Role of genetics in inflammatory cardiomyopathy

Cardiac sarcoidosis; update for the heart failure specialist

PURPOSE OF REVIEW

This review presents contemporary data on epidemiology, common presentations, investigations and diagnostic algorithms, treatment and prognosis. It particularly focuses on topics of most relevance to heart failure specialists, including what left ventricle (LV) function changes can be expected after treatment and outcomes to all standard and advanced heart failure therapies.

RECENT FINDINGS

Around 5% of sarcoidosis patients have clinically manifest cardiac sarcoidosis (CS), presenting with significant arrhythmias (such as conduction disturbances and ventricular arrhythmias) or newly developed unexplained heart failure. These cardiac symptoms (including sudden cardiac death) may be the initial manifestations of CS. While cardiac magnetic resonance imaging (CMR) is the preferred method for identifying fibrosis in the myocardium, FDG-positron emission tomography (FDG-PET) helps in identifying active inflammation within the myocardium and aids in managing immunosuppressive treatment. The concept of isolated CS is much debated. However very importantly, recent data have shown that some patients diagnosed with 'clinically and imaging isolated CS' are subsequently found to have genetic cardiomyopathy. The management of CS involves a comprehensive approach including medications for immunosuppression, all standard heart failure medication and, in high-risk patient's implantable cardioverter defibrillators (ICDs). In CS patients with terminal heart failure who do not respond to medical and surgical interventions, heart transplantation and ventricular assist devices should be considered. Long-term results after transplantation are generally favorable and comparable to non-CS patients. The degree of left ventricular dysfunction remains a crucial prognostic factor in CS cases. Outcomes for CS have very significantly improved, over the last two decades due to earlier diagnosis, advanced heart failure treatments, and the strategic use of ICD therapy.

SUMMARY

Outcomes for CS have significantly improved, over the last two decades due to earlier diagnosis, advanced heart failure treatments, and the strategic use of ICD therapy.

Management of patients with myocarditis and arrhythmogenic phenotype

Acute myocarditis (AM) is an inflammatory condition of the myocardium that may lead to severe complications, including acute heart failure and life-threatening ventricular arrhythmias (VAs). In-hospital VAs are estimated to affect 2.5% of adult patients with AM. Recent insights suggest a genetic predisposition to develop VA in a subset of patients with AM. This review will focus on arrhythmogenic manifestations of AM, highlighting risk stratification for VA after an acute episode and the contribution of genetic factors, emphasizing the need to integrate clinical, imaging, and genetic findings. In addition, prognostic information derived from cardiac magnetic resonance imaging will be discussed, pointing out the association between VA and the presence, extension, and septal localization of late gadolinium enhancement. The overlap between inherited arrhythmogenic and inflammatory cardiomyopathies will be explored, with specific attention to the identification of desmosomal gene variants, which are associated with recurrent myocarditis-like episodes and a higher risk of VA. Cardiac sarcoidosis, giant cell myocarditis, and immune checkpoint inhibitors-related myocarditis will be discussed as a paradigm of inflammatory cardiomyopathies with increased arrhythmic burden. Finally, the clinical challenges of managing patients with AM and arrhythmogenic presentation will be tackled, looking at indications for implantable cardioverter defibrillators after the acute phase.

Optimized machine learning framework for cardiovascular disease diagnosis: a novel ethical perspective

