The Heart's Small Molecules: The Importance of MicroRNAs in Cardiovascular Health.

This comprehensive review explores the critical roles of microRNAs (miRNAS) in cardiovascular diseases, emphasizing their regulatory functions in gene expression and their involvement in disease progression. miRNAS are small, evolutionarily conserved non-coding RNAs that regulate gene expression post-transcriptionally and play essential roles in various cardiac conditions, including fibrosis, cardiac remodeling, apoptosis, ischemia/reperfusion injury, hypertrophy, heart failure, arrhythmias, coronary artery disease (CAD), congenital heart diseases (CHDs), cardiomyopathies, and valvular heart disease (VHD). miRNAS are increasingly recognized as sensitive and specific biomarkers for early diagnosis, disease monitoring, and evaluation of therapeutic responses across the cardiovascular disease spectrum. Ischemia/reperfusion injury leads to significant cardiac damage through elevated oxidative stress, mitochondrial dysfunction, and apoptosis. CAD, a major contributor to global morbidity and mortality, is primarily driven by atherosclerosis and chronic inflammation. Cardiac hypertrophy is initially an adaptive response to stress but may progress to heart failure if sustained. Arrhythmias arise from electrical disturbances such as reentry, abnormal automaticity, and triggered activity. Heart failure is a complex and progressive syndrome marked by poor prognosis and increasing global prevalence. VHD involves intricate molecular alterations, including myocardial fibrosis and calcification, which contribute to disease progression and adverse outcomes. Cardiomyopathies-including hypertrophic, dilated, restrictive, and arrhythmogenic forms-are influenced by genetic mutations, systemic diseases, and disrupted molecular signaling. CHDs, the most common congenital malformations, stem from structural abnormalities in cardiac development and remain a major cause of infant morbidity and mortality. Novel therapeutic methods, such as antisense oligonucleotides, miR mimics, and exosome-based delivery mechanisms, demonstrate the translational promise of miRNAs in the realm of personalized cardiovascular medicine. However, issues such as small sample sizes, inconsistent results, interspecies differences, and delivery challenges restrict the clinical application of miRNA-based therapies. This review integrates mechanistic insights, critiques the quality of available evidence, and identifies translational shortcomings. It highlights the diagnostic, prognostic, and therapeutic potential of miRNAs in reshaping cardiovascular disease treatment.