Donor-recipient size matching and mortality in heart transplantation: Influence of body mass index and gender

BACKGROUND: The International Society for Heart and Lung Transplantation (ISHLT) guidelines advise against inappropriate weight match (IWM) for heart transplant, defined as donor weight <70% of recipient's weight. Few studies have explored in detail this size-matching recommendation, especially with regard to body mass index (BMI) and gender matching. We aimed to determine whether any difference could be observed between size-matching in obese and non-obese recipients with regard to mortality after cardiac transplantation. METHODS: Data from 52,455 adult heart transplants (recipients >= 18 years of age) between 1994 and 2013 were obtained from the ISHLT Registry. We defined the following subgroups of patients based on BMI: underweight, BMI <18.5; non-obese, BMI 18.5 to 30; and obese, BMI >30. The end-points were all-cause 30-day mortality and cumulative mortality. RESULTS: IWM was associated with increased 30-day mortality (odds ratio [OR] = 1.20, 95% confidence interval [CI] 1.01 to 1.43, p = 0.041) and cumulative mortality (hazard ratio [BR] = 1.14, 95% CI 1.07 to 1.22, p < 0.001). In non-obese recipients, IWM was associated with increased 30-day mortality (OR = 1.89, 95% CI 1.48 to 2.41, p < 0.001) as well as cumulative mortality (HR = 1.27, 95% CI 1.15 to 1.41, p < 0.001), whereas, for obese recipients, IWM was not associated with 30-day or cumulative mortality. Male recipients of female allografts (HR = 1.08, 95% CI 1.04 to 1.12, p < 0.001) as well as female recipients of male allografts (HR = 1.07, 95% CI 1.02 to 1.13, p = 0.003) had increased cumulative mortality compared with gender-matched transplants. There was no interaction between IWM and gender mismatch. CONCLUSIONS: Our results indicate that donor weight <70% of recipient weight increases mortality in non obese heart transplant recipients, but not in obese transplant recipients. Gender mismatch increases mortality independently of weight match. (C) 2017 International Society for Heart and Lung Transplantation. All rights reserved.