A Pilot Project to Identify Simple Echocardiographic Tools as an Alternative to Cardiac Magnetic Resonance Imaging to Predict a Reduced Right Ventricular Ejection Fraction in Patients with Repaired Tetralogy of Fallot

Abstract

Background: Right ventricular (RV) dysfunction is an important predictor of adverse events after tetralogy of Fallot (TOF) repair. A study comparing echocardiography with cardiac magnetic resonance (CMR) might provide simple tools for their serial inexpensive assessment. Methods: Echocardiographic RV functional parameters including fractional area change (FAC), rate of pressure rise (dP/dt), free wall strain, myocardial performance index (MPI), tricuspid annular plane systolic excursion (TAPSE), and tissue Doppler S' velocity in patients with repaired TOF were correlated with CMR-derived ejection fraction (EF) using receiver operator characteristic (ROC) curves. Bland–Altman plots analyzed agreement between the RV end-diastolic volumes (EDVs), end-systolic volumes (ESVs), and EF derived from three-dimensional echocardiography (3DE) and CMR. Results: Eighteen patients were included. The echocardiographic parameters that showed a good positive correlation with CMR-derived EF were FAC (r = 0.851, P = 0.001), dP/dt (r = 0.730, P = 0.001), and free wall strain (r = −0.660, P = 0.003). ROC curve analysis provided a cutoff value for FAC (<36.6), dP/dt (<370 mmHg/s), free wall strain (<−18.5) and MPI (>0.565) to predict EF <45%. TAPSE and S' velocity had poor correlation. Correlation was strong between 3DE and CMR-derived EDV (r = 0.938, P <0.001), ESV (r = 0.936, P <0.001) and EF (r = 0.916, P <0.001). 3DE underestimated volumes compared to CMR with a mean bias of − 31.78 ± 18.8 ml for EDV and −17.28 ± 11.6 ml for ESV, but EF was not affected (mean bias − 1% ± 3.7%). Conclusions: RV free wall strain, FAC and dP/dt were simple tools with good accuracy to predict RV EF <45% in patients with repaired TOF. TAPSE and S' velocity assessed basal longitudinal function without considering the dysfunctional outflow tract and showed poor correlation. EF assessment by 3DE was a good alternative to CMR. Underestimation of volumes by 3DE might restrict its use in timing surgery.