Abstract 1939: Non-Invasive Imaging of Right Ventricular Function and Pulmonary Insufficiency in Tetralogy of Fallot: A Cross Sectional Study on 117 Subjects
Background: Patients with repaired tetralogy of Fallot (TOF) are monitored for pulmonary insufficiency (PI), right ventricular (RV) dilation and RV function to identify those in need of pulmonary valve replacement. We sought to compare qualitative and quantitative measures of PI and RV function on echocardiogram to those on cardiac magnetic resonance (MRI). Such tests may improve longitudinal clinical assessment and identify endpoints for long-term research studies.
Methods: 117 patients with repaired TOF (12.7± 3.2 years) had nearly concurrent echocardiograms and MRI (within three months). On echocardiogram, RV function was assessed by
Doppler tissue imaging of the RV free wall just beneath the tricuspid valve annulus and
myocardial performance index (MPI); the main pulmonary artery was interrogated for PI and the time-velocity integrals of systolic and diastolic flow were measured.
MRI variables included RV ejection fraction, RV end-diastolic volume and pulmonary artery regurgitant fraction (RF), graded as mild PI <20%, moderate=20 – 40%, and severe > 40%.
Results: On MRI, mean RF was 35± 17% (range 0 – 65) and mean RV ejection fraction was 61± 8% (range 36 – 82). By qualitative measures, echocardiogram had good sensitivity in identifying cases with RF>20% (sensitivity 97%, 95% CI: 93– 100%) but overestimated the amount of PI when RF<20% (false positive rate 47%, 95% CI: 38–57%). The ratio of diastolic/systolic time velocity integrals on echocardiogram showed moderate correlation with RF on MRI (R=0.41, P<0.001). An MRI RF of 20% and 40% corresponded with a diastolic/systolic time-velocity integral ratio of 0.64 (95% CI: 0.53–0.75), and 0.86 (95% CI: 0.78 – 0.94), respectively. RV MPI correlated moderately with RV ejection fraction (R=0.37, P<0.001), but E/Ea Doppler tissue velocities correlated poorly (R= 0.06, P=0.55).
Conclusions: Echocardiography has high sensitivity to detect PI when compared to MRI. The time-velocity integral ratio of diastolic/systolic flow of the pulmonary artery may provide a quantitative tool to follow PI on echocardiograms, but further validation and longitudinal studies are required to confirm its utility. The MPI, but not Doppler tissue imaging, appeared to assist in assessment of RV systolic function.