Improved Cardiac Performance and Decreased Arrhythmia in Hypertrophic Cardiomyopathy With Non-β-Blocking R-Enantiomer Carvedilol

Mineralocorticoid receptor phase separation modulates cardiac preservation

Heart transplantation is the gold standard treatment for patients with end-stage heart failure. However, there is a shortage of donor hearts available. The short tolerable cold ischemic time for delivering donor hearts to matching recipients is closely responsible for this shortage. Here we uncover the phenomenon of mineralocorticoid receptor (MR) phase separation, which exacerbates injury to the murine and human donor heart during cold storage and can be modulated with pharmacological inhibition to improve preservation quality. Interestingly, donor cardiomyocytes strongly expressed MR, which undergoes preservation-related phase separation. The phenomenon of macromolecular phase separation is not limited to the heart or MR during preservation. Cold preservation of the lung, liver and kidney also displays phase separation of other transcriptional regulators including histone deacetylase 1 (HDAC1), bromodomain-containing 4 (BRD4) and MR. Our results reveal an understudied area of preservation biology that may be further exploited to improve the preservation of multiple solid organs.

Molecular Insights into Oxidative-Stress-Mediated Cardiomyopathy and Potential Therapeutic Strategies

Cardiomyopathies comprise a heterogeneous group of cardiac disorders characterized by structural and functional abnormalities in the absence of significant coronary artery disease, hypertension, valvular disease, or congenital defects. Major subtypes include hypertrophic, dilated, arrhythmogenic, and stress-induced cardiomyopathies. Oxidative stress (OS), resulting from an imbalance between reactive oxygen species (ROS) production and antioxidant defenses, has emerged as a key contributor to the pathogenesis of these conditions. ROS-mediated injury drives inflammation, protease activation, mitochondrial dysfunction, and cardiomyocyte damage, thereby promoting cardiac remodeling and functional decline. Although numerous studies implicate OS in cardiomyopathy progression, the precise molecular mechanisms remain incompletely defined. This review provides an updated synthesis of current findings on OS-related signaling pathways across cardiomyopathy subtypes, emphasizing emerging therapeutic targets within redox-regulatory networks. A deeper understanding of these mechanisms may guide the development of targeted antioxidant strategies to improve clinical outcomes in affected patients.

Temporal Patterns of Holter-Detected Arrhythmias in Hypertrophic Cardiomyopathy Patients Treated with Mavacamten

Background: Hypertrophic cardiomyopathy (HCM) is a genetic cardiomyopathy marked by increased left ventricular wall thickness, leading in some cases to left ventricular outflow tract (LVOT) obstruction, heart failure, and arrhythmias. Mavacamten, a selective allosteric inhibitor of cardiac myosin, has demonstrated benefits in improving hemodynamics and reducing LVOT obstruction. However, its impact on arrhythmic burden remains unclear, with reports of early atrial fibrillation (AF) risk contrasting with long-term reductions in arrhythmias. This study assesses the temporal patterns of Holter-detected arrhythmias in HCM patients treated with mavacamten. Methods: This retrospective study included HCM patients from three Mayo Clinic sites. Baseline demographic, clinical, and echocardiographic data were collected. Holter monitoring was performed at baseline, short-term (<6 months), and long-term (>6 months) follow-up. Arrhythmic events, including premature atrial contractions (PACs), premature ventricular contractions (PVCs), and supraventricular tachycardia (SVT), were analyzed using standardized rates per 24 h. Statistical comparisons utilized the Wilcoxon signed-rank test. Results: Twenty-seven patients (56% female, median age 66 years) were included. PACs, PVCs, and SVT duration transiently but not significantly increased at short-term follow-up but returned to baseline at long-term follow-up. No sustained or high-risk ventricular arrhythmias were observed. Conclusions: Mavacamten is associated with transient arrhythmic fluctuations early in treatment, followed by stabilization. These findings support its long-term electrophysiological safety and underscore the need for early rhythm monitoring. Further research should explore its role in arrhythmic risk stratification in HCM patients.

Hypertrophic cardiomyopathy: insights into pathophysiology and novel therapeutic strategies from clinical studies

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a frequently encountered cardiac condition worldwide, often inherited, and characterized by intricate phenotypic and genetic manifestations. The natural progression of HCM is diverse, largely due to mutations in the contractile and relaxation proteins of the heart. These mutations disrupt the normal structure and functioning of the heart muscle, particularly affecting genes that encode proteins involved in the contraction and relaxation of cardiac muscle.

MAIN BODY

This review focused on understanding the role of contractile and relaxation proteins in the pathogenesis of hypertrophic cardiomyopathy. Mutations in contractile proteins such as myosin, actin, tropomyosin, and troponin are associated with hypercontractility and increased sensitivity of the heart muscle, leading to HCM. Additionally, impaired relaxation of the heart muscle, linked to abnormalities in proteins like phospholamban, sarcolipin, titin, myosin binding protein-C, and calsequestrin, contributes significantly to the disease. The review also explored the impact of targeted therapeutic approaches aimed at modulating these proteins to improve patient outcomes. Recent advances in therapeutic strategies, including novel pharmacological agents like mavacamten and aficamten, were examined for their potential to help patients manage the disease and lead more accommodating lifestyles.

CONCLUSIONS

The review underscored the significance of early diagnosis and personalized treatment approaches in managing HCM. Future research should prioritize the development of robust biomarkers for early detection and risk stratification, particularly in diverse populations, to enhance clinical outcomes. Furthermore, it is imperative to delve deeper into the genetic mutations and molecular mechanisms associated with HCM, with a focus on exploring the roles of less-studied myocardial relaxation proteins and their interactions with sarcomere constituents.

