LVEF) and these serum proteins (P < .05, respectively). Importantly, uPA and MK were firstly identified to be associated with the development of cardiac remodelling. The present study contributes to a better understanding of the various cytokines expressed during adverse cardiac remodelling. The identified biomarkers may facilitate early identification of patients at high risk of ischaemic heart failure pending further confirmation through larger clinical trials.

Instantaneous In Vivo Imaging of Acute Myocardial Infarct by NIR-II Luminescent Nanodots

Fast and precise localization of ischemic tissues in the myocardium after an acute infarct is required by clinicians as the first step toward accurate and efficient treatment. Nowadays, diagnosis of a heart attack at early times is based on biochemical blood analysis (detection of cardiac enzymes) or by ultrasound-assisted imaging. Alternative approaches are investigated to overcome the limitations of these classical techniques (time-consuming procedures or low spatial resolution). As occurs in many other fields of biomedicine, cardiological preclinical imaging can also benefit from the fast development of nanotechnology. Indeed, bio-functionalized near-infrared-emitting nanoparticles are herein used for in vivo imaging of the heart after an acute myocardial infarct. Taking advantage of the superior acquisition speed of near-infrared fluorescence imaging, and of the efficient selective targeting of the near-infrared-emitting nanoparticles, in vivo images of the infarcted heart are obtained only a few minutes after the acute infarction event. This work opens an avenue toward cost-effective, fast, and accurate in vivo imaging of the ischemic myocardium after an acute infarct.

Inter-study repeatability of circumferential strain and diastolic strain rate by CMR tagging, feature tracking and tissue tracking in ST-segment elevation myocardial infarction

Strain assessment allows accurate evaluation of myocardial function and mechanics in ST-segment elevation myocardial infarction (STEMI). Strain using cardiovascular magnetic resonance (CMR) has traditionally been assessed with tagging but limitations of this technique have led to more widespread use of alternative methods, which may be more robust. We compared the inter-study repeatability of circumferential global peak-systolic strain (Ecc) and peak-early diastolic strain rate (PEDSR) derived by tagging with values obtained using novel cine-based software: Feature Tracking (FT) (TomTec, Germany) and Tissue Tracking (TT) (Circle cvi42, Canada) in patients following STEMI. Twenty male patients (mean age 56 ± 10 years, mean infarct size 13.7 ± 7.1% of left ventricular mass) were randomised to undergo CMR 1-5 days post-STEMI at 1.5 T or 3.0 T, repeated after ten minutes at the same field strength. Ecc and PEDSR were assessed using tagging, FT and TT. Inter-study repeatability was evaluated using Bland-Altman analyses, coefficients of variation (CoV) and intra-class correlation coefficient (ICC). Ecc (%) was significantly lower with tagging than with FT or TT at 1.5 T (- 9.5 ± 3.3 vs. - 17.5 ± 3.8 vs. -15.5 ± 5.2, respectively, p < 0.001) and 3.0 T (- 13.1 ± 1.8 vs. - 19.4 ± 2.9 vs. - 17.3 ± 2.1, respectively, p = 0.001). This was similar for PEDSR (.s-1): 1.5 T (0.6 ± 0.2 vs. 1.5 ± 0.4 vs. 1.0 ± 0.4, for tagging, FT and TT respectively, p < 0.001) and 3.0 T (0.6 ± 0.2 vs. 1.5 ± 0.3 vs. 0.9 ± 0.3, respectively, p < 0.001). Inter-study repeatability for Ecc at 1.5 T was good for tagging and excellent for FT and TT: CoV 16.7%, 6.38%, and 8.65%, respectively. Repeatability for Ecc at 3.0 T was good for all three techniques: CoV 14.4%, 11.2%, and 13.0%, respectively. However, repeatability of PEDSR was generally lower than that for Ecc at 1.5 T (CoV 15.1%, 13.1%, and 34.0% for tagging, FT and TT, respectively) and 3.0 T (CoV 23.0%, 18.6%, and 26.2%, respectively). Following STEMI, Ecc and PEDSR are higher when measured with FT and TT than with tagging. Inter-study repeatability of Ecc is good for tagging, excellent for FT and TT at 1.5 T, and good for all three methods at 3.0 T. The repeatability of PEDSR is good to moderate at 1.5 T and moderate at 3.0 T. Cine-based methods to assess Ecc following STEMI may be preferable to tagging.

