Even though some studies indicated that p300 plays a pivotal role in accelerated cardiac aging including myocardial infarction, diabetic cardiomyopathy, and myocardial matrix remodeling (Feng et al., 2016; Miyamoto et al., 2006; Sunagawa et al., 2011), the role of p300 in the natural aging heart, especially the atrium, is still unclear. Here, EP300 is linked to myocardial infarction.