Introduction: Despite the well-known mechanisms of Vitamin D (e.g. calcium absorption and bone health), knowledge about its functional role and clinical relevance for patients undergoing cardiac surgery with regard to complications, infections and mortality is largely unknown.
Hypothesis: We hypothesized that an intraoperative decrease of circulating vitamin D levels may influence clinical outcome in cardiac surgery patients.
Methods: 92 patients undergoing cardiac surgery were included to investigate the association between 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25(OH)2D) levels and postoperative outcome. Vitamin D levels were measured preoperative and 0, 6, 12 and 24 hours after surgery. The incidence of postoperative complications as well as secondary outcome parameters, including length of hospital and -ICU stay, organ dysfunctions, number and type of infections and mortality were collected.
Results: While 1,25(OH)2D levels experienced a significant decrease by 29,3% (p=0.000) intraoperative and at any time point postoperative compared to baseline values, 25OHD levels did not differ over time course. CABG patients had significant higher baseline 1,25(OH)2D values than valve (39.6912±13.9130 vs 30.0538±14.0531, p=0.010) or CABG+valve (39.6912±13.9130 vs 32.6040±11.8337, p=0.044) surgery patients. Patients developing complications postoperatively had significant (p=0.002) lower baseline 1,25(OH)2D serum levels (28.4125±13.3780) than patients without complications (37.6269±13.20077). In addition, patients with 1,25(OH)2D deficiency developed 1,83 times more frequently complications (p=0.040). Patients with 1,25(OH)2D deficiency stayed in average 6 days longer in hospital (p=0.028), whereas the ICU length of stay and invasive ventilation did not differ significantly between groups.
Conclusions: Present data are first that demonstrate a significant intraoperative decrease of 1,25(OH)2D levels in patients undergoing cardiac surgery, while serum levels of 25OHD did not show significant changes. Importantly, 1,25(OH)2D deficiency was associated with a significantly higher incidence of complications and prolonged hospital stay in cardiac surgery patients.