Routine thymectomy in congenital cardiac surgery changes adaptive immunity without clinical relevance

The actual importance of the thymus in both children and adults is largely unclear. In congenital cardiac surgery, a partial or total thymectomy is frequently performed to improve access to the heart and great vessels. We performed a literature search to evaluate the effect on the adaptive immune system of the removal of thymus tissue in patients with congenital heart disease. A PubMed search according to Dunning's standard provided 149 articles, of which 13 addressed our search question. Each study has been tabulated with author, cases, controls, follow-up, methods, results and limitations. A first group of articles repeatedly showed the effect on the T-cell compartment, including the impact on subgroups of this compartment. More recent studies, usually with a longer follow-up, confirm that the earlier changes in T-cell population appear to be permanent. Only one author found a normalization of T-cell population five years after thymectomy. In contrast to these clear changes in T-cell population, there is currently no clear clinical relevance. A literature search on thymectomy in congenital cardiac surgery revealed clear changes in T-cell-related immunity; however, there is a lack of clinical relevance. Further investigation of the adaptive immune system is required to explain this discrepancy.