Long-term outcome of patients with ST-segment elevation myocardial infarction treated with low-dose intracoronary thrombolysis during primary percutaneous coronary intervention: the 5-year results of the DISSOLUTION Trial

We tested the hypothesis that adjunctive thrombolysis at time of primary percutaneous coronary intervention (PCI) may affect favourably the long-term outcome of patients with ST elevation myocardial infarction (STEMI). To this end, we undertook a substudy of the DISSOLUTION (Delivery of thrombolytIcs before thrombectomy in patientS with ST-segment elevatiOn myocardiaL infarction Undergoing primary percuTaneous coronary interventION) trial. A total of 95 patients were randomized to local delivery of urokinase (n = 48) or placebo (n = 47). After PCI, a greater proportion of patients receiving urokinase had an improvement in myocardial perfusion, as indicated by a significantly higher final Thrombolysis in myocardial infarction (TIMI) grade 3, myocardial blush grade, and 60-min ST-segment resolution > 70%, as well as lower corrected TIMI frame count. At 1-year echocardiography, urokinase-treated patients exhibited significantly lower LV dimension, as well as higher LV ejection fraction and wall motion score index as compared with placebo-treated patients. At 5 years, major acute cardiovascular events (MACEs) were significantly less common in the urokinase group (P = 0.023), mainly due to a lower occurrence of hospitalisation for heart failure (P = 0.038). Multivariate analysis showed that factors independently associated with 5-year occurrence of MACEs were LV remodelling at 1-year echocardiography (P = 0.0001), 1-year LV ejection fraction (P = 0.0001), TIMI grade flow 0-2 (P = 0.0019), and age at time of PCI (P = 0.0173). In conclusion, low-dose intracoronary urokinase during primary PCI is associated with a more favourable 5-year outcome of patients with STEMI.

A Validated Echocardiographic Risk Model for Predicting Outcome Following ST-segment Elevation Myocardial Infarction

Many echocardiographic measures have been proposed as potential predictors of outcome following ST-elevation myocardial infarction (STEMI). We hypothesized that combining multiple echocardiographic measures in a risk model provides more prognostic information than individual echocardiographic measures. We prospectively included 373 STEMI patients which constituted our derivation cohort. We also identified 298 STEMI patients from a clinical registry that constituted our validation cohort. Echocardiogram was performed at a median of 2 days after infarction. The echocardiogram consisted of conventional and advanced measures. The end point was a composite of heart failure and/or cardiovascular death. During a median follow-up of 5.4 years, we observed 80 events in our derivation cohort. A stepwise backward Cox regression including all echocardiographic parameters identified global longitudinal strain, wall motion score index (WMSI), E/e', and E/global strain rate e (E/GLSRe) as significant predictors of outcome. A Classification and Regression Tree analysis outlined a risk model with WMSI, GLSRe, and E/e' as key echocardiographic parameters. Patients with WMSI ≥ 2.22 were at high risk, patients with WMSI < 2.22, GLSRe < 0.82s^-1 and E/e'≥7.6 at intermediate risk, and patients with WMSI < 2.22 and GLSRe ≥ 0.82s^-1 or GLSRe < 0.82s^-1 and E/e' < 7.6 at low risk of heart failure and/or cardiovascular death. When compared with the low-risk group, an incremental risk was observed (intermediate group: HR = 2.52 [1.24;5.11], p = 0.011; high-risk group: HR = 4.37 [1.40;13.66], p = 0.011). The risk model was validated in the validation cohort (C-statistic: 0.71). In conclusion, we devised an echocardiographic risk model for STEMI patients suggesting advanced and conventional measures of systolic function and filling pressures to be important for the prognosis.

