Regional dysfunction of the right ventricular outflow tract reduces the accuracy of Doppler tissue imaging assessment of global right ventricular systolic function in patients with repaired tetralogy of Fallot

Abstract

Background: The influence of regional right ventricular (RV) dysfunction on the accuracy of Doppler tissue imaging (DTI) assessment of global RV function is unknown. The objective of this study was to determine the effect of regional dysfunction of the RV outflow tract (RVOT) on the correlations between RV DTI indices and cardiac magnetic resonance (CMR) measurements of global RV function in patients with repaired tetralogy of Fallot.

Methods: Consecutive patients with repaired tetralogy of Fallot who underwent echocardiography with DTI of the right ventricle and CMR within 4 weeks of each other were retrospectively analyzed. RV DTI measurements were obtained from the lateral wall at the level of the tricuspid valve annulus. CMR measurements included end-diastolic and end-systolic volumes, stroke volume, and ejection fraction (EF) of the entire right ventricle and measured separately for the RV sinus and RVOT segments.

Results: The median age of the 51 patients included was 19 years (range, 9.7-71.6 years), and the median interval between echocardiography and CMR was 0 days. The mean RV free wall peak S', isovolumic acceleration, and global, sinus, and RVOT EFs were 8.4 ± 2.0 cm/s, 102 ± 37 cm/s(2), and 46.1 ± 9.8%, 47.9 ± 9.9%, and 33 ± 13.1%, respectively. The correlation between peak S' and global RV EF was weak (r = 0.23) in patients with RVOT dysfunction (RVOT EF <30%) but higher (r = 0.66) in those with RVOT EFs ≥30%. Peak S' ≥8.4 cm/s (area under the receiver operating characteristic curve, 0.77) and isovolumic acceleration ≥95 cm/s(2) (area under the receiver operating characteristic curve, 0.68) best discriminated between patients with global RV EFs >45% and <45%.

Conclusions: In this group of patients with repaired TOF, RV DTI indices showed reasonable correlation with CMR-derived global RV EF, but this correlation was substantially weaker in those with moderate and severe dysfunction of the RVOT. Peak S' <8.4 cm/s and isovolumic acceleration <95cm/s(2) by DTI should prompt an evaluation of RV function by CMR.