This study explores whether extracellular vesicles (EVs) tiny particles released into the bloodstream by cells can serve as early and minimally invasive biomarkers for transthyretin amyloid cardiomyopathy (ATTR-CM). Because ATTR-CM is often diagnosed only after significant heart damage has occurred, there is an urgent need for earlier detection methods. The study will enroll individuals with different clinical presentations of transthyretin amyloidosis, along with healthy controls. Participants will undergo blood sampling, cardiac imaging (including echocardiography, cardiac MRI, and scintigraphy when indicated), and molecular EV analysis. By comparing EV profiles across groups, the study aims to determine whether these vesicles reflect early cardiac involvement, track disease progression, and support more accurate and timely diagnosis. Ultimately, this research seeks to improve clinical decision-making and patient outcomes in ATTR cardiomyopathy.
Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive infiltrative disease caused by the deposition of misfolded transthyretin protein in the myocardium. Despite advances in imaging and treatment, early detection and accurate risk stratification remain major challenges, often resulting in delayed diagnosis and worse clinical outcomes. This prospective observational study will enroll 70 adult participants, distributed into four predefined groups: * ATTR-CM with myocardial dysfunction (n = 20) * Hereditary ATTR with predominant neurologic involvement (n = 20) * Genotype-positive individuals without clinical manifestation (n = 10) * Healthy controls (n = 20) All participants will undergo blood collection for extracellular vesicle (EV) isolation and molecular profiling. EVs are nanoscale particles released by cells that carry proteins, lipids, and nucleic acids reflective of their cellular origin and physiological state, potentially serving as minimally invasive biomarkers. Participants with cardiac involvement will additionally undergo standardized cardiac evaluations, including echocardiography, cardiac MRI, and nuclear imaging when indicated. Clinical data, functional status, and laboratory parameters will be correlated with EV characteristics to assess their association with disease severity and progression. By integrating EV profiling with clinical and imaging findings across different phenotypes and disease stages, this study aims to identify biomarkers capable of improving diagnostic accuracy, tracking disease evolution, and supporting personalized care strategies in ATTR amyloidosis.
Study Type
OBSERVATIONAL
Enrollment
70
Instituto do Coracao, HCFMUSP
São Paulo, São Paulo, Brazil
RECRUITINGSerum concentration of circulating extracellular vesicles (EVs)
Quantification of the total concentration of circulating extracellular vesicles isolated from peripheral blood, expressed as number of particles per mL, measured by Nanoparticle Tracking Analysis (NTA - NanoSight), in participants with different clinical presentations of transthyretin amyloidosis (ATTR) and in healthy controls.
Time frame: baseline
Circulating extracellular vesicle protein profile
Protein profiling of circulating extracellular vesicles isolated from peripheral blood, including protein identification and assessment of relative abundance by mass spectrometry, followed by targeted validation and quantification of selected proteins using Western blotting and/or ELISA. Results will be reported as relative protein expression intensity or, when applicable, as absolute concentration (ng/mL), in participants with transthyretin amyloidosis (ATTR) and healthy controls, assessed at baseline.
Time frame: baseline
Correlation between circulating extracellular vesicle concentration and echocardiographic parameters
Correlation between plasma concentration of circulating extracellular vesicles, measured as particles/mL by Nanoparticle Tracking Analysis, and cardiac structure and function parameters assessed by transthoracic echocardiography, including interventricular septal thickness (mm), left ventricular ejection fraction (%), and global longitudinal strain (%), analyzed using Pearson or Spearman correlation coefficients as appropriate, in participants with transthyretin amyloidosis (ATTR) and healthy controls.
Time frame: baseline
Correlation between extracellular vesicle molecular profile and cardiac magnetic resonance findings
Correlation between the molecular profile of circulating extracellular vesicles, including protein levels assessed by Western blotting and/or ELISA and microRNA expression assessed by RT-qPCR, and cardiac involvement parameters evaluated by cardiac magnetic resonance imaging, including extracellular volume fraction (ECV, %) and presence or absence of late gadolinium enhancement, analyzed using correlation methods as appropriate, in participants with transthyretin amyloidosis (ATTR) and healthy controls.
Time frame: baseline
Correlation between extracellular vesicle characteristics and myocardial uptake on scintigraphy
Correlation between circulating extracellular vesicle concentration, measured as particles/mL by Nanoparticle Tracking Analysis, and extracellular vesicle molecular characteristics assessed by RT-qPCR and Western blotting, and the degree of myocardial uptake evaluated by bone scintigraphy using an appropriate radiotracer and visual scoring system (e.g., Perugini grade 0-3), analyzed using correlation methods as appropriate, in participants with transthyretin amyloidosis (ATTR) and healthy controls.
Time frame: baseline
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