PTX3 and Myocardial fibrosis: The correlation between PTX3 and left atrial volume may be related to the fact that this relatively recently described biomarker has a strong association with myocardial fibrosis and, consistent with the endothelial inflammation hypothesis, is strongly expressed by vascular endothelium.21, 22, 23, 53 Whether PTX3 truly has a specific pathophysiologic role in HF is not known.