Fish oil before cardiac surgery: neutrophil activation is unaffected but myocardial damage is moderated

Could pre-operative dietary intervention with fish oil reduce neutrophil activation and myocardial damage associated with cardiopulmonary bypass (CPB)? Patients were randomised to receive either 8 g/day fish oil (n = 22) or placebo (n = 18) for 6 weeks. Neutrophil activation, apoptosis and cardiac damage were measured. Demographics and operative variables were similar. Fish oil diet decreased plasma VLDL from 0.69 +/- 0.34 to 0.51 +/- 0.24 mmol/l and triglycerides from 1.68 +/- 0.70 to 1.39 +/- 0.54 mmol/l. HDL cholesterol increased from 0.94 +/- 0.27 to 1.03 +/- 0.26 mmol/l demonstrating significant treatment effects (P = 0.007, 0.02 and 0.0003, respectively) as well as compliance with treatment. There were no significant differences in ex vivo N-formyl-methionyl-leucyl-phenylalanine-stimulated neutrophil superoxide anion generation or myeloperoxidase release at recruitment, pre-operatively and at end-CPB. Apoptosis at end-CPB was equally reduced in both groups from 23 +/- 9% to 13 +/- 4% in the fish oil group (P < 0.001) and 35 +/- 14% to 15 +/- 3% in the placebo group (P = 0.001). At end-CPB overall troponin I levels averaged 0.91 +/- 0.60 ng/ml which clearly exceeded diagnostic levels (0.15 ng/ml). At 24h troponin I fell significantly in the fish oil group to 46 +/- 23% of end-CPB levels (P = 0.0002) whereas it peaked in the placebo group to 107 +/- 72% (P = 0.098 vs. end-CPB); this difference was significant: P = 0.013. At 48h the placebo-treated patients had higher troponins but not significantly so (P = 0.059). Area-under-the-curve analysis did not conclusively support this (P = 0.068). We conclude that fish oil did not significantly decrease post-CPB neutrophil activation (as detected ex vivo) but may moderate post-operative myocardial damage. (c) 2005 Elsevier Ltd. All rights reserved.