Prognostic significance of microvascular obstruction by magnetic resonance imaging in patients with acute myocardial infarction

Efficacy and Safety of Alprostadil in Microcirculatory Disturbances During Emergency PCI: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The clinical advantage of alprostadil [prostaglandin E1 (PGE1)] in the treatment of microcirculatory disturbances (defined as no-reflow or slow-flow) in acute percutaneous coronary intervention (PCI) is still disputed. The purpose of our study was to review the efficacy of PGE1 supplements in patients with acute myocardial infarction (AMI) who had urgent PCI.

DESIGN

This study was a meta-analysis of randomized controlled trials.

DATA SOURCES

PubMed, Embase, the Cochrane Library, Ovid, ProQuest, Scopus, the Chinese BioMedical Literature Database, China National Knowledge Internet, the China Science and Technology Journal Database, and the Wanfang Data Knowledge Service Platform were used as sources.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included randomized controlled trials including PGE1 for the treatment of intraoperative microcirculatory disorders and major cardiovascular adverse events in emergency PCI in people with AMI. Independent data extraction was conducted, and study quality was assessed. The meta-analysis was carried out by using random effects models to calculate the risk ratio (RR) of microcirculatory disorders between groups receiving PGE1 and those receiving placebo, nitroglycerin, or tirofiban.

MAIN OUTCOME MEASURES

The primary endpoint of the study was the incidence of microcirculatory disturbances. Secondary outcomes included corrected thrombolysis in myocardial infarction (TIMI) frame count (cTFC), the percentage of patients with TIMI myocardial perfusion grade 3 (TMPG3), and the percentage of patients with myocardial blush grade 3 (MBG3) as efficacy indicators. Additionally, major adverse cardiovascular events (MACE) at 30 days and 180 days were assessed as safety indicators.

RESULTS

There were 18 trials involving a total of 1458 participants. PGE1 significantly reduced the occurrence of microcirculation disorders compared with conventional medications and placebo [risk ratio 0.48, 95% confidence interval (CI) 0.36-0.63, I2 = 46%; cTFC (RR -4.74, 95% -6.85 to -2.63, I2 93%); percentage of patients with TMPG3 (RR 1.34, 95% CI 1.07-1.68, I2 70%) or MBG3 (RR 1.33, 95% CI 1.19-1.49, I2 0%); major adverse cardiovascular events (MACEs) in 30 days (RR 0.48, 95% CI 0.27-0.86, I2 0%); and MACEs in 180 days (RR 0.41, 95% CI 0.28-0.60, I2 0%)].

CONCLUSIONS

We found that PGE1 decreased the occurrence of micro-circulation disturbance in AMI and enhanced the outcome of PCI. Additional studies should be conducted to confirm these findings.

Reperfusion Injury in Patients With Acute Myocardial Infarction: JACC Scientific Statement

Despite impressive improvements in the care of patients with ST-segment elevation myocardial infarction, mortality remains high. Reperfusion is necessary for myocardial salvage, but the abrupt return of flow sets off a cascade of injurious processes that can lead to further necrosis. This has been termed myocardial ischemia-reperfusion injury and is the subject of this review. The pathologic and molecular bases for myocardial ischemia-reperfusion injury are increasingly understood and include injury from reactive oxygen species, inflammation, calcium overload, endothelial dysfunction, and impaired microvascular flow. A variety of pharmacologic strategies have been developed that have worked well in preclinical models and some have shown promise in the clinical setting. In addition, there are newer mechanical approaches including mechanical unloading of the heart prior to reperfusion that are in current clinical trials.

Ability of the coronary angiography-derived index of microcirculatory resistance to predict microvascular obstruction in patients with ST-segment elevation

Background

The coronary angiography-derived index of microvascular resistance (caIMR) correlates well with the index of microcirculatory resistance (IMR), which predicts microvascular obstruction (MVO). However, the relationship between caIMR and MVO remains unclear.

Aim

To evaluate the predictive ability of caIMR of MVO after ST-segment elevation myocardial infarction (STEMI).

Methods

CaIMR was calculated using computational flow and pressure simulation in patients with STEMI in whom MVO status had been assessed by cardiac magnetic resonance (CMR) after successful primary percutaneous intervention at Peking University First Hospital between December 2016 and August 2019. The clinical, biochemical, echocardiographic, and CMR characteristics were assessed according to MVO status. The predictive value of the clinical parameters and caIMR was evaluated.

Results

Fifty-three eligible patients were divided into an MVO group (n = 32) and a no-MVO group (n = 21). The caIMR tended to be higher in the MVO group (41.6 U vs. 30.1 U; p = 0.136). CaIMR and peak cardiac troponin-I (cTNI) were independent predictors of MVO (per 1-U increment in caIMR: odds ratio [OR] 1.044, 95% confidence interval [CI] 1.004-1.086, p = 0.030; per 1 ng/L increase in peak cTNI: OR 1.018, 95% CI 1.003-1.033, p = 0.022). In receiver-operating characteristic curve analysis, when a cut-off value of 45.17 U was used, caIMR had some ability to predict MVO (area under the curve 0.622, 95% CI 0.478-0.752, p = 0.127).

Conclusions

CaIMR and peak cTNI were independent predictors of short-term MVO in patients with STEMI who had undergone successful primary percutaneous coronary intervention and may help to identify those at high risk of MVO.

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.

Impact of Bivalirudin on Ischemia/Reperfusion Injury in Patients with Reperfused STEMI Assessed by Cardiac Magnetic Resonance

Thrombin is an important ischemia/reperfusion injury (IRI) mediator in patients with ST-elevation myocardial infarction (STEMI). This study examines the use of bivalirudin, a direct thrombin inhibitor, in reducing IRI in STEMI patients. STEMI patients (n = 21) were treated with bivalirudin and compared to 21 patients treated with unfractionated heparin (UFH) from the EARLY Assessment of Myocardial Tissue Characteristics by CMR in STEMI (EARLY-MYO-CMR) registry (NCT03768453). Infarct size (IS) and left ventricular ejection fraction (LVEF) were comparable between the two groups at follow up. During the first cardiac magnetic resonance (CMR) scan within the first week after percutaneous coronary intervention (PCI), all patients in both the bivalirudin and UFH groups exhibited myocardial edema. However, the myocardium edema volume was significantly less in the bivalirudin group (p < 0.05). At the one-month follow-up, a smaller proportion of patients in the bivalirudin group than in the UFH group exhibited myocardial edema (4.7% vs. 33.3%, p < 0.05). At the three-month follow-up, myocardial edema had completely resolved in the bivalirudin group, while it persisted in two patients in the UFH group. The incidence and volume of microvascular obstruction (MVO) were significantly lower in the bivalirudin group during the acute phase. Additionally, the incidence of intramyocardial hemorrhage (IMH) was significantly lower in the bivalirudin group during both the acute and follow up (p < 0.05). These findings were corroborated by T2 and T1 mapping results. The study concluded that the use of bivalirudin for anticoagulation is associated with attenuated IRI in STEMI patients who receive primary PCI.