The Effects of Granulocyte Colony-Stimulating Factor in Patients with a Large Anterior Wall Acute Myocardial Infarction to Prevent Left Ventricular Remodeling: A 10-Year Follow-Up of the RIGENERA Study

Background: the RIGENERA trial assessed the efficacy of granulocyte-colony stimulating factor (G-CSF) in the improvement of clinical outcomes in patients with severe acute myocardial infarction. However, there is no evidence available regarding the long-term safety and efficacy of this treatment. Methods: in order to evaluate the long-term effects on the incidence of major adverse events, on the symptom burden, on the quality of life and the mean life expectancy and on the left ventricular (LV) function, we performed a clinical and echocardiographic evaluation together with an assessment using the Minnesota Living with Heart Failure Questionnaire (MLHFQ) and the Seattle Heart Failure Model (SHFM) at 10-years follow-up, in the patients cohorts enrolled in the RIGENERA trial. Results: thirty-two patients were eligible for the prospective clinical and echocardiography analyses. A significant reduction in adverse LV remodeling was observed in G-CSF group compared to controls, 9% vs. 48% (p = 0.030). The New York Heart Association (NYHA) functional class was lower in G-CSF group vs. controls (p = 0.040), with lower burden of symptoms and higher quality of life (p = 0.049). The mean life expectancy was significantly higher in G-CSF group compared to controls (15 ± 4 years vs. 12 ± 4 years, p = 0.046. No difference was found in the incidence of major adverse events. Conclusions: this longest available follow-up on G-CSF treatment in patients with severe acute myocardial infarction (AMI) showed that this treatment was safe and associated with a reduction of adverse LV remodeling and higher quality of life, in comparison with standard-of-care treatment.

Growth Differentiation Factor-8 (GDF8)/Myostatin is a Predictor of Troponin I Peak and a Marker of Clinical Severity after Acute Myocardial Infarction

OBJECTIVE

Growth differentiation factor-8 (GDF8), also known as myostatin, is a member of the transforming growth factor-β superfamily that inhibits skeletal muscle growth. We aimed to investigate the association between GDF8 and peak troponin I levels after acute myocardial infarction (AMI).

METHODS

All consecutive patients admitted from June 2016 to February 2018 for type 1 AMI in the Coronary Care Unit of University Hospital of Dijon Bourgogne (France) were included in our prospective study. Blood samples were harvested on admission, and serum levels of GDF8 were measured using a commercially available enzyme-linked immunosorbent assay kit.

RESULTS

Among the 296 patients with type 1 AMI, median age was 68 years and 27% were women. GDF8 levels (median (IQR) = 2375 ng/L) were negatively correlated with age, sex and diabetes (p < 0.001 for all). GDF8 levels were higher in patients with in-hospital ventricular tachycardia or fibrillation (VT/VF) than those without in-hospital VT/VF. GDF8 was positively correlated with troponin I peak (r = 0.247; p < 0.001). In multivariate linear regression analysis, log GDF8 (OR: 21.59; 95% CI 34.08-119.05; p < 0.001) was an independent predictor of troponin I peak.

CONCLUSIONS

These results suggest that GDF8 levels could reflect the extent of myocardial damage during AMI, similar to peak troponin I, which is currently used to estimate infarct size. Further studies are needed to elucidate the underlying mechanisms linking the GDF8 cytokine with troponin I levels.

Association between Galectin-3 levels within central and peripheral venous blood, and adverse left ventricular remodelling after first acute myocardial infarction

Our study investigates association between Galectin-3 levels and adverse left ventricular remodelling (LVR) at six months. Fifty-seven patients following first acute myocardial infarction (AMI) were enrolled in this study and blood samples collected on day 1 from the femoral vein and artery, the right atrium near the coronary sinus and the aortic root, and on day 30, from the cubital vein. Patients with LVESV ≥20% at six months, were included in the LVR group. On day 1, Galectin-3 plasma levels in the femoral vein (10.34 ng/ml ± 3.81 vs 8.22 ng/ml ± 2.34, p = 0.01), and near coronary sinus (10.7 ng/ml ± 3.97 vs 8.41 ng/ml ± 2.56, p = 0.007) were higher in the LVR group. Positive correlations between Galectin-3 levels from aortic root and coronary sinus, aortic root and femoral vein, and coronary sinus and femoral vein, were observed in both groups. On day 30, Galectin-3 concentration in the cubital vein was an independent risk factor of LVR six months post-AMI, demonstrating 1.5-fold increased risk. Day-30 Galectin-3 also showed positive correlations with echocardiography parameters indicative of diastolic and systolic dysfunction. Determining Galectin-3 plasma concentration on day 30 following AMI could have beneficial prognostic value in predicting LVR.

