Cardiothoracic Ratio for Assessment of Ventricular Volumes and Function in Patients with Repaired Tetralogy of Fallot

Background: The role of CTR from the chest radiograph for assessment of ventricular enlargement and function in repaired tetralogy of Fallot (TOF) is conflicting. This study aimed to determine the associations between CTR and cardiac magnetic resonance (CMR)-derived ventricular volumes and indices of ventricular function in adolescents and young adults with repaired TOF. Methods: The CTR and CMR findings, performed within 12 months of each other, were reviewed in 76 patients aged 22.1 ± 6.4 years. Associations between CTR and CMR parameters including right RV and left ventricular (LV) volumes and ejection fraction were determined. Diagnostic accuracies of CTR in identifying moderate to severe RV or LV dilation were assessed by calculation of area under the receiver operator characteristic curves (AUC). Results: Patients with normal CTR and those with increased CTR > 0.5 had similar right and LV volumes, ejection fraction, and PR fraction (all p > 0.05). There were no significant correlations between CTR and RV end-diastolic (r = 0.06, p = 0.65) and end-systolic (r = 0.06, p = 0.65) volumes, LV end-diastolic (r = 0.23, p = 0.08) and end-systolic (r = 0.18, p = 0.16) volumes, and LV (r = −0.07, p = 0.60) and RV (r < −0.01, p = 0.97) ejection fraction. The CTR failed to distinguish between patients with moderate to severe RV (AUC 0.50) or LV (AUC 0.46) dilation from patients without ventricular dilation. Conclusions: The CTR based on the chest radiograph failed to reflect dilation or reduced ejection fraction of either the right or the LV in adolescents and young adults with repaired TOF.