Cardiothoracic ratio may be misleading in the assessment of right- and left-ventricular size in patients with repaired tetralogy of Fallot

Abstract

Aim: To assess the relationship between cardiothoracic ratio (CTR) and ventricular and atrial volumes in patients with repaired tetralogy of Fallot (TOF).

Materials and methods: Patients with repaired TOF undergoing cardiac magnetic resonance (CMR) and chest radiography within 1 day were included (n = 82; median age: 24.7 years, interquartile range: 21.5-35.9). The CTR was obtained from upright posteroanterior chest roentgenograms. Analyses of CMR images and radiographs were performed in a blinded fashion.

Results: There were 35.1% (13/37) of patients with normal CTR (<0.5) who had severe right ventricular (RV) dilatation. There were six patients (13.3%, 6/45) with high CTR with both normal RV and left-ventricular (LV) volumes. CTR did not correlate with either RV or LV volumes but showed a weak correlation with right- and left-atrial volumes (r = 0.43, p = 0.0001; r = 0.27, p = 0.01, respectively). CTR ≥0.5 showed poor ability in the identification of severe RV dilatation (sensitivity: 61.8%, specificity: 50%). The combination of CTR and signs of RV enlargement on lateral radiographs did not improve the diagnostic accuracy of any of those parameters alone.

Conclusion: CTR in patients with repaired TOF reflected atrial rather than ventricular dilatation. The use of CTR or lateral radiographs in patients with repaired TOF may lead to false conclusions concerning ventricular size.