Lymphopenia in thymectomized infants following congenital heart disease repair: implications for protective measures

Abstract Background Congenital heart disease (CHD) is a common birth defect frequently requiring surgical repair with thymectomy. While transient neonatal lymphopenia is usually benign, persistent lymphopenia may increase susceptibility to infections and immune dysregulation. This study examines the prevalence and longitudinal course of lymphopenia after thymectomy in infants with CHD, contributory factors, and infection risk. Method This is a retrospective cohort study in which all children <2 years who underwent first congenital heart surgery with thymectomy between 2017–2022 for conotruncal defects were recruited. Baseline, post-operative, long-term lymphocyte counts, and episodes of infections for 3 years following the surgery were collected. Results The data were collected from 95 patients with median age at the time of surgery 9.0 (IQR 5.0, 12.0) months and median weight 5.0 (1.0, 25.0) Kg. Tetralogy of Fallot (TOF) represented 53.68% of the sample. Prevalence of baseline lymphopenia was 11.6%, and within 1 week following the surgery increased to 54.7%. Being lymphopenic at baseline was associated with a decrement in lymphocyte count postoperatively by 1.2 × 10^9/L ( P = 0.02) even after adjustment for failure to thrive. Conclusion Immediate and long-term lymphopenia is highly prevalent post CHD surgical repair. Earlier age at the time of surgery, baseline lymphopenia, and being failure to thrive were significant predictors for lymphopenia post CHD surgical repair with total thymectomy. Subsequent lymphopenia not necessarily correlates with increase rate or severity of the infections. Pre-, post-operative and long-term lymphocyte count screening and clinical monitoring are warranted.