Cardiovascular Magnetic Resonance in Acute ST-Segment-Elevation Myocardial Infarction: Recent Advances, Controversies, and Future Directions

A coronary CT angiography-derived myocardial radiomics model for predicting adverse outcomes in chronic myocardial infarction

BACKGROUND

The prognostic efficacy of a coronary computed tomography angiography (CCTA)-derived myocardial radiomics model in patients with chronic myocardial infarction (MI) is unclear.

METHODS

In this retrospective study, a cohort of 236 patients with chronic MI who underwent both CCTA and cardiac magnetic resonance (CMR) examinations within 30 days were enrolled and randomly divided into training and testing datasets at a ratio of 7:3. The clinical endpoints were major adverse cardiovascular events (MACE), defined as all-cause death, myocardial reinfarction and heart failure hospitalization. The entire three-dimensional left ventricular myocardium on CCTA images was segmented as the volume of interest for the extraction of radiomics features. Five models, namely the clinical model, CMR model, clinical+CMR model, CCTA-radiomics model, and clinical+CCTA-radiomics model, were constructed using multivariate Cox regression. The prognostic performances of these models were evaluated through receiver operating characteristic curve analysis and the index of concordance (C-index).

RESULTS

Fifty-one (20.16%) patients experienced MACE during a median follow-up of 1439.5 days. The predictive performance of the CCTA-radiomics model surpassed that of the clinical model, CMR model, and clinical+CMR model in both the training (area under the curve (AUC) of 0.904 vs. 0.691, 0.764, 0.785; C-index of 0.88 vs. 0.71, 0.75, 0.76, all p values <0.001) and testing (AUC of 0.893 vs. 0.704, 0.851, 0.888; C-index of 0.86 vs. 0.73, 0.85, 0.85, all p values <0.05) datasets.

CONCLUSIONS

The CCTA-based myocardial radiomics model is a valuable tool for predicting adverse outcomes in chronic MI, providing incremental value to conventional clinical and CMR parameters.

Conditions for late gadolinium enhancement MRI in myocardial infarction model rats that better reflect microscopic tissue staining

Late gadolinium enhancement (LGE) is a widely used magnetic resonance imaging method for assessing cardiac disease. However, the relationship between different LGE signal thresholds and microscopic tissue staining images is unclear. In this study, we performed cardiovascular MRI on myocardial infarction (MI) model rats and evaluated the relationship between LGE with different signal thresholding methods and tissue staining images. We prepared 16 rats that underwent MRI 14-18 days following a surgery to create an MI model. We captured cine and LGE images of the cardiac short-axis and longitudinal two- and four-chamber views. The mean ± 2SD, ± 3SD, and ± 5SD of the pixel values in the non-infarcted area were defined as the LGE area. We compared areas of Sirius red staining, determined by the color tone, with their respective LGE areas at end-diastole and end-systole. We observed that the LGE area calculated as the mean ± 2SD of the non-infarcted area at end-diastole demonstrated a significant positive correlation with the area of Sirius red staining (Pearson's correlation coefficient in both: 0.81 [p < 0.01]). Therefore, the LGE area calculated as the mean ± 2SD of the non-infarcted area at end-diastole best reflected the MI area in tissue staining.

Precision imaging of cardiac function and scar size in acute and chronic porcine myocardial infarction using ultrahigh-field MRI

BACKGROUND

7 T cardiac magnetic resonance imaging (MRI) studies may enable higher precision in clinical metrics like cardiac function, ventricular mass, and more. Higher precision may allow early detection of functional impairment and early evaluation of treatment responses in clinical practice and pre-clinical studies.

METHODS

Seven female German Landrace pigs were scanned prior to and at three time points (3-4 days, 7-10 days, and ~60 days) post myocardial infarction using a whole body 7 T system and three radiofrequency (RF) coils developed and built in-house to accompany animal growth.

RESULTS

The combination of dedicated RF hardware and 7 T MRI enables a longitudinal study in a pig model of acute and chronic infarction, providing consistent blood tissue contrast and high signal-to-noise ratio (SNR) in measurements of cardiac function, as well as low coefficients of variation (CoV) for ejection fraction (CoVintra-observer: 2%, CoVinter-observer: 3.8%) and infarct size (CoVintra-observer: 8.4%, CoVinter-observer: 3.8%), despite drastic animal growth.

CONCLUSIONS

Best results are achieved via manual segmentation. We define state-of-the-art procedures for large animal studies at 7 T.

Effect of Cangrelor on Infarct Size in ST-Segment-Elevation Myocardial Infarction Treated by Primary Percutaneous Coronary Intervention: A Randomized Controlled Trial (The PITRI Trial)

BACKGROUND

The administration of intravenous cangrelor at reperfusion achieves faster onset of platelet P2Y12 inhibition than oral ticagrelor and has been shown to reduce myocardial infarction (MI) size in the preclinical setting. We hypothesized that the administration of cangrelor at reperfusion will reduce MI size and prevent microvascular obstruction in patients with ST-segment-elevation MI undergoing primary percutaneous coronary intervention.

METHODS

This was a phase 2, multicenter, randomized, double-blind, placebo-controlled clinical trial conducted between November 2017 to November 2021 in 6 cardiac centers in Singapore. Patients were randomized to receive either cangrelor or placebo initiated before the primary percutaneous coronary intervention procedure on top of oral ticagrelor. The key exclusion criteria included presenting <6 hours of symptom onset; previous MI and stroke or transient ischemic attack; on concomitant oral anticoagulants; and a contraindication for cardiovascular magnetic resonance. The primary efficacy end point was acute MI size by cardiovascular magnetic resonance within the first week expressed as percentage of the left ventricle mass (%LVmass). Microvascular obstruction was identified as areas of dark core of hypoenhancement within areas of late gadolinium enhancement. The primary safety end point was Bleeding Academic Research Consortium-defined major bleeding in the first 48 hours. Continuous variables were compared by Mann-Whitney U test (reported as median [first quartile-third quartile]), and categorical variables were compared by Fisher exact test. A 2-sided P<0.05 was considered statistically significant.

RESULTS

Of 209 recruited patients, 164 patients (78%) completed the acute cardiovascular magnetic resonance scan. There were no significant differences in acute MI size (placebo, 14.9% [7.3-22.6] %LVmass versus cangrelor, 16.3 [9.9-24.4] %LVmass; P=0.40) or the incidence (placebo, 48% versus cangrelor, 47%; P=0.99) and extent of microvascular obstruction (placebo, 1.63 [0.60-4.65] %LVmass versus cangrelor, 1.18 [0.53-3.37] %LVmass; P=0.46) between placebo and cangrelor despite a 2-fold decrease in platelet reactivity with cangrelor. There were no Bleeding Academic Research Consortium-defined major bleeding events in either group in the first 48 hours.

CONCLUSIONS

Cangrelor administered at the time of primary percutaneous coronary intervention did not reduce acute MI size or prevent microvascular obstruction in patients with ST-segment-elevation MI given oral ticagrelor despite a significant reduction of platelet reactivity during the percutaneous coronary intervention procedure.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03102723.

[Predictive value of global longitudinal strain measured by cardiac magnetic resonance imaging for left ventricular remodeling after acute ST-segment elevation myocardial infarction: a multi-centered prospective study]

OBJECTIVE

To evaluate the predictive value of global longitudinal strain (GLS) measured by cardiac magnetic resonance (CMR) feature-tracking technique for left ventricular remodeling (LVR) after percutaneous coronary intervention (PCI) in patients with acute ST-segment elevation myocardial infarction (STEMI).

