Background: Atrial fibrillation occurs in 20-40% of patients following cardiac surgery with extra-corporeal circulation. Among the multiple factors leading to atrial fibrillation, the oxidative stress resulting from the reperfusion of ischemic myocardial tissue has been shown to play a major role. The reactive oxygen species (ROS) generated by the ischemic-reperfusion event results in direct cellular damage, an increased inflammatory response, and an upregulation of apoptotic gene expression. Atrial fibrillation occurs due to the electrical remodeling caused by changes at the cellular level. However, exposure to low to moderate levels of ROS prior to oxidative stress has been shown to be responsible for an upregulation in the expression of endogenous antioxidant enzymes. For this reason, n-3 polyunsaturated fatty acids (PUFA) have been studied and proven to reduce the incidence of post-operative atrial fibrillation (POAF). The use of exogenous antioxidants such as vitamin C and E have also been shown to reduce POAF. Therefore, a combined therapy should result in increased antioxidant reinforcement resulting in a markedly lower occurrence of atrial fibrillation.
Methods: Exhaustive search of available medical literature was conducted using Medline, CINAHL, and Web of Science using the keywords: antioxidants and atrial fibrillation. The results were limited to articles published from 2011 to the present, written in English regarding human test subjects, and directly answering the clinical question. Articles were critically appraised for quality using GRADE.
Results: Two studies met inclusion criteria and were included in this systematic review. A randomized, double blind, placebo controlled trial with 203 participants demonstrated a statistically significant reduction in post-operative atrial fibrillation when n-3 unsaturated fatty acid and vitamins C and E were administered. A second randomized, double blind, placebo controlled trial with 152 participants demonstrated a statistically significant reduction in post-operative atrial fibrillation in patients over 60 years of age with moderate improvement with participants under 60 years after the administration of unsaturated fatty acid and vitamins C and E.
Conclusion: The prophylactic use of antioxidants in cardiac surgery patients has proven to be an effective low-cost low-risk intervention for the prevention of post-operative atrial fibrillation. The indirect effects of n-3 PUFAs brought about the upregulation of endogenous antioxidant enzymes while exogenous antioxidants, vitamin C and E, reduced ROS both by directly scavenging ROS, and down-regulating their production. This readily available treatment would reduce the risk of POAF for on-pump cardiac surgeries resulting in reduced hospital stay, overall costs, and cardiovascular pathology.
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