Establishment and validation of a prediction model for nonrecovery of left ventricular ejection fraction in acute myocardial infarction patients combined with decreased left ventricular ejection fraction

BACKGROUND

This study aimed to investigate the risk factors for nonrecovery of left ventricular ejection fraction (LVEF) during follow-up in patients with acute myocardial infarction (AMI) who underwent percutaneous coronary intervention (PCI) combined with reduced LVEF, and establish and verify a risk prediction model based on these factors.

METHODS

In this study, patients with AMI who underwent PCI in a high-volume PCI center between December 2018 and December 2021 were consecutively enrolled, screened, and randomly assigned to the model establishment and validation cohorts. A predictive model method based on least absolute shrinkage and selection operator regression was used for establishment and validation.

RESULTS

Cardiac troponin I, myoglobin, left ventricular end-diastolic dimension, multivessel disease, and no-reflow were identified as potential predictors of LVEF recovery failure. The areas under the curve were 0.703 and 0.665 in the model establishment and validation cohorts, respectively, proving that the prediction model had some predictive ability. The calibration curves of the two cohorts showed good agreement with those of the nomogram model. In addition, the decision curve analysis showed that the model had a net clinical benefit.

CONCLUSION

This prediction model can assess the risk of nonrecovery of LVEF in patients with AMI undergoing PCI combined with LVEF reduction during follow-up, and conveniently screen high-risk patients with nonrecoverable LVEF early.

Sex differences in diagnostic modalities of coronary artery disease: Evidence from coronary microcirculation

Although atherosclerosis is usually considered a disease of the large arteries, risk factors for atherosclerosis also trigger structural and functional abnormalities at a microvascular level. In cardiac disease, microvascular dysfunction is especially relevant in women, among whom the manifestation of ischemic disease due to impaired coronary microcirculation is more common than in men. This sex-specific clinical phenotype has important clinical implications and, given the higher pre-test probability of coronary microvascular dysfunction in females, different diagnostic modalities should be used in women compared to men. In this review, we summarize invasive and non-invasive diagnostic modalities to assess coronary microvascular function, ranging from catheter-based evaluation of endothelial function to Doppler echocardiography and positron emission tomography. Moreover, we discuss different clinical settings in which microvascular disease plays an important role, underlining the importance of choosing the right diagnostic modality depending on the sex of the patients.

Arginine Vasopressin Plays a Role in Microvascular Dysfunction After ST-Elevation Myocardial Infarction

Background Coronary microvascular dysfunction (CMD) predicts mortality after ST-elevation-myocardial infarction (STEMI). Arginine vasopressin (AVP) may be implicated, but data in humans are lacking, and no study has investigated the link between arginine vasopressin and invasive measures of CMD. Methods and Results We invasively assessed CMD in 55 patients with STEMI treated with primary percutaneous coronary intervention (PPCI), by measuring the index of microcirculatory resistance after PPCI. In a separate group of 45 patients with STEMI/PPCI, recruited for a clinical trial, we measured infarct size and microvascular obstruction with cardiac magnetic resonance (CMR) imaging at 1 week and 12 weeks post-STEMI. Serum copeptin was measured at 4 time points before and after PPCI in all patients with STEMI. Plasma copeptin levels fell from 92.5 pmol/L before reperfusion to 6.4 pmol/L at 24 hours. Copeptin inversely correlated with diastolic, but not systolic, blood pressure (r=-0.431, P=0.001), suggesting it is released in response to myocardial ischemia. Persistently raised copeptin at 24 hours was correlated with higher index of microcirculatory resistance (r=0.372, P=0.011). Patients with microvascular obstruction on early CMR imaging showed a trend toward higher admission copeptin, which was not statistically significant. Copeptin levels were not associated with infarct size on either early or late CMR. Conclusions Patients with CMD after STEMI have persistently elevated copeptin at 24 hours, suggesting arginine vasopressin may contribute to microvascular dysfunction. Arginine vasopressin receptor antagonists may represent a novel therapeutic option in patients with STEMI and CMD.

Coronary No-Reflow after Primary Percutaneous Coronary Intervention-Current Knowledge on Pathophysiology, Diagnosis, Clinical Impact and Therapy

Coronary no-reflow (CNR) is a frequent phenomenon that develops in patients with ST-segment elevation myocardial infarction (STEMI) following reperfusion therapy. CNR is highly dynamic, develops gradually (over hours) and persists for days to weeks after reperfusion. Microvascular obstruction (MVO) developing as a consequence of myocardial ischemia, distal embolization and reperfusion-related injury is the main pathophysiological mechanism of CNR. The frequency of CNR or MVO after primary PCI differs widely depending on the sensitivity of the tools used for diagnosis and timing of examination. Coronary angiography is readily available and most convenient to diagnose CNR but it is highly conservative and underestimates the true frequency of CNR. Cardiac magnetic resonance (CMR) imaging is the most sensitive method to diagnose MVO and CNR that provides information on the presence, localization and extent of MVO. CMR imaging detects intramyocardial hemorrhage and accurately estimates the infarct size. MVO and CNR markedly negate the benefits of reperfusion therapy and contribute to poor clinical outcomes including adverse remodeling of left ventricle, worsening or new congestive heart failure and reduced survival. Despite extensive research and the use of therapies that target almost all known pathophysiological mechanisms of CNR, no therapy has been found that prevents or reverses CNR and provides consistent clinical benefit in patients with STEMI undergoing reperfusion. Currently, the prevention or alleviation of MVO and CNR remain unmet goals in the therapy of STEMI that continue to be under intense research.

A historical literature review of coronary microvascular obstruction and intra-myocardial hemorrhage as functional/structural phenomena

The analysis of experimental data demonstrates that platelets and neutrophils are involved in the no-reflow phenomenon, also known as microvascular obstruction (MVO). However, studies performed in the isolated perfused hearts subjected to ischemia/reperfusion (I/R) do not suggest the involvement of microembolization and microthrombi in this phenomenon. The intracoronary administration of alteplase has been found to have no effect on the occurrence of MVO in patients with acute myocardial infarction. Consequently, the major events preceding the appearance of MVO in coronary arteries are independent of microthrombi, platelets, and neutrophils. Endothelial cells appear to be the target where ischemia can disrupt the endothelium-dependent vasodilation of coronary arteries. However, reperfusion triggers more pronounced damage, possibly mediated by pyroptosis. MVO and intra-myocardial hemorrhage contribute to the adverse post-infarction myocardial remodeling. Therefore, pharmacological agents used to treat MVO should prevent endothelial injury and induce relaxation of smooth muscles. Ischemic conditioning protocols have been shown to prevent MVO, with L-type Ca ²⁺ channel blockers appearing the most effective in treating MVO.

