Old mice fully recapitulated the pathologic cardiac hypertrophy seen in human HFpEF, demonstrating increased cardiomyocyte size, myocardial fibrosis, and microvascular rarefaction (Figure 3a), which was associated with increased cardiac BNP expression, a biomarker of increased myocardial stress and HF (Figure 3b). Here, NPPB is linked to cardiac hypertrophy.