Plasma concentrations of N-terminal pro-B-type natriuretic peptide ( NT-proBNP ) and high-sensitivity cardiac troponin T ( hs-cTnT ) were measured at enrollment , on the morning of cardiac surgery , at end surgery , and @ days postsurgery in @ patients undergoing cardiac surgery , randomized to perioperative supplementation with oral fish oil or placebo in the Omega-@ Fatty Acids for Prevention of Post-Operative Atrial Fibrillation trial ( OPERA ) .