Abstract Body: Introduction: A liquid biopsy approach to monitor cardiomyocyte (CM) transcriptional state would be a critical step towards personalized treatment of patients with cardiovascular disease (CVD). POPDC2-decorated CM-enriched extracellular vesicles (CEEVs) allow for selective immunocapture and transcriptomic profiling to enable real-time monitoring of CM transcriptional states.

Hypothesis: CEEV RNA cargo mirrors myocardial transcriptional states across cardiac stress from chronic disease remodeling to acute perturbation.

Methods: Building on cardiovesicle profiling in myocardial infarction and heart failure, we performed paired patient tissue-plasma snRNA-seq in aortic stenosis (AS, n=11) with donor controls (n=7), using donor-paired analysis to resolve disease from inter-individual heterogeneity, benchmarked against bulk EV and non-cardiomyocyte panels. Tissue and plasma were collected pre- and post-CPB (~73 minutes) in cardiac surgery patients (n=9), enabling snRNA-seq and cardiovesicle profiling across acute ischemic stress. Cell-type-specific regulatory elements for concordant transcripts were identified via epigenomic profiling and Hi-C chromatin contacts, linked to HF and MI GWAS loci.

Results: Across cohorts, ~95% of cardiovesicle RNAs overlapped with cardiomyocyte-enriched genes; 49 conserved heart-enriched transcripts spanned all conditions, with longitudinal profiling confirming temporal stability. In AS, profiles distinguished these patients with Wnt activation and fibrotic remodeling concordant with tissue snRNA-seq; non-cardiac transcripts (platelets, erythrocytes, thymocytes) were instead enriched in bulk EVs. For CPB, 9/13 cardiomyocyte-selective transcripts showed directional concordance — both upregulated (MYH7, NPPA, NPPB) and downregulated (DDX5, SPAG1) — while non-cardiomyocyte transcripts were excluded. Of these, 77% of SNPs mapped to cardiomyocyte-restricted regions (XIRP1, SPAG1, NPPA) with GWAS links to HF and MI, genetic evidence that CEEVs encode cardiomyocyte-specific disease liability.

Conclusions: POPDC2+ cardiovesicles provide a cardiomyocyte-resolved liquid biopsy tracking chronic remodeling and acute stress-induced transcriptional dynamics, with GWAS-supported cell-type specificity, enabling patient-level myocardial monitoring from plasma.