Right- and Left-Ventricular Strain Evaluation in Repaired Pediatric Tetralogy of Fallot Patients Using Magnetic Resonance Tagging

Residual pulmonary insufficiency in post-repair Tetralogy of Fallot (rToF) patients often mediates biventricular dysfunction which is associated with long-term adverse clinical outcomes. The objective of this study was to demonstrate the presence of impaired left ventricle (LV) circumferential strain (CS) in pediatric rToF patients as compared to controls using cardiac magnetic resonance imaging (CMRI). Additionally, bivariate analysis between right ventricle (RV) and LV functional measures in rToF patients was performed to further characterize the interventricular interactions thought to mediate LV dysfunction secondary to RV volume overload. The medical records of 12 rToF patients (mean age 13.3 years) and 9 controls (mean age 10.9 years) were analyzed. LV global CS was significantly decreased in rToF patients versus controls (p = 0.04). This impairment was differentially distributed within the LV, with only the LV anterior and anterior lateral walls significantly decreased versus controls (p = 0.04, p = 0.03). Bivariate analysis revealed a significant correlation between RV mean CS and LV EF (r = 0.71, p = 0.01), RV infundibulum CS and LV EF (r = 0.70, p = 0.01), RV infundibulum CS and LV anterolateral wall CS (r = 0.59, p = 0.04), and RV infundibulum CS and pulmonary regurgitation fraction (r = -0.63, p = 0.03). These findings support existing research implicating interventricular interactions in the development of LV dysfunction. Furthermore, the segment specific CS impairment in the LV suggests a possible spatial component to these interactions. The success of this study in identifying regional myocardial strain impairment indicates CMRI based techniques may be useful in localizing otherwise undetectable myocardial dysfunction.