The use of contrast-enhanced magnetic resonance imaging to identify reversible myocardial dysfunction

Effects of sacubitril/valsartan on cardiac remodeling in heart failure with reduced ejection fraction: An integrated study of molecular biomarkers and imaging techniques

Treatment of heart failure and reduced ejection fraction (HFrEF) using angiotensin receptor-neprilysin inhibitor demonstrates beneficial effects on cardiac remodeling (CR). We assessed the impact of sacubitril/valsartan on the concentrations of HF biomarkers in relation to parameters of CR using imaging techniques in patients with HFrEF. In a prospective single-center open-label study, 68 patients with symptomatic HFrEF were treated with sacubitril/valsartan and followed-up every three months for 12 months. Soluble suppression of tumorigenicity 2 (sST2), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and high-sensitivity cardiac troponin I (hs-cTnI) were measured in blood samples. Additionally, echocardiography and cardiac magnetic resonance imaging (cMRI) were performed to assess heart structural and functional changes. Following treatment initiation, follow-up visits revealed an improved NYHA functional class in these patients, alongside significant decreases in all circulating biomarkers, increases in left ventricular ejection fraction (LVEF), and reductions in volume- and diameter-related LV parameters. Sustained gradual decreases in sST2 concentrations over time correlated with NT-proBNP concentrations (rho=+0.26, P < 0.001). Both biomarkers were inversely correlated with LVEF, and positively correlated with volume- and diameter-related LV parameters from echocardiography and cMRI. However, NT-proBNP concentrations exhibited stronger correlations with these LV parameters and were associated with the number of LV segments showing fibrosis, unlike sST2. Sacubitril/valsartan treatment in HFrEF leads to reduced sST2 and NT-proBNP concentrations with distinct decreasing curves, which are linked to reverse CR through LV-related parameters. In contrast to sST2, NT-proBNP is also associated with fibrosis, suggesting that both biomarkers unveil distinct mechanisms during CR in patients treated with sacubitril/valsartan.

The complex role of cardiovascular imaging in viability testing

Myocardial viability assessment is used to determine if chronically dysfunctional myocardium may benefit from coronary revascularization. Cardiac magnetic resonance with late gadolinium enhancement is the current gold standard for visualizing myocardial scar and provides valuable insight into myocardial viability. Viability assessments can also be made with Cardiac Positron Emission Tomography, Echocardiography, Single Photon Emission Tomography, and Cardiac Computed Tomography with each having advantages and disadvantages. Despite the classical interpretation that viability predicts segmental functional improvement, more recent studies have found that revascularization of viable myocardium has conflicting roles in predicting benefits for patients, especially as it relates to major adverse cardiovascular events, development of heart failure symptoms, and all-cause mortality. This review covers these conflicts along with an in-depth review of the pathophysiologic processes that are fundamental to myocardial viability and the various methods used for determining viability.

Atrial Cardiomyopathy: From Diagnosis to Treatment

With a better understanding of the susceptibility to atrial fibrillation (AF) and the thrombogenicity of the left atrium, the concept of atrial cardiomyopathy (ACM) has emerged. The conventional viewpoint holds that AF-associated hemodynamic disturbances and thrombus formation in the left atrial appendage are the primary causes of cardiogenic embolism events. However, substantial evidence suggests that the relationship between cardiogenic embolism and AF is not so absolute, and that ACM may be an important, underestimated contributor to cardiogenic embolism events. Chronic inflammation, oxidative stress response, lipid accumulation, and fibrosis leading to ACM form the foundation for AF. Furthermore, persistent AF can exacerbate structural and electrical remodeling, as well as mechanical dysfunction of the atria, creating a vicious cycle. To date, the relationship between ACM, AF, and cardiogenic embolism remains unclear. Additionally, many clinicians still lack a comprehensive understanding of the concept of ACM. In this review, we first appraise the definition of ACM and subsequently summarize the noninvasive and feasible diagnostic techniques and criteria for clinical practice. These include imaging modalities such as echocardiography and cardiac magnetic resonance imaging, as well as electrocardiograms, serum biomarkers, and existing practical diagnostic criteria. Finally, we discuss management strategies for ACM, encompassing "upstream therapy" targeting risk factors, identifying and providing appropriate anticoagulation for patients at high risk of stroke/systemic embolism events, and controlling heart rhythm along with potential atrial substrate improvements.

The Feasibility of a Model-Based Iterative Reconstruction Technique Tuned for the Myocardium on Myocardial Computed Tomography Late Enhancement

OBJECTIVES

This study evaluated the feasibility of a model-based iterative reconstruction technique (MBIR) tuned for the myocardium on myocardial computed tomography late enhancement (CT-LE).

METHODS

Twenty-eight patients who underwent myocardial CT-LE and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) within 1 year were retrospectively enrolled. Myocardial CT-LE was performed using a 320-row CT with low tube voltage (80 kVp). Myocardial CT-LE images were scanned 7 min after CT angiography (CTA) without additional contrast medium. All myocardial CT-LE images were reconstructed with hybrid iterative reconstruction (HIR), conventional MBIR (MBIR_cardiac), and new MBIR tuned for the myocardium (MBIR_myo). Qualitative (5-grade scale) scores and quantitative parameters (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]) were assessed as image quality. The sensitivity, specificity, and accuracy of myocardial CT-LE were evaluated at the segment level using an American Heart Association (AHA) 16-segment model, with LGE-MRI as a reference standard. These results were compared among the different CT image reconstructions.

RESULTS

In 28 patients with 448 segments, 160 segments were diagnosed with positive by LGE-MRI. In the qualitative assessment of myocardial CT-LE, the mean image quality scores were 2.9 ± 1.2 for HIR, 3.0 ± 1.1 for MBIR_cardiac, and 4.0 ± 1.0 for MBIR_myo. MBIR_myo showed a significantly higher score than HIR ( P < 0.001) and MBIR_cardiac ( P = 0.018). In the quantitative image quality assessment of myocardial CT-LE, the median image SNR was 10.3 (9.1-11.1) for HIR, 10.8 (9.8-12.1) for MBIR_cardiac, and 16.8 (15.7-18.4) for MBIR_myo. The median image CNR was 3.7 (3.0-4.6) for HIR, 3.8 (3.2-5.1) for MBIR_cardiac, and 6.4 (5.0-7.7) for MBIR_myo. MBIR_myo significantly improved the SNR and CNR of CT-LE compared to HIR and MBIR_cardiac ( P < 0.001). The sensitivity, specificity, and accuracy for the detection of myocardial CT-LE were 70%, 92%, and 84% for HIR; 71%, 92%, and 85% for MBIR_cardiac; and 84%, 92%, and 89% for MBIR_myo, respectively. MBIR_myo showed significantly higher image quality, sensitivity, and accuracy than the others ( P < 0.05).

CONCLUSIONS

MBIR tuned for myocardium improved image quality and diagnostic performance for myocardial CT-LE assessment.

Role of advanced CMR features in identifying a positive genotype of hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disease that affects approximately one in 500 people. Cardiac magnetic resonance (CMR) imaging has emerged as a powerful tool for the non-invasive assessment of HCM. CMR can accurately quantify the extent and distribution of hypertrophy, assess the presence and severity of myocardial fibrosis, and detect associated abnormalities. We will study basic and advanced features of CMR in 2 groups of HCM patients with negative and positive genotype, respectively.