Tailored Therapies for Cardiogenic Shock in Hypertrophic Cardiomyopathy: Navigating Emerging Strategies

Hypertrophic cardiomyopathy (HCM) is a complex and heterogeneous cardiac disorder, often complicated by cardiogenic shock, a life-threatening condition marked by severe cardiac output failure. Managing cardiogenic shock in HCM patients presents unique challenges due to the distinct pathophysiology of the disease, which includes dynamic left ventricular outflow tract obstruction, diastolic dysfunction, and myocardial ischemia. This review discusses current and emerging therapeutic strategies tailored to address the complexities of HCM-associated cardiogenic shock and other diseases with similar pathophysiology that provoke left ventricular outflow tract obstruction. We explore the role of pharmacological interventions, including the use of vasopressors and inotropes, which are crucial in stabilizing hemodynamics but require careful selection to avoid exacerbating the outflow obstruction. Additionally, the review highlights advancements in mechanical circulatory support devices such as extracorporeal membrane oxygenation (ECMO) and left ventricular assist devices (LVADs), which have become vital in the acute management of cardiogenic shock. These devices provide temporary support and bridge patients to recovery, definitive therapy, or heart transplantation, which remains a critical option for those with end-stage disease. Furthermore, the review delves into the latest research and clinical trials that are refining these therapeutic approaches, ensuring they are optimized for HCM patients. The impact of these treatments on patient outcomes, including survival rates and quality of life, is also critically assessed. In conclusion, this review underscores the importance of a tailored therapeutic approach in managing cardiogenic shock in HCM patients, integrating pharmacological and mechanical support strategies to improve outcomes in this high-risk population.

Long-term therapeutic efficacy and safety profiles of hpCas13d RNA editing in treating early-onset hypertrophic cardiomyopathy

AIMS

Through evolving a precise RNA nuclease, hpCas13d, we have successfully inhibited hypertrophic cardiomyopathy in a compound heterozygous model. However, further investigation is needed to assess the long-term therapeutic effects and safety profiles of hpCas13d treatment.

MATERIALS AND METHODS

AAV-hpCas13d[RQ] was subcutaneously injected into neonatal Myh6RH/RQ mice. Sequential echocardiography analyses were conducted at 4 months and 12 months to evaluate the sustained therapeutic effects of hpCas13d. Electrocardiography was employed to assess cardiac arrhythmias, and mice were euthanized at 12 months. Quantification of Myh6RQ degradation induced by hpCas13d[RQ] was performed using digital droplet PCR and cDNA sequencing. Histological analysis, RNA sequencing, and proteomic analyses were utilized to examine the inhibitory effects on pathological phenotypes and downstream signaling pathways. Biodistribution, tissue damage, and host immune response to AAV-hpCas13d[RQ] were assessed to evaluate long-term safety profiles.

KEY FINDINGS

The allele-specific RNA degradation persisted for 12 months in AAV-hpCas13d[RQ]-treated Myh6RH/RQ mice. Partial degradation of pathogenic Myh6RQ transcripts proved adequate for the long-term inhibition of cardiac hypertrophy, arrhythmias, fibrosis, and cellular apoptosis in Myh6RH/RQ mice. RNA sequencing and proteomic analyses revealed that hpCas13d[RQ] treatment impeded hypertrophy and fibrosis, mitochondrial dysfunction, and abnormalities in ion channels downstream of mutant Myh6. Prolonged treatment with AAV-hpCas13d from the neonatal stage did not induce significant tissue damage, liver toxicity, humoral responses, or cellular immune reactions against the AAV9 capsid and bacterial hpCas13d.

SIGNIFICANCE

These results underscore the promising translational potential of AAV-hpCas13d in treating cardiovascular diseases and advancing in vivo gene therapy.

Clinical trials in-a-dish for cardiovascular medicine

Cardiovascular diseases persist as a global health challenge that requires methodological innovation for effective drug development. Conventional pipelines relying on animal models suffer from high failure rates due to significant interspecies variation between humans and animal models. In response, the recently enacted Food and Drug Administration Modernization Act 2.0 encourages alternative approaches including induced pluripotent stem cells (iPSCs). Human iPSCs provide a patient-specific, precise, and screenable platform for drug testing, paving the way for cardiovascular precision medicine. This review discusses milestones in iPSC differentiation and their applications from disease modelling to drug discovery in cardiovascular medicine. It then explores challenges and emerging opportunities for the implementation of 'clinical trials in-a-dish'. Concluding, this review proposes a framework for future clinical trial design with strategic incorporations of iPSC technology, microphysiological systems, clinical pan-omics, and artificial intelligence to improve success rates and advance cardiovascular healthcare.

Advances in induced pluripotent stem cell-derived cardiac myocytes: technological breakthroughs, key discoveries and new applications

A transformation is underway in precision and patient-specific medicine. Rapid progress has been enabled by multiple new technologies including induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs). Here, we delve into these advancements and their future promise, focusing on the efficiency of reprogramming techniques, the fidelity of differentiation into the cardiac lineage, the functional characterization of the resulting cardiac myocytes, and the many applications of in silico models to understand general and patient-specific mechanisms controlling excitation-contraction coupling in health and disease. Furthermore, we explore the current and potential applications of iPSC-CMs in both research and clinical settings, underscoring the far-reaching implications of this rapidly evolving field.