RNA Therapies for Coronary Microvascular Dysfunction: Mechanisms, Clinical Insights, and Therapeutic Advances

Abstract

Coronary microvascular dysfunction (CMD) represents a significant clinical challenge due to its elusive presentation and impact on cardiac morbidity and mortality. Recent advancements in molecular medicine have introduced RNA-based therapies as promising modalities targeting the intricate pathophysiology of CMD. This review synthesizes current epidemiological data, underlying mechanisms, clinical features, diagnostic approaches, and management strategies, with a special focus on the role of RNA therapeutics. We further discuss recent breakthroughs, clinical recommendations, and future perspectives, providing a comprehensive resource for clinicians and researchers seeking evidence-based insights into this evolving field.

Introduction

Coronary microvascular dysfunction is increasingly recognized as a major contributor to angina, ischemia with non-obstructive coronary arteries (INOCA), and adverse cardiovascular outcomes. Traditional therapies often fall short due to the unique pathobiology of microvascular disease. The emergence of RNA therapeutics including small interfering RNA (siRNA), antisense oligonucleotides (ASOs), and microRNA (miRNA) modulators offers novel avenues for disease modification. This article aims to provide a nuanced, clinically oriented overview of CMD and the potential of RNA therapies to transform its management.

Epidemiology / Disease Burden

CMD affects an estimated 50–70% of patients presenting with chest pain and non-obstructive coronary arteries, with a higher prevalence among women and individuals with metabolic syndrome. It constitutes a significant fraction of patients with heart failure with preserved ejection fraction (HFpEF). Epidemiological studies highlight CMD as an independent predictor of adverse cardiovascular events, including myocardial infarction, hospitalization, and mortality. Despite these data, CMD remains underdiagnosed, partly due to the limitations of conventional coronary imaging and underappreciation of non-obstructive disease in clinical practice.

Pathophysiology

CMD arises from dysfunction of the coronary microcirculation, encompassing both structural and functional abnormalities. Endothelial dysfunction, impaired nitric oxide bioavailability, inflammation, oxidative stress, and microvascular rarefaction are central to its pathogenesis. Recent molecular research implicates aberrant gene expression, dysregulated non-coding RNAs, and altered vascular signaling cascades. RNA therapies target these maladaptive pathways by modulating gene and microRNA expression, reducing inflammation, and restoring endothelial homeostasis. For example, miRNA-126 and miRNA-155 have been shown to regulate endothelial repair and inflammation, respectively, making them attractive RNA therapeutic targets.

Risk Factors

Traditional cardiovascular risk factors including hypertension, diabetes mellitus, dyslipidemia, obesity, and smoking are strongly associated with CMD. Additionally, systemic inflammatory conditions, autoimmune diseases, and hormonal influences contribute to microvascular vulnerability. Genetic predispositions and epigenetic modifications, including those affecting non-coding RNA expression, are emerging as important determinants of individual risk profiles.

Clinical Features

CMD commonly presents with angina or angina-like chest discomfort, often indistinguishable from obstructive coronary artery disease. Patients may experience exertional dyspnea, fatigue, and even acute coronary syndromes without significant epicardial stenosis. The chronicity and variability of symptoms can lead to repeated hospitalizations and impaired quality of life. Importantly, CMD is frequently underdiagnosed, particularly in women and younger patients, due to its non-classic presentation and normal findings on routine angiography.

Diagnosis

Accurate diagnosis of CMD requires a high index of suspicion and specialized testing. Invasive coronary function testing such as measurement of coronary flow reserve (CFR) and index of microvascular resistance (IMR) remains the gold standard. Non-invasive approaches include transthoracic Doppler echocardiography, cardiac MRI with perfusion imaging, and positron emission tomography (PET). Biomarkers reflecting endothelial injury and inflammation, as well as gene and microRNA expression profiling, are under investigation for their diagnostic and prognostic utility. RNA-based assays may soon provide novel means for CMD stratification and monitoring.

Treatment & Management

Management of CMD centers on aggressive risk factor control, including optimization of blood pressure, glycemic status, and lipid profiles. Anti-anginal agents such as beta-blockers, calcium channel blockers, and nitrates provide symptomatic relief, though their efficacy in CMD is variable. Statins and ACE inhibitors are recommended for their pleiotropic vascular effects. Lifestyle modification, including exercise and dietary interventions, remains foundational. However, current therapies do not directly address the molecular underpinnings of CMD, underscoring the need for targeted approaches.

Recent Advances / Emerging Therapies

RNA-based therapies are at the frontier of CMD management. siRNAs and ASOs can silence or modulate the expression of pathogenic genes implicated in endothelial dysfunction and inflammation. For example, RNA therapeutics targeting PCSK9 and lipoprotein(a) have demonstrated vascular benefits in clinical trials. Modulation of specific microRNAs such as miR-21, miR-92a, and miR-126 has shown promise in preclinical studies for enhancing endothelial repair, reducing fibrosis, and attenuating inflammatory responses in the microvasculature. Ongoing clinical trials are evaluating the safety and efficacy of these agents in patients with CMD and related cardiovascular conditions. Delivery systems, including nanoparticle-based vectors and conjugated oligonucleotides, are improving tissue specificity and therapeutic index.

Guideline Recommendations

Current international guidelines emphasize the need for early recognition, comprehensive risk factor modification, and individualized therapy in CMD. While RNA-based therapies are not yet standard of care, recent consensus statements acknowledge their potential and encourage enrollment in clinical trials. The European Society of Cardiology and American Heart Association highlight the importance of research into novel therapeutics, including RNA modalities, for CMD and related microvascular disorders. Clinicians are advised to remain abreast of emerging data to facilitate timely integration of new therapies into practice.

Conclusion

Coronary microvascular dysfunction is a prevalent and impactful cardiovascular disorder with limited effective therapies. RNA-based treatments offer a novel approach by directly targeting the molecular drivers of microvascular dysfunction. While these therapies remain in early clinical stages, accumulating evidence supports their potential to address unmet needs in CMD management. Continued translational research, well-designed clinical trials, and multidisciplinary collaboration are essential to realize the promise of RNA therapeutics in improving outcomes for this challenging patient population.