Application of donor predicted heart mass in heart transplant recipients with left ventricular assist device

An association between predicted heart mass (PHM) and post heart transplantation outcomes has been well established; however, there is limited data on the effect of donor PHM on recipients bridged with a durable left ventricular assist device (LVAD). This retrospective observational study seeks to challenge the theoretical benefit of oversizing donor hearts for recipients bridged with LVADs. Analysis of the United Network for Organ Sharing database revealed 10,806 adult patients with 1 of 3 durable LVADs (HeartMate 2, HeartMate 3 [HM3], HeartWare Ventricular Assist Device) between January 1, 2015 and December 31, 2021. Baseline characteristics were compared between 7 equally sized groups based on donor-to-recipient PHM. Univariable and multivariable Cox regression analyses were constructed to evaluate the effect of PHM size-matching on the primary outcome of 1-year post-transplant survival. Further analyses were performed specifically on HM3 patients and with PHM as a continuous variable. Multivariable analysis revealed that severely undersized donor hearts (PHM ratio <0.86) resulted in worse outcomes with respect to 1-year mortality (hazard ratio 1.30; confidence interval 1.03-1.64, p = 0.03). There was no significant benefit to oversizing donor hearts. Similar results were found in patients bridged to transplant with HM3. Similar to prior studies on heart transplant recipients, recipients bridged with durable LVAD had worse outcomes when using severely undersized donor hearts. Oversized donor hearts did not significantly improve 1-year mortality, compared to size-matched references. These results were consistent in a subgroup analysis of patients bridged only with HM3 LVADs.