Sphingolipid Synthesis Inhibition by Myriocin Administration Enhances Lipid Consumption and Ameliorates Lipid Response to Myocardial Ischemia Reperfusion Injury

Myocardial infarct requires prompt thrombolytic therapy or primary percutaneous coronary intervention to limit the extent of necrosis, but reperfusion creates additional damage. Along with reperfusion, a maladaptive remodeling phase might occur and it is often associated with inflammation, oxidative stress, as well as a reduced ability to recover metabolism homeostasis. Infarcted individuals can exhibit reduced lipid turnover and their accumulation in cardiomyocytes, which is linked to a deregulation of peroxisome proliferator activated receptors (PPARs), controlling fatty acids metabolism, energy production, and the anti-inflammatory response. We previously demonstrated that Myriocin can be effectively used as post-conditioning therapeutic to limit ischemia/reperfusion-induced inflammation, oxidative stress, and infarct size, in a murine model. In this follow-up study, we demonstrate that Myriocin has a critical regulatory role in cardiac remodeling and energy production, by up-regulating the transcriptional factor EB, PPARs nuclear receptors and genes involved in fatty acids metabolism, such as VLDL receptor, Fatp1, CD36, Fabp3, Cpts, and mitochondrial FA dehydrogenases. The overall effects are represented by an increased β–oxidation, together with an improved electron transport chain and energy production. The potent immunomodulatory and metabolism regulatory effects of Myriocin elicit the molecule as a promising pharmacological tool for post-conditioning therapy of myocardial ischemia/reperfusion injury.

Accurate identification of myocardial viability after myocardial infarction with novel manganese chelate-based MR imaging

We developed a novel manganese (Mn²⁺ ) chelate for magnetic resonance imaging (MRI) assessment of myocardial viability in acute and chronic myocardial infarct (MI) models, and compared it with Gadolinium-based delay enhancement MRI (Gd³⁺ -DEMRI) and histology. MI was induced in 14 rabbits by permanent occlusion of the left circumflex coronary artery. Gd³⁺ -DEMRI and Mn²⁺ chelate-based delayed enhancement MRI (Mn²⁺ chelate-DEMRI) were performed at 7 days (acute MI, n = 8) or 8 weeks (chronic MI, n = 6) after surgery with sequential injection of 0.15 mmol/kg Gd³⁺ and Mn²⁺ chelate. The biodistribution of Mn²⁺ in tissues and blood was measured at 1.5 and 24 h. Blood pressure, heart rate (HR), left ventricular (LV) function, and infarct fraction (IF) were analyzed, and IF was compared with the histology. The Mn²⁺ chelate group maintained a stable hemodynamic status during experiment. For acute and chronic MI, all rabbits survived without significant differences in HR or LV function before and after injection of Mn²⁺ chelate or Gd³⁺ (p > 0.05). Mn²⁺ chelate mainly accumulated in the kidney, liver, spleen, and heart at 1.5 h, with low tissue uptake and urine residue at 24 h after injection. In the acute MI group, there was no significant difference in IF between Mn²⁺ chelate-DEMRI and histology (22.92 ± 2.21% vs. 21.79 ± 2.25%, respectively, p = 0.87), while Gd³⁺ -DEMRI overestimated IF, as compared with histology (24.54 ± 1.73%, p = 0.04). In the chronic MI group, there was no significant difference in IF between the Mn²⁺ chelate-DEMRI, Gd³⁺ -DEMRI, and histology (29.50 ± 11.39%, 29.95 ± 9.40%, and 29.00 ± 10.44%, respectively, p > 0.05), and all three were well correlated (r = 0.92-0.96, p < 0.01). We conclude that the use of Mn²⁺ chelate-DEMRI is reliable for MI visualization and identifies acute MI more accurately than Gd³⁺ -DEMRI.

