Nowadays, the fraction of ejection (FE) is no longer considered as the unique way of expression of the efficiency of cardiac labor. The development of strain imaging (SI), in echocardiography and in MRI, has led to a better understanding of ventricular contraction, especially in cases of cardiac dysfunction with preserved FE. But SI still under-exploited in clinical practice despite the fact that it is a proved prognostic factor in many cardiomyopathies. Recently, a new framework was developed to associate the FE and the deformation parameters, the global longitudinal (GLS) and circular strain (GCS), to give the opportunity of a global assessment of the cardiac function. This mathematical relationship was validated on the adult population. This work intends to determine the more accurate evaluation of the GCS and GLS values in pediatric population and its use in order to validate the mathematic model described.

Retrospective monocentric study carried out in the cardiopediatric unit of Florence University Hospital. Inclusion of all pediatric patients who completed cardiac MRI between November 2021 and December 2022. An assessment of the left ventricle FE, GCS and GLS and a double reading was made by two specialized cardiologists.

In total, 134 CMR were studied. A good reproducibility between readers was observed (GCS: r=0,94, GLS: r=0,83). The correlation between isolated strain parameters and FE (GCS: r=0,84 and GLS: r=0,68) and between theorical FE (GCS+GLS) and FE was high (FE/FE(th): r=0,88). The use of endocardial strain and the assessment of GCS with short axis slice assured the best correlation with the FE.

The evaluation of GCS and GLS with CMR are a safe way to evaluate the mechanical contraction of the left ventricle in pediatric population. The use of an integrated mathematical formula gives a summarized information of SI with a very good correlation to the FE.