Does perioperative thyroxine have a role during adult cardiac surgery?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the use of prophylactic perioperative thyroxine therapy during cardiopulmonary bypass in the euthyroid adult patient undergoing routine cardiac surgery can result in an improved cardiac output leading to better clinical outcomes. Altogether 86 papers were identified on Medline and 113 on Embase using the reported search. A further paper was identified by hand-searching of reference lists. Thirteen papers represented the best evidence on the topic. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. We conclude that it is clear that triiodothyronine levels decrease by 50% or more during cardiopulmonary bypass. However, there is conflicting evidence that prophylactic perioperative thyroxine/triiodothyronine therapy is a useful inotropic adjunct in adult patients undergoing routine cardiac surgery and whilst some studies report improved haemodynamic parameters in the immediate post-bypass period there is no evidence that its use influences postoperative morbidity, mortality or length of stay in the elective patient. It may, however, have a role as rescue therapy in supporting some high risk cases during weaning from CPB or bridging to LVAD or transplant.