Individual Association of Predicted Left and Right Ventricular Mass Ratios With Survival After Heart Transplantation: A UNOS Database Analysis.

Background: Predicted heart mass (PHM) ratio is a commonly used metric for donor-to-recipient size matching that has been associated with survival after heart transplantation (HTx). PHM represents a sum of two separate statistical models for predicted left ventricular mass (PLVM) and predicted right ventricular mass (PRVM); however, their individual contributions have not been sufficiently studied. We sought to assess the association of donor-to-recipient PLVM (PLVMR) and PRVM ratios (PRVMR) with overall posttransplant survival individually.

Methods: Adult heart transplant recipients from 2005 to 2021 were queried from the UNOS database. A three-dimensional tensor product spline model assessed the association of PLVMR and PRVMR with survival simultaneously on a continuous distribution. Subsequently, PLVMR and PRVMR were explored individually using individual restricted cubic spline models.

Results: A total of 25 549 patients were analyzed. Of these, female recipients comprised 26.7% (n = 6818), and the median age was 56 [IQR 46-63] years. In the three-dimensional restricted cubic spline (3D-RCS) model, PLVMR and PRVMR were significantly associated with survival (p value: overall = 0.002, PLVMR = 0.0006, PRVMR = 0.0006, PLVMR*PRVMR = 0.0002). When analyzed with two-dimensional restricted cubic spline (2D-RCS) models, PLVMR was not associated with survival (p = 0.59), while PRVMR retained its significant association (p = 0.04).

Conclusions: While both PLVMR and PRVMR appear to be associated with posttransplant survival, the effect of PRVMR might be disproportionately high as PRVM makes up a much smaller fraction of PHM than PLVM.