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Outcomes of the First 1300 Adult Heart Transplants in the United States After the Allocation Policy Change

Originally publishedhttps://doi.org/10.1161/CIRCULATIONAHA.119.045354Circulation. 2020;141:1662–1664

    Heart allocation policy was changed on October 18, 2018, to address several concerns with the previous system.1 We reviewed adult heart transplants performed in the United States between January 1, 2018, and March 31, 2019, and stratified patients based on date of waitlist registration and transplantation, with follow-up data through June 6, 2019. Changes in baseline characteristics, as well as waitlist and posttransplant outcomes, were compared. The institutional review board approved this study at the University of Pittsburgh Medical Center.

    The primary end point was overall survival after transplantation. Secondary end points included waitlist outcomes: waitlist mortality or clinical deterioration, rate of transplantation, and removal from the waitlist because of recovery. Student t test and χ2 tests were used. Time-to-event analyses were performed using the Kaplan-Meier method. Multivariable Cox regression analysis was used for risk adjustment. Waitlist outcomes were analyzed by using competing risks regression and the Fine and Gray method.

    A total of 3258 adult patients were waitlisted before the policy change and 1759 were waitlisted after the policy change. A total of 2371 and 1311 adult heart transplants were performed before and after the policy change, respectively. After the policy change, recipients were younger (54.3±12.7 versus 52.9±13.2 years; P=0.002) and more had nonischemic dilated cardiomyopathy (50.9% versus 52.0%) and congenital heart disease (3.4% versus 5.3%; P=0.03). Higher risk characteristics, including serum bilirubin (0.91±1.45 versus 1.17±2.44; P<0.001), mechanical ventilation (0.7% versus 2.4%; P<0.001), pretransplant intensive care unit (28.7% versus 47.0%; P<0.001), and bridging with the percutaneous Impella device (0.2% versus 0.6%; P=0.02), intra-aortic balloon pump (IABP; 7.1% versus 22.4%; P<0.001), surgically implanted temporary left ventricular assist devices (LVADs; 1.5% versus 3.9%; P<0.001), or extracorporeal membrane oxygenation (1.1% versus 4.9%; P<0.001) were greater after the policy change. Fewer recipients had durable LVADs after the change (44.8% versus 36.0%; P<0.001). More donors were hepatitis C positive (7.9% versus 11.1%; P=0.001) and had higher creatinine (1.51±1.52 versus 1.65±1.76; P=0.01) in the latter era. There were longer donor-to-recipient hospital distances (156.7±189.4 versus 264.6±241.9 miles; P<0.001) and cold ischemic times (3.02±1.01 versus 3.38±1.02 hours; P<0.001) after the policy change. Under the new policy, the distribution of statuses at transplantation was as follows: 8.6% status 1, 42.8% status 2, 26.2% status 3, 18.3% status 4, 0.3% status 5, and 3.7% status 6.

    Waitlist outcomes were improved after the policy change, with higher rates of transplantation (P<0.001) and lower rates of waitlist mortality or clinical deterioration (P=0.01; Figure, A and B). Rates of waitlist removal for recovery were low in both groups but lower after the policy change (P=0.01). Posttransplant survival was worse after the policy change, with 6-month survivals of 93.7% versus 86.5% (P<0.001). Similar findings persisted when limiting the analysis to first-time, primary isolated heart transplants (6-month survival: 93.9% versus 88.2%; P<0.001; Figure, C). In multivariable analysis, transplantation after the policy change remained a significant predictor of posttransplant mortality (hazard ratio, 1.41 [95% CI, 1.01–1.95]; P=0.04).

    Figure.

    Figure. Higher rates of transplantation coupled with lower rates of waitlist mortality or deterioration and lower posttransplant survival after the policy change.A, Transplantation. B, Waitlist mortality or deterioration. C, Overall survival.

    This study demonstrates substantial changes in the landscape of adult heart transplantation in the United States after the allocation policy change on October 18, 2018. Foremost, higher-risk recipients are undergoing transplantation. This includes mechanically ventilated patients and those bridged with IABP, extracorporeal membrane oxygenation, or temporary LVADs, as well, all of which have been demonstrated to be associated with increased mortality risk after transplantation.2–4 In particular, bridging with IABP has increased >3-fold, suggesting that many programs are favoring the use of IABP when hemodynamically indicated rather than increasing intravenous inotropes or durable LVAD implantation. These changes reflect the priority statuses that are applied under the new system, whereby patients with IABP are prioritized as status 2, and only in the setting of device malfunction, mechanical right ventricular support, or significant ventricular arrhythmias are patients with durable LVADs able to get priority status 1 or 2 listing.