[Diagnosis of myocardial infarction in critically ill, ventilated patients]

Elevated cardiac troponin values are frequently observed in critically ill patients. These are often not due to myocardial infarction (MI) but caused by various other etiologies of myocardial injury. Understanding the etiology of any troponin elevation is of enormous importance for management and therapy. According to the fourth version of the Universal Definition of MI, myocardial injury is present if at least one troponin value is above the 99th percentile upper reference limit and considered acute, when a rise and/or fall occurs. Patients with acute MI are a subgroup of patients with acute myocardial injury, who present in an ischemic clinical context. Variables defining the clinical criteria of MI include symptoms of ischemia, presumably new electrocardiographic (ECG) changes or imaging evidence of new loss of viable myocardium or regional wall motion abnormalities, or detection of an intracoronary thrombus. In critically ill or mechanically ventilated patients, the diagnosis of MI is challenging due to limitations in history taking, co-existence of comorbidities, overlapping symptoms and equivocal or unspecific ECG changes. This article presents the diagnostic criteria of the Universal MI definition, discusses subtypes of MI and focuses on various differential diagnoses. Furthermore, implications of diagnosis of MI in critically ill patients, especially regarding the use of ECG and troponin assays, are discussed.

Determinants of Myocardial Strain in Experimental Chronic Myocardial Infarction

We evaluated the relationships between regional myocardial strain measured by speckle tracking echocardiography and viability, fibrosis, hypertrophy and oxygen consumption in the infarcted or remote myocardium in a pig model of chronic myocardial infarction (MI). Thirteen farm pigs with surgical occlusion of the left anterior descending coronary artery and five sham-operated pigs were studied 3 mo post-MI. Computed tomography revealed significant left ventricle remodeling. Reduced radial or circumferential strain identified areas of transmural infarction (area under the curve: 0.82 and 0.79, respectively). In the remote non-infarcted area, radial strain correlated inversely with the amount of fibrosis (r = -0.66, p = 0.04) and myocyte hypertrophy (r = -0.68, p = 0.03). Radial strain rate inversely correlated with myocardial resting oxygen consumption assessed with ¹¹C-labeled acetate positron emission tomography (r = -0.71, p = 0.006). In conclusion, myocardial strain and strain rate reflect fibrosis, hypertrophy and oxygen consumption of the remote areas after MI.

Developing a panel of biomarkers and miRNA in patients with myocardial infarction for early intervention strategies of heart failure in West Virginian population

Background

Myocardial infarction is the most common cause of heart failure. MI has been intricately linked to ventricular remodeling, subsequently leading to the reduction in the cardiac ejection fraction causing HF. The cumulative line of evidence suggests an important role of several biomarkers in modulating the cardiac vasculature, further contributing towards the progression of post-MI complications. Studies have demonstrated, yet not fully established, that an important biomarker, IL-10, has a causal relationship with MI and associated cardiac dysfunction.

Hypothesis

This study aims to establish the role of IL-10 as a prognostic marker for the cardiovascular outcomes and to develop a panel of biomarkers and circulating miRNAs that could potentially result in the early detection of HF resulting from MI, allowing for early intervention strategies.

Methods and results

Blood was withdrawn and echocardiography assessment was performed on a total of 43 patients that were enrolled, within 24 hours of the incidence of MI. Patients were divided in three main groups, based on the ejection fraction measurement from echocardiography: control (n = 14), MI with normal EF (MI+NEF, n = 13) and MI with low EF (MI+LEF, n = 16). Our results showed that TGFβ-1, TNF-α, IL-6 and MMP-9 were upregulated significantly in MI+NEF group and more so in MI+LEF group, as compared to control group (p<0.01). The circulating levels of miR-34a, miR-208b and miR-126 were positively correlated and showed elevated levels in the MI+NEF group, even higher in MI+LEF group, while levels of miR-24 and miR-29a were reduced in MI+NEF, and much lower in MI+LEF, as compared to the control group (p<0.01). Our results also demonstrated a direct correlation of IL-10 with the ejection fraction in patients with MI: IL-10 was elevated in MI+NEF group, however, the levels were significantly low in MI+LEF group suggesting an important role of IL-10 in predicting heart failure. Importantly, our study confirmed the correlation of IL-10 with EF by our follow-up echocardiography assessment that was performed 2 months after the incidence of MI.

