Echocardiography and cardiac magnetic resonance in children with repaired tetralogy of Fallot: New insights in cardiac mechanics and exercise capacity

Background: Pulmonary regurgitation (PR) and right ventricular (RV) dilatation and disfunction are common in patients with repaired Tetralogy of Fallot (r-TOF).

Aims: To compare Echo data with the gold standard CMR in a paediatric population of r-TOF with significant PR, to assess the reliability of standard and advanced echo parameters. In addition, to evaluate their correlation with peak oxygen consumption (VO₂).

Methods and results: All patients underwent standard echo-Doppler study, speckle tracking analysis, and CMR to assess PR and RV size and function. Thirty-six patients underwent also cardiopulmonary exercise test. Fourty-six patients (aged 13.7 ± 3.0) were included. Echo derived RV areas correlated with CMR RV volumes (p < .0001, r = 0.72). RV end-diastolic area > 21.9 cm²/m² had a good sensitivity (83.3%) and specificity (73.5%) to identify a RV end-diastolic volume ≥ 150 ml/m². RVEF was preserved in all patients, while TAPSE was reduced in 78.2% and RVGLS in 60.8%. Flow-reversal in pulmonary branches showed a sensitivity of 95.8% and a specificity of 59.1% to identify CMR pulmonary regurgitant fraction (RF) ≥ 35%. None of the CMR parameters correlated with peak VO₂. Among the Echo data only right atrial strain (RAS) correlated with peak VO_2. CONCLUSION: In children, flow-reversal in pulmonary branches identifies hemodynamically significant RF with a good sensitivity but poor specificity. RV area by echocardiogram is a valid first-line parameter to screen RV dilation. RV longitudinal systolic dysfunction coexists with a still preserved EF. RAS correlates strongly with peak VO₂ and should be added in their follow up.