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

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

Coronary Microvascular Disease in Contemporary Clinical Practice

Coronary microvascular disease (CMD) causes myocardial ischemia in a variety of clinical scenarios. Clinical practice guidelines support routine testing for CMD in patients with ischemia with nonobstructive coronary artery disease. Invasive testing to identify CMD requires Doppler or thermodilution measures of flow to determine the coronary flow reserve and measures of microvascular resistance. Acetylcholine coronary reactivity testing identifies concomitant endothelial dysfunction, microvascular spasm, or epicardial coronary spasm. Comprehensive testing may improve symptoms, quality of life, and patient satisfaction by establishing a diagnosis and guiding-targeted medical therapy and lifestyle measures. Beyond ischemia with nonobstructive coronary artery disease, testing for CMD may play a role in patients with acute myocardial infarction, angina following coronary revascularization, heart failure with preserved ejection fraction, Takotsubo syndrome, and after heart transplantation. Additional education and provider awareness of CMD and its role in cardiovascular disease is needed to improve patient-centered outcomes of ischemic heart disease.

Ticagrelor vs. clopidogrel for coronary microvascular dysfunction in patients with STEMI: a meta-analysis of randomized controlled trials

Purpose

Approximately half of ST-segment elevation myocardial infarction (STEMI) patients who undergo revascularization present with coronary microvascular dysfunction. Dual antiplatelet therapy, consisting of aspirin and a P2Y12 inhibitor (e.g., clopidogrel or ticagrelor), is recommended to reduce rates of cardiovascular events after STEMI. The present study performed a pooled analysis of randomized controlled trials (RCTs) to compare effects of ticagrelor and clopidogrel on coronary microcirculation dysfunction in STEMI patients who underwent the primary percutaneous coronary intervention.

Methods

The PubMed, Embase, Cochrane Library, and Web of Science databases were searched for eligible RCTs up to September 2022, with no language restriction. Coronary microcirculation indicators included the corrected thrombolysis in myocardial infarction (TIMI) frame count (cTFC), myocardial blush grade (MBG), TIMI myocardial perfusion grade (TMPG), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR).

Results

Seven RCTs that included a total of 957 patients (476 who were treated with ticagrelor and 481 who were treated with clopidogrel) were included. Compared with clopidogrel, ticagrelor better accelerated microcirculation blood flow [cTFC = -2.40, 95% confidence interval (CI): -3.38 to -1.41, p < 0.001] and improved myocardial perfusion [MBG = 3, odds ratio (OR) = 1.99, 95% CI: 1.35 to 2.93, p < 0.001; MBG ≥ 2, OR = 2.57, 95% CI: 1.61 to 4.12, p < 0.001].

Conclusions

Ticagrelor has more benefits for coronary microcirculation than clopidogrel in STEMI patients who undergo the primary percutaneous coronary intervention. However, recommendations for which P2Y12 receptor inhibitor should be used in STEMI patients should be provided according to results of studies that investigate clinical outcomes.

Cardiovascular Magnetic Resonance from Fetal to Adult Life-Indications and Challenges: A State-of-the-Art Review

Cardiovascular magnetic resonance (CMR) imaging offers a comprehensive, non-invasive, and radiation-free imaging modality, which provides a highly accurate and reproducible assessment of cardiac morphology and functions across a wide spectrum of cardiac conditions spanning from fetal to adult life. It minimises risks to the patient, particularly the risks associated with exposure to ionising radiation and the risk of complications from more invasive haemodynamic assessments. CMR utilises high spatial resolution and provides a detailed assessment of intracardiac and extracardiac anatomy, ventricular and valvular function, and flow haemodynamic and tissue characterisation, which aid in the diagnosis, and, hence, with the management of patients with cardiac disease. This article aims to discuss the role of CMR and the indications for its use throughout the different stages of life, from fetal to adult life.

Conductive and Thermo-Responsive Composite Hydrogels with Poly(N-isopropylacrylamide) and Carbon Nanotubes Fabricated by Two-Step Photopolymerization

Biocompatible and conductive polymer hydrogels are the subject of intensive research in the bioengineering field because of their use in bioelectronic devices and for the fabrication of electro-responsive tissues and drug delivery systems. In this study, we report the synthesis of conductive composite hydrogels consisting of a poly(N-isopropylacrylamide) (PNIPAM) matrix embedding carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH) using a two-step photopolymerization method. Thermo-responsive hydrogels with controlled hydrophilicity and conductivity were prepared by varying the carbon nanotube concentration in the range 0.5-3 wt%. The thermal response of the PNIPAM-based composite hydrogels was measured by differential scanning calorimetry with both ultrapure water and PBS solution as swelling liquid. Results show that the endothermic peak associated with the temperature-induced volume phase transition (VPT) shifts to higher temperatures upon increasing the concentration of the nanotubes, indicating that more energy is required to dissociate the hydrogen bonds of the polymer/filler network. In PBS solution, the swelling ratios and the VPT temperatures of the composite hydrogels are reduced because of salt-induced screening of the oppositely charged polymer/filler assembly, and the electrical resistivity decreases by a factor of 10 with respect to the water-swollen hydrogels.

Zinc supplementation in patients with acute myocardial infarction

This single-centre prospective feasibility study (UMIN000030232) evaluated whether zinc supplementation was safe and effective for improving outcomes among patients with acute myocardial infarction (AMI). Within 24 h after successful primary percutaneous coronary intervention, consenting patients with AMI were randomly assigned 1:1 to receive conventional treatment (conventional treatment group) or conventional treatment plus zinc acetate supplementation (zinc supplementation group). The two groups were compared in terms of major adverse cardiovascular events (MACE), and scar size, which was evaluated using cardiac magnetic resonance imaging (CMR) at 4 weeks after discharge. A total of 56 patients underwent randomization (with 26 assigned to the zinc supplementation group and 27 to the conventional treatment group). The two groups had generally similar laboratory findings and clinical characteristics. The two groups also had similar lengths of hospital stay and rates of MACE. Forty of the 53 patients underwent CMR and it revealed that % core zone was numerically lower in the zinc supplementation group than in the conventional treatment group (9.3 ± 6.9% vs. 14.2 ± 9.1%, P = 0.07). This small single-centre study failed to detect a significant reduction in mid-term MACE after AMI among patients who received zinc supplementation.

Effect of Ultrasound Pulse Length on Sonoreperfusion Therapy

In recent years, long- and short-pulse ultrasound (US)-targeted microbubble cavitation (UTMC) has been found to increase perfusion in healthy and ischemic skeletal muscle, in pre-clinical animal models of microvascular obstruction and in the myocardium of patients presenting with acute myocardial infarction. There is evidence that the observed microvascular vasodilation is driven by the nitric oxide pathway and purinergic signaling, but the time course of the response and the dependency on US pulse length are not well elucidated. Because our prior data supported that sonoreperfusion efficacy is enhanced by long-pulse US versus short-pulse US, in this study, we sought to compare long-pulse (5000 cycles) and short-pulse (500 × 10 cycles) US at a pressure of 1.5 MPa with an equivalent total number of acoustical cycles, hence constant acoustic energy, and at the same frequency (1 MHz), in a rodent hind limb model with and without microvascular obstruction (MVO). In quantifying perfusion using burst replenishment contrast-enhanced US imaging, we made three findings: (i) Long and short pulses result in different vasodilation kinetics in an intact hind limb model. The long pulse causes an initial spasmic reduction in flow that spontaneously resolved at 4 min, followed by sustained higher flow rates (approximately twofold) compared with baseline, starting 10 min after therapy (p < 0.05). The short pulse caused a short-lived approximately twofold increase in flow rate that peaked at 4 min (p < 0.05), but without the initial spasm. (ii) The sustained increased response with the long pulse is not simply reactive hyperemia. (iii) Both pulses are effective in reperfusion of MVO in our hindlimb model by restoring blood volume, but only the long pulse caused an increase in flow rate after treatment ii, compared with MVO (p < 0.05). Histological analysis of hind limb muscle post-UTMC with either pulse configuration indicates no evidence of tissue damage or hemorrhage. Our findings indicate that the microbubble oscillation induces vasodilation, and therapeutic efficacy for the treatment of MVO can be tuned by varying pulse length; relative to short-pulse US, longer pulses drive greater microbubble cavitation and more rapid microvascular flow rate restoration after MVO, warranting further optimization of the pulse length for sonoreperfusion therapy.