Conclusion

Our results support the clinical application of these serum biomarkers to develop a panel for appropriate prognosis and management of adverse cardiac remodeling and development of heart failure post-myocardial infarction.

Discrepant myocardial microvascular perfusion and mechanics after acute myocardial infarction: Characterization of the "Tako-tsubo effect" with real-time myocardial perfusion contrast echocardiograph

BACKGROUND

In patients with acute anterior myocardial infarction (MI), sometimes an "apical ballooning" contractile dysfunction pattern that exceeds factual myocardial injury is identified in the ventriculography and bedside echocardiography. The hemodynamic consequences/sequela of this "Tako-tsobu effect" has not been well delineated. Of note, this anatomic imaging finding often misleads frontline physicians who assume reciprocal causation of persistent cardiac pump failure and ventricular pressure overload.

METHODS AND RESULTS

Using real-time myocardial perfusion contrast echocardiography (MCE), we investigated myocardial (microvascular) perfusion in 60 patients after acute MI and coronary revascularization. Twenty-eight percent of the studied patients showed significantly mismatched myocardial perfusion and contractile defects. In these patients, an integrated imaging assessment with coronary angiography/ventriculography, deformation echocardiography, and MCE proved that the myocardial mechanic abnormalities significantly exceeded the defected perfusion areas. Compared with 72% of the patients without perfusion-contractility mismatch, apparently worse systolic functions (left ventricular ejection, wall motion score, and systolic longitudinal strain) in these patients did not change diastolic ventricular filling pressures (E/E' and E/A) or hemodynamic consequences/adverse events. Both systolic and diastolic functions in patients with perfusion-contractility mismatch appeared to be comparable with those in patients with Tako-tsubo syndrome.

CONCLUSIONS

Real-time MCE identifies discrepant myocardial microvascular perfusion and mechanics in patients with acute MI. The "Tako-tsubo effect" in patients with perfusion-contractility mismatch does not cause diastolic filling pressure change or worse hemodynamic consequence/cardiac event.

Coronary artery bypass graft surgery complications: A review for emergency clinicians

INTRODUCTION

Coronary artery bypass graft (CABG) surgery remains a high-risk procedure, and many patients require emergency department (ED) management for complications after surgery.

OBJECTIVE

This narrative review provides an evidence-based summary of the current data for the emergency medicine evaluation and management of post-CABG surgery complications.

DISCUSSION

While there has been a recent decline in all cardiac revascularization procedures, there remains over 200,000 CABG surgeries performed in the United States annually, with up to 14% of these patients presenting to the ED within 30 days of discharge with post-operative complications. Risk factors for perioperative mortality and morbidity after CABG surgery can be divided into three categories: patient characteristics, clinician characteristics, and postoperative factors. Emergency physicians will be faced with several postoperative complications, including sternal wound infections, pneumonia, thromboembolic phenomena, graft failure, atrial fibrillation, pulmonary hypertension, pericardial effusion, strokes, renal injury, gastrointestinal insults, and hemodynamic instability. Critical patients should be evaluated in the resuscitation bay, and consultation with the primary surgical team is needed, which improves patient outcomes. This review provides several guiding principles for management of acute complications. Understanding these complications and an approach to the management of hemodynamic instability is essential to optimizing patient care.

CONCLUSIONS

Postoperative complications of CABG surgery can result in significant morbidity and mortality. Physicians must rapidly diagnose these conditions while evaluating for other diseases. Early surgical consultation is imperative, as is optimizing the patient's hemodynamics, including preload, heart rate, cardiac rhythm, contractility, and afterload.

