Red Blood Cell Distribution Width as a Predictor of Pulmonary Valve Replacement in Patients with Repaired Tetralogy of Fallot

Background: The timing of pulmonary valve replacement (PVR) in patients with repaired Tetralogy of Fallot (rToF) is an important factor in adult congenital heart disease care. High red blood cell distribution width (RDW) is an independent predictor for recourse to cardiac surgery. This study assesses the relation between RDW and cardiac magnetic resonance imaging (cMRI) in predicting recourse to PVR. Methods: The study is a retrospective observational cohort analysis. Data were gathered by review of electronic medical records. The relation between a high RDW and PVR was assessed, with a focus on comparing the area under the receiver operating characteristics (AUC) with those of the cMRI-based right ventricle (RV) measurements: RV end diastolic volume index (RVEDVI) >150 ml/m2, RV end systolic volume Index (RVESVI) >85 ml/m2, and RV ejection fraction (RVEF) <45%. Results: In 44 rToF patients (26 PVR), the cMRI-RV measurements did not show any statistically significant association with PVR (RVEDVI OR 1.04, p=0.979; RVESVI OR 1.62, p=0.765; RVEF OR 0.64, p=0.573 respectively). An RDW=15% was associated with PVR (OR 2.05) but did not reach statistical significance (p=0.559). The AUCs showed similar findings. There was no statistically significant difference between the C-statistics (p=0.868). Conclusion: In a sample population of adult rToF patients, there was no statistically significant difference between a high RDW and cMRI-based RV measurements in predicting PVR. An inexpensive and readily available marker, RDW warrants further investigation in large multicenter datasets to fully determine its role as an additional predictive biomarker for PVR in adult ToF patients.