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

Abstract

Background: 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. Methods: 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. Results: 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. Conclusions: 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.

Keywords

• heart transplant
• mechanical circulatory support
• left ventricular assist device
• bridge-to-transplantation
• predicted heart mass