Impact of low donor to recipient weight ratios on cardiac transplantation.

Background: International Society of Heart and Lung Transplantation guidelines for adult heart transplantation (HT) suggest a donor to recipient body weight ratio (WR) of greater than 0.8. For female to male transplants, a WR of greater than 0.9 is recommended.

Methods: The United Network for Organ Sharing database was examined for adult HT from 1999 to 2011. Controls with a WR of 0.9 or greater (normal donor to recipient weight ratio) were compared with patients with a WR of 0.6 to 0.89 (WRL) and a WR of less than 0.59 (WRVL). The primary measured outcome was survival.

Results: Of the 21,928 patients undergoing HT, 14,592 (66.6%) were performed with a normal donor to recipient weight ratio, 7212 (32.9%) were performed with WRL, and 124 (0.6%) were performed with WRVL. In male donor to male recipient, male donor to female recipient, and female donor to female recipient HT, the use of WRL did not influence median survival (P = .3621) and was not associated with increased mortality (P = .7273). In female donor to male recipient HT, WRL was associated with decreased median survival (435 days, P = .0241) and was associated with increased mortality (hazard ratio, 1.201; P = .0383).

Conclusions: HT can be safely performed using WRL donors between sex-matched and male to female transplants. However, in female to male transplants, WRL donors are associated with decreased survival. Although clinical circumstances will guide decision making, consensus criteria may be revisited to liberalize the pool of acceptable donors in an era of unprecedented donor shortage.