The relative importance and interactions of CMR-derived parameters of ventricular mechanics in the prediction of death and transplant late after the Fontan operation
© Rathod et al. 2016
Published: 27 January 2016
We have previously shown that a larger indexed end-diastolic volume (EDVi) of a functional single ventricle as determined by cardiac magnetic resonance (CMR) is an independent predictor of death and heart transplant late after the Fontan operation. Other reports have suggested that decreased ventricular strain and ejection fraction (EF) are associated with poor outcomes. The objective of this study was to identify the relative importance and interactions of CMR-based parameters for risk of death and transplant after the Fontan operation.
Clinical CMR studies from 1/2002 to 1/2015 were retrospectively reviewed. Ventricular size and function measurements were calculated using commercially available software (Medis Medical Imaging Systems, Leiden the Netherlands). Global circumferential strain (GCS) and longitudinal strain (GLS) were measured for the single or dominant ventricle at the mid-ventricular level using commercial software (TomTec Imaging Systems, Unterschleissheim, Germany). The primary endpoint was defined as time to death or listing for heart transplantation. Classification and regression tree (CART) survival analysis was performed to identify the subgroups at highest risk for the endpoint without pre-specification of possible interactions. Candidate predictors were indexed EDV, indexed end-systolic volume, EF, indexed ventricular mass, GCS, and GLS. Where applicable, CMR parameters were indexed to BSA1.3.
CMR-derived functional single ventricle EDVi is the strongest independent predictor of transplant-free survival in patients late after the Fontan operation. In patients with moderate or worse ventricular dilatation, GCS rather than EF has additional discriminating power for the endpoint. These data highlight the interactions between ventricular dilation and strain and the importance of CMR imaging in this population.
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