Unpacking the Impact of Policy on Practice: Effect of the 2018 UNOS Policy Change on the Practice of Heart Transplantation

Abstract

Background: This study examines the impact of the 2018 United Network for Organ Sharing (UNOS) policy change on heart transplant candidates in the United States. Methods: Changes in waitlist times, patterns of MCS use as a bridge to transplantation, post-transplant survival, and hospital readmission trends before and after the policy implementation were analyzed. Analysis of heart transplant recipients transplanted between January 2013 and June 2022, classified into two periods: Period A (pre-policy) and Period B (post-policy). Statistical methods such as binary logistic regression and ARIMA modeling were applied to assess trends and outcomes. Results: There was increased reliance on temporary MCS, specifically IABP and ECMO, following the policy change. The use of IABP at listing rose from 5.1% in Period A to 15.5% in Period B, while ECMO use increased from 1.1% to 3.6%. At the time of transplant, IABP usage surged from 7.6% to 27.8%, and ECMO use increased from 1.0% to 5.6%. Regression analysis confirmed that the odds of using IABP and ECMO at transplant were significantly higher in Period B (OR 5.36 and OR 7.39, respectively, p < 0.001). Sub-group analysis on escalation revealed that transitioning from IABP to ECMO significantly increased adverse post-transplant outcomes, including higher rates of dialysis (33.1% vs. 15.0%, p < 0.01), prolonged ventilation (35% vs. 1%, p < 0.01), and reduced survival at 1000 days (61.6% vs. 83.6%, p < 0.01). Analysis comparing durable LVAD with temporary MCS revealed that patients bridged with durable LVADs, had lower rates of adverse outcomes, including reduced requirements for prolonged inotropes (43.1% vs. 57.6%, p < 0.01), dialysis (14.2% vs. 17.9%, p < 0.01), and chronic steroid therapy (3.6% vs. 5.8%, p < 0.01). While stroke incidence was slightly higher in the LVAD group (4.1% vs. 3.9%, p = 0.19), this increase was not statistically significant. Additionally, 1000-day survival was comparable between temporary MCS (82%) and durable LVAD (80%) groups (p = 0.02), indicating that LVADs offer a viable alternative to temporary support strategies. Conclusion: The 2018 UNOS policy change has led to significant shifts in MCS utilization, with an increased reliance on temporary support. However, careful consideration must be given to escalation strategies, as transitioning from IABP to ECMO is associated with worse post-transplant outcomes. Prioritizing the use of durable LVADs, particularly HM3, as a primary bridge to transplant rather than escalating from temporary devices such as IABP and ECMO is recommended. The addition of ECMO to IABP significantly reduces survival, making it a less favorable strategy. Early implantation of durable LVADs may improve patient outcomes and reduce complications associated with prolonged temporary MCS use. Durable LVADs, particularly HM3, may be considered the preferred bridging strategy to optimize long-term survival and reduce perioperative complications in heart transplant candidates.