Background: Cardiac amyloidosis (CA) is an increasingly recognized cause of heart failure with preserved ejection fraction, resulting from myocardial deposition of misfolded amyloid fibrils derived predominantly from transthyretin (ATTR wild-type [ATTRwt] or variant [ATTRv]) or immunoglobulin light chains (AL). Despite advances in noninvasive imaging and disease-modifying therapies, delayed diagnosis remains common, and clinically actionable molecular biomarkers for early detection, phenotypic discrimination, and therapeutic monitoring are limited. MicroRNAs (miRNAs), small noncoding regulators of post-transcriptional gene expression, have emerged as key modulators of cardiovascular remodeling and systemic amyloid biology. Methods: We performed a comprehensive review of experimental, translational, and clinical studies to evaluate the role of miRNAs in transthyretin and light-chain cardiac amyloidosis, incorporating data from myocardial tissue analyses, circulating miRNA profiling, and mechanistic studies in cellular and animal models. Results: Dysregulated miRNA networks contribute to amyloid-induced cardiac injury by modulating mitochondrial energetics, oxidative stress, inflammation, fibrosis, proteostasis, and neurocardiac signaling. Specific miRNAs, including members of the miR-21, miR-29, and miR-30 families, as well as miR-150-5p and miR-339, have been associated with amyloid burden, adverse myocardial remodeling, plasma cell biology, and disease severity. Distinct circulating and tissue miRNA signatures differentiate transthyretin from light-chain cardiac amyloidosis and correlate with functional status, heart failure biomarkers, and clinical outcomes. Conclusions: MiRNAs represent promising diagnostic and prognostic biomarkers in cardiac amyloidosis and offer mechanistic insights into disease pathogenesis. Integration of miRNA profiling with multimodality imaging and emerging RNA-based therapeutics may enable earlier diagnosis and support precision management of amyloid-related heart failure.

Background/Objectives: Pacing-induced cardiomyopathy (PiCM) is a recognized complication of chronic right ventricular pacing (RVP), characterized by left ventricular (LV) dysfunction, adverse remodeling, and progression to heart failure. MicroRNAs (miRs) regulate gene expression and play an important role in ventricular remodeling. This study aimed to observe whether dynamic changes in miRs according to a novel peripheral blood mononuclear cell (PBMC)-based approach could serve as early predictive biomarkers of PiCM. Methods: A prospective, single-center cohort study was conducted in adult patients undergoing pacemaker implantation. Clinical characteristics, echocardiographic parameters and expression levels of miR-208b-3p and miR-9 were assessed immediately and 3 months post-pacemaker implantation. PiCM was defined as a ≥10% reduction in LVEF at one year, with no alternative cause. Statistical analyses included correlation testing, ROC curve analysis, and multivariate regression to identify factors associated with PiCM. Results: Among 126 patients, 11.1% developed PiCM. Compared with the non-PiCM group, those who developed PiCM exhibited more pronounced 3-month changes in miR-208b-3p (median Δ₃log miR: +1.3 vs. −0.4, p = 0.013) and miR-9 (median Δ₃log miR: −1.7 vs. +0.21, p = 0.011). In multivariate analyses, Δ₃LV-GLS, Δ₃logmiR-208b-3p, and Δ₃logmiR-9 were associated with a higher likelihood of PiCM. Among PiCM patients, Δ₃logmiR-208b-3p correlated inversely with Δ₃LV-GLS (r = −0.73, p = 0.016), while Δ₃logmiR-9 correlated positively (r = 0.88, p < 0.001). ROC analyses demonstrated good predictive ability for Δ₃LV-GLS (AUC = 0.924), Δ₃log miR-208b-3p (AUC = 0.783), and Δ₃log miR-9 (AUC = 0.835), with no significant differences between curves. Conclusions: Early LV-GLS deterioration and dynamic changes in expression of miR-208b-3p and miR-9 in PBMCs precede overt LV systolic dysfunction. These miRs may serve as early predictive biomarkers for PiCM.

Background: Titin (TTN), a giant structural and signaling protein of striated muscle, participates in intracellular signaling networks and cytoskeletal organization, potentially influencing cell activation, trafficking, and interactions with other tissues, including the heart. Methods: In this pilot study, 29 patients with acute myocarditis and 10 healthy individuals were prospectively enrolled. Peripheral blood was obtained on the first day of hospital admission, total RNA was isolated from peripheral blood mononuclear cells (PBMCs), and TTN mRNA expression was quantified. Results: TTN expression in PBMCs was significantly higher in patients with acute myocarditis compared with healthy controls (p = 0.015), corresponding to a 2.8-fold median increase. Moreover, TTN expression showed a strong positive correlation with global longitudinal strain impairment (Spearman’s r = 0.576, p < 0.001), a moderate positive correlation with peak hs-cTnI levels (r = 0.435, p = 0.021; and a moderate inverse correlation with baseline LVEF (r = −0.421, p = 0.025). Conclusions: These findings support a pathophysiological link between TTN-related pathways in peripheral immune cells and myocardial injury in acute myocarditis and raise the hypothesis that TTN expression in PBMCs may serve as a novel biomarker of disease severity and long-term ventricular remodeling. Further studies in larger cohorts are warranted to validate these results and to elucidate the mechanistic role of titin in immune–cardiac cross-talk.

Background: Cardiac amyloidosis (CA) is an increasingly recognized cause of heart failure with preserved ejection fraction, resulting from myocardial deposition of misfolded amyloid fibrils derived predominantly from transthyretin (ATTR wild-type [ATTRwt] or variant [ATTRv]) or immunoglobulin light chains (AL). Despite advances in noninvasive imaging and disease-modifying therapies, delayed diagnosis remains common, and clinically actionable molecular biomarkers for early detection, phenotypic discrimination, and therapeutic monitoring are limited. MicroRNAs (miRNAs), small noncoding regulators of post-transcriptional gene expression, have emerged as key modulators of cardiovascular remodeling and systemic amyloid biology. Methods: We performed a comprehensive review of experimental, translational, and clinical studies to evaluate the role of miRNAs in transthyretin and light-chain cardiac amyloidosis, incorporating data from myocardial tissue analyses, circulating miRNA profiling, and mechanistic studies in cellular and animal models. Results: Dysregulated miRNA networks contribute to amyloid-induced cardiac injury by modulating mitochondrial energetics, oxidative stress, inflammation, fibrosis, proteostasis, and neurocardiac signaling. Specific miRNAs, including members of the miR-21, miR-29, and miR-30 families, as well as miR-150-5p and miR-339, have been associated with amyloid burden, adverse myocardial remodeling, plasma cell biology, and disease severity. Distinct circulating and tissue miRNA signatures differentiate transthyretin from light-chain cardiac amyloidosis and correlate with functional status, heart failure biomarkers, and clinical outcomes. Conclusions: MiRNAs represent promising diagnostic and prognostic biomarkers in cardiac amyloidosis and offer mechanistic insights into disease pathogenesis. Integration of miRNA profiling with multimodality imaging and emerging RNA-based therapeutics may enable earlier diagnosis and support precision management of amyloid-related heart failure.