METHODS

A total of 403 patients undergoing PCI for acute STEMI were prospectively recruited from multiple centers in China.CMR examinations were performed one week (7±2 days) and 6 months after myocardial infarction to obtain GLS, global radial strain (GRS), global circumferential strain (GCS), ejection fraction (LVEF) and infarct size (IS).The primary endpoint was LVR, defined as an increase of left ventricle end-diastolic volume by ≥20% or an increase of left ventricle end-systolic volume by ≥15% from the baseline determined by CMR at 6 months.Logistic regression analysis was performed to evaluate the predictive value of CMR parameters for LVR.

RESULTS

LVR occurred in 101 of the patients at 6 months after myocardial infarction.Compared with those without LVR (n=302), the patients in LVR group exhibited significantly higher GLS and GCS (P < 0.001) and lower GRS and LVEF (P < 0.001).Logistic regression analysis indicated that both GLS (OR=1.387, 95%CI: 1.223-1.573;P < 0.001) and LVEF (OR=0.951, 95%CI: 0.914-0.990;P=0.015) were independent predictors of LVR.ROC curve analysis showed that at the optimal cutoff value of-10.6%, GLS had a sensitivity of 74.3% and a specificity of 71.9% for predicting LVR.The AUC of GLS was similar to that of LVEF for predicting LVR (P=0.146), but was significantly greater than those of other parameters such as GCS, GRS and IS (P < 0.05);the AUC of LVEF did not differ significantly from those of the other parameters (P>0.05).

CONCLUSION

In patients receiving PCI for STEMI, GLS measured by CMR is a significant predictor of LVR occurrence with better performance than GRS, GCS, IS and LVEF.

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

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

Cardiac Magnetic Resonance Evaluation of LV Remodeling Post-Myocardial Infarction: Prognosis, Monitoring and Trial Endpoints

Adverse left ventricular remodeling (ALVR) and subsequent heart failure after myocardial infarction (MI) remain a major cause of patient morbidity and mortality worldwide. Overt inflammation has been identified as the common pathway underlying myocardial fibrosis and development of ALVR post-MI. With its ability to simultaneously provide information about cardiac structure, function, perfusion, and tissue characteristics, cardiac magnetic resonance (CMR) is well poised to inform prognosis and guide early surveillance and therapeutics in high-risk cohorts. Further, established and evolving CMR-derived biomarkers may serve as clinical endpoints in prospective trials evaluating the efficacy of novel anti-inflammatory and antifibrotic therapies. This review provides an overview of post-MI ALVR and illustrates how CMR may help clinical adoption of novel therapies via mechanistic or prognostic imaging markers.

Coronary microvascular obstruction and dysfunction in patients with acute myocardial infarction

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

Predicting left ventricular remodeling post-MI through coronary physiological measurements based on computational fluid dynamics

Early detection of left ventricular remodeling (LVR) is crucial. While cardiac magnetic resonance (CMR) provides valuable information, it has limitations. Coronary angiography-derived fractional flow reserve (caFFR) and index of microcirculatory resistance (caIMR) offer viable alternatives. 157 patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention were prospectively included. 23.6% of patients showed LVR. Machine learning algorithms constructed three LVR prediction models: Model 1 incorporated clinical and procedural parameters, Model 2 added CMR parameters, and Model 3 included echocardiographic and functional parameters (caFFR and caIMR) with Model 1. The random forest algorithm showed robust performance, achieving AUC of 0.77, 0.84, and 0.85 for Models 1, 2, and 3. SHAP analysis identified top features in Model 2 (infarct size, microvascular obstruction, admission hemoglobin) and Model 3 (current smoking, caFFR, admission hemoglobin). Findings indicate coronary physiology and echocardiographic parameters effectively predict LVR in patients with STEMI, suggesting their potential to replace CMR.

Comprehensive characterization of cardiac contraction for improved post-infarction risk assessment

This study aims at identifying risk-related patterns of left ventricular contraction dynamics via novel volume transient characterization. A multicenter cohort of AMI survivors (n = 1021) who underwent Cardiac Magnetic Resonance (CMR) after infarction was considered for the study. The clinical endpoint was the 12-month rate of major adverse cardiac events (MACE, n = 73), consisting of all-cause death, reinfarction, and new congestive heart failure. Cardiac function was characterized from CMR in 3 potential directions: by (1) volume temporal transients (i.e. contraction dynamics); (2) feature tracking strain analysis (i.e. bulk tissue peak contraction); and (3) 3D shape analysis (i.e. 3D contraction morphology). A fully automated pipeline was developed to extract conventional and novel artificial-intelligence-derived metrics of cardiac contraction, and their relationship with MACE was investigated. Any of the 3 proposed directions demonstrated its additional prognostic value on top of established CMR indexes, myocardial injury markers, basic characteristics, and cardiovascular risk factors (P < 0.001). The combination of these 3 directions of enhancement towards a final CMR risk model improved MACE prediction by 13% compared to clinical baseline (0.774 (0.771-0.777) vs. 0.683 (0.681-0.685) cross-validated AUC, P < 0.001). The study evidences the contribution of the novel contraction characterization, enabled by a fully automated pipeline, to post-infarction assessment.

Cardiac Magnetic Resonance Imaging as a Risk Stratification Tool in COVID-19 Myocarditis

The aim of this retrospective study was to identify myocardial injury after COVID-19 inflammation and explore whether myocardial damage could be a possible cause of the persistent symptoms following COVID-19 infection in previously healthy individuals. This study included 139 patients who were enrolled between January and June 2021, with a mean age of 46.7 ± 15.2 years, of whom 68 were men and 71 were women without known cardiac or pulmonary diseases. All patients underwent clinical work-up, laboratory analysis, cardiac ultrasound, and CMR on a 1.5 T scanner using a recommended protocol for morphological and functional assessment before and after contrast media application with multi-parametric sequences. In 39% of patients, late gadolinium enhancement (LGE) was found as a sign of myocarditis. Fibrinogen was statistically significantly higher in patients with LGE than in those without LGE (4.3 ± 0.23 vs. 3.2 ± 0.14 g/L, p < 0.05, respectively), as well as D-dimer (1.8 ± 0.3 vs. 0.8 ± 0.1 mg/L FEU). Also, troponin was statistically significantly higher in patients with myocardial LGE (13.1 ± 0.4 ng/L) compared to those with normal myocardium (4.9 ± 0.3 ng/L, p < 0.001). We demonstrated chest pain, fatigue, and elevated troponin to be independent predictors for LGE. Septal LGE was shown to be a predictor for arrhythmias. The use of CMR is a potential risk stratification tool in evaluating outcomes following COVID-19 myocarditis.

[Predictive value of cardiac magnetic resonance imaging for adverse left ventricular remodeling after acute ST-segment elevation myocardial infarction]

OBJECTIVE

To assess the value of cardiac magnetic resonance (CMR) imaging for predicting adverse left ventricular remodeling in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

We retrospectively analyzed the clinical data and serial CMR (cine and LGE sequences) images of 86 STEMI patients within 1 week and 5 months after percutaneous coronary intervention (PCI), including 25 patients with adverse LV remodeling and 61 without adverse LV remodeling, defined as an increase of left ventricular end-systolic volume (LVESV) over 15% at the second CMR compared to the initial CMR. The CMR images were analyzed for LV volume, infarct characteristics, and global and infarct zone myocardial function. The independent predictors of adverse LV remodeling following STEMI were analyzed using univariate and multivariate Logistic regression methods.

