BACKGROUND Utilization of temporary mechanical circulatory support, including veno-arterial extra-corporeal membrane oxygenation as a bridge to heart transplantation (HT) has increased significantly under the revised United Network for Organ Sharing (UNOS) donor heart allocation system. The revised heart allocation system aimed to lower waitlist times and mortality for the most critically ill patients requiring biventricular, nondischargeable, mechanical circulatory support. While previous reports have shown improved 1-year post-HT survival in the current era, 3-year survival and factors associated with mortality among bridge-to-transplant (BTT) extra-corporeal membrane oxygenation (ECMO) patients are not well described. METHODS We queried the UNOS database for all adult (age ≥ 18 years) heart-only transplants performed between 2010 and 2019. Patients were stratified as either pre- (January 2010-September 2018; era 1) or post-allocation change (November 2018-December 2019; era 2) cohort based on their HT date. Baseline recipient characteristics and post-transplant outcomes were compared. A Cox regression analysis was performed to explore risk factors for 3-year mortality among BTT-ECMO patients in era 2. For each era, 3-year mortality was also compared between BTT ECMO patients and those transplanted without ECMO support. RESULTS During the study period, 116 patients were BTT ECMO during era 1 and 154 patients during era 2. Baseline recipient characteristics were similar in both groups. Median age was 48 (36-58 interquartile range (IQR)) years in era 2, while it was 51 (27-58 IQR) years in era 1. The majority of BTT-ECMO patients were males in both era 2 and era 1 (77.7% vs 71.5%, p = 0.28). Median ECMO run times while listed for HT were significantly shorter (4 days vs 7 days, p < 0.001) in era 2. Waitlist mortality among BTT ECMO patients was also significantly lower in era 2 (6.3% vs 19.3%, p < 0.001). Post-HT survival at 6 months (94.2% vs 75.9%, p < 0.001), 1 year (90.3% vs 74.2%, p < 0.001), and 3 years (87% vs 66.4%, p < 0.001) was significantly improved in era 2 as compared to era 1. Graft failure at 1 year (10.3% vs 25.8%, p = 0.0006) and 3 years (13.6% vs 33.6%, p = 0.0001) was also significantly lower in era 2 compared to era 1. Three-year survival among BTT ECMO patients in era 2 was similar to that of patients transplanted in era 2 without ECMO support (87% vs 85.7%, p = 0.75). In multivariable analysis of BTT-ECMO patients in era 2, every 1 kg/m2 increase in body mass index was associated with higher mortality at 3 years (hazard ratio (HR) 1.09, 95% CI 1.02-1.15, p = 0.006). Similarly, both post-HT stroke (HR 5.58, 95% CI 2.57-12.14, p < 0.001) and post-HT renal failure requiring hemodialysis (HR 4.36, 95% CI 2.43-7.82, p < 0.001) were also associated with 3-year mortality. CONCLUSIONS Three years post-HT survival in patients bridged with ECMO has significantly improved under the revised donor heart allocation system compared to prior system. BTT ECMO recipients under the revised system have significantly shorter ECMO waitlist run times, lower waitlist mortality and 3-year survival similar to those not bridged with ECMO. Overall, the revised allocation system has allowed more rapid transplantation of the sickest patients without a higher post-HT mortality.

中文翻译：

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移植桥接后三年结果 2018 年 UNOS 修订后的 ECMO 前后心脏分配系统。


背景 在修订后的器官共享联合网络 （UNOS） 供体心脏分配系统下，临时机械循环支持的利用，包括静脉-动脉体外膜肺氧合作为心脏移植 （HT） 的桥梁，已显着增加。修订后的心脏分配系统旨在降低需要双心室、不可放电、机械循环支持的最危重患者的候补时间和死亡率。虽然以前的报告显示当前时代 HT 后 1 年生存率有所提高，但桥接移植 （BTT） 体外膜肺氧合 （ECMO） 患者的 3 年生存率和与死亡率相关的因素尚未得到很好的描述。方法 我们在 UNOS 数据库中查询了 2010 年至 2019 年间进行的所有成人 （≥ 18 岁） 仅心脏移植。根据 HT 日期，将患者分为分配前（2010 年 1 月至 2018 年 9 月;时代 1）或分配变更后 （2018 年 11 月至 2019 年 12 月;时代 2）队列。比较基线受者特征和移植后结局。进行 Cox 回归分析，探讨第 2 时代 BTT-ECMO 患者 3 年死亡的危险因素。对于每个时代，还比较了 BTT ECMO 患者和无 ECMO 支持移植患者的 3 年死亡率。结果 在研究期间，116 例患者在第 1 时期接受 BTT ECMO，154 例患者在第 2 时期接受 BTT ECMO。两组的基线受者特征相似。时代 2 的中位年龄为 48 （36-58 四分位距 （IQR）） 岁，而时代 1 的中位年龄为 51 （27-58 IQR） 岁。第 2 时代和第 1 时代的大多数 BTT-ECMO 患者均为男性 （77.7% vs 71.5%，p = 0.28）。 在时代 2 中，列出 HT 的中位 ECMO 运行时间显著缩短 （4 天 vs 7 天，p < 0.001）。在第 2 时代，BTT ECMO 患者的候补名单死亡率也显着降低 （6.3% 对 19.3%，p < 0.001）。与时代 1 相比，第 2 时期 6 个月 （94.2% vs 75.9%，p < 0.001） 、1 年 （90.3% vs 74.2%，p < 0.001） 和 3 年 （87% vs 66.4%，p < 0.001） 的生存率显着提高。与时代 1 相比，时代 2 的 1 年 （10.3% vs 25.8%，p = 0.0006） 和 3 年 （13.6% vs 33.6%，p = 0.0001） 的移植失败也显着降低。时代 2 的 BTT ECMO 患者的三年生存率与时代 2 中无 ECMO 支持的移植患者相似 （87% vs 85.7%，p = 0.75）。在第 2 时代 BTT-ECMO 患者的多变量分析中，体重指数每增加 1 kg/m2 与 3 年死亡率较高相关 （风险比 （HR） 1.09,95% CI 1.02-1.15，p = 0.006）。同样，HT 后卒中 （HR 5.58,95% CI 2.57-12.14，p < 0.001） 和 HT 后需要血液透析的肾功能衰竭 （HR 4.36,95% CI 2.43-7.82，p < 0.001） 也与 3 年死亡率相关。结论 与以前的系统相比，在修订后的供体心脏分配系统下，经 ECMO 桥接的患者 3 年后 HT 生存率显著提高。与未使用 ECMO 桥接的接受者相比，修订系统下的 BTT ECMO 接受者的 ECMO 等待名单运行时间明显缩短，等待名单死亡率较低，并且 3 年生存率相似。总体而言，修订后的分配系统允许更快速地移植病情最严重的患者，而不会降低 HT 后死亡率。