Monitoring reperfused myocardial infarction with delayed left ventricular systolic dysfunction in rabbits by longitudinal imaging

Background

An experimental imaging platform for longitudinal monitoring and evaluation of cardiac morphology-function changes has been long desired. We sought to establish such a platform by using a rabbit model of reperfused myocardial infarction (MI) that develops chronic left ventricle systolic dysfunction (LVSD) within 7 weeks.

Methods

Fifty-five New Zeeland white (NZW) rabbits received sham-operated or 60-min left circumflex coronary artery (LCx) ligation followed by reperfusion. Cardiac magnetic resonance imaging (cMRI), transthoracic echocardiography (echo), and blood samples were collected at baseline, in acute (48 hours or 1 week) and chronic (7 weeks) stage subsequent to MI for in vivo assessment of infarct size, cardiac morphology, LV function, and myocardial enzymes. Seven weeks post MI, animals were sacrificed and heart tissues were processed for histopathological staining.

Results

The success rate of surgical operation was 87.27%. The animal mortality rates were 12.7% and 3.6% both in acute and chronic stage separately. Serum levels of the myocardial enzyme cardiac Troponin T (cTnT) were significantly increased in MI rabbits as compared with sham animals after 4 hours of operation (P<0.05). According to cardiac morphology and function changes, 4 groups could be distinguished: sham rabbits (n=12), and MI rabbits with no (MI_NO_LVSD; n=10), moderate (MI_M_LVSD; n=9) and severe (MI_S_LVSD; n=15) LVSD. No significant differences in cardiac function or wall thickening between sham and MI_NO_LVSD rabbits were observed at both stages using both cMRI and echo methods. cMRI data showed that MI_M_LVSD rabbits exhibited a reduction of ejection fraction (EF) and an increase in end-systolic volume (ESV) at the acute phase, while at the chronic stage these parameters did not change further. Moreover, in MI_S_LVSD animals, these observations were more striking at the acute stage followed by a further decline in EF and increase in ESV at the chronic stage. Lateral wall thickening determined by cMRI was significantly decreased in MI_M_LVSD versus MI_NO_LVSD animals at both stages (P<0.05). As for MI_S_LVSD versus MI_M_LVSD rabbits, the thickening of anterior, inferior and lateral walls was significantly more decreased at both stages (P<0.05). Echo confirmed the findings of cMRI. Furthermore, these in vivo outcomes including those from vivid cine cMRI could be supported by exactly matched ex vivo histomorphological evidences.

Conclusions

Our findings indicate that chronic LVSD developed over time after surgery-induced MI in rabbits can be longitudinally evaluated using non-invasive imaging techniques and confirmed by the entire-heart-slice histomorphology. This experimental LVSD platform in rabbits may interest researchers in the field of experimental cardiology and help strengthen drug development and translational research for the management of cardiovascular diseases.

Injectable Hydrogels for Cardiac Tissue Engineering

In light of the limited efficacy of current treatments for cardiac regeneration, tissue engineering approaches have been explored for their potential to provide mechanical support to injured cardiac tissues, deliver cardio-protective molecules, and improve cell-based therapeutic techniques. Injectable hydrogels are a particularly appealing system as they hold promise as a minimally invasive therapeutic approach. Moreover, injectable acellular alginate-based hydrogels have been tested clinically in patients with myocardial infarction (MI) and show preservation of the left ventricular (LV) indices and left ventricular ejection fraction (LVEF). This review provides an overview of recent developments that have occurred in the design and engineering of various injectable hydrogel systems for cardiac tissue engineering efforts, including a comparison of natural versus synthetic systems with emphasis on the ideal characteristics for biomimetic cardiac materials.

State-of-the-art diagnosis of myocardial infarction

The current version of the Universal Definition of Myocardial Infarction (MI) was published in 2012. An acute myocardial infarction (AMI) is characterized by evidence of myocardial necrosis in a clinical setting of acute myocardial ischemia. Diagnostic criteria include a rise and/or fall of serially tested cardiac biomarkers (preferentially cardiac troponins) with at least one value above the 99th percentile of the upper reference limit combined with symptoms of ischemia, new changes on electrocardiogram (ECG), imaging evidence of a new loss of viable myocardium or new regional wall motion abnormalities or the identification of an intracoronary thrombus by angiography or autopsy. Compared to previous versions, the current definition of MI includes minor modifications regarding ECG criteria and subtypes of MI as well as the use of cardiac imaging and high sensitivity troponin assays. This article summarizes the Universal MI definition and includes recommendations from the current guidelines for the management of patients with acute coronary syndrome. Strategies for "early rule-in" and "rule-out" of non-ST-elevation MI with high sensitivity cardiac troponin assays, risk scores for assessment of ischemic and bleeding risk and criteria for optimal timing of angiography are presented.