RESULTS

The initial CMR showed no significant differences in LV volume or LV ejection fraction (LVEF) between the two groups, but the infarct mass and microvascular obstructive (MVO) mass were significantly greater in adverse LV remodeling group (P < 0.05). Myocardial injury and cardiac function of the patients recovered over time in both groups. At the second CMR, the patients with adverse LV remodeling showed a significantly lower LVEF, a larger left ventricular end-systolic volume index (LVESVI) and a greater extent of infarct mass (P < 0.001) with lower global peak strains and strain rates in the radial, circumferential, and longitudinal directions (P < 0.05), infarct zone peak strains in the 3 directions, and infarct zone peak radial and circumferential strain rates (P < 0.05). The independent predictors for adverse LV remodeling following STEMI included the extent of infarct mass (AUC=0.793, 95% CI: 0.693-0.873; cut-off value: 30.67%), radial diastolic peak strain rate (AUC=0.645, 95% CI: 0.534-0.745; cut-off value: 0.58%), and RAAS inhibitor (AUC= 0.699, 95% CI: 0.590-0.793).

CONCLUSION

The extent of infarct mass, peak radial diastolic strain rate, and RAAS inhibitor are independent predictors of adverse LV remodeling following STEMI.

A novel intracoronary hypothermia device reduces myocardial reperfusion injury in pigs

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mechanisms of Myocardial Edema Development in CVD Pathophysiology

Myocardial edema is the excess accumulation of fluid in the myocardial interstitium or cardiac cells that develops due to changes in capillary permeability, loss of glycocalyx charge, imbalance in lymphatic drainage, or a combination of these factors. Today it is believed that this condition is not only a complication of cardiovascular diseases, but in itself causes aggravation of the disease and increases the risks of adverse outcomes. The study of molecular, genetic, and mechanical changes in the myocardium during edema may contribute to the development of new approaches to the diagnosis and treatment of this condition. This review was conducted to describe the main mechanisms of myocardial edema development at the molecular and cellular levels and to identify promising targets for the regulation of this condition based on articles cited in Pubmed up to January 2024.

No-reflow after stroke reperfusion therapy: An emerging phenomenon to be explored

In the field of stroke thrombectomy, ineffective clinical and angiographic reperfusion after successful recanalization has drawn attention. Partial or complete microcirculatory reperfusion failure after the achievement of full patency of a former obstructed large vessel, known as the "no-reflow phenomenon" or "microvascular obstruction," was first reported in the 1960s and was later detected in both experimental models and patients with stroke. The no-reflow phenomenon (NRP) was reported to result from intraluminal occlusions formed by blood components and extraluminal constriction exerted by the surrounding structures of the vessel wall. More recently, an emerging number of clinical studies have estimated the prevalence of the NRP in stroke patients following reperfusion therapy, ranging from 3.3% to 63% depending on its evaluation methods or study population. Studies also demonstrated its detrimental effects on infarction progress and neurological outcomes. In this review, we discuss the research advances, underlying pathogenesis, diagnostic techniques, and management approaches concerning the no-reflow phenomenon in the stroke population to provide a comprehensive understanding of this phenomenon and offer references for future investigations.

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

Background and Aims

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

Methods and Results

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

Conclusion

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

[Novel Application of Post-contrast T1map for Detection of Subendocardial Infarction]

In cardiac magnetic resonance (CMR) for myocardial infarction, there have been quite a few cases of obscure image contrast between subendocardial lesion and left ventricular (LV) blood pool on late gadolinium enhancement (LGE) images. This study was motivated by confirmation of usefulness of post-contrast T1map for detection of subendocardial infarction. From June 2017 to May 2018, forty-eight consecutive patients who underwent contrast-enhanced CMR to assess myocardial infarction were reviewed. We measured the contrast ratio (CR) between the infarcted myocardium and LV blood pool on LGE and on post-contrast T1map images, and compared them. The CR (mean±standard deviation) was -0.04±0.11 for LGE images and 0.02±0.04 for post-contrast T1map images (P<0.05). These results suggest that the post-contrast T1map, which uses the difference in T1 value as image contrast rather than magnitude image, can clearly depict the boundary between the infarcted myocardium and LV blood pool. The addition of post-contrast T1map to image interpretation might provide valuable information in the evaluation of subendocardial infarction.

Cardiac magnetic resonance for the early prediction of reverse left ventricular remodeling in patients with ST-segment elevation myocardial infarction

OBJECTIVES

To evaluate the changes in cardiac magnetic resonance (CMR) characteristics and investigate the predictors of reverse left ventricular remodeling (r-LVR) in ST-segment elevation myocardial infarction (STEMI) patients.

MATERIALS AND METHODS

Eighty-six STEMI patients (median 56 years) were retrospectively studied. The patients were divided into r-LVR and without r-LVR groups. CMR analysis included LV volume, infarct characteristics, and global and regional myocardial function. The strain and displacement were assessed by CMR-feature tracking. The predictors of r-LVR were analyzed by the logistic regression method.

RESULTS

There were 37 patients in the r-LVR group and 49 patients in the without r-LVR group. At initial CMR, there was no difference in LV volume and global cardiac function between the two groups. However, the infarct zone radial and longitudinal displacements were higher in the r-LVR group (p < 0.05, respectively). At the second CMR, the r-LVR group showed higher LVEF, lower LV volume, and total enhanced mass (all p < 0.05). The infarct zone radial and circumferential strains and radial displacement were higher in the r-LVR group (all p < 0.05). The r-LVR group had better recovery of myocardial injury and function. Of note, microvascular obstruction (MVO) mass (odds ratio: 0.779 (0.613-0.989), p = 0.041) and infarct zone peak longitudinal displacement (PLD) (odds ratio: 1.448 (1.044-2.008), p = 0.026) were independent predictors of r-LVR.

CONCLUSIONS

At initial CMR, there were no differences in global cardiac function between the two groups, but infarct zone displacements were higher in the r-LVR group. The r-LVR group had better recovery of cardiac function. In addition, MVO mass and infarct zone PLD were independent predictors of r-LVR.

CLINICAL RELEVANCE STATEMENT

Our study assessed changes in cardiac structure, function, and tissue characteristics after STEMI by CMR, investigated the best predictors of r-LVR in STEMI patients, and laid the foundation for the development of new parameter-guided treatment strategies for STEMI patients.

KEY POINTS

• At initial CMR, the reverse left ventricular remodeling (r-LVR) group had less myocardial damage and higher infarct zone displacement, but there were no differences in global function between the two groups. • Both groups showed recovery of myocardial injury and cardiac function over time, but the r-LVR group had less enhanced mass and better cardiac function compared to the without r-LVR group at the second CMR. • Microvascular obstruction mass and infarct zone peak longitudinal displacement by cardiac magnetic resonance feature-tracking were significant predictors of r-LVR in STEMI patients.

MRI Investigation of the Differential Impact of Left Ventricular Ejection Fraction After Myocardial Infarction in Elderly vs. Nonelderly Patients to Predict Readmission for Heart Failure

BACKGROUND

Patients with ST-segment elevation myocardial infarction (STEMI), especially elderly individuals, have an increased risk of readmission for acute heart failure (AHF).

PURPOSE

To study the impact of left ventricular ejection fraction (LVEF) by MRI to predict AHF in elderly (>70 years) and nonelderly patients after STEMI.