Alignment of advanced cutting-edge technologies such as Artificial Intelligence (AI) has emerged as a significant driving force to achieve greater precision and timeliness in identifying cardiovascular diseases (CVDs). However, it is difficult to achieve high accuracy and reliability in CVD diagnostics due to complex clinical data and the selection and modeling process of useful features. Therefore, this paper studies advanced AI-based feature selection techniques and the application of AI technologies in the CVD classification. It uses methodologies such as Chi-square, Info Gain, Forward Selection, and Backward Elimination as an essence of cardiovascular health indicators into a refined eight-feature subset. This study emphasizes ethical considerations, including transparency, interpretability, and bias mitigation. This is achieved by employing unbiased datasets, fair feature selection techniques, and rigorous validation metrics to ensure fairness and trustworthiness in the AI-based diagnostic process. In addition, the integration of various Machine Learning (ML) models, encompassing Random Forest (RF), XGBoost, Decision Trees (DT), and Logistic Regression (LR), facilitates a comprehensive exploration of predictive performance. Among this diverse range of models, XGBoost stands out as the top performer, achieving exceptional scores with a 99% accuracy rate, 100% recall, 99% F1-measure, and 99% precision. Furthermore, we venture into dimensionality reduction, applying Principal Component Analysis (PCA) to the eight-feature subset, effectively refining it to a compact six-attribute feature subset. Once again, XGBoost shines as the model of choice, yielding outstanding results. It achieves accuracy, recall, F1-measure, and precision scores of 98%, 100%, 98%, and 97%, respectively, when applied to the feature subset derived from the combination of Chi-square and Forward Selection methods.

Acute myocarditis: 2024 state of the art

Acute myocarditis (AM) is an inflammatory injury of the myocardium secondary to infections, systemic autoimmune disorders, medications, or toxic agents. The patient's genetic underground is a likely concurrent aetiology/contributory mechanism recently implicated in a proportion of AM. This review focuses on some critical new concepts of AM, updated indications for endomyocardial biopsy when cardiac magnetic resonance imaging is not sufficient or feasible, and estimation of long-term events after discharge. Furthermore, studies exploring AM as the cause of sudden cardiac death will be examined to assess the characteristics of patients who die due to AM before hospital admission. Managing the most severe clinical presentation, termed fulminant myocarditis (FM) characterized by haemodynamic instability due to ventricular arrhythmias or severe acute pump failure, will be summarized. Specific issues aimed to reduce the high mortality rate of FM, like early recognition, referring these patients from spoke centres to a hub centre, timely temporary mechanical circulatory support when indicated, early endomyocardial biopsy, and eventually immunosuppression, will be briefly discussed. Immune checkpoint inhibitors and desmosomal gene variant-associated AM will be highlighted as paradigmatic new forms of myocarditis.

The Role of Signalling Pathways in Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most prevalent hereditary cardiovascular disorder, characterised by left ventricular hypertrophy and cardiac fibrosis. Cardiac fibroblasts, transformed into myofibroblasts, play a crucial role in the development of fibrosis. However, interactions between fibroblasts, cardiomyocytes, and immune cells are considered major mechanisms driving fibrosis progression. While the disease has a strong genetic background, its pathogenetic mechanisms remain complex and not fully understood. Several signalling pathways are implicated in fibrosis development. Among these, transforming growth factor-beta and angiotensin II are frequently studied in the context of cardiac fibrosis. In this review, we summarise the most current evidence on the involvement of signalling pathways in the pathogenesis of HCM. Additionally, we discuss the potential role of monitoring pro-fibrotic molecules in predicting clinical outcomes in patients with HCM.

The "Padua classification" of cardiomyopathies: Combining pathobiological basis and morpho-functional remodeling

Over the last 20 years, the scientific progresses in molecular biology and genetics in combination with the increasing use in the clinical setting of contrast-enhanced cardiac magnetic resonance (CMR) for morpho-functional imaging and structural myocardial tissue characterization have provided important new insights into our understanding of the distinctive aspects of cardiomyopathy, regarding both the genetic and biologic background and the clinical phenotypic features. This has led to the need of an appropriate revision and upgrading of current nosographic framework and pathobiological categorization of heart muscle disorders. This article proposes a new definition and classification of cardiomyopathies that rely on the combination of the distinctive pathobiological basis (genetics, molecular biology and pathology) and the clinical phenotypic pattern (morpho-functional and structural features), leading to the proposal of three different disease categories, each of either genetic or non-genetic etiology and characterized by a combined designation based on both "anatomic" and "functional" features, i.e., hypertrophic/restrictive (H/RC), dilated/hypokinetic (D/HC) and scarring/arrhythmogenic cardiomyopathy (S/AC). The clinical application of the newly proposed classification approach in the real-world practice appears crucial to design a targeted clinical management and evaluation of outcomes of affected patients. Although current treatment of cardiomyopathies is largely palliative and based on drugs, catheter ablation, device or surgical interventions aimed to prevent and manage heart failure and malignant arrhythmias, better knowledge of basic mechanisms involved in the onset and progression of pathobiologically different heart muscle diseases may allow to the development of disease-specific curative therapy.

