The predicted heart mass (PHM) ratio has recently emerged as a better metric for donor-to-recipient size-matching than weight ratios. It is unknown whether this applies to transplant candidates on left ventricular assist device (LVAD) support. Our study examines if PHM ratio is optimal for size-matching specifically in the LVAD patient population. Patients with LVAD who received a heart transplant from January 1997 to December 2020 in the Scientific Registry of Transplant Recipients database were studied. We compared 5 size-matching metrics, including donor-recipient ratios of weight, height, body mass index, body surface area, and PHM. Single and multivariable Cox proportional hazards models for 1-year mortality were calculated. Our sample consisted of 11,891 patients. In our multivariate analysis, we found that patients in the undersized group with PHM ratios <0.83 had a hazard ratio for 1-year mortality of 1.34 (95% confidence interval 1.08 to 1.65, p = 0.007) suggestive of increased mortality with the use of undersized donors. There was no statistical difference in mortality between the matched (PHM ratio 0.83 to 1.2) and oversized group (PHM ratio ≥1.2). In heart transplant recipients on LVAD support, the PHM ratio provides better risk stratification than other metrics. Use of undersized donor hearts with PHM ratio <0.83 confers higher 1-year mortality. Using oversized donor hearts for transplantation in recipients on LVAD support has no benefit.
Keywords: heart transplant; left ventricular assist device; predicted heart mass.
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