STUDY TYPE

Prospective.

POPULATION

Multicenter registry of 759 reperfused STEMI patients (23.3% elderly).

FIELD STRENGTH/SEQUENCE

1.5-T. Balanced steady-state free precession (cine imaging) and segmented inversion recovery steady-state free precession (late gadolinium enhancement) sequences.

ASSESSMENT

One-week MRI-derived LVEF (%) was quantified. Sequential MRI data were recorded in 579 patients. Patients were categorized according to their MRI-derived LVEF as preserved (p-LVEF, ≥50%), mildly reduced (mr-LVEF, 41%-49%), or reduced (r-LVEF, ≤40%). Median follow-up was 5 [2.33-7.54] years.

STATISTICAL TESTS

Univariable (Student's t, Mann-Whitney U, chi-square, and Fisher's exact tests) and multivariable (Cox proportional hazard regression) comparisons and continuous-time multistate Markov model to analyze transitions between LVEF categories and to AHF. Hazard ratios (HR) with 95% confidence intervals (CIs) were computed. P < 0.05 was considered statistically significant.

RESULTS

Over the follow-up period, 79 (10.4%) patients presented AHF. MRI-LVEF was the most robust predictor in nonelderly (HR 0.94 [0.91-0.98]) and elderly patients (HR 0.94 [0.91-0.97]). Elderly patients had an increased AHF risk across the LVEF spectrum. An excess of risk (compared to p-LVEF) was noted in patients with r-LVEF both in nonelderly (HR 11.25 [5.67-22.32]) and elderly patients (HR 7.55 [3.29-17.34]). However, the mr-LVEF category was associated with increased AHF risk only in elderly patients (HR 3.66 [1.54-8.68]). Less transitions to higher LVEF states (n = 19, 30.2% vs. n = 98, 53%) and more transitions to AHF state (n = 34, 53.9% vs. n = 45, 24.3%) were observed in elderly than nonelderly patients.

DATA CONCLUSION

MRI-derived p-LVEF confers a favorable prognosis and r-LVEF identifies individuals at the highest risk of AHF in both elderly and nonelderly patients. Nevertheless, an excess of risk was also found in the mr-LVEF category in the elderly group.

EVIDENCE LEVEL

2.

TECHNICAL EFFICACY

Stage 2.

Four- to seven-year follow-up of pharmacological postconditioning with mangafodipir as an adjunct to primary PCI in ST-segment elevation myocardial infarction

INTRODUCTION

Adverse left ventricular remodelling (AR) develops over time in approximately 30% of patients with a history of coronary artery disease. AR manifests as a structural change in the left ventricle (LV) in terms of increased volumes and reduced left ventricular ejection fraction (LVEF). Manganese dipyridoxyl diphosphate (mangafodipir) has demonstrated interesting cardioprotective features in acute myocardial ischaemia. Pharmacological postconditioning (PP) with mangafodipir as an adjunct to primary percutaneous coronary intervention may possibly reduce the development of AR over time in ST-elevation myocardial infarction (STEMI). The aim of this 4-7-year follow-up study is to investigate the potential benefits of PP with mangafodipir in STEMI patients.

METHOD

Thirteen out of the initial 20 patients that were included in the primary study of Karlsson et al. were followed up between April and June 2017. The study group underwent review of the hospital records, a clinical examination with ECG and blood sample analysis before cardiac magnetic resonance examination of the patient. LVEF, left ventricular diastolic volume, left ventricular end systolic volume, LV mass and myocardial strain in all directions were computed.

RESULTS

The PP group showed a decrease in LV volume, mass and higher LVEF at follow-up (p < 0.05) while the individual response of the placebo group showed features that are seen in AR. Although there was no difference in myocardial strain, measurement for the PP-group was higher in absolute terms.

CONCLUSION

Pharmacological postconditioning with mangafodipir in STEMI demonstrated cardioprotective features compared to the placebo group at follow-up. This article is protected by copyright. All rights reserved.

The role and mechanisms of microvascular damage in the ischemic myocardium

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

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.

An updated Lagrangian constrained mixture model of pathological cardiac growth and remodelling

Progressive left ventricular (LV) growth and remodelling (G&R) is often induced by volume and pressure overload, characterized by structural and functional adaptation through myocyte hypertrophy and extracellular matrix remodelling, which are dynamically regulated by biomechanical factors, inflammation, neurohormonal pathways, etc. When prolonged, it can eventually lead to irreversible heart failure. In this study, we have developed a new framework for modelling pathological cardiac G&R based on constrained mixture theory using an updated reference configuration, which is triggered by altered biomechanical factors to restore biomechanical homeostasis. Eccentric and concentric growth, and their combination have been explored in a patient-specific human LV model under volume and pressure overload. Eccentric growth is triggered by overstretching of myofibres due to volume overload, i.e. mitral regurgitation, whilst concentric growth is driven by excessive contractile stress due to pressure overload, i.e. aortic stenosis. Different biological constituent's adaptations under pathological conditions are integrated together, which are the ground matrix, myofibres and collagen network. We have shown that this constrained mixture-motivated G&R model can capture different phenotypes of maladaptive LV G&R, such as chamber dilation and wall thinning under volume overload, wall thickening under pressure overload, and more complex patterns under both pressure and volume overload. We have further demonstrated how collagen G&R would affect LV structural and functional adaption by providing mechanistic insight on anti-fibrotic interventions. This updated Lagrangian constrained mixture based myocardial G&R model has the potential to understand the turnover processes of myocytes and collagen due to altered local mechanical stimuli in heart diseases, and in providing mechanistic links between biomechanical factors and biological adaption at both the organ and cellular levels. Once calibrated with patient data, it can be used for assessing heart failure risk and designing optimal treatment therapies. STATEMENT OF SIGNIFICANCE: Computational modelling of cardiac G&R has shown high promise to provide insight into heart disease management when mechanistic understandings are quantified between biomechanical factors and underlying cellular adaptation processes. The kinematic growth theory has been dominantly used to phenomenologically describe the biological G&R process but neglecting underlying cellular mechanisms. We have developed a constrained mixture based G&R model with updated reference by taking into account different mechanobiological processes in the ground matrix, myocytes and collagen fibres. This G&R model can serve as a basis for developing more advanced myocardial G&R models further informed by patient data to assess heart failure risk, predict disease progression, select the optimal treatment by hypothesis testing, and eventually towards a truly precision cardiology using in-silico models.

Cardiac Magnetic Resonance-Detected Acute Myocardial Edema as Predictor of Favourable Prognosis: A Comprehensive Review

Acute myocardial edema (AME) is increased water content in the myocardium and represents the first and transient pathophysiological response to an acute myocardial injury. In-vivo and non-invasive evaluation is feasible with cardiac magnetic resonance (CMR), which is a powerful imaging technique capable of tissue characterization. In the clinical setting, early demonstration of AME has a recognized diagnostic value for acute coronary syndromes and acute myocarditis, although its prognostic value is not well established. This article provides a comprehensive narrative review on the clinical meaning of AME in heart diseases. In particular, the available evidence of a possible favourable prognostic value in several clinical scenarios is addressed.

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

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

Imaging Predictors of Left Ventricular Functional Recovery after Reperfusion Therapy of ST-Elevation Myocardial Infarction Assessed by Cardiac Magnetic Resonance

BACKGROUND

Left ventricular global longitudinal strain (LV GLS) is a superior predictor of adverse cardiac events in patients with myocardial infarction and heart failure. We investigated the ability of morphological features of infarcted myocardium to detect acute left ventricular (LV) dysfunction and predict LV functional recovery after three months in patients with acute ST-segment elevation myocardial infarction (STEMI).