Cardiac magnetic resonance feature tracking global and segmental strain in acute and chronic ST-elevation myocardial infarction

Strain is an important imaging parameter to determine myocardial deformation. This study sought to 1) assess changes in left ventricular strain and ejection fraction (LVEF) from acute to chronic ST-elevation myocardial infarction (STEMI) and 2) analyze strain as a predictor of late gadolinium enhancement (LGE). 32 patients with STEMI and 18 controls prospectively underwent cardiac magnetic resonance imaging. Patients were scanned 8 [Formula: see text] 5 days and six months after infarction (± 1.4 months). Feature tracking was performed and LVEF was calculated. LGE was determined visually and quantitatively on short-axis images and myocardial segments were grouped according to the LGE pattern (negative, non-transmural and transmural). Global strain was impaired in patients compared to controls, but improved within six months after STEMI (longitudinal strain from -14 ± 4 to -16 ± 4%, p < 0.001; radial strain from 38 ± 11 to 42 ± 13%, p = 0.006; circumferential strain from -15 ± 4 to -16 ± 4%, p = 0.023). Patients with microvascular obstruction showed especially attenuated strain results. Regional strain persisted impaired in LGE-positive segments. Circumferential strain could best distinguish between LGE-negative and -positive segments (AUC 0.73- 0.77). Strain improves within six months after STEMI, but remains impaired in LGE-positive segments. Strain may serve as an imaging biomarker to analyze myocardial viability. Especially circumferential strain could predict LGE.

Epicardial transplantation of autologous atrial appendage micrografts: evaluation of safety and feasibility in pigs after coronary artery occlusion

Objectives. Several approaches devised for clinical utilization of cell-based therapies for heart failure often suffer from complex and lengthy preparation stages. Epicardial delivery of autologous atrial appendage micrografts (AAMs) with a clinically used extracellular matrix (ECM) patch provides a straightforward therapy alternative. We evaluated the operative feasibility and the effect of micrografts on the patch-induced epicardial foreign body inflammatory response in a porcine model of myocardial infarction. Design. Right atrial appendages were harvested and mechanically processed into AAMs. The left anterior descending coronary artery was ligated to generate acute infarction. Patches of ECM matrix with or without AAMs were transplanted epicardially onto the infarcted area. Four pigs received the ECM and four received the AAMs patch. Cardiac function was studied by echocardiography both preoperatively and at 3-week follow-up. The primary outcome measures were safety and feasibility of the therapy administration, and the secondary outcome was the inflammatory response to ECM. Results. Neither AAMs nor ECM patch-related complications were detected during the follow-up time. AAMs patch preparation was feasible according to time and safety. Inflammation was greatly reduced in AAMs when compared with ECM patches as measured by the amount of infiltrated inflammatory cells and area of inflammation. Immunohistochemistry demonstrated an increased CD3+ cell density in the AAMs patch infiltrate. Conclusions. Epicardial AAMs transplantation demonstrated safety and clinical feasibility. The use of micrografts significantly inhibited ECM-induced foreign body inflammatory reactivity. Transplantation of AAMs shows good clinical applicability as adjuvant therapy to cardiac surgery and can suppress acute inflammatory reactivity.

The Merits, Limitations, and Future Directions of Cost-Effectiveness Analysis in Cardiac MRI with a Focus on Coronary Artery Disease: A Literature Review

Cardiac magnetic resonance (CMR) imaging has a wide range of clinical applications with a high degree of accuracy for many myocardial pathologies. Recent literature has shown great utility of CMR in diagnosing many diseases, often changing the course of treatment. Despite this, it is often underutilized possibly due to perceived costs, limiting patient factors and comfort, and longer examination periods compared to other imaging modalities. In this regard, we conducted a literature review using keywords “Cost-Effectiveness” and “Cardiac MRI” and selected articles from the PubMed MEDLINE database that met our inclusion and exclusion criteria to examine the cost-effectiveness of CMR. Our search result yielded 17 articles included in our review. We found that CMR can be cost-effective in quality-adjusted life years (QALYs) in select patient populations with various cardiac pathologies. Specifically, the use of CMR in coronary artery disease (CAD) patients with a pretest probability below a certain threshold may be more cost-effective compared to patients with a higher pretest probability, although its use can be limited based on geographic location, professional society guidelines, and differing reimbursement patterns. In addition, a stepwise combination of different imaging modalities, with conjunction of AHA/ACC guidelines can further enhance the cost-effectiveness of CMR.

Soluble ST2 in coronary artery disease: Clinical biomarkers and treatment guidance

The IL-33/ST2 L signaling pathway is involved in the pathophysiological processes of several diseases and mainly exerts anti-inflammatory and antifibrotic effects. Soluble suppression of tumorigenicity 2 (sST2), which serves as a competitive inhibitory molecule of this pathway, is a member of the interleukin (IL)-1 family, a decoy receptor for IL33, thought to play a role in cardiac remodeling and the inflammatory process. However, the association between sST2 and coronary artery disease (CAD), one of the most common causes of heart failure, is still being explored. We therefore reviewed the research on sST2 in the field of CAD, including reflecting the atherosclerosis burden, predicting no-reflow, predicting prognosis, responding to myocardial remodeling, and guiding management, hoping to provide cardiologists with new perspectives.

Hyperglycemia and intramyocardial hemorrhage in patients with ST-segment elevation myocardial infarction

BACKGROUND

Hyperglycemia at admission and intramyocardial hemorrhage (IMH) are associated with poor prognosis in patients with ST-segment elevation myocardial infarction (STEMI). Little is known about the relationship between glucose levels at admission and IMH. The association between matrix metalloproteinase-9 (MMP-9), which plays an important role in the development of IMH, and hyperglycemia is also unknown. This study aimed to investigate the relationship between hyperglycemia at admission and IMH in patients with STEMI.

METHODS

We enrolled 174 patients with first STEMI who underwent primary percutaneous coronary intervention (PCI) and cardiovascular magnetic resonance (CMR) imaging. T2-weighted imaging and late gadolinium enhancement (LGE)-CMR were performed to detect IMH and microvascular obstruction (MVO), respectively. Two patient groups were created: IMH group and non-IMH group. MMP-9 levels were measured in the culprit coronary arteries of 13 patients.