MATERIALS AND METHODS

The study population consisted in consecutive HCM patients referred to Centro Cardiologico Monzino who performed both CMR and genetic testing. Clinical CMR images were acquired at 1.5 T Discovery MR450 scanner (GE Healthcare, Milwaukee, Wisconsin)) using standardized protocols T1 mapping, T2 mapping and late gadolinium enhancement (LGE). Population was divided in 2 groups: group 1 with HCM patients with a negative genotype and group 2 with a positive genotype.

RESULTS

The analytic population consisted of 110 patients: 75 in group 1 and 35 patients in group 2. At CMR evaluation, patients with a positive genotype had higher LV mass (136 vs. 116 g, p = 0.02), LV thickness (17.5 vs. 16.9 mm), right ventricle ejection fraction (63 % vs. 58 %, p = 0.002). Regarding the LGE patients with positive genotype have a higher absolute (33.8 vs 16.7 g, p = 0.0003) and relative LGE mass (31.6 % vs 14.6 %, p = 0.0007). On a segmental analysis all the septum (segments 2, 8, 9, and 14) had a significantly increased native T1 compared to others segments. ECV in the mid antero and infero-septum (segments 8 and 9) have lower values in positive genotype HCM. Interestingly the mean T2 was lower in positive genotype HCM as compared to negative genotype HCM (50,1 ms vs 52,4).

CONCLUSIONS

Our paper identifies the mid septum (segments 8 and 9) as a key to diagnose a positive genotype HCM.

Magnetization-transfer flow-independent dark-blood delayed enhancement cardiac MRI optimizes discrimination of ST-elevation myocardial infarct borders

OBJECTIVES

To prospectively compare image quality and infarct sizing methods between magnetization-transfer "flow-independent dark-blood delayed enhancement" (MT-FIDDLE) and standard "bright-blood"-late gadolinium enhancement (LGE) cardiac-magnetic-resonance (CMR) sequence.

METHODS

"Bright-blood"-LGE and MT-FIDDLE sequence were acquired in 110 patients at 4 days (n = 33), 4 months (n = 39) and 12 months (n = 38) after acute ST-elevation myocardial infarction (STEMI). Subjective image quality, including confidence in infarct segmentation and blood-pool bordering, were each rated on a 4-point Likert scale. Objective image quality was assessed by the detectability index (DI). Infarct volumes derived via full-width at half-maximum (FWHM) and different number of standard deviations ("n-SD") methods on MT-FIDDLE images were compared with FWHM and reference 5-SD results from "bright-blood-LGE images.

RESULTS

Overall subjective median image quality was excellent for both LGE sequences. Qualitative analysis revealed a significantly higher confidence in infarct segmentation and in blood-pool bordering for MT-FIDDLE as compared to "bright-blood"-LGE (all p < 0.001). Infarct volumes assessed by the FWHM technique on MT-FIDDLE and "bright-blood"-LGE showed excellent agreement overall (Concordance correlation coefficient, CCC = 0.96). The 3-SD technique for MT-FIDDLE showed the best agreement with the 5-SD method for "bright-blood"-LGE overall (CCC = 0.94), as well as in the subgroup with excellent confidence in infarct segmentation on "bright-blood"-LGE (CCC = 0.96). DI of scar versus LV blood-pool was higher for MT-FIDDLE (8.9 ± 5.5) compared to "bright-blood"-LGE sequence (2.0 ± 1.5; p < 0.001).

CONCLUSION

MT-FIDDLE significantly optimizes the discrimination between myocardial infarction and adjacent blood-pool in STEMI patients. As compared to the established 5-SD technique on "bright-blood"-LGE, the 3-SD method on MT-FIDDLE results in consistent infarct volumes.

KEY POINTS

Question Does magnetization-transfer "flow-independent dark-blood delayed enhancement" (MT-FIDDLE) offer any benefits over standard "bright-blood"-late gadolinium enhancement (LGE) cardiac-magnetic-resonance (CMR) for identifying STEMI infarct borders? Findings MT-FIDDLE image quality was higher than LGE CMR and measured infarct volume comparability to the standard 5-SD-threshold-technique. Clinical relevance MT-FIDDLE facilitates the assessment of myocardial infarctions at the subendocardial border, improving the discrimination between myocardial infarction and adjacent blood-pool in STEMI patients.

Outcomes of Coronary Artery Bypass Grafting in Patients With Impaired Left Ventricular Function and the Role of Preoperative Myocardial Viability

Background Coronary artery bypass grafting (CABG) improves outcomes in patients with ischemic left ventricular (LV) dysfunction, but accurate patient selection remains critical. Late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging aids in assessing myocardial viability, a key predictor of surgical outcomes. This study aimed to evaluate the impact of myocardial viability on postoperative outcomes in patients undergoing CABG. Methods This was a single-center prospective analysis of clinical outcomes in 37 patients with impaired LV function (mean ejection fraction: 35.59%); myocardial viability was assessed using LGE-CMR prior to CABG. Patient demographics, perioperative details, and short-term outcomes, including in-hospital mortality and recovery metrics, were analyzed. Results Patients exhibited high myocardial viability (mean: 88.16%), with an average of 2.35 non-viable segments. In-hospital mortality was 5.4% (n=2), and the mean hospital stay was six days. Patients with greater viability demonstrated better recovery and fewer complications. Multivessel coronary artery disease was prevalent (94.6%, n=35), with tailored graft configurations addressing individual anatomical and disease complexities. Conclusion LGE-CMR is a valuable tool for predicting outcomes in ischemic LV dysfunction. Myocardial viability strongly correlates with improved surgical recovery, highlighting the importance of integrating LGE-CMR into preoperative decision-making. Further studies are required to explore the long-term impact of myocardial viability on treatment outcomes and quality of life.

Late gadolinium enhancement cardiovascular magnetic resonance with generative artificial intelligence

BACKGROUND

Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging enables imaging of scar/fibrosis and is a cornerstone of most CMR imaging protocols. CMR imaging can benefit from image acceleration; however, image acceleration in LGE remains challenging due to its limited signal-to-noise ratio. In this study, we sought to evaluate a rapid two-dimensional (2D) LGE imaging protocol using a generative artificial intelligence (AI) algorithm with inline reconstruction.

METHODS

A generative AI-based image enhancement was used to improve the sharpness of 2D LGE images acquired with low spatial resolution in the phase-encode direction. The generative AI model is an image enhancement technique built on the enhanced super-resolution generative adversarial network. The model was trained using balanced steady-state free-precession cine images, readily used for LGE without additional training. The model was implemented inline, allowing the reconstruction of images on the scanner console. We prospectively enrolled 100 patients (55 ± 14 years, 72 males) referred for clinical CMR at 3T. We collected three sets of LGE images in each subject, with in-plane spatial resolutions of 1.5 × 1.5-3-6 mm2. The generative AI model enhanced in-plane resolution to 1.5 × 1.5 mm2 from the low-resolution counterparts. Images were compared using a blur metric, quantifying the perceived image sharpness (0 = sharpest, 1 = blurriest). LGE image sharpness (using a 5-point scale) was assessed by three independent readers.

