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Donor heart availability may rise with elimination of troponin I test
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Elevated donor troponin I levels in the setting of preserved left ventricular ejection fraction may not be a contraindication to heart transplantation, researchers reported in Circulation: Heart Failure.
Eliminating this test could increase the availability of donor hearts, the researchers wrote.
“Heart transplantation is an incredible therapy for patients with end-stage [HF] ... but there is also a problem in that only an average of one in three donor hearts are placed,” Snehal R. Patel, MD, assistant professor of medicine at Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York, said in a press release.
Snehal R. Patel
“If the heart looks OK but troponin I is elevated, many centers will reject the organ out of concern that this marker indicates dysfunction of the heart that will become evident after the stress of the transplant process,” Patel said. “We looked at whether this is true.”
Heart transplant outcomes
Patel and colleagues used the United Network for Organ Sharing database to evaluate whether donor serum troponin levels had an effect on the outcomes in heart transplant recipients. The analysis included 10,943 adult heart transplants from donors aged 55 years or younger with LVEF of at least 50% that took place between 2007 and September 2014. The recipients were divided into three groups based on their donors’ peak troponin I level: less than 1 ng/mL (n = 7,812), 1 ng/mL to 10 ng/mL (n = 2,770) and greater than 10 ng/mL (n = 361).
According to the results, peak donor troponin I levels as a continuous variable were not associated with 1-year recipient mortality in an unadjusted Cox model (HR = 0.999; 95% CI, 0.997-1.002) and after adjustment (HR = 1; 95% CI, 0.997-1.002). No differences were observed between the three groups at 30 days, 1 year, 3 years or 5 years of follow-up. Although there were incidences of cardiac allograft vasculopathy and primary graft failure, there did not seem to be a difference in risk between the three groups of troponin level, according to the researchers.
Patel and colleagues did not observe an effect of donor troponin I level on posttransplant length of hospital stay (median length of stay for < 1 ng/mL group, 14 days; interquartile range, 10-21; median length of stay for 1-10 ng/mL group, 14 days; interquartile range, 10-21; median length of stay for > 10 ng/mL group, 15 days; interquartile range, 10-22; P = .539).
“Our research shows that transplant centers should not exclude donor hearts based solely on elevated troponin I if the organ is otherwise suitable. At our institution it has already changed how we evaluate donors, and I think [these] data will lead to changes nationwide,” Patel said in the release.
Further research needed
In an accompanying editorial, Shravani Pasupneti, MD, from the division of pulmonary and critical care medicine, department of medicine, Stanford University School of Medicine, and Kiran Khush, MD, MAS, from the division of cardiovascular medicine, department of medicine, Stanford University School of Medicine, wrote: “Although this article concludes that troponin elevation in donors with intact systolic function does not portend poor recipient outcomes, there is still need for further investigation. Given the variability of troponin levels over time, it may be more insightful to follow trends (ie, rise, decline or persistent elevation) rather than a single value. The timing of troponin levels relative to donor cardiopulmonary resuscitation and brain stem herniation should be considered with respect to heart utilization and recipient outcomes.”
Pasupneti and Khush also recommended further study on this relationship in donors with LV dysfunction (LVEF < 55%) because decisions on whether to accept these hearts are more difficult compared with decisions on normal-function hearts.
“Regardless, this article should go a long way toward reassuring transplant centers when evaluating heart offers from donors with normal cardiac function in the setting of elevated troponin levels,” Pasupneti and Khush wrote. “Hopefully, this will represent a concrete step toward safely expanding donor heart utilization.” – by Tracey Romero
Disclosure: The researchers and Pasupneti report no relevant financial disclosures. Khush reports serving as the principal investigator of an NIH-sponsored multicenter study that aims to establish evidence-based criteria for donor heart selection.
Perspective
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Frank W. Smart, MD, FACC, FACP
The retrospective analysis of outcomes of donor hearts with elevated troponins is a well-done study and has a very robust number of cardiac donors included. Additionally, breaking down the troponin levels to 3 groups; less than 1, 1-10, and greater than 10 is also a strength of the study. The fact that only 363 people had troponins greater than 10 is a slight limitation, as is the trend in the troponins not being indicated in the study. A donor with an initial troponin of less than 0.01 ng/mL who is elevating to 15 ng/mL is likely quite different than a donor who had a troponin of 11 ng/mL at the time of brain herniation. As was pointed out in the editorial, it should be reinforced that this is only hearts that were accepted for transplantation; others that were turned down based on either the troponin or other factors associated with the donor were eliminated from the analysis.
I do not believe the troponin test should be eliminated from screening laboratory studies when we are evaluating cardiac donors. However, the manuscript does a fine job of detailing that the donor heart should not be refused based solely on an elevated troponin level. Prospectively, it would be interesting to look at the trend in troponin and whether this biomarker was rising or falling at the time of organ procurement.
Most busy cardiac transplant centers would not eliminate a donor organ simply on the basis of an isolated elevated troponin. Certainly other factors such as age, CV risk factors, the presence of CAD, high doses of inotropic or pressor drugs and systolic dysfunction all play into the complex decision as to whether to take a donor heart for a particular recipient. This study is encouraging in that it details that troponin level in isolation cannot predict long-term survival of the recipient.
I believe the next phase of research similar to this would be to look at other biochemical markers present in prospective donors and further to evaluate biochemical and biomarker changes in the donor population that was not used for cardiac transplant. Such comparisons would not only identify donor acceptance practices that may not be uniform across programs, but also allow for a critical evaluation of donor criteria involved in selection of a suitable cardiac donor.
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