Using equations that incorporate height, weight, age, and sex to predict heart mass may better allocate donor hearts to transplant recipients than considering body mass alone, a retrospective study suggested.
Although differences in body mass were not predictive of survival after heart transplantation, differences in predicted heart mass using those equations were related to survival up to 5 years after the operation, according to Robert Reed, MD, of the University of Maryland School of Medicine in Baltimore, and colleagues.
Specifically, patients who received the most undersized hearts had significantly increased risks of dying at 1 year (HR 1.25, 95% CI 1.02-1.54) and 5 years (HR 1.20, 95% CI 1.04-1.39), the researchers reported online in JACC: Heart Failure.
The study also pointed to heart size as an explanation for the worse transplant outcomes seen among men who receive donor hearts from women. Before adjustment, a sex mismatch between the donor and recipient was associated with increased mortality in male patients, but not in female patients. In a multivariate analysis that included predicted heart mass, a sex mismatch was no longer associated with survival in men.
"Differences in donor-recipient predicted total heart mass modulated the survival associated with donor-recipient sex mismatch and identified donor heart undersizing as an otherwise occult and potentially preventable cause of mortality following orthotopic heart transplantation," the authors wrote.
In an interview, Reed said that incorporating the equations used in the study into the national organ allocation scheme -- which he suspects will be done at some point -- likely would not affect access to organs.