Alteration of plasma trace elements magnesium, copper, zinc, iron and calcium during and after coronary artery bypass grafting surgery

Background: Dietary factors including trace elements contribute to the development of disorders including coronary artery diseases. Whether there are differences in concentrations of trace elements between on-pump and off-pump coronary artery bypass grafting (CABG) surgery remains unclear. The aim of this study was to investigate the differences in the plasma level of four trace elements Cu, Fe, Zn, magnesium (Mg), and calcium (Ca) during and after CABG between on-pump and off-pump procedure and the correlation between these trace elements and the development of postoperative AF.

Methods: Fifty-three CABG patients using on-pump or off-pump methods were enrolled. The blood sample was taken before skin incision (T1), 4 h after skin incision (T2), postoperative day1 (T3), and day3 (T4) respectively. Plasma concentrations of Mg, Ca, Fe, Zn, and Cu were determined.

Results: The plasma Mg concentration reached the highest level at T3 (0.94 ± 0.03 vs. 1.20 ± 0.03 mmol/L,P < 0.001) and completely recovered at T4 whereas Zn (11.28 ± 0.23 vs. 6.80 ± 0.20 mmol/L, P < 0.001) and Fe (10.97 ± 0.51 vs. 2.22 ± 0.1 μmol/L, P < 0.001) was lowest at T3 and partially recovered at T4. Cu was lowest at T2 (12.10 ± 0.33 vs. 9.62 ± 0.25 μmol/L, P < 0.001) then increased until T4. There were significant differences in Mg and Fe (P < 0.05), as well as Cu (P < 0.01) between on-pump and off-pump groups. No significant differences were detected between postoperative atrial fibrillation and sinus rhythm groups.

Conclusions: In CABG, Cu and Zn are significantly reduced and Cu is recovered at postoperative Day 1 but Zn takes longer to recover. Addition of Mg and Ca during CABG are sufficient to maintain the plasma concentration. However, supplementation of Cu and Zn during and after CABG may be necessary. Further, the correlation between these trace elements and postoperative AF is to be further determined.