The effects of low dose N-acetylcysteine (NAC) as an adjunct to cardioplegia in coronary artery bypass surgery.

Objective: We aimed to evaluate the efficacy of low dose N-acetylcysteine (NAC) against myocardial ischemia-reperfusion damage in coronary artery bypass surgery accompanied by cardiopulmonary bypass (CPB).

Methods: Thirty patients operated due to triple coronary artery disease were enrolled into this prospective randomized study (control group -n=15 and NAC group - n=15). N-acetylcysteine was added to induction cardioplegia solution in dose of 4 mmol/l and in dose of 2 mmol/l to maintenance cardioplegia solution in the NAC group. Hemodynamic measurements were performed before and after anesthesia with different intervals. Creatine kinase-MB (CK-MB) levels were analyzed during 24 hours postoperatively. Blood samples were obtained from coronary sinus before CPB (T1), just before the cross-clamp removed (T2) and 30 minutes later (T3). Malondialdehyde (MDA), glutathione peroxidase (GSH-Px), nitric oxide (NO) levels and neutrophil percentage were determined. Statistical analysis was performed using student's t test, Chi-square and two-way ANOVA tests.

Results: There were no significant differences between the two groups with regard to the hemodynamic parameters, and CK-MB levels. The MDA levels were significantly lower in NAC group than in control group during reperfusion period (0.75 nmol/l vs 0.88 nmol/l, p<0.05). Neutrophil percentage in coronary sinus blood was significantly lower in NAC group than in control group during the reperfusion period (77.6% vs 82.7%, p<0.05). The GSH-Px and NO levels were also not statistically different between groups.

Conclusion: Low dose NAC as an adjunct to cardioplegic solutions effectively reduces myocardial oxidative stress in coronary bypass surgery with cardiopulmonary bypass, but may not restore the myocardial injury.