Statistical shape modeling of the left ventricle: myocardial infarct classification challenge

Statistical shape modeling is a powerful tool for visualizing and quantifying geometric and functional patterns of the heart. After myocardial infarction (MI), the left ventricle typically remodels in response to physiological challenges. Several methods have been proposed in the literature to describe statistical shape changes. Which method best characterizes left ventricular remodeling after MI is an open research question. A better descriptor of remodeling is expected to provide a more accurate evaluation of disease status in MI patients. We therefore designed a challenge to test shape characterization in MI given a set of three-dimensional left ventricular surface points. The training set comprised 100 MI patients, and 100 asymptomatic volunteers (AV). The challenge was initiated in 2015 at the Statistical Atlases and Computational Models of the Heart workshop, in conjunction with the MICCAI conference. The training set with labels was provided to participants, who were asked to submit the likelihood of MI from a different (validation) set of 200 cases (100 AV and 100 MI). Sensitivity, specificity, accuracy and area under the receiver operating characteristic curve were used as the outcome measures. The goals of this challenge were to (1) establish a common dataset for evaluating statistical shape modeling algorithms in MI, and (2) test whether statistical shape modeling provides additional information characterizing MI patients over standard clinical measures. Eleven groups with a wide variety of classification and feature extraction approaches participated in this challenge. All methods achieved excellent classification results with accuracy ranges from 0.83 to 0.98. The areas under the receiver operating characteristic curves were all above 0.90. Four methods showed significantly higher performance than standard clinical measures. The dataset and software for evaluation are available from the Cardiac Atlas Project website1.

Lower diastolic wall strain is associated with coronary revascularization in patients with stable angina

Background

Left ventricular (LV) diastolic dysfunction occurs earlier in the ischemic cascade than LV systolic dysfunction and electrocardiographic changes. Diastolic wall strain (DWS) has been proposed as a marker of LV diastolic stiffness. Therefore, the objectives of this study were to define the relationship between DWS and coronary revascularization and to evaluate other echocardiographic parameters in patients with stable angina who were undergoing coronary angiography (CAG).

Methods

Four hundred forty patients [mean age: 61 ± 10; 249 (57%) men] undergoing CAG and with normal left ventricular systolic function without regional wall motion abnormalities were enrolled. Among them, 128 (29%) patients underwent revascularization (percutaneous intervention: 117, bypass surgery: 11). All patients underwent echocardiography before CAG and the DWS was defined using posterior wall thickness (PWT) measurements from standard echocardiographic images [DWS = PWT(systole)-PWT(diastole)/PWT(systole)].

Results

Patients who underwent revascularization had a significantly lower DWS than those who did not (0.26 ± 0.08 vs. 0.38 ± 0.09, p < 0.001). Age was comparable between the two groups (61 ± 9 vs. 60 ± 11, p = 0.337), but the proportion of males was significantly higher among patients who underwent revascularization (69 vs. 52%, p = 0.001). The LV ejection fraction was similar but slightly decreased (60.9 ± 5.7 vs. 62.4 ± 6.2%, p = 0.019) and the E/E’ ratio was elevated (10.3 ± 4.0 vs. 9.0 ± 3.1, p < 0.001) among patients who underwent revascularization. In multiple regression analysis, lower DWS was an independent predictor of revascularization (cut-off value: 0.34; sensitivity: 89%; AUC: 0.870; SE: 0.025; p < 0.001).

Conclusion

DWS, a simple parameter that can be calculated from routine 2D echocardiography, is inversely associated with the presence of coronary artery disease and the need for revascularization.