Introduction: End stage heart failure is often associated with progressive kidney dysfunction. Combined heart and kidney transplant (HKTx) or kidney transplant after heart transplant (KAH) are treatment options, however with limited evidence on outcomes for either strategy.
Methods: We selected all adult patients (n=973) from 2006-2016 who underwent combined HKTx (n=822) and compared them to KAH patients (n=151) using the United Network for Organ Sharing database. Patients with retransplant of heart (N= 120) and those on dialysis but did not receive a kidney at the time of heart transplant (n=8) were excluded which resulted in final sample of 845 patients. Kaplan Meier curves and Cox models compared the risk of death among combined HKTx to KAH patients.
Results: Combined HKTx increased significantly from 59 annually in 2007 to 146 in 2016 whereas number of KAH decreased (34 in year 2007 to 6 in year 2016). For KAH patients, average wait time for kidney transplant was 3.0 years and time to dialysis or to kidney transplant after heart transplant did not differ with varying severity of kidney disease (p>0.05 for both). Compared to KAH patients, those with combined HKTx were significantly older, 54.5±11.6 years vs 51.3±14.5 years (p=0.0006), had longer wait time on the transplant list 222.6 days vs 151.1 days (p=0.03) and had higher prevalence of diabetes mellitus type 2 (35% vs 23%; p=0.03). Upon follow up (mean 3.47±2.74 years), 97 of the 845 patients died. Kaplan Meier curves shows higher risk of death for combined HKTx patients (with or without dialysis) compared to KAH patients (Figure). In addition, in stepwise Cox model, multivariable-adjusted risk of death for patients who underwent combined HKTx was 2.79-fold (p=0.005) greater than KAH patients.
Conclusions: National registry data show increasing numbers of combined HKTx but poorer survival compared to KAH patients. Differences in patient characteristics does not explain this higher risk so far hence further studies are needed.