METHODS

Sixty-six STEMI patients were included in the C-reactive protein (CRP) apheresis in Acute Myocardial Infarction Study (CAMI-1). LV ejection fraction (LVEF), LV GLS, LV global circumferential strain (LV GCS), infarct size (IS), area-at-risk (AAR), and myocardial salvage index (MSI) were assessed by CMR 5 ± 3 days (baseline) and 12 ± 2 weeks after (follow-up) the diagnosis of first acute STEMI.

RESULTS

Significant changes in myocardial injury parameters were identified after 12 weeks of STEMI diagnosis. IS decreased from 23.59 ± 11.69% at baseline to 18.29 ± 8.32% at follow-up (p < 0.001). AAR and MVO also significantly reduced after 12 weeks. At baseline, there were reasonably moderate correlations between IS and LVEF (r = -0.479, p < 0.001), LV GLS (r = 0.441, p < 0.001) and LV GCS (r = 0.396, p = 0.001) as well as between AAR and LVEF (r = -0.430, p = 0.003), LV GLS (r = 0.501, p < 0.001) and weak with LV GCS (r = 0.342, p = 0.020). At follow-up, only MSI and change in LV GCS over time showed a weak but significant correlation (r = -0.347, p = 0.021). Patients with larger AAR at baseline improved more in LVEF (p = 0.019) and LV GLS (p = 0.020) but not in LV GCS.

CONCLUSION

The CMR tissue characteristics of myocardial injury correlate with the magnitude of LV dysfunction during the acute stage of STEMI. AAR predicts improvement in LVEF and LV GLS, while MSI is a sensitive marker of LV GCS recovery at three months follow-up after STEMI.

Adropin - A new player in energy regulation predicts long-term prognosis of patients with acute myocardial infarction

Background

As a novel energy homeostasis regulator, Adropin not only plays a vital part in meditating energy metabolism, but also has a certain correlation with atherosclerotic diseases. The purpose of this study was to evaluate the effect of Adropin on the long-term prognosis of patients with acute myocardial infarction (AMI).

Methods

162 recruited patients with AMI were divided into low Adropin group (Adropin<166.3 pg/mL, n = 82) and high Adropin group (Adropin≥166.3 pg/mL, n = 80), according to the mean value of serum Adropin level. Patients were followed up and major adverse cardiac events (MACEs) were recorded. The Kaplan-Meier method and Cox regression model were used to evaluate the survival of patients and the related factors of cardiac events.

Results

Diabetes was more common in low Adropin group than that in high Adropin group (P < 0.05). Patients were followed up for an average of 50.3 ± 19.2 months. MACEs occurred in 37 patients (22.8%), including 6 cardiac deaths (3.7%), 14 recurrent myocardial infarction (8.6%) and 17 rehospitalization of heart failure (10.5%). The incidence of recurrent myocardial infarction in low Adropin group was higher than that in high Adropin group (13.4% vs 3.8%, P < 0.05). There was no significant difference in the overall incidence of MACE, cardiac death and rehospitalization of heart failure between the two groups. Kaplan-Meier method (log rank test) analysis results showed that patients with low Adropin had lower survival rate without recurrent myocardial infarction (log rank P = 0.035).

Conclusion

Low Adropin level was associated with an increased risk of long-term recurrent myocardial infarction in patients with AMI.

Pixel-wise statistical analysis of myocardial injury in STEMI patients with delayed enhancement MRI

Objectives

Myocardial injury assessment from delayed enhancement magnetic resonance images is routinely limited to global descriptors such as size and transmurality. Statistical tools from computational anatomy can drastically improve this characterization, and refine the assessment of therapeutic procedures aiming at infarct size reduction. Based on these techniques, we propose a new characterization of myocardial injury up to the pixel resolution. We demonstrate it on the imaging data from the Minimalist Immediate Mechanical Intervention randomized clinical trial (MIMI: NCT01360242), which aimed at comparing immediate and delayed stenting in acute ST-Elevation Myocardial Infarction (STEMI) patients.

Methods

We analyzed 123 patients from the MIMI trial (62 ± 12 years, 98 male, 65 immediate 58 delayed stenting). Early and late enhancement images were transported onto a common geometry using techniques inspired by statistical atlases, allowing pixel-wise comparisons across population subgroups. A practical visualization of lesion patterns against specific clinical and therapeutic characteristics was also proposed using state-of-the-art dimensionality reduction.

Results

Infarct patterns were roughly comparable between the two treatments across the whole myocardium. Subtle but significant local differences were observed for the LCX and RCA territories with higher transmurality for delayed stenting at lateral and inferior/inferoseptal locations, respectively (15% and 23% of myocardial locations with a p-value <0.05, mainly in these regions). In contrast, global measurements were comparable for all territories (no statistically significant differences for all-except-one measurements before standardization / for all after standardization), although immediate stenting resulted in more subjects without reperfusion injury.

Conclusion

Our approach substantially empowers the analysis of lesion patterns with standardized comparisons up to the pixel resolution, and may reveal subtle differences not accessible with global observations. On the MIMI trial data as illustrative case, it confirmed its general conclusions regarding the lack of benefit of delayed stenting, but revealed subgroups differences thanks to the standardized and finer analysis scale.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

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.

Role of Cardiac Magnetic Resonance Imaging in the Evaluation of MINOCA

Myocardial infarction with Non Obstructive Coronary Arteries (MINOCA) is defined by patients presenting with signs and symptoms similar to acute myocardial infarction, but are found to have non-obstructive coronary arteries angiography. What was once considered a benign phenomenon, MINOCA has been proven to carry with it significant morbidity and worse mortality when compared to the general population. As the awareness for MINOCA has increased, guidelines have focused on this unique situation. Cardiac magnetic resonance (CMR) has proven to be an essential first step in the diagnosis of patients with suspected MINOCA. CMR has also been shown to be crucial when differentiating between MINOCA like presentations such as myocarditis, takotsubo and other forms of cardiomyopathy. The following review focuses on demographics of patients with MINOCA, their unique clinical presentation as well as the role of CMR in the evaluation of MINOCA.

Practical Approach to Diagnosis, Prevention, and Management of Coronary No-Reflow

Coronary no-reflow (NR) defined as inadequate myocardial perfusion despite restoration of coronary artery patency is a bane for an interventional cardiologist. It can complicate percutaneous coronary interventions especially in the setting of STEMI and dampens the potential benefits of PPCI. Broadly classified as Reperfusion NR and Interventional NR, mechanism is multifactorial. The basic underlying culprit is microvascular obstruction either secondary to distal embolization, intravascular plugging, or ischemic reperfusion injury. Coronary angiogram is an easy, readily available, and essential modality to diagnose no-reflow, but the gold standard is gadolinium-enhanced cardiovascular magnetic resonance imaging. Preventive strategies for NR should be integral part of prePCI planning especially in clinical scenario where NR is expected such as STEMI with delayed presentation and high thrombus burden, atherectomy, and SVG PCI. The cornerstone of treatment for NR is local vasodilators and antiplatelet therapy to ameliorate vasospasm and thromboembolism respectively, and different combinations of the two should be used in no specific order to achieve reversal of NR. NR phenomenon is associated with poor short-term and long-term prognosis and every attempt should be made to avoid or reverse it. Therapeutic hypothermia, hyperoxemic reperfusion therapy, targeted anti-inflammatory approach, and cellular approach appear proising but further research is mandatory.

