Association between routine measures of graft function and mortality in heart transplant recipients

OBJECTIVE: To date, long-term graft dysfunction, an important cause of death after heart transplantation, has been defined as a left ventricular ejection fraction (LVEF) of ≤40% or right atrial pressure (RAP) of ≥15 mm Hg. Empirical associations between measures of cardiac function and mortality post-transplant remain, however, unestablished. METHODS: We conducted a retrospective two-centre cohort study of consecutive adults who underwent heart transplant between 2002 and 2017. We evaluated the association between LVEF and RAP and mortality, including rejection and cardiac allograft vasculopathy as additional time-dependent covariates using Cox proportional hazard models. We applied restricted cubic splines to both LVEF and RAP. RESULTS: Of 590 eligible heart transplant recipients, of whom 72% were male with a mean age of 49 years, 410 received their transplant at Toronto General Hospital and 180 at Rigshospitalet. We observed a 5% absolute risk increase for 1-year mortality, from 11% to 16%, when the LVEF dropped to 53% (HR 1.71 for LVEF of 53% compared with 60%, 95% CI 1.36 to 2.14) or when the RAP increased to 12 mm Hg (HR 1.49 for RAP of 12 mm Hg compared with 5 mm Hg, 95% CI 1.04 to 2.13). CONCLUSION: In this study, we observed that small changes in graft function at any time post-transplant are associated with an increased mortality. Our results suggest that the current definition of graft dysfunction may underestimate patient risk of adverse outcomes.