Small Pre-Implant LV Size Mediates Worse Post-Implant Outcomes in Female CF-LVAD Recipients

Purpose Females have an increased risk of post-operative right ventricular failure (RVF) and early 3-month mortality after LVAD implantation, however the underlying mechanisms are unclear. We hypothesize that LV size-LVAD pump speed mismatch driven by smaller LVEDDs in females results in shifting of the interventricular septum (IVS), which contributes to the sex-differences in outcomes post-LVAD. Methods In this translational study, we utilized clinical and bench-top approaches. Adult CF-LVAD recipients from the ISHLT Mechanically Assisted Circulatory Support (IMACS) registry (n=15,498, Implant years: 2013-17, age: 56 + 13 yrs, 21% female) were studied to determine association of female sex with outcomes of 3-month post-implant mortality and RVF (RVAD/ > 14 days post-LVAD inotropes), with and without LVEDD in the models. On the benchtop, four bi-ventricular patient-specific silicone heart phantoms (LVEDD = 6.1, 6.3, 8.1, 8.3 cm) were subjected to variable bi-ventricular loading states (Δ volume = LV volume - RV volume), while observing IVS position. Results There were 1,466 deaths (9.5%) within 3 months of implant, and 2,550 patients (16.5%) with RVF. Female sex was associated with 42% increased odds of 3-month mortality (p Conclusion Smaller LV size partially mediates worse post-LVAD outcomes for female patients, due to lower Δ volume thresholds for leftward shift of the IVS in smaller hearts.