Cardiac Size and Sex-Matching in Heart Transplantation

Abstract

Objective This study evaluated whether worsened outcomes in sex mismatch are related to mismatch of organ size in heart transplantation. Background Sizing for organ allocation in heart transplantation currently incorporates only body weight differences between the donor and recipient. Weight correlates poorly to cardiac size, and donor–recipient weight differences are not associated with differential survival. Heart size correlates with sex, and donor–recipient sex mismatch conveys worse-than-expected outcomes. Methods We performed a retrospective cohort study of 31,634 donor–recipient adult heart transplant pairings from the United Network for Organ Sharing transplantation registry. We used predictive models to calculate the predicted total heart mass (pHM) for recipient and donor pairs. We assessed organ size mismatch by calculating the percent difference between the donor and recipient pHM as [(pHMrecipient − pHMdonor)/(pHMrecipient)]*100. Results The most-undersized pHM septile demonstrated higher mortality during the first year post-transplantation (hazard ratio [HR]: 1.27; p < 0.001), which remained robust in adjusted models (HR: 1.25; p = 0.03). Survival did not vary across septiles of weight differences. On univariate analysis, sex mismatch was associated with higher mortality in male patients, but not in female patients. Controlling for differences in pHM reversed these associations. Adjusted models demonstrated worse survival associated with sex mismatch in female patients (1-year HR: 1.28; p = 0.02) but no difference in male patients (1-year HR, 1.00; p = 1.0). Conclusions Differences in donor–recipient pHM 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.

Mortality, rehospitalization, and post-transplant complications in gender-mismatched heart transplant recipients

“…Worse survival in the male-mismatch patients is usually attributed to weight-mismatch or size-mismatch, in which the heart from a smaller female donor cannot meet the cardiac demands of the larger male recipient. 18,24 However, only 1 study reported worse survival in the female-mismatch HT patients but not in the male-mismatch patients, 10 as our study found.…”

“…Higher post-HT mortality has been reported in both types of gender-mismatch in 8 articles, 2–9 only in the female-mismatch patients (male donor/female recipient) in 1 article, 10 and only in the male-mismatch patients (female donor/male recipient) in 14 articles. 11–24 However, 2 studies found no difference in HT mortality due to gender-mismatch of either kind.…”

Repolarization parameters in heart transplant subjects

“…Males with female hearts have maximal heart rate. This probably corresponds to heart size; male recipients/females donors are mostly undersized in heart size and have the shortest survival [12,13].…”

Selection of Patients for Initial Clinical Trials of Solid Organ Xenotransplantation

“…41,42 Ideal donor/recipient body mass index (BMI) ratios within 20–30% are the generally accepted criteria. 43 The selection of a pig graft that is appropriately size-matched to a particular recipient, eg, one who is rapidly deteriorating, may thereby conserve the supply of allografts and potentially optimize posttransplant outcome.…”