Simultaneous Heart-Kidney Transplant-Does Hospital Experience With Heart Transplant or Kidney Transplant Have a Greater Impact on Patient Outcomes?

High institutional transplant volume is associated with improved outcomes in isolated heart and kidney transplant. The aim of this study was to assess trends and outcomes of simultaneous heart-kidney transplant (SHKT) nationally, as well as the impact of institutional heart and kidney transplant volume on survival. All adult patients who underwent SHKT between 2005-2019 were identified using the United Network for Organ Sharing (UNOS) database. Annual institutional volumes in single organ transplant were determined. Univariate and multivariable analyses were conducted to assess the impact of demographics, comorbidities, and institutional transplant volumes on 1-year survival. 1564 SHKT were identified, increasing from 54 in 2005 to 221 in 2019. In centers performing SHKT, median annual heart transplant volume was 35.0 (IQR 24.0-56.0) and median annual kidney transplant volume was 166.0 (IQR 89.5-224.0). One-year survival was 88.4%. In multivariable analysis, increasing heart transplant volume, but not kidney transplant volume, was associated with improved 1-year survival. Increasing donor age, dialysis requirement, ischemic times, and bilirubin were also independently associated with reduced 1-year survival. Based on this data, high-volume heart transplant centers may be better equipped with managing SHKT patients than high-volume kidney transplant centers.