Association of thymectomy with infection following congenital heart surgery

Congenital absence of the thymus can lead to profound immunodeficiency, suggesting that thymic function during fetal development is essential to normal lymphocyte development. How vital the thymus after birth is to human immune competence and regulation is not known. Routine thymectomy, especially at an early age, may influence immunity, and therefore the risk of infection, autoimmunity, or malignancy.

A retrospective review of cardiac surgery patients followed at Seattle Children's Hospital was performed. The primary outcome was rate of serious infections requiring hospitalization. Secondary analyses included age, type of infection, cardiac diagnosis, surgical procedure, and comorbidities.

Patients fell into 2 groups: 60 with complete thymectomy and 35 with partial or no thymectomy. There was no statistical difference between groups in the overall prevalence of serious infections (16.7% vs 17.2%, P = 1.0). There was a nonsignificant trend toward reduced time between surgery and onset of first infection in patients in the total thymectomy group versus those without thymectomy (1.7 years vs 4.6 years, P = .07). Total thymectomy before 6 months of age also tended to increase infection rate, but the effect was not significant (0.09/year vs 0.02, P = .14). Gastroesophageal reflux in patients with total thymectomy increased the risk of infection (P = .013), suggesting a cumulative effect.

Though infections occurred frequently in the childhood cardiac surgery population, total thymectomy was not associated with increased risk of serious infection. Comorbid conditions may be more important contributing factors increasing the risk of infection in this complex and vulnerable population.