Cardiac magnetic resonance outperforms echocardiography to predict subsequent implantable cardioverter defibrillator therapies in ST-segment elevation myocardial infarction patients

Background

Implantable cardioverter defibrillators (ICD) are effective as a primary prevention measure of ventricular tachyarrhythmias in patients with ST-segment elevation myocardial infarction (STEMI) and depressed left ventricular ejection fraction (LVEF). The implications of using cardiac magnetic resonance (CMR) instead of echocardiography (Echo) to assess LVEF prior to the indication of ICD in this setting are unknown.

Materials and methods

We evaluated 52 STEMI patients (56.6 ± 11 years, 88.5% male) treated with ICD in primary prevention who underwent echocardiography and CMR prior to ICD implantation. ICD implantation was indicated based on the presence of heart failure and depressed LVEF (≤ 35%) by echocardiography, CMR, or both. Prediction of ICD therapies (ICD-T) during follow-up by echocardiography and CMR before ICD implantation was assessed.

Results

Compared to echocardiography, LVEF was lower by cardiac CMR (30.2 ± 9% vs. 37.4 ± 7.6%, p < 0.001). LVEF ≤ 35% was detected in 24 patients (46.2%) by Echo and in 42 (80.7%) by CMR. During a mean follow-up of 6.1 ± 4.2 years, 10 patients received appropriate ICD-T (3.16 ICD-T per 100 person-years): 5 direct shocks to treat very fast ventricular tachycardia or ventricular fibrillation, 3 effective antitachycardia pacing (ATP) for treatment of ventricular tachycardia, and 2 ineffective ATP followed by shock to treat ventricular tachycardia. Echo-LVEF ≤ 35% correctly predicted ICD-T in 4/10 (40%) patients and CMR-LVEF ≤ 35% in 10/10 (100%) patients. CMR-LVEF improved on Echo-LVEF for predicting ICD-T (area under the curve: 0.76 vs. 0.48, p = 0.04).

Conclusion

In STEMI patients treated with ICD, assessment of LVEF by CMR outperforms Echo-LVEF to predict the subsequent use of appropriate ICD therapies.

Mechanisms of the "No-Reflow" Phenomenon After Acute Myocardial Infarction: Potential Role of Pericytes

Pericytes contract during myocardial ischemia resulting in capillary constriction and no reflow. Reversing pericyte contraction pharmacologically reduces no reflow and infarct size. These findings open up an entire new venue of research aimed at altering pericyte function in myocardial ischemia and infarction.

Cardiac magnetic resonance predictors of left ventricular remodelling following acute ST elevation myocardial infarction: The VavirimS study

BACKGROUND

Left ventricular (LV) remodelling (REM) ensuing after ST-elevation myocardial infarction (STEMI), has typically been studied by echocardiography, which has limitations, or cardiac magnetic resonance (CMR) in early phase that may overestimate infarct size (IS) due to tissue edema and stunning. This prospective, multicenter study investigated LV-REM performing CMR in the subacute phase, and 6 months after STEMI.

METHODS AND RESULTS

patients with first STEMI undergoing successful primary angioplasty were consecutively enrolled. CMR was done at 30-days and 6-months. Primary endpoint was prevalence at 6 months of LV-REM [≥12% increase in LV end-diastolic volume index (LV-REMEDV)]; LV-REM by end-systolic volume index increase ≥12% (LV-REMESV) was also calculated. Of 325 patients enrolled, 193 with a full set of research-quality CMR images were analyzed. LV-REMEDV and LV-REMESV were present in 36/193 (19%) and 34/193 (18%) patients, respectively. At follow up, LV ejection fraction (EF) improved in patients with or without LV-REMEDV, whilst it decreased in those with LV-REMESV (p < 0.001 for interaction). Considering predictors of LV-REM, IS in the highest tertile was clearly separated from the two lower tertiles. In LV-REMEDV, the highest tertile was associated with significantly higher LV-EDV, LV-ESV, and lower EF.

CONCLUSIONS

In a contemporary cohort of STEMI patients studied by CMR, prevalence of LV-REMEDV was lower than previously reported. Importantly, our data indicate that LV-REMEDV might not be "adverse" per se, but rather "compensatory", being associated with LV-EF improvement at follow-up. Conversely, LV-REMESV might be an "adverse" phenomenon associated with decreased LV-EF, driven by IS.

The ebb and flow of cardiac lymphatics: a tidal wave of new discoveries

The heart is imbued with a vast lymphatic network that is responsible for fluid homeostasis and immune cell trafficking. Disturbances in the forces that regulate microvascular fluid movement can result in myocardial edema, which has profibrotic and proinflammatory consequences and contributes to cardiovascular dysfunction. This review explores the complex relationship between cardiac lymphatics, myocardial edema, and cardiac disease. It covers the revised paradigm of microvascular forces and fluid movement around the capillary as well as the arsenal of preclinical tools and animal models used to model myocardial edema and cardiac disease. Clinical studies of myocardial edema and their prognostic significance are examined in parallel to the recent elegant animal studies discerning the pathophysiological role and therapeutic potential of cardiac lymphatics in different cardiovascular disease models. This review highlights the outstanding questions of interest to both basic scientists and clinicians regarding the roles of cardiac lymphatics in health and disease.

Residual ST-segment elevation to predict long-term clinical and CMR-derived outcomes in STEMI

Residual ST-segment elevation after ST-segment elevation myocardial infarction (STEMI) has traditionally been considered a predictor of left ventricular (LV) dysfunction and ventricular aneurism. However, the implications in terms of long-term prognosis and cardiac magnetic resonance (CMR)-derived structural consequences are unclear. A total of 488 reperfused STEMI patients were prospectively included. The number of Q wave leads with residual ST-segment elevation > 1 mm (Q-STE) at pre-discharge ECG was assessed. LV ejection fraction (LVEF, %) and infarct size (IS, % of LV mass) were quantified in 319 patients at 6-month CMR. Major adverse cardiac events (MACE) were defined as all-cause death and/or re-admission for acute heart failure (HF), whichever occurred first. During a mean follow-up of 6.1 years, 92 MACE (18.9%), 39 deaths and 53 HF were recorded. After adjustment for baseline characteristics, Q-STE (per lead with > 1 mm) was independently associated with a higher risk of long-term MACE (HR 1.24 [1.07-1.44] per lead, p = 0.004), reduced (< 40%) LVEF (HR 1.36 [1.02-1.82] per lead, p = 0.04) and large (> 30% of LV mass) IS (HR 1.43 [1.11-1.85] per lead, p = 0.006) at 6-month CMR. Patients with Q-STE ≥ 2 leads (n = 172, 35.2%) displayed lower MACE-free survival, more depressed LVEF, and larger IS at 6-month CMR (p < 0.001 for all comparisons). Residual ST-segment elevation after STEMI represents a universally available tool that predicts worse long-term clinical and CMR-derived structural outcomes.

Unsupervised domain adaptive myocardial infarction MRI classification diagnostics model based on target domain confused sample resampling

OBJECTIVE

Inefficient circulatory system due to blockage of blood vessels leads to myocardial infarction and acute blockage. Myocardial infarction is frequently classified and diagnosed in medical treatment using MRI, yet this method is ineffective and prone to error. As a result, there are several implementation scenarios and clinical significance for employing deep learning to develop computer-aided algorithms to aid cardiologists in the routine examination of cardiac MRI.

