Among heart donors with brain death due to stroke, the effect on recipient and allograft survival rate is dependent on the age of the donor, with the strongest negative association at a young age, decreasing until the increased risk disappears for donors approximately aged 40 years. These study findings were published in the Journal of the American College of Cardiology.
Of the many risk factors in heart transplantation, cause of donor brain death has not been thought of as one of them. Previous studies have offered conflicting results about brain death due to stroke affecting heart transplant outcomes. Researchers sought to examine if stroke as the cause of donor brain death should be considered a risk for a heart recipient.
To accomplish this, researchers conducted a nationwide retrospective cohort study in the United States, with prospective data from the United Network for Organ Sharing (UNOS) registry. This included 18,438 multicenter heart transplant recipients from 2005 to 2018. Of the transplants, 3761 were from donors who died from stroke and 14,677 were donors who died from other causes. Donors less than 15 years of age, recipients less than 18 years of age, and multiorgan transplantation were excluded. The primary outcome for this study was all-cause mortality.
Donors who died from stroke were more likely to be women and older, with histories of smoking, cancer, and hypertension. Researchers noted that recipients from these donors were also more likely to be women, spent less time on the organ waiting list, have inotrope use at transplantation, and were less likely to have a ventricular-assist device before transplantation.
Follow-up was median 4.0 years (IQR, 2.0-5.0 years). In donors aged 40 years or younger, stroke as the cause of death was associated with increased risk of death in recipients at 5 years (stroke, 23%, vs other cause, 19%; HR, 1.17; 95% CI, 1.02-1.35) and allograft failure (HR 1.30; 95% CI, 1.04-1.63). The cause of brain death was not associated with heart transplant outcomes when donors were older than 40 years.
Study limitations included residual confounding and that the UNOS registry didn’t differentiate between hemorrhagic or ischemic stroke. There was missing data for hemodynamic parameters and right ventricular function.
“The detrimental effect of stroke as the cause of brain death might partially offset the benefit of younger donor ages, but this does not necessarily suggest that this particular donor group should be avoided as allografts from this group still have a better quality and result in better survival than those from most of the older donor groups,” the researchers wrote. “These results suggest an opportunity to identify modifiable factors that mediate this association so that changes in donor candidate management of this younger cohort could lead to improved transplantation outcomes.”
Mikami T, Itagaki S, Fujisaki T, et al. Association of donor brain death due to stroke with prognosis after heart transplantation. J Am Coll Cardiol. Published online March 14, 2022. doi:10.1016/j.jacc.2021.12.031