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

Cardiac Fibrosis in the Multi-Omics Era: Implications for Heart Failure

Cardiac fibrosis, a hallmark of heart failure and various cardiomyopathies, represents a complex pathological process that has long challenged therapeutic intervention. High-throughput omics technologies have begun revolutionizing our understanding of the molecular mechanisms driving cardiac fibrosis and are providing unprecedented insights into its heterogeneity and progression. This review provides a comprehensive analysis of how techniques-encompassing genomics, epigenomics, transcriptomics, proteomics, and metabolomics-are providing insight into our understanding of cardiac fibrosis. Genomic studies have identified novel genetic variants and regulatory networks associated with fibrosis susceptibility and progression, and single-cell transcriptomics has unveiled distinct cardiac fibroblast subpopulations with unique molecular signatures. Epigenomic profiling has revealed dynamic chromatin modifications controlling fibroblast activation states, and proteomic analyses have identified novel biomarkers and potential therapeutic targets. Metabolomic studies have uncovered important alterations in cardiac energetics and substrate utilization during fibrotic remodeling. The integration of these multi-omic data sets has led to the identification of previously unrecognized pathogenic mechanisms and potential therapeutic targets, including cell-type-specific interventions and metabolic modulators. We discuss how these advances are driving the development of precision medicine approaches for cardiac fibrosis while highlighting current challenges and future directions in translating multi-omic insights into effective therapeutic strategies. This review provides a systems-level perspective on cardiac fibrosis that may inform the development of more effective, personalized therapeutic approaches for heart failure and related cardiovascular diseases.

Risk stratification for future cardiac arrest after COVID-19 vaccination

Unheralded cardiac arrest among previously healthy young people without antecedent illness, months or years after coronavirus disease 2019 (COVID-19) vaccination, highlights the urgent need for risk stratification. The most likely underlying pathophysiology is subclinical myopericarditis and reentrant ventricular tachycardia or spontaneous ventricular fibrillation that is commonly precipitated after a surge in catecholamines during exercise or the waking hours of terminal sleep. Small patches of inflammation and/or edema can be missed on cardiac imaging and autopsy, and the heart can appear grossly normal. This paper reviews evidence linking COVID-19 vaccines to cardiac arrest where unfortunately the majority of victims have had no antecedent clinical evaluation. We propose a comprehensive strategy for evaluating cardiovascular risk post-vaccination, incorporating detailed patient history, antibody testing, and cardiac diagnostics in the best attempt to detect abnormalities before sudden cardiac death. This approach aims to identify individuals at higher risk of cardiac events after COVID-19 vaccination and guide appropriate clinical management. It is prudent for each primary care physician to have a pre-established plan when addressing this issue in their practice.

VASN knockout induces myocardial fibrosis in mice by downregulating non-collagen fibers and promoting inflammation

Myocardial fibrosis (MF) is an important cause of heart failure and cardiac arrest. Vasorin knockout (VASN-/-) leads to pathological cardiac hypertrophy (PCH); however, it is not yet clear whether this PCH transitions to MF in mice. VASN-knockout mice showed typical pathological, imaging, and molecular features of MF upon hematoxylin and eosin staining, Masson staining, Sirius red staining, quantitative polymerase chain reaction (qPCR), immunohistochemistry-paraffin (IHC-P), and immunofluorescence analyses. RNA was extracted from mouse heart tissue, identified, and sequenced in vitro. Differential analysis of the genes showed that the extracellular matrix (ECM) genes (COL6A1, COL9A1, and FRAS1) had strong correlations while their expression levels were significantly reduced by qPCR, IHC-P, and Western blotting. The expression levels of the ECM genes were significantly reduced but those of the inflammatory factors (IL1β and IL6) were significantly upregulated in the heart tissues of VASN-knockout mice. These preliminary results reveal that VASN knockout induces MF by regulating the non-collagen fibers and inflammation.

Imaging of Cardiac Fibrosis: How Far Have We Moved From Extracellular to Cellular?

Cardiovascular disease is the leading cause of morbidity and mortality worldwide. Myocardial fibrosis plays an important role in adverse outcomes such as heart failure and arrhythmias. As the pathological response and degree of scarring, and therefore clinical presentation varies from patient to patient, early detection of fibrosis is crucial for identifying the appropriate treatment approach and forecasting the progression of a disease along with the likelihood of disease-related mortality. Current imaging modalities provides information about either decreased function or extracellular signs of fibrosis. Targeting activated fibroblasts represents a burgeoning approach that could offer insights prior to observable functional alterations, presenting a promising focus for potential anti-fibrotic therapeutic interventions at cellular level. In this article, we provide an overview of imaging cardiac fibrosis and discuss the role of different advanced imaging modalities with the focus on novel non-invasive imaging of activated fibroblasts.