ECMO Helps Older Adults Bridge to Lung Transplant

Older adults not previously listed for transplant who were bridged to transplant via extracorporeal membrane oxygenation showed favorable survival rates and allograft function up to 5 years later, based on data from 50 individuals.
Although use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation has expanded, data on long-term outcomes and patient selection criteria are lacking, wrote Jared A. Darr, MD, pulmonary and critical care fellow at the Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, and colleagues. 
In a study published in Respiratory Research, the investigators reviewed data from 50 adults actively listed for lung transplantation at a single center who were bridged on ECMO before or after listing between January 2012 and December 2017. Of these, 25 survived to receive a transplant. The median age at the time of transplant listing was 58 years in those who received transplants and 65 years in those who died prior to transplant. 
Overall, 1-year, 3-year, and 5-year survival rates were 88%, 60%, and 44%, respectively. During the first year after transplant, the median time spent at home was 340 days.
Older age at the time of transplant listing was a significant negative predictor of survival (odds ratio, 0.92; P = .01). However, among the older patients who survived to receive transplants, the long-term survival was similarly favorable whether or not these patients had been listed prior to ECMO or bridged to a point of decision followed by listing and transplant.
No significant difference in survival was noted between patients placed on ECMO before listing and those who were already listed when placed on ECMO (P = .93).
In addition, posttransplant spirometry showed favorable allograft function and low rates of cellular rejection up to 5 years after transplant, with only two patients treated for acute or hyperacute antibody-mediated rejection.
Notably, 5-year survival rates were similar in the current study and in younger patient cohorts at similar high-volume transplant centers, the researchers noted.
The findings were limited by several factors including the retrospective, single-center design. Other limitations included the focus only on patient characteristics and hospital course, without accounting for intraoperative techniques or lung donor characteristics, the researchers noted.
However, the results suggest that ECMO BTT is a feasible option for older adults with advanced lung disease not previously listed for transplant, they concluded. 
Why was it important to conduct this study at this time?
The use of ECMO as a bridge to lung transplant has expanded considerably over the last two decades, yet evidence-based selection criteria remain lacking, with significant practice variation across centers. 
Both older age (with no well-defined upper bound) and not yet being listed for transplant (“bridge to decision”) are sometimes cited as reasons not to offer ECMO as a bridge to lung transplant in severely ill, hospitalized advanced lung disease patients. 
Given the large number of older and not previously listed lung transplant candidates bridged on ECMO at Temple since 2012, we aimed to analyze our center’s unique experience caring for this complex patient population to assess the feasibility of ECMO bridge to transplant in these understudied subgroups. In doing so, we were able to report outcome data up to 5 years posttransplant, whereas most prior studies have been limited to 36 months.
Were you surprised by any of the findings? Why or why not?
The study cohort, which included 50 lung transplant candidates bridged on ECMO from 2012 to 2017 with a median age at listing of 63, is one of the oldest described in the literature. This included 32% of patients who were not previously listed at the time of ECMO cannulation and bridged to decision.
We found that 1-year posttransplant survival (88%) closely approximated the national rate for all adult lung transplant recipients, with quality of life evidenced by time spent at home (median 340 days) in the year posttransplant. Favorable 3-year (60%) and 5-year (44%) posttransplant survival were also observed, with good allograft function and low rates of rejection.
One of the most notable findings was no significant difference in long-term posttransplant survival when comparing older ECMO-bridged patients who were previously listed to patients bridged to decision.
What might be some barriers to the use of ECMO as a bridge to lung transplantation in older adults, and how might these be overcome?
The major barrier in this area, where high pretransplant mortality on ECMO has been described by many centers, remains how best to select patients most likely to benefit from this high-risk bridging strategy.
While the effect was small, our data suggest that older age may be a negative predictor of survival on ECMO to transplant, even though these patients do well once transplanted.
“Ultimately, we hope this study provides additional insight to transplant centers weighing difficult decisions about ECMO candidate selection and management,” Daar said.
“As a retrospective single-center study, the findings cannot be generalized without caution,” he told Medscape Medical News. “A broader effort is necessary to identify characteristics of advanced lung disease patients most likely to benefit from ECMO as a bridge to lung transplant to ensure physicians across centers have optimal data to provide the best possible care to this complex patient population,” he said.
Data Support More Bridging
“This study is important because more transplant centers have been using ECMO to bridge patients to transplant, and this validates what many centers are currently doing, placing older and sicker patients on ECMO to get them to transplant,” said Dennis Lyu, MD, medical director of lung transplant and clinical associate professor of medicine at the University of Michigan, Ann Arbor, Michigan, in an interview. Among patients who survived to transplant, 1-year survival was similar to lung transplant patients who weren’t on ECMO, he noted.
“With recent changes in lung allocation policy in the US that were instituted in 2023, sicker patients on ECMO are being transplanted more quickly,” Lyu told Medscape Medical News. Fewer patients are dying while on the waiting list, and therefore the current study may provide centers with more incentive to place patients on ECMO as a bridge to transplant, knowing that wait times will be shorter than in the past, he said. 
The authors’ sharing their experience of placing patients on ECMO, when they were not yet listed for transplant, was interesting, as it is counter to the practice of many centers where clinicians are reluctant to place patients on ECMO unless they are already listed, Lyu noted.
In addition, “I was surprised by the high number of patients on ECMO who also required mechanical ventilation (80%),” said Lyu. “Generally, the best predictor of survival of patients on ECMO is that they are awake and ambulatory; it is informative that the majority of patients in this study were not ambulatory but still had good outcome,” he said.
“The takeaway message is that patients can be successfully placed on ECMO as a bridge to transplant even if they are older and need to stay on ECMO for longer, and even if they also need mechanical ventilation,” Lyu told Medscape Medical News.
“Given changes to increasing use of ECMO in recent years, and with the shortened time on the wait list of patients on ECMO, additional research is needed on what ages centers are placing patients on ECMO and what the outcomes are,” Lyu said. 
The study received no outside funding. The researchers had no financial conflicts to disclose. Lyu had no financial conflicts to disclose. 
 
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