Single-Cell Analysis of Human Heart Failure With Preserved Ejection Fraction

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is a poorly understood, multisystem disease with high morbidity and mortality. To improve understanding of its pathobiology, we analyzed single-nucleus RNA sequencing in human HFpEF myocardium versus controls. METHODS: Septal myocardial biopsies from 19 HFpEF and 24 nonfailing controls were analyzed using the 10× Genomics Chromium platform, with nuclei isolated from combined samples (6 patients/pool). Genotype-based demultiplexing was performed with souporcell, and gene expression was quantified with CellRanger and CellBender. After quality control, nuclei were annotated by cell types, and differential expression was performed between HFpEF versus controls using limma-voom. Functional analysis was performed using Gene Set Enrichment Analysis. Data were compared with prior single-nucleus RNA sequencing in dilated cardiomyopathy versus controls. RESULTS: We successfully demultiplexed pooled myocardial biopsies, assigning >70% of nuclei to individuals. After quality control, we recovered 48 886 nuclei and identified 14 cell types. Many differentially expressed genes across cell types were detected in HFpEF versus controls (fibroblasts, 5905; cardiomyocytes, 5159; endothelial cells, 2143; pericytes, 1812; and macrophages, 1405). Enriched pathways common to multiple cell types included immune activation, transcription/translation, metabolism, and protein quality control. They were particularly shared between cardiomyocytes and fibroblasts. Vascular smooth muscle cells had a more synthetic, proliferative phenotype. Immune cell analyses suggested enhanced T-cell activation and reduced macrophage clearance programs. Comparative analysis between HFpEF and dilated cardiomyopathy identified transcriptional differences primarily in cardiomyocytes. Two of 3 cardiomyocyte differential expression genes unique to HFpEF were validated to have concordant protein expression changes in HFpEF ( MAP2K6 and PLPP3 ). CONCLUSIONS: Our findings reveal a distinct, cell-type–specific transcriptomic landscape in the human HFpEF myocardium. While HFpEF and dilated cardiomyopathy share significant molecular pathways across most cell types, the profound divergence within cardiomyocytes suggests a unique pathological driver for HFpEF. These signatures may provide a high-resolution roadmap for identifying precision therapeutic targets in HFpEF.