Cell-free mitochondrial DNA may predict the risk of post-operative complications and outcomes in surgical aortic valve replacement patients.

Surgical aortic valve replacement (AVR) is the standard of care for severe aortic valve disease; however, post-operative complications continue to pose challenges. Inflammation caused by increased release of cell-free mitochondrial DNA (cf-mtDNA) during surgery may be a contributing factor. The aim of this pilot study was to investigate the relationship between cf-mtDNA release and the risk of inflammatory-mediated post-operative complications in adult AVR patients. Plasma was collected from patients undergoing an AVR with cardiopulmonary bypass (CPB) at baseline, intra-operatively and post ICU admission at 6, 12 and 18 h. Cf-mtDNA was quantified and inflammatory biomarker expression in leukocytes and plasma was assessed. Cf-mtDNA levels increased 16-fold at the end of CPB with a corresponding increase in average fragment size. Cf-mtDNA levels may be associated with post-operative bleeding, infection, hepatic failure and hospital length of stay. Gene expression and plasma analysis revealed altered levels of markers associated with inflammation and innate immune responses. Several markers were associated with post-operative complications and outcomes. Our results indicate that cf-mtDNA levels, including average fragment sizes, are increased following initiation of CPB in AVR patients, and may be associated with post-operative complications and outcomes. However, larger studies are needed to validate these findings.