Lower whole blood selenium level is associated with higher operative risk and mortality following cardiac surgery

The authors intended to test their hypothesis that a low blood selenium level is associated with higher mortality, morbidity, and increased inflammatory response following cardiac surgery. A single-center clinical survey was conducted on 197 consecutive patients undergoing on-pump operation in Debrecen, Hungary. Blood samples for whole blood selenium analysis were taken immediately before the surgery. Their risk profiles were evaluated according to the EuroSCORE. The outcome parameters were as follows: 30-day mortality, incidence of systemic inflammatory response syndrome, and cardiac and renal dysfunction. The main laboratory outcome variables were the postoperative concentrations of C-reactive protein and cardiac troponin I. The mean blood selenium level was significantly lower in non-survivors 102.2 +/- A 19.5 mu g/L compared with survivors 111.1 +/- A 16.9 mu g/L (p = 0.047), and the mean age, EuroSCORE values, and troponin concentrations were significantly higher in the non-survivors. To exclude these potential confounders a logistic regression model was fitted to our data, with mortality as the outcome and the EuroSCORE, the degree of troponin elevation, and selenium concentration as explanatory variables. This model revealed that a lower selenium level was a minor but apparently existing risk factor for postoperative mortality. Further examinations are required to clarify the question that remained unanswered in this study: the role of low selenium in the causality chain leading to higher postoperative mortality.