Low preoperative selenium is associated with post-operative atrial fibrillation in patients having intermediate-risk coronary artery surgery

BACKGROUND/OBJECTIVES: Post-operative atrial fibrillation (POAF) is a frequent complication of cardiac surgery. Oxidative stress and reduced antioxidant function have major roles in its development. Selenium is a key to normal antioxidant function, and levels are often low before cardiac surgery. This study investigated whether low preoperative selenium levels were associated with POAF in cardiac surgical patients. SUBJECTS/METHODS: Using the Society of Thoracic Surgeons (STS) Mortality risk score, 50 patients having primary coronary artery bypass grafts (CABG) surgery were divided into two groups: (i) low-risk group (STS <= 0.5%; n = 26) and (ii) intermediate-risk group (STS >= 2.0%; n = 24). Plasma levels of selenium, glutathione peroxidase (GPx) and malondialdehyde (MDA) were measured in all patients at anaesthetic induction, after aortic cross-clamp removal, 3 h post cardiopulmonary bypass and on post-operative days 1 and 5. Multiple logistic regression was used to assess whether selenium levels were associated with POAF development. RESULTS: Seventeen patients developed POAF (14 patients in the intermediate-risk group and 3 patients in the low-risk group). Preoperative selenium was lower in patients who developed POAF compared with those with normal sinus rhythm (0.73 +/- 0.16 vs 0.89 +/- 0.13 mu mol/l, P = 0.005), and this was independently associated with POAF (PR 0.32; 95% confidence credible interval (95% cI) 0.06-0.85, P = 0.016). Regardless of POAF, preoperative selenium was lower in the intermediate-risk patients than in the low-risk patients (0.77 +/- 0.15 vs 0.89 +/- 0.14 mu mol/l; P = 0.004). CONCLUSIONS: Intermediate-risk patients with low preoperative selenium levels may be at a greater risk of developing POAF following CABG. This raises the question of whether selenium supplementation in select cardiac surgical patients may reduce their POAF risk.