RESULTS

The scan times for the three imaging sets were 15 ± 3, 9 ± 2, and 6 ± 1 s, with inline generative AI-based images reconstructed time of ∼37 ms. The generative AI-based model improved visual image sharpness, resulting in lower blur metric compared to low-resolution counterparts (AI-enhanced from 1.5 × 3 mm2 resolution: 0.3 ± 0.03 vs 0.35 ± 0.03, P < 0.01). Meanwhile, AI-enhanced images from 1.5 × 3 mm2 resolution and original LGE images showed similar blur metric (0.30 ± 0.03 vs 0.31 ± 0.03, P = 1.0) Additionally, there was an overall 18% improvement in image sharpness between AI-enhanced images from 1.5 × 3 mm2 resolution and original LGE images in the subjective blurriness score (P < 0.01).

CONCLUSION

The generative AI-based model enhances the image quality of 2D LGE images while reducing the scan time and preserving imaging sharpness. Further evaluation in a large cohort is needed to assess the clinical utility of AI-enhanced LGE images for scar evaluation, as this proof-of-concept study does not provide evidence of an impact on diagnosis.

AI-powered contrast-free cardiovascular magnetic resonance imaging for myocardial infarction

Cardiovascular magnetic (CMR) resonance is a versatile tool for diagnosing cardiovascular diseases. While gadolinium-based contrast agents are the gold standard for identifying myocardial infarction (MI), their use is limited in patients with allergies or impaired kidney function, affecting a significant portion of the MI population. This has led to a growing interest in developing artificial intelligence (AI)-powered CMR techniques for MI detection without contrast agents. This mini-review focuses on recent advancements in AI-powered contrast-free CMR for MI detection. We explore various AI models employed in the literature and delve into their strengths and limitations, paving the way for a comprehensive understanding of this evolving field.

Deep Learning Synthesis of White-Blood From Dark-Blood Late Gadolinium Enhancement Cardiac Magnetic Resonance

OBJECTIVES

Dark-blood late gadolinium enhancement (DB-LGE) cardiac magnetic resonance has been proposed as an alternative to standard white-blood LGE (WB-LGE) imaging protocols to enhance scar-to-blood contrast without compromising scar-to-myocardium contrast. In practice, both DB and WB contrasts may have clinical utility, but acquiring both has the drawback of additional acquisition time. The aim of this study was to develop and evaluate a deep learning method to generate synthetic WB-LGE images from DB-LGE, allowing the assessment of both contrasts without additional scan time.

MATERIALS AND METHODS

DB-LGE and WB-LGE data from 215 patients were used to train 2 types of unpaired image-to-image translation deep learning models, cycle-consistent generative adversarial network (CycleGAN) and contrastive unpaired translation, with 5 different loss function hyperparameter settings each. Initially, the best hyperparameter setting was determined for each model type based on the Fréchet inception distance and the visual assessment of expert readers. Then, the CycleGAN and contrastive unpaired translation models with the optimal hyperparameters were directly compared. Finally, with the best model chosen, the quantification of scar based on the synthetic WB-LGE images was compared with the truly acquired WB-LGE.

RESULTS

The CycleGAN architecture for unpaired image-to-image translation was found to provide the most realistic synthetic WB-LGE images from DB-LGE images. The results showed that it was difficult for visual readers to distinguish if an image was true or synthetic (55% correctly classified). In addition, scar burden quantification with the synthetic data was highly correlated with the analysis of the truly acquired images. Bland-Altman analysis found a mean bias in percentage scar burden between the quantification of the real WB and synthetic white-blood images of 0.44% with limits of agreement from -10.85% to 11.74%. The mean image quality of the real WB images (3.53/5) was scored higher than the synthetic white-blood images (3.03), P = 0.009.

CONCLUSIONS

This study proposed a CycleGAN model to generate synthetic WB-LGE from DB-LGE images to allow assessment of both image contrasts without additional scan time. This work represents a clinically focused assessment of synthetic medical images generated by artificial intelligence, a topic with significant potential for a multitude of applications. However, further evaluation is warranted before clinical adoption.

Photon-counting detector computed tomography in cardiac imaging

Photon-counting detector computed tomography (PCD-CT) has emerged as a revolutionary technology in CT imaging. PCD-CT offers significant advancements over conventional energy-integrating detector CT, including increased spatial resolution, artefact reduction and inherent spectral imaging capabilities. In cardiac imaging, PCD-CT can offer a more accurate assessment of coronary artery disease, plaque characterisation and the in-stent lumen. Additionally, it might improve the visualisation of myocardial fibrosis through qualitative late enhancement imaging and quantitative extracellular volume measurements. The use of PCD-CT in cardiac imaging holds significant potential, positioning itself as a valuable modality that could serve as a one-stop-shop by integrating both angiography and tissue characterisation into a single examination. Despite its potential, large-scale clinical trials, standardisation of protocols and cost-effectiveness considerations are required for its broader integration into clinical practice. This narrative review provides an overview of the current literature on PCD-CT regarding the possibilities and limitations of cardiac imaging.

The Role of Cardiac Magnetic Resonance to Predict Response to Cardiac Resynchronization Therapy: A Systematic Review and Meta-analysis

Cardiac resynchronization therapy (CRT) has revolutionized heart failure (HF) management, offering benefits in morbidity, mortality, and symptom alleviation. However, optimal response rates are not universally achieved, necessitating enhanced patient-selection strategies. Myocardial scar patterns, quantified by delayed-enhancement cardiac magnetic resonance (DE-CMR), have been implicated in CRT outcomes. We conducted a meta-analysis of observational studies assessing CRT responses by performing a systematic literature search using PubMed, Embase, Ovid MEDLINE, Scopus, the Cochrane Library, ScienceDirect, and the Web of Science. Scar burden, left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV), and left ventricular end-diastolic volume (LVEDV) were evaluated. CRT response rates among ischemic and non-ischemic cardiomyopathy patients were also explored. This meta-analysis incorporated eight studies meeting the eligibility criteria. CRT responders exhibited a significantly lower scar burden (-11.7%; 95% confidence interval, 6.6%-16.8%) compared to non-responders, supporting the predictive value of scar quantification (I 2 = 95.25%; P < .001). Responders demonstrated an increased mean LVEF (from 25.2% to 31.9%), while non-responders showed modest changes (from 23.3% to 24.4%). Responders experienced a decrease in mean LVESV from 158.8 to 132.8 mL, contrasting with a more stable mean LVESV value in non-responders (reduction from 160.9 to 157.6 mL). Responders experienced a reduced mean LVEDV from 219.4 to 196.7 mL, while non-responders showed more minimal changes (from 213.4 to 210.6 mL). Limited data suggested a CRT response rate of 34.7% in ischemic cardiomyopathy; non-ischemic data were insufficient. In conclusion, DE-CMR, assessing the scar burden, emerges as a valuable tool for predicting the CRT response. A lower scar burden correlates with improved responses, supporting the role of DE-CMR in refining patient selection for CRT. This meta-analysis contributes insights into personalized CRT strategies, emphasizing the potential of imaging modalities to enhance therapeutic outcomes in HF patients. Further research is warranted to solidify these findings and refine clinical applications.