RESULTS

Glucose level at admission and the value of glycosylated hemoglobin were higher in the IMH group than in the non-IMH group [IMH group vs. non-IMH group; 208.5 (157.8-300.5) mg/dL vs. 157.0 (128.8-204.3) mg/dL, p < 0.001, and 6.2 (5.7-7.5) % vs. 5.8 (5.4-6.6) %, p = 0.030, respectively]. A multivariable logistic regression analysis revealed that only admission glucose level was an independent predictor of IMH (OR: 1.012; 95 % CI: 1.005-1.020, p = 0.001). The MMP-9 levels in patients with IMH were higher than those in patients without IMH [256.0 (161.0-396.0) ng/mL vs. 73.5 (49.5-131.0) ng/mL, p = 0.040]. There was a moderate positive correlation between glucose levels at admission and MMP-9 levels (r = 0.600, p = 0.030).

CONCLUSIONS

Hyperglycemia at admission is associated with the occurrence of IMH in patients with STEMI.

Pitfalls and pearls in the imaging of cardiac ischemia

Coronary artery disease is the most common cause of cardiac ischemia and a leading cause of death globally. There are multiple imaging modalities which can assess cardiac ischemia, in particular coronary CT calcium score, coronary CT angiography, and cardiac MRI. Each of these modalities offers insight into the overall patient picture. However, coronary CT and cardiac MRI are not free from limitations. This article will review the roles of CT and MRI in cardiac imaging, mimics, technical limitations, and potential pitfalls that may be encountered.

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

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

Value of Fast MVO Identification From Contrast-Enhanced Cine (CE-SSFP) Combined With Myocardial Strain in Predicting Adverse Events in Patients After ST-Elevation Myocardial Infarction

Objectives

Cardiac magnetic resonance imaging (CMR) can be used for a one-step evaluation of myocardial function and pathological features after acute ST-elevation myocardial infarction (STEMI). We aimed to evaluate the value of fast microvascular occlusion (MVO) identification from contrast-enhanced steady-state free precession (CE-SSFP) combined with myocardial strain in predicting major cardiovascular adverse events (MACEs) in primary percutaneous coronary intervention (pPCI) patients with STEMI.

Methods

In total, 237 patients with STEMI who received pPCI and completed CMR scans within the following week were enrolled, MVO identification and the myocardial strain analysis were performed in CE-SSFP images without an additional method. The primary endpoint was the presence of MACE, which is defined as a composite of death, reinfarction, and congestive heart failure (HF).

Results

After 13 months of follow-up [interquartile range (IQR): 11-24], 30 patients (14%) developed MACE; the MVO (hazard ratio (HR) was 3.10; 95% CI: 1.14-8.99, p = 0.028), and the infarct size (IS) (HR: 1.03; 95% CI: 1.0-1.06, p = 0.042) and global longitudinal strain (GLS) (HR: 1.08; 95% CI: 1.01-1.17, p = 0.029) were finally associated with MACE. Receiver operating characteristic (ROC) analyses show that the area under the curve (AUC) of GLS was large (0.73 [95% CI, 0.63-0.82], p = 0.001), and the best cut-off was -11.8%, with 76.7% sensitivity and 58.9% specificity, which are greater than those of IS (0.70, 95% CI, 0.60-0.81, p < 0.001) and MVO (0.68, 95% CI, 0.58-0.78, p < 0.001). However, combining MVO and GLS resulted in a much greater finding (AUC = 0.775, 95% CI: 0.727-0.824, p < 0.001) and better sensitivity and specificity (83.3%, 66.5%).

Conclusion

Microvascular occlusion identification from contrast-enhanced cine combined with myocardial strain could be a quick and reliable option for patients with STEMI who underwent pPCI; it correlates well with the prognosis of patients with STEMI in terms of MACE.

Late Gadolinium Enhancement Cardiac Magnetic Resonance Imaging: From Basic Concepts to Emerging Methods

BACKGROUND

 Late gadolinium enhancement (LGE) is a widely used cardiac magnetic resonance imaging (MRI) technique to diagnose a broad range of ischemic and non-ischemic cardiomyopathies. Since its development and validation against histology already more than two decades ago, the clinical utility of LGE and its span of applications have increased considerably.

METHODS

 In this review we will present the basic concepts of LGE imaging and its diagnostic and prognostic value, elaborate on recent developments and emerging methods, and finally discuss future prospects.

RESULTS

 Continuous developments in 3 D imaging methods, motion correction techniques, water/fat-separated imaging, dark-blood methods, and scar quantification improved the performance and further expanded the clinical utility of LGE imaging.

CONCLUSION

 LGE imaging is the current noninvasive reference standard for the assessment of myocardial viability. Improvements in spatial resolution, scar-to-blood contrast, and water/fat-separated imaging further strengthened its position.

KEY POINTS

  · LGE MRI is the reference standard for the noninvasive assessment of myocardial viability. · LGE MRI is used to diagnose a broad range of non-ischemic cardiomyopathies in everyday clinical practice.. · Improvements in spatial resolution and scar-to-blood contrast further strengthened its position. · Continuous developments improve its performance and further expand its clinical utility.

CITATION FORMAT

· Holtackers RJ, Emrich T, Botnar RM et al. Late Gadolinium Enhancement Cardiac Magnetic Resonance Imaging: From Basic Concepts to Emerging Methods. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1718-4355.

Development and Validation of a Clinical and Laboratory-Based Nomogram for Predicting Coronary Microvascular Obstruction in NSTEMI Patients After Primary PCI

Objective

Cardiac microvascular obstruction (CMVO) remains a severe complication in non-ST elevation myocardial infarction (NSTEMI) patients with reperfusion therapy. We aimed at developing and validating the nomogram to predict the possibility of CMVO after primary percutaneous coronary intervention (PCI) by integrating clinical and laboratory-based information.

Methods

A total of 325 patients undergoing primary PCI for NSTEMI were recruited and divided into the training cohort (n=226) and the validating cohort (n = 99). The development of the nomogram was based on independent predictors of CMVO, and these variables were selected by multivariable logistic regression analysis.

Results

Independent predictors contained in nomogram were identified by multivariable logistic regression analysis, and these independent predictors included neutrophils (OR 1.166, 95% CI 1.044–1.303, P<0.01), hemoglobin (OR 1.037, 95% CI 1.013–1.062, P<0.01), triglyceride (OR 1.343, 95% CI 1.059; 1.704, P=0.015), Killip grade (OR 2.190, 95% CI 1.065–4.503, P=0.033), high thrombus load (OR 3.146, 95% CI 1.424–6.952, P<0.01), no-reflow (OR 3.142, 95% CI 1.419–6.955, P<0.01) and ischemic postconditioning (OR 0.445, 95% CI 0.209–0.944, P=0.035). The nomogram accurately predicted the presentation of CMVO in both the training set and validating set (AUC, 0.835 and 0.881, respectively). The results predicted by nomogram were confirmed to be highly consistent with the results of DE-CMR, both the training and validating cohorts, by Calibration plot and Hosmer-Lemeshow test. Decision curve analysis (DCA) also suggested that the nomogram was applicable in the clinic.

