P2A092: Thrombocytopenia as a Marker of Venous Hypertension and Liver Disease Post-fontan

Background: After the Fontan procedure, patients require lifelong follow-up due to significant late morbidity and mortality. Elevated Fontan pressure and Fontan-associated liver disease (FALD) are important contributors to morbidity in this population. Complete blood count (CBC) is performed routinely, and thrombocytopenia is seen frequently post-Fontan, likely due to secondary hypersplenism from elevated Fontan pressure. The purpose of our study was to explore the relationship between thrombocytopenia and these key contributors to morbidity.

Methods: We collected data from 87 Fontan patients, 54 of whom had cardiac catheterization. We evaluated the relationship between thrombocytopenia and elevated Fontan pressure, defining thrombocytopenia as a platelet count of less than 150 (x 109/L), and elevated Fontan pressure as ≥ 15 mmHg. We defined advanced Fontan-associated liver disease (aFALD) as cirrhosis diagnosed by a hepatologist and/or 2 or more abnormal findings on a liver ultrasound such as hepatomegaly, ascites, elevated mean sheer wave speed (≥ 2.0 m/s), and irregular liver contour.

Results: At most recent follow-up, the mean age was 23 years, 38% (n = 33/87) were female, 36% (n = 32/87) had thrombocytopenia, and 39% (n = 21/54) of those who underwent catheterization had elevated Fontan pressure. There was a significant inverse correlation between platelet count and Fontan pressure (r = -0.39 and p = 0.002). Patients with thrombocytopenia had significantly higher Fontan pressures (14.9 ± 3.7 mmHg vs 12.5 ± 2.6 mmHg, p = 0.006), as seen in figure 1. Patients with thrombocytopenia had an odds ratio of 4.0 (95% CI 1.29-12.3, p = 0.02) to have Fontan pressure ≥ 15 mmHg. Thirty-five patients (40%) met our definition of aFALD. Patients with aFALD had significantly lower platelet counts (155 ± 58 vs 199 ± 66, p = 0.01), as seen in figure 2. Patients with thrombocytopenia had an odds ratio of 2.9 (95% CI 1.2 – 7.1, p = 0.02) to have aFALD. Patients with splenomegaly also had significantly lower platelet counts (152 ± 56 vs 189 ± 69, p = 0.01).

Conclusion: There is a significant negative correlation between Fontan pressure and thrombocytopenia. In addition, patients with thrombocytopenia are significantly more likely to have advanced FALD. This data supports using platelet count as a marker of late morbidity, in the form of venous hypertension and liver disease. Further studies to explore the value of using thrombocytopenia as an independent indication for invasive surveillance post-Fontan are needed.