Clinical applications, safety profiles, and future developments of contrast agents in modern radiology: A comprehensive review

Contrast agents have transformed the field of medical imaging, significantly enhancing the visualisation of internal structures and improving diagnostic accuracy across X‐rays, computed tomography, magnetic resonance imaging (MRI), and ultrasound. This review explores the historical development, physicochemical properties, and mechanisms of action of iodinated, gadolinium‐based, barium sulfate, microbubble, and nanoparticle contrast agents. It highlights key advancements, including the transition from high‐osmolar to low‐ and iso‐osmolar iodinated agents, the integration of gadolinium in MRI, and the innovative use of microbubbles and nanoparticles. The review critically examines the safety profiles and adverse reactions of these contrast agents, categorising them into hypersensitivity and physiological reactions. It outlines risk factors, common misconceptions, and management strategies for adverse reactions, emphasising the importance of personalised approaches in clinical practice. Additionally, it delves into broader implications, including ethical considerations, environmental impact, and global accessibility of contrast media. The review also discusses technological advancements such as targeted contrast agents and the integration of artificial intelligence to optimise contrast dosage. By synthesising current knowledge and emerging trends, this review underscores the pivotal role of contrast agents in advancing medical imaging. It aims to equip clinicians, researchers, and policymakers with a thorough understanding to enhance diagnostic efficacy, ensure patient safety, and address ethical and environmental challenges, thereby informing future innovations and regulatory frameworks to promote equitable access to advanced imaging technologies globally.

Multimodality imaging for the evaluation and management of patients with long-term (durable) left ventricular assist devices

Left ventricular assist devices (LVADs) are gaining increasing importance as therapeutic strategy in advanced heart failure (HF), not only as bridge to recovery or to transplant but also as destination therapy. Even though long-term LVADs are considered a precious resource to expand the treatment options and improve clinical outcome of these patients, these are limited by peri-operative and post-operative complications, such as device-related infections, haemocompatibility-related events, device mis-positioning, and right ventricular failure. For this reason, a precise pre-operative, peri-operative, and post-operative evaluation of these patients is crucial for the selection of LVAD candidates and the management LVAD recipients. The use of different imaging modalities offers important information to complete the study of patients with LVADs in each phase of their assessment, with peculiar advantages/disadvantages, ideal application, and reference parameters for each modality. This clinical consensus statement sought to guide the use of multimodality imaging for the evaluation of patients with advanced HF undergoing LVAD implantation.

Cardiac Magnetic Resonance Left Atrial Strain in the Prediction of Death, Ischemic Stroke, and Heart Failure

BACKGROUND

To determine the prognostic value of left atrial strain (LAS) using cardiac magnetic resonance for predicting death, heart failure, and ischemic stroke in patients with known or suspected coronary artery disease with preserved left ventricular systolic function and no prior history of ischemic stroke, heart failure, or atrial fibrillation.

METHODS AND RESULTS

This retrospective cohort analysis included patients referred for stress cardiac magnetic resonance or myocardial viability studies between September 2017 and December 2019. Patients with impaired left ventricular systolic function (<50%) or a history of atrial fibrillation, stroke, or heart failure were excluded. A multivariable Cox model assessed the prognostic value of LAS, with the primary outcomes being the composite outcomes of all-cause death, ischemic stroke, and heart failure. A total of 2030 participants were included in the study. The average LAS was 24.1±8.5%; 928 had LAS <23%, and 1102 had LAS ≥23%. The mean follow-up duration was 39.9±13.6 months. There were 49 deaths (2.4%), 32 ischemic strokes (1.6%), and 34 heart failure events (1.7%). Patients with LAS <23% were at greater risk for composite outcome, with an adjusted hazard ratio of 2.31 (95% CI, 1.50-3.55).

CONCLUSIONS

LAS by cardiac magnetic resonance has an independent and incremental prognostic value for death, ischemic stroke, and heart failure in patients with preserved left ventricular systolic function. This prognostic value is observed after adjusting for clinical and cardiac magnetic resonance parameters, including left ventricular systolic function, late gadolinium enhancement, and left atrial volume index.

Impact of Myocardial Viability on Long-term Outcomes after Surgical Revascularization

BACKGROUND

 This study was conducted to evaluate whether myocardial viability assessed with cardiac magnetic resonance (CMR) affected long-term clinical outcomes after coronary artery bypass grafting (CABG) in patients with ischemic cardiomyopathy (ICMP).

METHODS

 Preoperative CMR with late gadolinium enhancement (LGE) was performed in 103 patients (64.9 ± 10.1 years, male:female = 82:21) with 3-vessel disease and left ventricular dysfunction (ejection fraction ≤ 0.35). Transmural extent of LGE was evaluated on a 16-segment model, and transmurality was graded on a 5-point scale: grades-0, absence; 1, 1 to 25%; 2, 26 to 50%; 3, 51 to 75%; 4, 76 to 100%. Median follow-up duration was 65.5 months (interquartile range = 27.5-95.3 months). Primary endpoint was the composite of all-cause mortality or hospitalization for congestive heart failure.

RESULTS

 Operative mortality was 1.9%. During the follow-up, all-cause mortality and readmission for congestive heart failure occurred in 29 and 8 patients, respectively. The cumulative incidence of the primary endpoint was 31.3 and 46.8% at 5 and 10 years, respectively. Multivariable analysis demonstrated that the number of segments with LGE grade 4 was a significant risk factor (hazard ratio 1.42, 95% confidence interval 1.10-1.83, p = 0.007) for the primary endpoint among the variables assessed by CMR. Other risk factors included age, dialysis, chronic obstructive pulmonary disease, and EuroSCORE II.

CONCLUSION

 The number of myocardial segments with transmurality of LGE >75% might be a prognostic factor associated with the composite of all-cause mortality or hospitalization for congestive heart failure after CABG in patients with 3-vessel disease and ICMP.

Society for Cardiovascular Magnetic Resonance 2023 Cases of SCMR case series

"Cases of SCMR" is a case series on the SCMR website (https://www.scmr.org) for the purpose of education. The cases reflect the clinical presentation and the use of cardiovascular magnetic resonance in the diagnosis and management of cardiovascular disease. The 2023 digital collection of cases is presented in this article.

Coronary microvascular dysfunction in autoimmune rheumatic diseases: beyond coronary flow velocity reserve

Autoimmune rheumatic diseases (ARDs) are a heterogeneous group of disorders characterized by an inappropriate immune reactivity against different body tissues. Patients affected by ARDs present increased cardiovascular morbidity and mortality, which significantly impacts long-term prognosis. Endothelial dysfunction, inflammation, oxidative stress, and autoimmunity are strictly involved in atherosclerosis progression and coronary microvascular dysfunction (CMD), both of which contribute to increased cardiovascular risk. CMD represents the inability of the coronary microvasculature to respond with vasodilation to increased cardiac metabolic demands and can be assessed by non-invasive and invasive imaging tests. Coronary flow velocity reserve assessed by echocardiography has been demonstrated to accurately identify ARDs patients with CMD. However, stress cardiac magnetic resonance (CMR) accurately assesses myocardial ischemia, perfusion, and viability in ARDs patients. The myocardial perfusion reserve index (MPRI) is a robust semiquantitative imaging marker that represents the vasodilatory capacity of the coronary microcirculation in response to a vasodilator stress. In the absence of significant coronary stenosis, ARDs patients revealed a reduced MPRI in comparison with the general population, regardless of the presence of myocardial fibrosis. Identification of CMD in asymptomatic patients could be crucial to precociously start targeted medical therapy, avoiding major adverse cardiac events in this clinical setting. This review aims to summarize the current evidence regarding CMD in ARDs patients, focusing on the role of stress CMR and the promising myocardial perfusion analysis.