    The current analysis demonstrates a shift favoring the improvement of waitlist outcomes with a decline in posttransplant survival. This appears to be a reflection of performing transplants in sicker patients with broader sharing of organs and longer ischemic times. The 6-month survival rates we demonstrate after the new policy change are lower than previously reported rates from registry analyses. It is important to note, however, that individual transplant centers are evaluated based on observed-to-expected ratios and not absolute outcomes. The models used for expected risk incorporate many of the risk factors identified as increasing in frequency after the policy change.5 In this manner, the observed-to-expected ratios of outcomes may be maintained despite a decrease in the absolute survival rates after the allocation change. There is also the potential that individual transplant centers may adjust their risk tolerance based on outcomes. This is an early analysis with associated limitations in follow-up after the policy change, and a reevaluation of these outcomes will therefore be essential.

    Acknowledgments

    The data reported here have been supplied by the United Network for Organ Sharing as the contractor for the Organ Procurement and Transplantation Network. The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy of or interpretation by the Organ Procurement and Transplantation Network or the US government.

    Footnotes

    Data sharing: The authors declare that all supporting data are available within the article.

    https://www.ahajournals.org/journal/circ

    Arman Kilic, MD, Division of Cardiac Surgery, University of Pittsburgh Medical Center, 200 Lothrop St, Suite C-700, Pittsburgh, PA 15213. Email

    References

    • 1. Meyer DM, Rogers JG, Edwards LB, Callahan ER, Webber SA, Johnson MR, Vega JD, Zucker MJ, Cleveland JCThe future direction of the adult heart allocation system in the United States.Am J Transplant. 2015; 15:44–54. doi: 10.1111/ajt.13030CrossrefMedlineGoogle Scholar
    • 2. Castleberry AW, Patel CB, DeVore AD, Southerland KW, Rogers JG, Milano CA. Mortality differences after heart transplantation in patients bridged with balloon pumps vs left ventricular assist devices.J Heart Lung Transplant. 2013; 32:S23–S24.CrossrefMedlineGoogle Scholar
    • 3. Kilic A, Allen JG, Weiss ES. Validation of the United States-derived Index for Mortality Prediction After Cardiac Transplantation (IMPACT) using international registry data.J Heart Lung Transplant. 2013; 32:492–498. doi: 10.1016/j.healun.2013.02.001CrossrefMedlineGoogle Scholar
    • 4. Fukuhara S, Takeda K, Kurlansky PA, Naka Y, Takayama H. Extracorporeal membrane oxygenation as a direct bridge to heart transplantation in adults.J Thorac Cardiovasc Surg. 2018; 155:1607–1618.e6. doi: 10.1016/j.jtcvs.2017.10.152CrossrefMedlineGoogle Scholar
    • 5. SRTR risk adjustment model documentation: posttransplant outcomes. SRTR Scientific Registry of Transplant Recipients.https://www.srtr.org/reports-tools/posttransplant-outcomes/. Accessed October 18, 2019.Google Scholar

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    Comments and feedback on AHA/ASA Scientific Statements and Guidelines should be directed to the AHA/ASA Manuscript Oversight Committee via its Correspondence page.

    Thomas Hanff May. 27, 2020
    Reply to Kilic and Colleagues

    Thank you to Dr. Kilic and colleagues for addressing this important topic. Many of the secondary endpoints are particular notable. However, there may be a potential limitation in the primary endpoint analysis of post-transplant survival. As the authors describe, they used data on patients who were transplanted through March 31, 2019, but the last available follow-up date observed was June 6, 2019. At first glance, Kaplan Meier and Cox hazard methods should account for the missing follow-up time of patients who had fewer than 6 months of post-transplant follow-up (for the last available follow-up date of June 6, 2019, this would be after December 6, 2018). However, in order for these methods to work, missing follow-up time must obey non-informative censoring. It appears that this may not be the case in this analysis based on the timing of the data used, data reporting requirements set by the United Network for Organ Sharing (UNOS), and the large degree of missing data evident in Figure C.

    By UNOS policy, post-transplant deaths must be reported “within 30 days of the last day of the month” in which a patient died, but information on whether a patient survived to 6-months is only required within 30 days of the 6-month transplant anniversary (see https://optn.transplant.hrsa.gov/media/1200/optn_policies.pdf). As a consequence, any analysis in UNOS prior to 7 months from the last included transplant date will reflect nearly all of the deaths, but it risks significantly underreporting patients who survived; instead of counting as alive, they are censored as “missing” and fail to contribute positively towards survival. We and others have reported on this issue previously and how it can significantly overestimate post-transplant death in UNOS (PMID: 32307250 and 32037250). Notably, in recent reports using longer follow-up or restricting to allow 7 months to elapse before analyzing post-transplant survival, no significant change in post-transplant survival has been detected in the new vs prior systems (PMID 32307250, 32406597, and 32417413).

    Competing Interests
    None