Background: Strain imaging offers and alternative non-invasive method to qualify RV function. This study aims to utilize strain imaging in the assessment of right ventricular function among repaired tetralogy of fallot patients in order to determine subclinical right ventricular dysfunction and thereby aid the clinician in the follow-up and management of post-operative patients.
Methods: This is a prospective cross sectional study done at the Philippine Heart Center. Cardiac magnetic resonance imaging and echocardiographic strain imaging were done on all subjects during the same day. Statistical comparison was performed using mean standard deviation and percent distribution for quantitative variables. Sensitivity and specificity curves using cardiac magnetic resonance imaging (MRI) derived right ventricular ejection fraction (RVEF) as the reference test was used to determine optimal cutoff values for global and regional longitudinal systolic strain and strain rate. Paired t-test was used for the assessment of intra-observer variability for 2D strain measurements.
Results: Twenty-two subjects were included, with a mean age of 16.7±5.3 years old and a post-operative year interval of 8.95±4.3 years. There was significant inverse, moderate correlation between cardiac MRI derived RVEF and right ventricular free wall mid segment strain (r=0.42; p value =0.05) and global longitudinal strain (r= -0.62; p value = 0.002). The determined cut-off for right ventricular dysfunction for right ventricular global strain was -20.66% which showed a sensitivity of 88.83% and a specificity of 100%, PPV of 100%, NPV of 88.83%; right ventricular free wall mid segment strain determined cut-off was -16.59 which showed sensitivity of 88.83% and a specificity of 100%, PPV of 100%, NPV of 8.83%.
Conclusion: Strain imaging is an easy, feasible and reproducible parameter in two dimensional echocardiography that can be used as a good screening tool with high sensitivity and specificity for detecting right ventricular dysfunction among repaired tetralogy of fallot.