Wideband radiofrequency pulse sequence for evaluation of myocardial scar in patients with cardiac implantable devices

Background

Cardiac magnetic resonance is a useful clinical tool to identify late gadolinium enhancement in heart failure patients with implantable electronic devices. Identification of LGE in patients with CIED is limited by artifact, which can be improved with a wide band radiofrequency pulse sequence.

Objective

The authors hypothesize that image quality of LGE images produced using wide-band pulse sequence in patients with devices is comparable to image quality produced using standard LGE sequences in patients without devices.

Methods

Two independent readers reviewed LGE images of 16 patients with CIED and 7 patients without intracardiac devices to assess for image quality, device-related artifact, and presence of LGE using the American Society of Echocardiography/American Heart Association 17 segment model of the heart on a 4-point Likert scale. The mean and standard deviation for image quality and artifact rating were determined. Inter-observer reliability was determined by calculating Cohen's kappa coefficient. Statistical significance was determined by T-test as a p {less than or equal to} 0.05 with a 95% confidence interval.

Results

All patients underwent CMR without any adverse events. Overall IQ of WB LGE images was significantly better in patients with devices compared to standard LGE in patients without devices (p = 0.001) with reduction in overall artifact rating (p = 0.05).

Conclusion

Our study suggests wide-band pulse sequence for LGE can be applied safely to heart failure patients with devices in detection of LV myocardial scar while maintaining image quality, reducing artifact, and following routine imaging protocol after intravenous gadolinium contrast administration.

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.

T1 mapping: a non-invasive tool to assess the systemic right ventricle

Ventricular remodeling leads to fibrotic changes in systemic right ventricles (RV). Native T1 mapping provides a quantitative measure in myocardial tissue characterization. The aim of our study was to correlate native T1 values of the systemic RV to function and volumetric data. Native T1 maps were generated with a single breath hold Modified Look-Locker Inversion-recovery pulse (MOLLI) sequence was acquired in the mid-ventricular short axis. Regions of interest (ROI) were drawn in both ventricular free walls, the interventricular septum (IVS), superior insertion point (SIP) and inferior insertion point (IIP) to obtain native T1 values. T1 values were compared to CMR ventricular volumes and function using Spearman correlation. The median age was 36 years (IQR 27-48 years). There were elevated mean native left ventricular (LV) T1 and IIP T1 values at 1122 ± 171 ms and 1117 ± 96 ms, respectively. RV dysfunction was associated with elevated IIP T1 (p = 0.007). Significant moderate negative correlations were seen between RV T1 and LV ejection fraction (LVEF) (r= -0.63, p = 0.01), between RV: IVS T1 ratio and LVEF (r= -0.68, p = 0.006), between LVEF and SIP: IVS T1 ratios (r= -0.54, p = 0.04), and RVEF and IIP T1 (r= -0.59, p = 0.02). Fibrosis measured by native T1 mapping in the systemic RV is most prominent in the LV wall and septal insertion point and correlates with decreased function. T1 values can be used in non-invasive imaging assessment of the RV, but further studies with larger cohorts are needed to assess ability to risk stratify and guide therapy.

Current indications and surgical strategies for myocardial revascularization in patients with left ventricular dysfunction: a scoping review

BACKGROUND

Ischemic cardiomyopathy (ICM) accounts for more than 60% of congestive heart failure cases and is associated with high morbidity and mortality rates. Myocardial revascularization in patients with left ventricular dysfunction (LVD) and a left ventricular ejection fraction (LVEF) ≤35% aims to improve survival and quality of life and reduce complications associated with heart failure and coronary artery disease. The majority of randomized clinical trials have consistently excluded those patients, resulting in evidence primarily derived from observational studies.

MAIN BODY

We performed a scoping review using the Arksey and O'Malley methodology in five stages: 1) formulating the research question; 2) locating relevant studies; 3) choosing studies; 4) organizing and extracting data; and 5) compiling, summarizing, and presenting the findings. This literature review covers primary studies and systematic reviews focusing on surgical revascularization strategies in adult patients with ischemic left ventricular dysfunction (LVD) and a left ventricular ejection fraction (LVEF) of 35% or lower. Through an extensive search of Medline and the Cochrane Library, a systematic review was conducted to address three questions regarding myocardial revascularization in these patients. These questions outline the current knowledge on this topic, current surgical strategies (off-pump vs. on-pump), and graft options (including hybrid techniques) utilized for revascularization. Three independent reviewers (MAE, DP, and AM) applied the inclusion criteria to all the included studies, obtaining the full texts of the most relevant studies. The reviewers subsequently assessed these articles to make the final decision on their inclusion in the review. Out of the initial 385 references, 156 were chosen for a detailed review. After examining the full articles were examined, 134 were found suitable for scoping review.

CONCLUSION

The literature notes the scarcity of surgical revascularization in LVD patients in randomized studies, with observational data supporting coronary revascularization's benefits. ONCABG is recommended for multivessel disease in LVD with LVEF < 35%, while OPCAB is proposed for older, high-risk patients. Strategies like internal thoracic artery skeletonization harvesting and postoperative glycemic control mitigate risks with BITA in uncontrolled diabetes. Total arterial revascularization maximizes long-term survival, and hybrid revascularization offers advantages like shorter hospital stays and reduced costs for significant LAD lesions.

Simultaneous Positron Emission Tomography and Molecular Magnetic Resonance Imaging of Cardiopulmonary Fibrosis in a Mouse Model of Left Ventricular Dysfunction

BACKGROUND

Aging-associated left ventricular dysfunction promotes cardiopulmonary fibrogenic remodeling, Group 2 pulmonary hypertension (PH), and right ventricular failure. At the time of diagnosis, cardiac function has declined, and cardiopulmonary fibrosis has often developed. Here, we sought to develop a molecular positron emission tomography (PET)-magnetic resonance imaging (MRI) protocol to detect both cardiopulmonary fibrosis and fibrotic disease activity in a left ventricular dysfunction model.

METHODS AND RESULTS

Left ventricular dysfunction was induced by transverse aortic constriction (TAC) in 6-month-old senescence-accelerated prone mice, a subset of mice that received sham surgery. Three weeks after surgery, mice underwent simultaneous PET-MRI at 4.7 T. Collagen-targeted PET and fibrogenesis magnetic resonance (MR) probes were intravenously administered. PET signal was computed as myocardium- or lung-to-muscle ratio. Percent signal intensity increase and Δ lung-to-muscle ratio were computed from the pre-/postinjection magnetic resonance images. Elevated allysine in the heart (P=0.02) and lungs (P=0.17) of TAC mice corresponded to an increase in myocardial magnetic resonance imaging percent signal intensity increase (P<0.0001) and Δlung-to-muscle ratio (P<0.0001). Hydroxyproline in the heart (P<0.0001) and lungs (P<0.01) were elevated in TAC mice, which corresponded to an increase in heart (myocardium-to-muscle ratio, P=0.02) and lung (lung-to-muscle ratio, P<0.001) PET measurements. Pressure-volume loop and echocardiography demonstrated adverse left ventricular remodeling, function, and increased right ventricular systolic pressure in TAC mice.