METHODS

This research uses two distinct domain classifiers to address this issue and achieve domain adaptation between the particular field and the specific part is a problem Current research on environment adaptive systems cannot effectively obtain and apply classification information for unsupervised scenes of target domain images. Insufficient information interchange between specific domains and specific domains is a problem. In this study, two different domain classifiers are used to solve this problem and achieve domain adaption. To effectively mine the source domain images for classification understanding, an unsupervised MRI classification technique for myocardial infarction called CardiacCN is proposed, which relies on adversarial instructions related to the interpolation of confusion specimens in the target domain for the conflict of confusion specimens for the target domain classification task.

RESULTS

The experimental results demonstrate that the CardiacCN model in this study performs better on the six domain adaption tasks of the Sunnybrook Cardiac Dataset (SCD) dataset and increases the mean target area myocardial infarction MRI classification accuracy by approximately 1.2 percent. The classification performance of the CardiacCN model on the target domain does not vary noticeably when the temperature-controlled duration hyper-parameter rl falls in the region of 5-30. According to the experimental findings, the CardiacCN model is more resistant to the excitable rl. The CardiacCN model suggested in this research may successfully increase the accuracy of the source domain predictor for the target domain myocardial infarction clinical scanning classification in unsupervised learning, as shown by the visualization analysis infrastructure provision nurture. It is evident from the visualization assessment of embedded features that the CardiacCN model may significantly increase the source domain classifier's accuracy for the target domain's classification of myocardial infarction in clinical scans under unsupervised conditions.

CONCLUSION

To address misleading specimens with the inconsistent classification of target-domain myocardial infarction medical scans, this paper introduces the CardiacCN unsupervised domain adaptive MRI classification model, which relies on adversarial learning associated with resampling target-domain confusion samples. With this technique, implicit image classification information from the target domain is fully utilized, knowledge transfer from the target domain to the specific domain is encouraged, and the classification effect of the myocardial ischemia medical scan is improved in the target domain of the unsupervised scene.

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

Aims

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

Methods and results:

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

Conclusion

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

KEY POINTS

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

A head-to-head comparison of myocardial strain by fast-strain encoding and feature tracking imaging in acute myocardial infarction

Background

Myocardial infarction (MI) is a major cause of heart failure. Left ventricular adverse remodeling is common post-MI. Several studies have demonstrated a correlation between reduced myocardial strain and the development of adverse remodeling. Cardiac magnetic resonance (CMR) with fast-strain encoding (fast-SENC) or feature tracking (FT) enables rapid assessment of myocardial deformation. The aim of this study was to establish a head-to-head comparison of fast-SENC and FT in post-ST-elevated myocardial infarction (STEMI) patients, with clinical 2D speckle tracking echocardiography (2DEcho) as a reference.

Methods

Thirty patients treated with primary percutaneous coronary intervention for STEMI were investigated. All participants underwent CMR examination with late gadolinium enhancement, cine-loop steady-state free precession, and fast-SENC imaging using a 1.5T scanner as well as a 2DEcho. Global longitudinal strain (GLS), segmental longitudinal strain (SLS), global circumferential strain (GCS), and segmental circumferential strain (SCS) were assessed along with the MI scar extent.

Results

The GCS measurements from fast-SENC and FT were nearly identical: the mean difference was 0.01 (2.5)% (95% CI - 0.92 to 0.95). For GLS, fast-SENC values were higher than FT, with a mean difference of 1.8 (1.4)% (95% CI 1.31-2.35). Tests of significance for GLS did not show any differences between the MR methods and 2DEcho. Average strain in the infarct-related artery (IRA) segments compared to the remote myocardium was significantly lower for the left anterior descending artery and right coronary artery culprits but not for the left circumflex artery culprits. Fast-SENC displayed a higher area under the curve for detecting infarcted segments than FT for both SCS and SLS.

Conclusion

GLS and GCS did not significantly differ between fast-SENC and FT. Both showed acceptable agreement with 2DEcho for longitudinal strain. Segments perfused by the IRA showed significantly reduced strain values compared to the remote myocardium. Fast-SENC presented a higher sensitivity and specificity for detecting infarcted segments than FT.

Artificial intelligence and cardiovascular magnetic resonance imaging in myocardial infarction patients

Cardiovascular magnetic resonance (CMR) is an important cardiac imaging tool for assessing the prognostic extent of myocardial injury after myocardial infarction (MI). Within the context of clinical trials, CMR is also useful for assessing the efficacy of potential cardioprotective therapies in reducing MI size and preventing adverse left ventricular (LV) remodelling in reperfused MI. However, manual contouring and analysis can be time-consuming with interobserver and intraobserver variability, which can in turn lead to reduction in accuracy and precision of analysis. There is thus a need to automate CMR scan analysis in MI patients to save time, increase accuracy, increase reproducibility and increase precision. In this regard, automated imaging analysis techniques based on artificial intelligence (AI) that are developed with machine learning (ML), and more specifically deep learning (DL) strategies, can enable efficient, robust, accurate and clinician-friendly tools to be built so as to try and improve both clinician productivity and quality of patient care. In this review, we discuss basic concepts of ML in CMR, important prognostic CMR imaging biomarkers in MI and the utility of current ML applications in their analysis as assessed in research studies. We highlight potential barriers to the mainstream implementation of these automated strategies and discuss related governance and quality control issues. Lastly, we discuss the future role of ML applications in clinical trials and the need for global collaboration in growing this field.

Assessment of myocardial salvage in patients with STEMI undergoing thrombolysis: ticagrelor versus clopidogrel

Background

In the setting of ST-segment elevation myocardial infarction (STEMI), the faster and stronger antiplatelet action of ticagrelor compared to clopidogrel, as well as its pleiotropic effects, could result in a greater degree of cardioprotection and final infarct size (FIS) limitation. The aim of our study was to comparatively evaluate the effect of ticagrelor and clopidogrel on myocardial salvage index (MSI) in STEMI patients undergoing thrombolysis.

Methods

Forty-two STEMI patients treated with thrombolysis were randomized to receive clopidogrel (n = 21) or ticagrelor (n = 21), along with aspirin. Myocardial area at risk (AAR) was calculated according to the BARI and the APPROACH jeopardy scores. FIS was quantified by cardiac magnetic resonance imaging (CMR) performed 5–6 months post-randomization. MSI was calculated as (AAR-FIS)/AAR × 100%. Primary endpoint of our study was MSI. Secondary endpoints were FIS and CMR-derived left ventricular ejection fraction (LVEF) at 5 –6 months post-randomization.

Results

By using the BARI score for AAR calculation, mean MSI was 52.25 ± 30.5 for the clopidogrel group and 54.29 ± 31.08 for the ticagrelor group (p = 0.83), while mean MSI using the APPROACH score was calculated at 51.94 ± 30 and 53.09 ± 32.39 (p = 0.9), respectively. Median CMR-derived FIS—as a percentage of LV—was 10.7% ± 8.25 in the clopidogrel group and 12.09% ± 8.72 in the ticagrelor group (p = 0.6). Mean LVEF at 5–6 months post-randomization did not differ significantly between randomization groups.

Conclusions

Our results suggest that the administration of ticagrelor in STEMI patients undergoing thrombolysis offer a similar degree of myocardial salvage, compared to clopidogrel.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02735-1.