Long-term prognostic performance of cardiac magnetic resonance imaging markers versus complicated clinical presentation after an acute myocarditis

BACKGROUND

Identifying markers associated with adverse events after acute myocarditis (AM) is relevant to plan follow-up. We assessed the prognostic performance of previously described cardiac magnetic resonance imaging (CMRI) markers and their combination: septal late gadolinium enhancement (LGE) localization and left ventricular ejection fraction (LVEF) < 50 % on baseline CMRI versus complicated clinical presentation (CCP: the presence of sustained ventricular tachycardia, or LVEF<50 % on the first echocardiogram or fulminant presentation).

METHODS

We retrospectively assessed 248 AM patients (median age of 34 years, 87.1 % male) from 6 hospitals with onset of cardiac symptoms<30 days, increased troponin, and CMRI/histology consistent with myocarditis to identify those at risk of major cardiac events (cardiac death, heart transplantation, aborted sudden cardiac death, sustained ventricular tachycardia, or heart failure hospitalization).

RESULTS

Thirteen patients (5.2 %) experienced at least one major cardiac event after a median follow-up of 4.7 years with a significant hazard ratio of 35.8 for CCP vs. 9.2 for septal LGE vs. 12.4 for LVEF<50 % on baseline CMRI (p = 0.001). CCP had the best c-index to identify patients with events: 0.836 vs. 0.786 for septal LGE and 0.762 for LVEF<50 %, while the combination of CCP plus LVEF<50 % or septal LGE has the highest c-index of 0.866. All 3 markers had high negative predictive value (NPV) of ≥0.98.

CONCLUSIONS

Major cardiac events after an AM are relatively low, and CCP, septal LGE, and LVEF<50 % are significantly associated with events. These markers have especially high NPV to identify patients without events after an AM. These observations can help clinicians to monitor the patients after an AM.

The Desmoplakin Phenotype Spectrum: Is the Inflammation the "Fil Rouge" Linking Myocarditis, Arrhythmogenic Cardiomyopathy, and Uncommon Autoinflammatory Systemic Disease?

Myocarditis is an inflammatory condition of cardiac tissue presenting significant variability in clinical manifestations and outcomes. Its etiology is diverse, encompassing infectious agents (primarily viruses, but also bacteria, protozoa, and helminths) and non-infectious factors (autoimmune responses, toxins, and drugs), though often the specific cause remains unidentified. Recent research has highlighted the potential role of genetic susceptibility in the development of myocarditis (and in some cases the development of inflammatory dilated cardiomyopathy, i.e., the condition in which there is chronic inflammation (>3 months) and left ventricular dysfunction\dilatation), with several studies indicating a correlation between myocarditis and genetic backgrounds. Notably, pathogenic genetic variants linked to dilated or arrhythmic cardiomyopathy are found in 8-16% of myocarditis patients. Genetic predispositions can lead to recurrent myocarditis and a higher incidence of ventricular arrhythmias and heart failure. Moreover, the presence of DSP mutations has been associated with distinct pathological patterns and clinical outcomes in arrhythmogenic cardiomyopathy (hot phases). The interplay between genetic factors and environmental triggers, such as viral infections and physical stress, is crucial in understanding the pathogenesis of myocarditis. Identifying these genetic markers can improve the diagnosis, risk stratification, and management of patients with myocarditis, potentially guiding tailored therapeutic interventions. This review aims to synthesize current knowledge on the genetic underpinnings of myocarditis, with an emphasis on desmoplakin-related arrhythmogenic cardiomyopathy, to enhance clinical understanding and inform future research directions.

Clinical Characteristics and Mechanisms of Acute Myocarditis

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05335928.