CONCLUSIONS

Administration of collagen-targeted PET and allysine-targeted MR probes led to elevated PET-magnetic resonance imaging signals in the myocardium and lungs of TAC mice. The study demonstrates the potential to detect fibrosis and fibrogenesis in cardiopulmonary disease through a dual molecular PET-magnetic resonance imaging protocol.

The Role of Multimodality Imaging in Cardiomyopathy

PURPOSE OF REVIEW

There has been increasing use of multimodality imaging in the evaluation of cardiomyopathies.

RECENT FINDINGS

Echocardiography, cardiac magnetic resonance (CMR), cardiac nuclear imaging, and cardiac computed tomography (CCT) play an important role in the diagnosis, risk stratification, and management of patients with cardiomyopathies. Echocardiography is essential in the initial assessment of suspected cardiomyopathy, but a multimodality approach can improve diagnostics and management. CMR allows for accurate measurement of volumes and function, and can easily detect unique pathologic structures. In addition, contrast imaging and parametric mapping enable the characterization of tissue features such as scar, edema, infiltration, and deposition. In non-ischemic cardiomyopathies, metabolic and molecular nuclear imaging is used to diagnose rare but life-threatening conditions such amyloidosis and sarcoidosis. There is an expanding use of CCT for planning electrophysiology procedures such as cardioversion, ablations, and device placement. Furthermore, CCT can evaluate for complications associated with advanced heart failure therapies such as cardiac transplant and mechanical support devices. Innovations in multimodality cardiac imaging should lead to increased volumes and better outcomes.

Clinical impact of multimodality assessment of myocardial viability

Coronary artery disease (CAD) is a prevalent cause of left ventricular dysfunction. Nevertheless, effective elective revascularization, particularly surgical revascularization, can enhance long-term outcomes and, in selected cases, global left ventricular contractility. The assessment of myocardial viability and scars is still relevant in guiding treatment decisions and selecting patients who are likely to benefit most from blood flow restoration. Although the most recent randomized studies challenge the notion of "hibernating myocardium" and the clinical usefulness of assessing myocardial viability, the advancement of imaging techniques still renders this assessment valuable in specific situations. According to the guidelines of the European Society of Cardiology, non-invasive stress imaging may be employed to define myocardial ischemia and viability in patients with CAD and heart failure before revascularization. Currently, several non-invasive imaging techniques are available to evaluate the presence and extent of viable myocardium. The selection of the most suitable technique should be based on the patient, clinical context, and resource availability. This narrative review evaluates the characteristics of available imaging modalities for assessing myocardial viability to determine the most appropriate therapeutic strategy.

Left ventricular structural integrity on tetralogy of Fallot patients: approach using longitudinal relaxation time mapping

Purpose

Tetralogy of Fallot (TOF) is a congenital heart disease, and patients undergo surgical repair early in their lives. The evaluation of TOF patients is continuous through their adulthood. The use of cardiac magnetic resonance imaging (CMR) is vital for the evaluation of TOF patients. We aim to correlate advanced MRI sequences [parametric longitudinal relaxation time (T1), extracellular volume (ECV) mapping] with cardiac functionality to provide biomarkers for the evaluation of these patients.

Methods

A complete CMR examination with the same imaging protocol was conducted in a total of 11 TOF patients and a control group of 25 healthy individuals. A Modified Look-Locker Inversion recovery (MOLLI) sequence was included to acquire the global T1 myocardial relaxation times of the left ventricular (LV) pre and post-contrast administration. Appropriate software (Circle cmr42) was used for the CMR analysis and the calculation of native, post-contrast T1, and ECV maps. A regression analysis was conducted for the correlation between global LV T1 values and right ventricular (RV) functional indices.

Results

Statistically significant results were obtained for RV cardiac index [RV_CI= -32.765 + 0.029 × T1 native; p = 0.003 ], RV end diastolic volume [RV_EDV/BSA = -1023.872 + 0.902 × T1 native; p = 0.001 ], and RV end systolic volume [RV_ESV/BSA = -536.704 + 0.472 × T1 native; p = 0.011 ].

Conclusions

We further support the diagnostic importance of T1 mapping as a structural imaging tool in CMR. In addition to the well-known affected RV function in TOF patients, the LV structure is also impaired as there is a strong correlation between LV T1 mapping and RV function, evoking that the heart operates as an entity.

How to use MRI in cardiac disease with diastolic dysfunction?

Left ventricular (LV) diastolic dysfunction (DD) is an initially asymptomatic condition that can progress to heart failure, either with preserved or reduced ejection fraction. As such, DD is a growing public health problem. Impaired relaxation, the first stage of DD, is associated with altered LV filling. With progression, reducing LV compliance leads to restrictive cardiomyopathy. While cardiac magnetic resonance (CMR) imaging is the reference for LV systolic function assessment, transthoracic echocardiography (TTE) with Doppler flow measurements remains the standard for diastolic function assessment. Rather than simply replicating TTE measurements, CMR should complement and further advance TTE findings. We provide herein a step-by-step review of CMR findings in DD as well as imaging features which may help identify the underlying cause.

Diagnostic efficacy of complexity metrics from cardiac MRI myocardial segmental motion curves in detecting late gadolinium enhancement in myocardial infarction patients

Background

Myocardial segmental motion is associated with cardiovascular pathology, often assessed through myocardial strain features. The stability of the motion can be influenced by myocardial fibrosis. This research aimed to explore the complexity metrics (CM) of myocardial segmental motion curves, observe their correlation with late gadolinium enhancement (LGE) transmural extension (TE), and assess diagnostic efficacy combined with segmental strains in different TE segments.

Methods

We included 42 myocardial infarction patients, dividing images into 672 myocardial segments (208 remote, 384 viable, and 80 unviable segments based on TE). Radial and circumferential segmental strain, along with CM for motion curves, were extracted. Correlation between CM and LGE, as well as the potential distinguishing role of CM, was evaluated using Pearson correlation, univariate linear regression (F-test), multivariate regression analysis (T-test), area under curve (AUC), machine learning models, and DeLong test.

Results

All CMs showed significant linear correlation with TE (P < 0.001). Six CMs were correlated with TE (r > 0.3), with radial frequency drift (FD) displayed the strongest correlation (r = 0.496, P < 0.001). Radial and circumferential FD significantly differed in higher TE myocardium than in remote segments (P < 0.05). Radial FD had practical diagnostic efficacy (remote vs. unviable AUC = 0.89, viable vs. unviable AUC = 0.77, remote vs. viable AUC = 0.65). Combining CM with segmental strain features boosted diagnostic efficacy than models using only segmental strain features (DeLong test, P < 0.05).

Conclusions

The CM of myocardial motion curves has been associated with LGE infarction, and combining CM with strain features improves the diagnosis of different myocardial LGE infarction degrees.