Efficacy of comprehensive remote ischemic conditioning in elderly patients with acute ST-segment elevation myocardial infarction underwent primary percutaneous coronary intervention

BACKGROUND

Remote ischemic conditioning (RIC) is used to protect against myocardial injury. However, there is no adequate evidence for comprehensive RIC in elderly patients with ST-segment elevation myocardial infarction (STEMI). This study aimed to test whether comprehensive RIC, started pre-primary percutaneous coronary intervention (PPCI) and repeated daily on 1-30 days post-PPCI, can improve myocardial salvage index (SI), left ventricular ejection fraction (LVEF), Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS) and 6-min walk test distance (6MWD) in elderly patients with acute STEMI during 12 months follow-up.

METHODS

328 consenting elderly patients were randomized to receive standard PPCI plus comprehensive RIC (the treatment group) or standard PPCI (the control group). SI at 5-7 days after PPCI, LVEF, left ventricular end-diastolic volume index (LVEDVI), left ventricular end-systolic volume index (LVESVI), KCCQ-CSS, 6MWD and adverse events rates were measured and assessed.

RESULTS

SI was significantly higher in the treatment group [interquartile range (IQR): 0.38-0.66, P = 0.037]. There were no significant differences in major adverse events at 12 months. Although the differences of LVEDVI, LVESVI and LVEF between the treatment group and the control group did not reach statistical significance at 6 months and 12 months, LVEF tended to be higher, LVEDVI tended to be lower in the treatment group. The KCCQ-CSS was significantly higher in the treatment group at 1 month (IQR: 46.5-87, P = 0.001) and 12 months (IQR: 55-93, P = 0.008). There was significant difference in 6MWD between the treatment group and the control group (IQR: 258-360 vs. IQR: 250-345, P = 0.002) at 1 month and (IQR: 360-445 vs. IQR: 345-432, P = 0.035) at 12 months. A modest correlation was found between SI and LVEF (r = 0.452, P < 0.01), KCCQ-CSS ( r = 0.440, P < 0.01) and 6MWD ( r = 0.384, P < 0.01) respectively at 12 months.

CONCLUSIONS

The comprehensive RIC can improve SI, KCCQ-CSS and 6MWD. It may be an adjunctive therapy to PPCI in elderly patients with STEMI.

Theranostic Contribution of Extracellular Matrix Metalloprotease Inducer-Paramagnetic Nanoparticles Against Acute Myocardial Infarction in a Pig Model of Coronary Ischemia-Reperfusion

Rapid screening and accurate diagnosis of acute myocardial infarction are critical to reduce the progression of myocardial necrosis, in which proteolytic degradation of myocardial extracellular matrix plays a major role. In previous studies, we found that targeting the extracellular matrix metalloprotease inducer (EMMPRIN) by injecting nanoparticles conjugated with the specific EMMPRIN-binding peptide AP9 significantly improved cardiac function in mice subjected to ischemia/reperfusion.

Segmental strain for scar detection in acute myocardial infarcts and in follow-up exams using non-contrast CMR cine sequences

Background

The purpose of the study was to investigate feasibility of infarct detection in segmental strain derived from non-contrast cardiac magnetic resonance (CMR) cine sequences in patients with acute myocardial infarction (AMI) and in follow-up (FU) exams.

Methods

57 patients with AMI (mean age 61 ± 12 years, CMR 2.8 ± 2 days after infarction) were retrospectively included, FU exams were available in 32 patients (35 ± 14 days after first CMR). 43 patients with normal CMR (54 ± 11 years) served as controls. Dedicated software (Segment CMR, Medviso) was used to calculate global and segmental strain derived from cine sequences. Cine short axis stacks and segmental circumferential strain calculations of every patient and control were presented to two blinded readers in random order, who were advised to identify potentially infarcted segments, blinded to LGE and clinical information.

Results

Impaired global strain was measured in AMI patients compared to controls (global peak circumferential strain [GPCS] p = 0.01; global peak longitudinal strain [GPLS] p = 0.04; global peak radial strain [GPRS] p = 0.01). In both imaging time points, mean segmental peak circumferential strain [SPCS] was impaired in infarcted tissue compared to remote segments (AMI: p = 0.03, FU: p = 0.02). SPCS values in infarcted segments were similar between AMI and FU (p = 0.8). In SPCS calculations, 141 from 189 acutely infarcted segments were accurately detected (74.6%), visual evaluation of correlating cine images detected 43.4% infarcts. In FU, 80% infarcted segments (91/114 segments) were detected in SPCS and 51.8% by visual evaluation of correlating short axis cine images (p = 0.01).

Conclusion

Segmental circumferential strain derived from routinely acquired native cine sequences detects nearly 75% of acute infarcts and 80% of infarcts in subacute follow-up CMR, significantly more than visual evaluation of correlating cine images alone. Acute infarcts may display only subtle impairment of wall motion and no obvious wall thinning, thus SPCS calculation might be helpful for scar detection in patients with acute infarcts, when LGE images are not available.

Intrapericardial Administration of Secretomes from Menstrual Blood-Derived Mesenchymal Stromal Cells: Effects on Immune-Related Genes in a Porcine Model of Myocardial Infarction

Acute myocardial infarction (AMI) is a manifestation of ischemic heart disease where the immune system plays an important role in the re-establishment of homeostasis. We hypothesize that the anti-inflammatory activity of secretomes from menstrual blood-derived mesenchymal stromal cells (S-MenSCs) and IFNγ/TNFα-primed MenSCs (S-MenSCs*) may be considered a therapeutic option for the treatment of AMI. To assess this hypothesis, we have evaluated the effect of S-MenSCs and S-MenSCs* on cardiac function parameters and the involvement of immune-related genes using a porcine model of AMI. Twelve pigs were randomly divided into three biogroups: AMI/Placebo, AMI/S-MenSCs, and AMI/S-MenSCs*. AMI models were generated using a closed chest coronary occlusion-reperfusion procedure and, after 72 h, the different treatments were intrapericardially administered. Cardiac function parameters were monitored by magnetic resonance imaging before and 7 days post-therapy. Transcriptomic analyses in the infarcted tissue identified 571 transcripts associated with the Gene Ontology term Immune response, of which 57 were differentially expressed when different biogroups were compared. Moreover, a prediction of the interactions between differentially expressed genes (DEGs) and miRNAs from secretomes revealed that some DEGs in the infarction area, such as STAT3, IGFR1, or BCL6 could be targeted by previously identified miRNAs in secretomes from MenSCs. In conclusion, the intrapericardial administration of secretome early after infarction has a significant impact on the expression of immune-related genes in the infarcted myocardium. This confirms the immunomodulatory potential of intrapericardially delivered secretomes and opens new therapeutic perspectives in myocardial infarction treatment.

Role of cardiac magnetic resonance imaging in troponinemia syndromes

Cardiac magnetic resonance imaging (MRI) is an evolving technology, proving to be a highly accurate tool for quantitative assessment. Most recently, it has been increasingly used in the diagnostic and prognostic evaluation of conditions involving an elevation in troponin or troponinemia. Although an elevation in troponin is a nonspecific marker of myocardial tissue damage, it is a frequently ordered investigation leaving many patients without a specific diagnosis. Fortunately, the advent of newer cardiac MRI protocols can provide additional information. In this review, we discuss several conditions associated with an elevation in troponin such as myocardial infarction, myocarditis, Takotsubo cardiomyopathy, coronavirus disease 2019 related cardiac dysfunction and athlete’s heart syndrome.