Impact of predicted heart mass-based size matching on survival after heart transplantation in Korea: Analysis of the Korean Organ Transplant Registry

Previous studies regarding donor-recipient size and sex matching in heart transplantation (HTx) mainly included Caucasians with only a small portion of Asians. Even predicted heart mass (PHM) has not yet been elucidated in Asians. We evaluated the association between donor-recipient sex and size matching, including mismatching by PHM, and post-heart transplant survival in Korea.We enrolled 660 adult HTx recipients between January 2014 and December 2020 using the Korean Organ Transplant Registry data. Recipients were categorized based on donor-recipient PHM, body weight, and sex matching. The primary outcome was 1-year mortality and retransplantation after HTx and survival analyses were performed using Kaplan-Meier method and Cox proportional hazard models.Among 660 patients, 74 (11.2%), 404 (61.2%), and 182 (27.6%) received undersized (-15%), matched (-15% to 20%), and oversized (20%) hearts by PHM, respectively. Size mismatching by PHM was present in a large number of sex-mismatched patients with 85.1% of male donor-female recipients being classified as oversized by PHM and 62.2% of female donor-male recipients being classified as undersized by PHM. Recipients of undersized or oversized hearts by PHM showed an increased 1-year mortality compared with recipients of matched-size hearts (14.8% versus 9.7%; log-rank p = 0.038). The increased mortality persisted after adjusting for other factors affecting mortality (hazard ratio = 1.60, 95% confidence interval: 1.01-2.56). These associations were not shown in obese recipients (body mass index ≥25 kg/mHeart size matching by PHM, not by body weight or sex, was associated with increased 1-year mortality after HTx in Korea.