Fully automated contrast selection of joint bright- and black-blood late gadolinium enhancement imaging for robust myocardial scar assessment

PURPOSE

Joint bright- and black-blood MRI techniques provide improved scar localization and contrast. Black-blood contrast is obtained after the visual selection of an optimal inversion time (TI) which often results in uncertainties, inter- and intra-observer variability and increased workload. In this work, we propose an artificial intelligence-based algorithm to enable fully automated TI selection and simplify myocardial scar imaging.

METHODS

The proposed algorithm first localizes the left ventricle using a U-Net architecture. The localized left cavity centroid is extracted and a squared region of interest ("focus box") is created around the resulting pixel. The focus box is then propagated on each image and the sum of the pixel intensity inside is computed. The smallest sum corresponds to the image with the lowest intensity signal within the blood pool and healthy myocardium, which will provide an ideal scar-to-blood contrast. The image's corresponding TI is considered optimal. The U-Net was trained to segment the epicardium in 177 patients with binary cross-entropy loss. The algorithm was validated retrospectively in 152 patients, and the agreement between the algorithm and two magnetic resonance (MR) operators' prediction of TI values was calculated using the Fleiss' kappa coefficient. Thirty focus box sizes, ranging from 2.3mm2 to 20.3cm2, were tested. Processing times were measured.

RESULTS

The U-Net's Dice score was 93.0 ± 0.1%. The proposed algorithm extracted TI values in 2.7 ± 0.1 s per patient (vs. 16.0 ± 8.5 s for the operator). An agreement between the algorithm's prediction and the MR operators' prediction was found in 137/152 patients (κ= 0.89), for an optimal focus box of size 2.3cm2.

CONCLUSION

The proposed fully-automated algorithm has potential of reducing uncertainties, variability, and workload inherent to manual approaches with promise for future clinical implementation for joint bright- and black-blood MRI.

Imaging of Cardiac Fibrosis: An Update, From the AJR Special Series on Imaging of Fibrosis

Myocardial fibrosis (MF) is defined as excessive production and deposition of extra-cellular matrix proteins that result in pathologic myocardial remodeling. Three types of MF have been identified: replacement fibrosis from tissue necrosis, reactive fibrosis from myocardial stress, and infiltrative interstitial fibrosis from progressive deposition of nondegradable material such as amyloid. Although echocardiography, nuclear medicine, and CT play important roles in the assessment of MF, MRI is pivotal in the evaluation of MF, with the late gadolinium enhancement (LGE) technique used as a primary end point. The LGE technique focuses on the pattern and distribution of gadolinium accumulation in the myocardium and assists in the diagnosis and establishment of the cause of both ischemic and nonischemic cardiomyopathy. LGE MRI also aids prognostication and risk stratification. In addition, LGE MRI is used to guide the management of patients considered for ablation for arrhythmias. Parametric mapping techniques, including T1 mapping and extracellular volume measurement, allow detection and quantification of diffuse fibrosis, which may not be detected by LGE MRI. These techniques also allow monitoring of disease progression and therapy response. This review provides an update on the imaging of MF, including prognostication and risk stratification tools, electrophysiologic considerations, and disease monitoring.

Deep learning for automatic volumetric segmentation of left ventricular myocardium and ischaemic scar from multi-slice late gadolinium enhancement cardiovascular magnetic resonance

AIMS

This study details application of deep learning for automatic volumetric segmentation of left ventricular (LV) myocardium and scar and automated quantification of myocardial ischaemic scar burden from late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR).

METHODS AND RESULTS

We included 501 images and manual segmentations of short-axis LGE-CMR from over 20 multinational sites, from which 377 studies were used for training and 124 studies from unique participants for internal validation. A third test set of 52 images was used for external evaluation. Three models, U-Net, Cascaded U-Net, and U-Net++, were trained with a novel adaptive weighted categorical cross-entropy loss function. Model performance was evaluated using concordance correlation coefficients (CCCs) for LV mass and per cent myocardial scar burden. Cascaded U-Net was found to be the best model for the quantification of LV mass and scar percentage. The model exhibited a mean difference of -5 ± 23 g for LV mass, -0.4 ± 11.2 g for scar mass, and -0.8 ± 7% for per cent scar. CCC were 0.87, 0.77, and 0.78 for LV mass, scar mass, and per cent scar burden, respectively, in the internal validation set and 0.75, 0.71, and 0.69, respectively, in the external test set. For segmental scar mass, CCC was 0.74 for apical scar, 0.91 for mid-ventricular scar, and 0.73 for basal scar, demonstrating moderate to strong agreement.

CONCLUSION

We successfully trained a convolutional neural network for volumetric segmentation and analysis of LV scar burden from LGE-CMR images in a large, multinational cohort of participants with ischaemic scar.

Sudden Cardiac Death Risk Stratification in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) poses a significant clinical challenge, with sudden cardiac death (SCD) emerging as one of the leading causes of mortality. Despite advancements in cardiovascular medicine, predicting and preventing SCD in HFpEF remains complex due to multifactorial pathophysiological mechanisms and patient heterogeneity. Unlike heart failure with reduced ejection fraction, where impaired contractility and ventricular remodeling predominate, HFpEF pathophysiology involves heavy burden of comorbidities such as hypertension, obesity, and diabetes. Diverse mechanisms, including diastolic dysfunction, microvascular abnormalities, and inflammation, also contribute to distinct disease and SCD risk profiles. Various parameters such as clinical factors and electrocardiogram features have been proposed in SCD risk assessment. Advanced imaging modalities and biomarkers offer promise in risk prediction, yet comprehensive risk stratification models specific to HFpEF ar0e lacking. This review offers recent evidence on SCD risk factors and discusses current therapeutic strategies aimed at reducing SCD risk in HFpEF.

Using diffusion tensor imaging to depict myocardial changes after matured pluripotent stem cell-derived cardiomyocyte transplantation

BACKGROUND

Novel treatment strategies are needed to improve the structure and function of the myocardium post-infarction. In vitro-matured pluripotent stem cell-derived cardiomyocytes (PSC-CMs) have been shown to be a promising regenerative strategy. We hypothesized that mature PSC-CMs will have anisotropic structure and improved cell alignment when compared to immature PSC-CMs using cardiovascular magnetic resonance (CMR) in a guinea pig model of cardiac injury.

METHODS

Guinea pigs (n = 16) were cryoinjured on day -10, followed by transplantation of either 108 polydimethylsiloxane (PDMS)-matured PSC-CMs (n = 6) or 108 immature tissue culture plastic (TCP)-generated PSC-CMs (n = 6) on day 0. Vehicle (sham-treated) subjects were injected with a pro-survival cocktail devoid of cells (n = 4), while healthy controls (n = 4) did not undergo cryoinjury or treatment. Animals were sacrificed on either day +14 or day +28 post-transplantation. Animals were imaged ex vivo on a 7T Bruker MRI. A 3D diffusion tensor imaging (DTI) sequence was used to quantify structure via fractional anisotropy (FA), mean diffusivity (MD), and myocyte alignment measured by the standard deviation of the transverse angle (TA).