Conclusion

The nomogram showed good performance in predicting CMVO, and it could help clinicians optimize the clinical treatments to improve the prognosis of NSTEMI patients.

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.

Circulating Monocyte Subsets Are Associated With Extent of Myocardial Injury but Not With Type of Myocardial Infarction

Inflammation is a hallmark of the period after a myocardial infarction (MI) that is either promoted or resolved by distinct subtypes of circulating inflammatory cells. The three main monocyte subpopulations play different roles inflammation. This study examined whether the type of MI (type 1 or type 2) or the extent of myocardial injury is associated with differences in monocyte subpopulations. For this purpose, peripheral whole blood from patients with a suspected MI was used for flow cytometric measurements of the monocyte subpopulations, and myocardial injury was classified by cardiac troponin levels in serum. In patients with acute coronary syndrome (n = 82, 62.2% male) similar proportions of the monocyte subsets were associated with the two types of MI, whereas total monocyte counts were increased in patients with substantial myocardial injury vs. those with minor injury (p = 0.045). This was accompanied by a higher proportion of intermediate (p = 0.045) and classical monocytes (p = 0.059); no difference was found for non-classical monocytes (p = 0.772). In patients with chronic coronary syndrome (n = 144, 66.5% male), an independent association with myocardial injury was also observed for classical monocytes (p = 0.01) and intermediate monocytes (p = 0.08). In conclusion, changes in monocyte subpopulation counts, particularly for classical and intermediate monocytes, were related to the extent of myocardial injury in acute and stable coronary artery disease but not to the type of MI.

The Index of Microcirculatory Resistance after Primary Percutaneous Coronary Intervention Predicts Long-Term Clinical Outcomes in Patients with ST-Segment Elevation Myocardial Infarction

The index of microcirculatory resistance (IMR) is a simple method that can measure microvascular function after primary percutaneous coronary intervention (PCI) in patients with ST-segment Elevation Myocardial Infarction (STEMI). This study is to find out whether IMR predicts clinical long-term outcomes in STEMI patients. A total of 316 patients with STEMI who underwent primary PCI from 2005 to 2015 were enrolled. The IMR was measured using pressure sensor/thermistor-tipped guidewire after primary PCI. The primary endpoint was the rate of death or hospitalization for heart failure (HF) over a mean follow-up period of 65 months. The mean corrected IMR was 29.4 ± 20.0. Patients with an IMR > 29 had a higher rate of the primary endpoint compared to patients with an IMR ≤ 29 (10.3% vs. 2.1%, p = 0.001). During the follow-up period, 13 patients (4.1%) died and 6 patients (1.9%) were hospitalized for HF. An IMR > 29 was associated with an increased risk of death or hospitalization for HF (OR 5.378, p = 0.004). On multivariable analysis, IMR > 29 (OR 3.962, p = 0.022) remained an independent predictor of death or hospitalization for HF with age (OR 1.048, p = 0.049) and symptom-to-balloon time (OR 1.002, p = 0.049). High IMR was an independent predictor for poor long-term clinical outcomes in STEMI patients after primary PCI.

Quantification of myocardial hemorrhage using T2* cardiovascular magnetic resonance at 1.5T with ex-vivo validation

BACKGROUND

T2* cardiovascular magnetic resonance (CMR) is commonly used in the diagnosis of intramyocardial hemorrhage (IMH). For quantifying IMH with T2* CMR, despite the lack of consensus studies, two different methods [subject-specific T2* (ssT2*) and absolute T2* thresholding (aT2* < 20 ms)] are interchangeably used. We examined whether these approaches yield equivalent information.

METHODS

ST elevation myocardial infarction (STEMI) patients (n = 70) were prospectively recruited for CMR at 4-7 days post revascularization and for 6-month follow up (n = 43). Canines studies were performed for validation purposes, where animals (n = 20) were subject to reperfused myocardial infarction (MI) and those surviving the MI (n = 16) underwent CMR at 7 days and 8 weeks and then euthanized. Both in patients and animals, T2* of IMH and volume of IMH were determined using ssT2* and aT2* < 20 ms. In animals, ex-vivo T2* CMR and mass spectrometry for iron concentration ([Fe]Hemo) were determined on excised myocardial sections. T2* values based on ssT2* and absolute T2* threshold approaches were independently regressed against [Fe]Hemo and compared. A range of T2* cut-offs were tested to determine the optimized conditions relative to ssT2*.

RESULTS

While both approaches showed many similarities, there were also differences. Compared to ssT2*, aT2* < 20 ms showed lower T2* and volume of IMH in patients and animals independent of MI age (all p < 0.005). While T2* determined from both methods were highly correlated against [Fe]Hemo (R2 = 0.9 for both), the slope of the regression curve for ssT2* was significantly larger as compared to aT2* < 20 ms (0.46 vs. 0.32, p < 0.01). Further, slightly larger absolute T2* cut-offs (patients: 23 ms; animals: 25 ms) showed similar IMH characteristics compared to ssT2*.

CONCLUSION

Current quantification methods have excellent capacity to identify IMH, albeit the T2*of IMH and volume of IMH based on aT2* < 20 ms are smaller compared to ssT2*. Thus the method used to quantify IMH from T2* CMR may influence the diagnosis for IMH.

Tissue Mitral Annular Displacement in Patients With Myocardial Infarction - Comparison With Global Longitudinal Strain

Background: Global longitudinal strain (GLS) can predict prognosis after myocardial infarction (MI). Tissue mitral annular displacement (TMAD) is another index of longitudinal left ventricular deformity, and is less dependent on image quality than GLS. We investigated the relationship between TMAD and GLS, and their ability to predict outcomes after MI. Methods and Results: GLS and TMAD were measured on echocardiograms 2 weeks after MI in 246 consecutive patients (median age 62 years, 85.7% male). TMAD was measured from apical 4- and 2-chamber views (TMAD_4ch and TMAD_2ch, respectively), and a mean value (TMAD_av) was calculated. TMAD_4ch, TMAD_2ch, and GLS were successfully measured in 240 (97.5%), 210 (85.3%) and 214 patients (87.0%), respectively. All TMAD parameters were significantly correlated with GLS (R=0.71-0.75) and left ventricular ejection fraction (LVEF; R=0.48-0.53). TMAD parameters were weakly correlated with peak creatine kinase (CK; R=0.20) and CK-MB (R=0.21-0.25). GLS and TMAD_av were significantly associated with LVEF after 6 months (R=0.48-0.53) and all-cause mortality during the follow-up period (median 1,242 days). TMAD_av discriminated patients with higher all-cause mortality when patients were divided into 3 groups, namely upper 25%, middle range, and lower 25% of TMAD_av (P=0.041, log-rank test). GLS detected high-risk patients using 15.0% as a cut-off value. Conclusions: TMAD could be a simple and reliable alternative to GLS for predicting outcomes in patients with MI.

