Open Access

Julia Ney, Daren K. Heyland, Karin Amrein, Gernot Marx, Oliver Grottke, Michael Choudrakis, Teresa Autschbach, Aileen Hill, Patrick Meybohm, Carina Benstöm, Andreas Goetzenich, Christina Fitzner, Christian Stoppe

• Background & aims: Recent studies indicate that vitamin D deficiency is associated with increased morbidity and mortality in critically ill patients. Knowledge about the functional role and clinical relevance of vitamin D for patients undergoing cardiac surgery is sparse. Therefore, we investigated the clinical significance of vitamin D levels on outcome of cardiac surgery patients. Methods: 92 patients undergoing elective cardiac surgery with cardiopulmonary arrest were included in this prospective observational pilot study. 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25(OH)2D) levels were measured prior to surgery, immediately postoperatively as well as 6, 12 and 24 h after surgery. We assessed postoperative organ dysfunctions, infections and death until hospital discharge. Results: The serum concentration of 1,25(OH)2D significantly decreased intraoperatively by 29.3% (p < 0.001) and was significantly lower at any postoperative time point compared to baseline values, whereas 25OHD levels did not show significant changes during the observation period. Coronary artery bypass graft (CABG) patients had significant higher baseline 1,25(OH)2D values than patients with valve surgery (39.7 ± 13.9 ng/l vs. 30.1 ± 14.1 ng/l, p = 0.010) or CABG + valve surgery (39.7 ± 13.9 ng/l vs. 32.6 ± 11.8 ng/l, p = 0.044). Our data showed a significant odds ratio to develop postoperative organ dysfunction (OR 0.95; p = 0.009) and PCT levels ≥5 μg/l (OR 0.94; p = 0.046) for every ng/l increment in 1,25(OH)2D, when performing multivariable analysis and after adjusting for preoperative illness and demographics. In addition, multivariable-adjusted statistical analyses revealed that patients stayed significantly shorter on ICU (−0.21 h; p = 0.001) and in hospital (−2.6 days; p = 0.009) for every ng/l increment in 1,25(OH)2D. Conclusion: Our data highlight important evidence about the clinical significance of 1,25(OH)2D levels in cardiac surgery patients. Higher levels were associated with significantly less postoperative organ dysfunctions, elevated PCT levels, death and prolonged hospital stay. 1,25(OH)2D levels decreased significantly intra- and postoperatively, while serum levels of 25OHD did not. Trial registration: clinicaltrials.gov (NCT 02488876), registered May 1, 2015.