Sex-specific aspects of left and right ventricular volume regulation in patients following tetralogy of Fallot repair
Ejection fraction (EF) is applied as a clinically relevant metric to assess both left (LV) and right ventricular (RV) function. EF depends on the interplay between end-systolic volume (ESV) and end-diastolic volume (EDV). The role of the two constitutive components is of particular interest for the follow-up study of Fallot patients at risk for RV volume overload. The volume regulation graph (VRG) relates ESV to EDV and has been advanced as a central tool to describe LV and RV function. The method permits additional analysis of the impact of clinically relevant determinants such as sex and age. Following Fallot repair and using MRI we evaluated LV and RV volumes in 124 patients (50 females), who were not taking any medication. Volumes were indexed for body surface area (BSA). The VRG regression lines are similar for both sexes, also when stratified for age (i.e. younger or older than 18 years), and different for LV and RV. However, RV ESV is larger (P=0.039) for adult males, as is RV EDV (P=0.026) in boys, relative to their female counterparts. For LV ESV we also found larger volumes, but only in boys (P=0.023) compared to girls. Average EF (only for RV) is lower in adult men compared to women (P=0.012), and to boys (P=0.007). These findings are partly in contrast with common observations made in individuals without a history of cardiac disease, where (with BSA indexation) LV and RV volumes are similar in children, but consistently larger in adult males. These results highlight the age- and sex-specific volumetric aspects of remodeling following surgery in Fallot patients, and emphasize the pivotal role of ESV size in both RV and LV.