RESULTS

MD and FA of mature PDMS grafts demonstrated anisotropy was not significantly different than the healthy control hearts (MD = 1.1 ± 0.12 × 10-3 mm2/s vs 0.93 ± 0.01 × 10-3 mm2/s, p = 0.4 and FA = 0.22 ± 0.05 vs 0.26 ± 0.001, p = 0.5). Immature TCP grafts exhibited significantly higher MD than the healthy control (1.3 ± 0.08 × 10-3 mm2/s, p < 0.05) and significantly lower FA than the control (0.12 ± 0.02, p < 0.05) but were not different from mature PDMS grafts in this small cohort. TA of healthy controls showed low variability and was not significantly different than mature PDMS grafts (p = 0.4) while immature TCP grafts were significantly different (p < 0.001). DTI parameters of mature graft tissue trended toward that of the healthy myocardium, indicating the grafted cardiomyocytes may have a similar phenotype to healthy tissue. Contrast-enhanced magnetic resonance images corresponded well to histological staining, demonstrating a non-invasive method of localizing the repopulated cardiomyocytes within the scar.

CONCLUSIONS

The DTI measures within graft tissue were indicative of anisotropic structure and showed greater myocyte organization compared to the scarred territory. These findings show that MRI is a valuable tool to assess the structural impacts of regenerative therapies.

Transient Left Ventricular Dysfunction from Cardiomyopathies to Myocardial Viability: When and Why Cardiac Function Recovers

Transient left ventricular dysfunction (TLVD), a temporary condition marked by reversible impairment of ventricular function, remains an underdiagnosed yet significant contributor to morbidity and mortality in clinical practice. Unlike the well-explored atherosclerotic disease of the epicardial coronary arteries, the diverse etiologies of TLVD require greater attention for proper diagnosis and management. The spectrum of disorders associated with TLVD includes stress-induced cardiomyopathy, central nervous system injuries, histaminergic syndromes, various inflammatory diseases, pregnancy-related conditions, and genetically determined syndromes. Furthermore, myocardial infarction with non-obstructive coronary arteries (MINOCA) origins such as coronary artery spasm, coronary thromboembolism, and spontaneous coronary artery dissection (SCAD) may also manifest as TLVD, eventually showing recovery. This review highlights the range of ischemic and non-ischemic clinical situations that lead to TLVD, gathering conditions like Tako-Tsubo Syndrome (TTS), Kounis syndrome (KS), Myocarditis, Peripartum Cardiomyopathy (PPCM), and Tachycardia-induced cardiomyopathy (TIC). Differentiation amongst these causes is crucial, as they involve distinct clinical, instrumental, and genetic predictors that bode different outcomes and recovery potential for left ventricular function. The purpose of this review is to improve everyday clinical approaches to treating these diseases by providing an extensive survey of conditions linked with TLVD and the elements impacting prognosis and outcomes.

Outcomes of Percutaneous Revascularization in Severe Ischemic Left Ventricular Dysfunction

PURPOSE OF REVIEW

This article presents a comprehensive review of coronary revascularization versus optimal medical therapy (OMT) in patients with severe ischemic left ventricular dysfunction.

RECENT FINDINGS

The REVIVED-BCIS2 trial randomized 700 patients with extensive coronary artery disease and left ventricular (LV) ejection fraction (LVEF) ≤ 35% and viability in more than four dysfunctional myocardial segments to percutaneous coronary intervention (PCI) plus OMT versus OMT alone. Over a median duration of 41 months, there was no difference in the composite of all-cause mortality, heart failure hospitalization, or improvement in LVEF with PCI plus OMT versus OMT alone at 6 and 12 months, quality of life scores at 24 months, or fatal ventricular arrhythmia. The STICH randomized trial was conducted between 2002 and 2007, involving patients with LV dysfunction and coronary artery disease. The patients were assigned to either CABG plus medical therapy or medical therapy alone. At the 5-year follow-up, the trial showed that CABG plus medical therapy reduced cardiovascular disease-related deaths and hospitalizations but no reduction in all-cause mortality. However, a 10-year follow-up showed a significant decrease in all-cause mortality with CABG. The currently available evidence showed no apparent benefit of PCI in severe ischemic cardiomyopathy as compared to OMT, but that CABG improves outcomes in this patient population. The paucity of data on the advantages of PCI in this patient population underscores the critical need for optimization of medical therapy for better survival and quality of life until further evidence from RCTs is available.

Simultaneous Viability Assessment and Invasive Coronary Angiography Using a Therapeutic CT System in Chronic Myocardial Infarction Patients

PURPOSE

In a preclinical study using a swine myocardial infarction (MI) model, a delayed enhancement (DE)-multi-detector computed tomography (MDCT) scan was performed using a hybrid system alongside diagnostic invasive coronary angiography (ICA) without the additional use of a contrast agent, and demonstrated an excellent correlation in the infarct area compared with histopathologic specimens. In the present investigation, we evaluated the feasibility and diagnostic accuracy of a myocardial viability assessment by DE-MDCT using a hybrid system comprising ICA and MDCT alongside diagnostic ICA without the additional use of a contrast agent.

MATERIALS AND METHODS

We prospectively enrolled 13 patients (median age: 67 years) with a previous MI (>6 months) scheduled to undergo ICA. All patients underwent cardiac magnetic resonance (CMR) imaging before diagnostic ICA. MDCT viability scans were performed concurrently with diagnostic ICA without the use of additional contrast. The total myocardial scar volume per patient and average transmurality per myocardial segment measured by DE-MDCT were compared with those from DE-CMR.

RESULTS

The DE volume measured by MDCT showed an excellent correlation with the volume measured by CMR (r=0.986, p<0.0001). The transmurality per segment by MDCT was well-correlated with CMR (r=0.900, p<0.0001); the diagnostic performance of MDCT in differentiating non-viable from viable myocardium using a 50% transmurality criterion was good with a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 87.5%, 99.5%, 87.5%, 99.5%, and 99.1%, respectively.

CONCLUSION

The feasibility of the DE-MDCT viability assessment acquired simultaneously with conventional ICA was proven in patients with chronic MI using DE-CMR as the reference standard.

A history of cardiovascular magnetic resonance imaging in clinical practice and population science

Cardiovascular magnetic resonance (CMR) imaging has become an invaluable clinical and research tool. Starting from the discovery of nuclear magnetic resonance, this article provides a brief overview of the key developments that have led to CMR as it is today, and how it became the modality of choice for large-scale population studies.

Myocardial scar and left ventricular ejection fraction classification for electrocardiography image using multi-task deep learning

Myocardial scar (MS) and left ventricular ejection fraction (LVEF) are vital cardiovascular parameters, conventionally determined using cardiac magnetic resonance (CMR). However, given the high cost and limited availability of CMR in resource-constrained settings, electrocardiograms (ECGs) are a cost-effective alternative. We developed computer vision-based multi-task deep learning models to analyze 12-lead ECG 2D images, predicting MS and LVEF < 50%. Our dataset comprises 14,052 ECGs with clinical features, utilizing ground truth labels from CMR. Our top-performing model achieved AUC values of 0.838 (95% CI 0.812-0.862) for MS and 0.939 (95% CI 0.921-0.954) for LVEF < 50% classification, outperforming cardiologists. Moreover, MS predictions in a prevalence-specific test dataset recorded an AUC of 0.812 (95% CI 0.810-0.814). Extracted 1D signals from ECG images yielded inferior performance, compared to the 2D approach. In conclusion, our results demonstrate the potential of computer-based MS and LVEF < 50% classification from ECG scan images in clinical screening offering a cost-effective alternative to CMR.