Waitlist and transplant outcomes in heart transplant candidates bridged with temporary endovascular right ventricular assist devices

BACKGROUND

Advances in mechanical circulatory support and changes in allocation policy have shifted waitlisting practices for heart transplantation (HT) in the United States. This analysis reports waitlist and transplant outcomes among HT candidates bridged with temporary endovascular right ventricular assist devices (tRVADs).

METHODS

Patients awaiting HT from 2008 to 2022 in the United Network of Organ Sharing registry were grouped by the presence of tRVAD while waitlisted and propensity matched. Waitlist outcomes were HT and a competing outcome of death/deterioration requiring waitlist inactivation. Competing-risks regression was used to model waitlist outcomes. Subanalyses were performed to compare waitlist outcomes among patients with durable and temporary left ventricular assist devices (LVADs) with and without concomitant tRVADs. One-year posttransplant mortality was estimated using Kaplan-Meier analysis.

RESULTS

Of 41,507 HT candidates, 133 (0.3%) had tRVADs. After propensity matching, patients with tRVAD had a similar likelihood of HT and an elevated hazard for death/deterioration (hazard ratio 2.2, 95% confidence interval 1.4-3.2, p < 0.001) compared to those without tRVAD. Most patients with tRVAD (84%) had concomitant LVADs. tRVAD was associated with an elevated risk for deterioration/death among those with temporary LVADs but not durable LVADs. For patients undergoing HT, tRVAD was associated with an increased risk for 1-year mortality compared to propensity-matched recipients.

CONCLUSIONS

Bridging with tRVAD is uncommon and primarily used in patients requiring biventricular support. tRVADs are associated with waitlist inactivation or death, particularly with concomitant temporary LVAD support. As temporary devices are increasingly used as a bridge to HT, outcomes of patients with tRVADs should inform future allocation policy, particularly for candidates with biventricular failure.

Revised Heart Allocation Policy Improved Waitlist Mortality and Waiting Time With Maintained Outcomes in En-Bloc Heart-Lung Transplant Candidates and Recipients

The revised United Network for Organ Sharing heart allocation policy was implemented in October 2018. Using a national transplant database, this study evaluated the transplant rate, waitlist mortality, waiting time, and other outcomes of en-bloc heart-lung transplantation recipients. Adult patients registered on the national database for heart-lung transplants before and after the policy update were selected as cohorts. Baseline characteristics, transplant rates, waitlist mortality, waiting times, and other outcomes were compared between the two periods. In total, 370 patients were registered for heart-lung transplants during the pre- and post-periods. There were significantly higher transplant rates, shorter waitlist times, and substantially reduced waitlist mortality in the post-period. Registered patients waitlisted in the post-period had significantly higher utilization of intra-aortic balloon pumps, extracorporeal membrane oxygenation, and overall life support, including ventricular assist devices. Transplant recipients had significantly longer ischemic times, increased transport distances, and shorter waiting times before transplantation in the post-policy period. Transplant recipients held similar short-term survival before and after the policy change (log-rank test, p = 0.4357). Therefore, the revised policy significantly improved access to en-bloc heart-lung allografts compared with the prior policy, with better waitlist outcomes and similar post-transplant outcomes.

New system, old problem: Increased wait time for high-priority transplant candidates

The 2018 heart allocation policy sought to improve risk stratification and reduce waitlist mortality for the sickest patients. This study sought to evaluate changes in wait times for the highest priority patients since policy implementation. All adult single-organ transplant recipients were identified in the United Network for Organ Sharing registry from October 18, 2018, to July 8, 2022, and separated into 4 periods. Outcomes were compared by blood type and UNOS region. Over the study period, 897 of 9,143 patients were listed as status 1 with no significant change in median wait time by blood type or region. More patients were listed as status 2 (4,523/9,143), and each subsequent period postpolicy change was associated with a 4.2-day increase in mean status 2 waitlist time (95% confidence interval 3.0-5.5, p < 0.0001). Wait times were longest for candidates with blood type O and shortest for AB & A. Regional variations continued, however, wait time increased in every region over time.

Use of exception status listing and related outcomes during two heart allocation policy periods

BACKGROUND

The October 2018 update to the heart allocation policy was intended to decrease exception status requests, whereby candidates are listed at a specific status due to perceived need despite not meeting prespecified criteria of illness severity. We assessed the use of exception status and waitlist outcomes before and after the 2018 policy.

METHODS

We used data from the Scientific Registry of Transplant Recipients on adult heart transplant candidates listed from 2015 to 2021. We assessed (1) the use of exception status across patient characteristics between the two periods and (2) transplant rate and waitlist mortality or delisting due to deterioration in each period. Patients listed by exception versus standard criteria were compared with multivariable logistic regression, and waitlist outcomes were assessed using Cox proportional hazard models with medical urgency and exception status as time-dependent covariates.

RESULTS

During the study period (n = 19,213), heart transplants under exception status increased postpolicy from 10.0% to 32.3%, with 20.6% of transplants performed for patients at status 2 exception. Exception status candidates postpolicy were more frequently Black or Hispanic/Latino and less likely to have hypertrophic or restrictive cardiomyopathy and had worse hemodynamics. Exception status listing was associated with higher transplant rates in both periods. Postpolicy, candidates listed status 1 exception had a lower likelihood for waitlist mortality or delisting (hazard ratio, 0.60; 95% CI, 0.37-0.99; and p = 0.05).

CONCLUSIONS

Under the 2018 policy, exception status listings dramatically increased. The policy change shifted the population of patients listed by exception status and affected waitlist mortality, which suggests a need to further evaluate the policy's impact.