Lymphopenia is common in adults who have had a Fontan operation although its aetiology and clinical implications remain unknown. Previous work suggests an association between lymphopenia and both liver disease and splenomegaly. The objective of this study was to assess the prevalence of lymphopenia in adults with a Fontan circulation and evaluate its associations with risk factors and clinical outcomes. Using a retrospective cohort study design, we studied 73 adult Fontan patients (age 25.0 ± 8.4 years) who had a complete blood count and abdominal imaging performed. Patients with protein-losing enteropathy were excluded. Clinical data were extracted from hospital records. The mean white blood cell count was 6580 ± 220/ml with a mean lymphocyte count of 1223 ± 508/ml. Lymphopenia, defined as lymphocyte count <1000/ml, was present in 23 (32%) patients. Patients with lymphopenia had a lower total white blood cell count (5556 ± 2517 versus 7136 ± 1924/ml, p = 0.009) and a lower platelet count (162 ± 69 versus 208 ± 69 k/ml, p = 0.008). Lymphopenia was also associated with findings of portal hypertension, including splenomegaly (36 versus 14%, p = 0.04), varices (22 versus 6%, p = 0.04), and ascites (39 versus 14%, p = 0.02). Lymphopenia did not correlate with any cardiac imaging, haemodynamic or exercise testing variables. In conclusion, lymphopenia is common in adult Fontan patients and is associated with markers of portal hypertension. Larger studies are needed to better define the relationship between lymphopenia and clinical outcomes.
Keywords: Fontan operation; adult CHD; lymphopenia; portal hypertension; single-ventricle CHD; splenomegaly.