Acute Coronary Syndromes (ACS)-Unravelling Biology to Identify New Therapies-The Microcirculation as a Frontier for New Therapies in ACS

In acute coronary syndrome (ACS) patients, restoring epicardial culprit vessel patency and flow with percutaneous coronary intervention or coronary artery bypass grafting has been the mainstay of treatment for decades. However, there is an emerging understanding of the crucial role of coronary microcirculation in predicting infarct burden and subsequent left ventricular remodelling, and the prognostic significance of coronary microvascular obstruction (MVO) in mortality and morbidity. This review will elucidate the multifaceted and interconnected pathophysiological processes which underpin MVO in ACS, and the various diagnostic modalities as well as challenges, with a particular focus on the invasive but specific and reproducible index of microcirculatory resistance (IMR). Unfortunately, a multitude of purported therapeutic strategies to address this unmet need in cardiovascular care, outlined in this review, have so far been disappointing with conflicting results and a lack of hard clinical end-point benefit. There are however a number of exciting and novel future prospects in this field that will be evaluated over the coming years in large adequately powered clinical trials, and this review will briefly appraise these.

Functional Coronary Angiography-Derived Index of Microcirculatory Resistance in Patients With ST-Segment Elevation Myocardial Infarction

OBJECTIVES

The aim of this study was to evaluate the diagnostic accuracy and prognostic implications of angiography-derived index of microcirculatory resistance (angio-IMR) in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

The index of microcirculatory resistance (IMR) is a reliable invasive measure of coronary microvascular dysfunction in patients with STEMI. A functional coronary angiography-derived method to estimate IMR is a wire- and hyperemic agent-free alternative to IMR.

METHODS

The study population consisted of 2 independent cohorts. The diagnostic cohort comprised patients with IMR from the culprit vessel immediately after successful primary percutaneous coronary intervention (n = 31). The prognostic cohort was patients with STEMI who were successfully treated with primary percutaneous coronary intervention and followed for 10 years from the index procedure (n = 309). Angio-IMR was calculated using computational flow and pressure simulation. The primary outcome was a composite of cardiac death and readmission for heart failure over 10 years of follow-up.

RESULTS

In the diagnostic cohort, angio-IMR correlated well with IMR (R = 0.778; P < 0.001). Sensitivity, specificity, accuracy, and area under the curve of angio-IMR to predict IMR >40 U were 75.0%, 84.2%, 80.6%, and 0.899 (95% confidence interval: 0.786-0.949), respectively. In the prognostic cohort, patients with angio-IMR >40 U showed significantly higher risk for cardiac death or readmission for heart failure than did those with angio-IMR ≤40 U (46.7% vs 16.6%; adjusted hazard ratio: 2.909; 95% CI: 1.670-5.067; P < 0.001). Angio-IMR >40 U was an independent predictor of cardiac death or readmission for heart failure (hazard ratio: 2.173; 95% CI: 1.157-4.079; P = 0.016) and showed incremental prognostic value compared with a model with clinical risk factors only (C index = 0.726 vs 0.666 [P < 0.001], net reclassification index = 0.704 [P < 0.001]).

CONCLUSIONS

Angio-IMR showed high correlation and diagnostic accuracy to predict IMR. Patients with STEMI with angio-IMR >40 U showed a significantly higher risk for cardiac death or readmission for heart failure than those with preserved angio-IMR values. (Prognostic Implication of Angiography-Derived IMR in STEMI Patients; NCT04628377).

Relationship between blood viscosity and no-reflow phenomenon in ST-segment elevation myocardial infarction performed in primary percutaneous coronary interventions

Background: This study aimed to analyze the associations between no-reflow (NR) phenomenon development and whole-blood viscosity in patients with ST-elevated myocardial infarction. Methods: A total of 217 patients with ST-elevated myocardial infarction were included. whole-blood viscosity values were assessed using hematocrit and total protein values, and low shear rate (LSR) and high shear rate (HSR) were calculated. Results: The average LSR and HSR values of the study group were significantly higher than the control group (p < 0.001). Multivariate logistic regression analysis showed that both HSR (odds ratio: 4.957; p < 0.001) and LSR (odds ratio: 1.114; p < 0.001) were independent predictors for NR development. Conclusion: This study found that increased blood viscosity was an independent predictor for NR development.

Enhancement patterns detected by multidetector computed tomography are associated with the long-term prognosis of patients with acute myocardial infarction

The present study investigated the clinical value of myocardial contrast-delayed enhancement (DE) with multidetector computed tomography (MDCT) without iodine re-injection immediately after primary percutaneous coronary intervention (PCI) for predicting future cardiovascular events after acute myocardial infarction (AMI). We performed a prospective study in which 263 consecutive patients with first AMI successfully treated with primary PCI were enrolled. Sixty-four-slice MDCT without the re-injection of contrast medium was performed immediately after PCI. Myocardial DE was considered to be transmural when involving myocardial thickness ≥ 75% (Group A; n = 104), subendocardial (< 75%, Group B; n = 108), or normal (Group C; n = 51). A semiquantitative scale score was defined for 17 left ventricular segments to investigate the extent of the DE area assessed. We examined the relationship between the presence or absence of transmural DE and long-term cardiovascular event rates. The median follow-up period was 3.5 years. Kaplan-Meier survival curves showed that patient prognosis was poorer in the group with Group A than that in the group with Group B, which was equivalent to that with Group C. A multivariate analysis identified the presence of transmural DE as the strongest predictor for future cardiovascular events (hazard ratio: 3.7; P = 0.023). Transmural myocardial DE immediately following primary PCI without an iodine re-injection for AMI is a major risk factor for future cardiovascular events.

Cardiovascular Magnetic Resonance Imaging and Heart Failure

Purpose of Review

The purpose of this review is to summarize the application of cardiac magnetic resonance (CMR) in the diagnostic and prognostic evaluation of patients with heart failure (HF).

Recent Findings

CMR is an important non-invasive imaging modality in the assessment of ventricular volumes and function and in the analysis of myocardial tissue characteristics. The information derived from CMR provides a comprehensive evaluation of HF. Its unique ability of tissue characterization not only helps to reveal the underlying etiologies of HF but also offers incremental prognostic information.

Summary

CMR is a useful non-invasive tool for the diagnosis and assessment of prognosis in patients suffering from heart failure.

Low Ankle-Brachial Index is Associated with Microvascular Coronary Obstruction After Primary PCI

Introduction

Percutaneous coronary intervention (PCI) has improved recanalization of infarct-related arteries (IRA); however, TIMI-III flow does not always mean an efficient myocardial reperfusion. Myocardial blush grade (MBG) is used as a predictor for coronary microvascular obstruction. We assessed the association between ankle-brachial index (ABI), a widely used method for diagnosis of peripheral arterial disease (PAD), and coronary microvascular obstruction (MVO) as detected by MBG after primary PCI.

Patients and Methods

The study included 335 patients with ST-elevation myocardial infarction who had primary PCI. History taking, clinical examination, laboratory assessment, ECG and Echocardiography were done for every participant. MBG was assessed for patients after PCI procedure. ABI for all participating patients was calculated.

