1. Study Rationale: An open heart surgery (OHS) induces injury of the vessel wall and is characterized by post-operative complications. Post-operative atrial fibrillation (POAF) is a major cause of morbidity and mortality after cardiac surgery. Both systemic inflammation and oxidative stress play a role in the initiation of POAF after a cardiac surgery. Consumption of polyphenol-rich foods (PRFs), such as fruits and vegetables, and beverages derived from plants, such as cocoa, red wine and tea, may represent a beneficial diet in terms of cardiovascular protection. Indeed, epidemiological studies demonstrate a significant inverse correlation between PRFs consumption and cardiovascular risk, due to antioxidant, vasorelaxant and antithrombotic properties of their polyphenolic components. In particular, procyanidins from grape seeds are the principal vasoactive polyphenols in red wine and protect endothelial cells from oxidative damage. However, there are no studies that have addressed the relationship of PRFs consumption with prognosis in patients undergoing an OHS.