Isoprostanes and oxidative stress in off-pump and on-pump coronary bypass surgery

Background. Conventional on-pump coronary artery bypass grafting (CABG) is associated with a systemic inflammatory response and by an increased production of reactive oxygen species, whereas off-pump coronary artery bypass grafting (OPCAB) is thought to be accompanied by less oxidative stress. Urinary isoprostane iPF(2 alpha)-III is a new marker reflecting oxidative stress; it has emerged as the most reliable marker of oxidative stress status in vivo. This study was designed to ascertain whether OPCAB compared with CABG represents a surgical strategy that avoids oxidative stress. To this end urinary isoprostanes and other established oxidative stress markers were measured during the first 24 hours after CABG and OPCAB. Methods. Fifty low-risk coronary patients W? ere randomly assigned to CABG or OPCAB. Urinary isoprostane iPF(2 alpha)-III levels, plasma levels of free malondialdehyde, and total antioxidant status were measured before, during, and up to 24 hours after surgery. Results. In OPCAB iPF(2 alpha)-III excretion remained unchanged throughout the study. As expected, in CABG iPF(2 alpha)-III levels significantly increased during surgery and returned at baseline 24 hours later. Free malondialdehyde behaved similarly, with no change in OPCAB and sharp increases during CABG. Conversely, total antioxidant status showed a sharp drop during CABG, followed by a slow recovery, whereas a significantly lower drop occurred in OPCAB. Conclusions. In this randomized study in low-risk coronary patients, OPCAB revealed less perioperative oxidative stress, as reflected by lack of excretion of iPF(2 alpha)-III in urine, by lack of increase of plasma free malondialdehyde, and by lower decreases in plasma total antioxidant status.