Results

Two hundred and sixty-one patients fulfilled the inclusion criteria with mean age 58.8 ± 10.7 years, 84% were males. Sixty-one percent had anterior wall myocardial infarction. After primary PCI, despite achieving TIMI flow III in all study patients, only 37% had normal MBG. There was a statistically significant relationship between MBG and site of infarction, left ventricular ejection fraction and ABI. Low ABI was found to predict poor MBG.

Conclusion

Coronary artery disease (CAD) is well linked to PAD. MBG can be used to assess coronary MVO after primary PCI. Poor MBG is associated with low ABI. This could establish a relationship between PAD and coronary MVO after primary PCI.

Index of microvascular resistance and outcomes following intra-coronary thrombolysis with percutaneous intervention in STEMI: a meta-analysis of randomized control trials

Microvascular obstruction following percutaneous coronary intervention (PCI) is highly prevalent and independently associated with adverse clinical outcomes. Microvascular obstruction is determined by index of the microvascular resistance. We performed a systematic review with meta-analysis of all published randomized clinical trials (RCTs) studying the effect of intra-coronary thrombolysis with PCI as compared to standard treatment among patients with ST-segment elevated myocardial infarction. We included 6 RCTs summing up to 947 patients in the final analysis. Intra-coronary thrombolysis resulted in significantly lower index of microvascular resistance [standardized mean difference: - 13.74, 95% confidence interval (CI): - 16.74 to - 10.73, P value < 0.001, I² = 0%]. There was no difference noted in the occurrence of major adverse cardiac events with intra-coronary thrombolysis as compared to standard treatment [Odds ratio:  0.71, 95% CI: 0.46-1.08, P value = 0.11,  I² = 0%]. The absence of heterogeneity deferred us from using dose-response analysis to account for altering dose used across studies. The results of the present meta-analysis highlights the role of intra-coronary thrombolysis in reducing microvascular obstruction. No effect of intra-coronary thrombolysis was noted on the occurrence of major adverse cardiac events.

Prognosis of early pre-discharge and late left ventricular dilatation by cardiac magnetic resonance imaging after acute myocardial infarction

To study the long-term prognosis of early pre-discharge and late left ventricular (LV) dilatation in patients with first ST-elevation myocardial infarction (STEMI) treated by percutaneous coronary intervention (PCI) and contemporary medical therapy. Long-term follow-up > 15 years was available in 53 consecutive patients (55 ± 13 years) with first STEMI. Late gadolinium enhanced (LGE) cardiac magnetic resonance imaging (CMR) was obtained at baseline 5 ± 3 days and follow-up 8 ± 3 months after STEMI to measure LV function, volumes and infarct size. Early pre-discharge dilatation was defined as increased left ventricular end-diastolic volume index (LVEDVi) at baseline CMR with > 97 ml/m² for males and > 90 ml/m² for females. Late dilatation was defined as initially normal LVEDVi, which increased ≥ 20% at follow-up. Early dilatation was present in 7 patients (13%), whereas late dilatation occurred in 11 patients (21%). Patients with early LV dilatation had highest mortality (57%), whereas patients with late dilatation had similar mortality (27%) compared to patients without dilatation (26%). Multivariate Cox analysis showed that age (P < 0.001), ejection fraction at baseline (P < 0.01) and early dilatation (P < 0.01) were independent predictors of death. Early dilatation qualified as an exclusive independent predictor of long-term mortality after adjustment for age and ejection fraction (P < 0.05, hazard ratio: 2.2, 95% confidence interval: 1.2 to 7.9). Early pre-discharge LV dilatation by CMR enabled strong long-term risk stratification after STEMI. The high mortality of early LV dilatation underscores the clinical importance of this post-infarction complication, which occurred despite PCI and contemporary medical therapy.

Hemorrhage promotes chronic adverse remodeling in acute myocardial infarction: a T1 , T2 and BOLD study

Hemorrhage is recognized as a new independent predictor of adverse outcomes following acute myocardial infarction. However, the mechanisms of its effects are less understood. The aim of our study was to probe the downstream impact of hemorrhage towards chronic remodeling, including inflammation, vasodilator function and matrix alterations in an experimental model of hemorrhage. Myocardial hemorrhage was induced in the porcine heart by intracoronary injection of collagenase. Animals (N = 18) were subjected to coronary occlusion followed by reperfusion in three groups (six/group): 8 min ischemia with hemorrhage (+HEM), 45 min infarction with no hemorrhage (I - HEM) and 45 min infarction with hemorrhage (I + HEM). MRI was performed up to 4 weeks after intervention. Cardiac function, edema (T₂ , T₁ ), hemorrhage (T₂ *), vasodilator function (T₂ BOLD), infarction and microvascular obstruction (MVO) and partition coefficient (pre- and post-contrast T₁ ) were computed. Hemorrhage was induced only in the +HEM and I + HEM groups on Day 1 (low T₂ * values). Infarct size was the greatest in the I + HEM group, while the +HEM group showed no observable infarct. MVO was seen only in the I + HEM group, with a 40% occurrence rate. Function was compromised and ventricular volume was enlarged only in the hemorrhage groups and not in the ischemia-alone group. In the infarct zone, edema and matrix expansion were the greatest in the I + HEM group. In the remote myocardium, T₂ elevation and matrix expansion associated with a transient vasodilator dysfunction were observed in the hemorrhage groups but not in the ischemia-alone group. Our study demonstrates that the introduction of myocardial hemorrhage at reperfusion results in greater myocardial damage, upregulated inflammation, chronic adverse remodeling and remote myocardial alterations beyond the effects of the initial ischemic insult. A systematic understanding of the consequences of hemorrhage will potentially aid in the identification of novel therapeutics for high-risk patients progressing towards heart failure.

Estimation of Major Adverse Cardiovascular Events in Patients With Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A Risk Prediction Score Model From a Derivation and Validation Study

Background: The population with myocardial infarction (MI) undergoing primary percutaneous coronary intervention (PPCI) is growing, but validated models to guide their clinical management are lacking. This study aimed to develop and validate prognostic models to predict major adverse cardiovascular events (MACEs) in patients with MI undergoing PPCI.

Methods and Results: Models were developed in 4,151 patients with MI who underwent PPCI in Fuwai Hospital between January 2010 and June 2017, with a median follow-up of 698 days during which 544 MACEs occurred. The predictors included in the models were age, a history of diabetes mellitus, atrial fibrillation, chronic kidney disease, coronary artery bypass grafting, the Killip classification, ejection fraction at admission, the high-sensitivity C-reactive protein (hs-CRP) level, the estimated glomerular filtration rate, the d-dimer level, multivessel lesions, and the culprit vessel. The models had good calibration and discrimination in the derivation and internal validation with C-indexes of 0.74 and 0.60, respectively, for predicting MACEs. The new prediction model and Thrombolysis in Myocardial Infarction (TIMI) risk score model were compared using the receiver operating characteristic curve. The areas under the curve of the new prediction model and TIMI risk score model were 0.806 and 0.782, respectively (difference between areas = 0.024 < 0.05; z statistic, 1.718).

Conclusion: The new prediction model could be used in clinical practice to support risk stratification as recommended in clinical guidelines.