What is the role of leukocyte depletion in cardiac surgery?

Leukocytes play an important pathogenic role in ischaemia-reperfusion injury. During cardiopulmonary bypass, leukocyte filters have the potential to remove leukocytes, thereby reducing contact of activated leukocytes with the endothelium of target organs. Improvement in the safety and efficacy of commercially available leukocyte filters in recent years has led to their increasing use in cardiac surgery. However, the benefits have been inconsistent. Current evidence suggests that leukocyte depletion may not have a significant impact in low risk elective coronary artery bypass grafting but may be beneficial in valve surgery and high-risk cardiac surgery. High-risk surgical groups that may benefit from leukocyte filtration are those with left ventricular hypertrophy (LV mass>300 g), poor ejection fraction (EF<40%), chronic obstructive airways disease (predicted FEV1<75%), prolonged ischaemia (cross clamp time>120 min or cardiac transplantation), paediatric cardiac surgery and patients in cardiogenic shock requiring emergency coronary artery bypass grafting. Future trials should be powered to detect important clinical end points and be designed to avoid premature exhaustion of the filter.