Utility of Right Ventricular Mass Ratios in Recipients With Pulmonary Hypertension: A United Network for Organ‐Sharing Database Analysis

PURPOSE: There is a lack of data reviewing the role of predicted cardiac mass ratio (PCMR) in transplant recipients with pulmonary hypertension (PH). In particular, the right ventricular (RV) mass ratio (RVMR) is a component of PCMR not yet studied separately for this purpose. We aimed to review the relationship of PCMR and RVMR with PH in terms of post-transplant overall survival. METHODS: The United Network for Organ-Sharing (UNOS) database was queried for primary heart transplant (HTx) patients from 2004 to 2023. Predicted RVMR was calculated for donors and recipients. A parsimonious multivariable model Cox model was formed for risk adjustment. Covariates with statistically significant relationships to the outcomes were further evaluated with tensor product spline models. RESULTS: A total of 37 904 patients were identified. After risk adjustment, diastolic pulmonary artery pressure (dPAP) was protective (HR 0.993 [0.989-0.997], p = 0.001), whereas increasing systolic pulmonary artery pressures (sPAPs) (HR 1.007 [1.005-1.009], p < 0.001) and diastolic pulmonary gradient (DPG) (HR 1.011 [1.007-1.015], p < 0.001) were associated with increased overall mortality. Increasing RV mass ratio (RVMR) was protective (OR 0.663 [0.589-0.747], p < 0.001)). This was appreciated in a restricted cubic spline analysis as a nonlinear relation was evident with any RVMR less than 1 (p < 0.001). Subsequent tensor product spline models evaluating the complex relationship between RVMR and pulmonary pressures demonstrated increasing relative hazards in patients with PH and smaller RVMR (p < 0.001). CONCLUSION: In HTx patients with PH, RVMR ≥ 1 is significantly associated with a reduced hazard of overall mortality. This indicates RV undersizing may be harmful in the population.