Modern outcomes of heart-lung transplantation: assessing the impact of the updated US allocation system.

Abstract

In 2018, the United Network for Organ Sharing modified their heart allocation policy to reduce waitlist mortality and prioritize patients with the greatest acuity. Considering declining rates of combined heart-lung transplantation, this study sought to investigate the impact of the new allocation system on waitlist and post-transplant outcomes of patients listed for combined heart-lung transplantation. Adult patients listed for combined heart-lung transplant between 2012 and 2021 were included. Patients were stratified according to listing era. Competing risk regression was used to assess waitlist outcomes. Cox proportional hazards regression was used to establish risk factors for post-transplant mortality. A total of 511 patients were included, of whom 295 (57.8%) were listed in era 1 and 216 (42.2%) in era 2. Era 2 was associated with increased likelihood of transplant (adjusted standard hazard ratio (aSHR): 1.60 [1.23-2.07]; P < 0.01) and decreased waitlist mortality (aSHR: 0.43 [0.25-0.73]; P < 0.01). Despite longer ischaemic times and increased use of preoperative veno-arterial extracorporeal membrane oxygenation (ECMO) in era 2, early post-transplant survival was equivalent. Predicted heart mass ratio <0.8 (Hazard ratio (HR); 3.24; P = 0.01), ventilator support (HR: 3.83; P < 0.01) and greater ischaemic times (HR: 1.80; P < 0.01) independently predicted the mortality. Procedures at high centre volumes (HR: 0.36; P = 0.04) were associated with decreased mortality. Use of ECMO was not predictive of mortality in the modern era. The allocation policy change has led to improvements in waitlist outcomes in patients listed for heart-lung transplantation. Despite increased ischaemic times and use of ECMO, early post-transplant survival was equivalent.