In this study, we investigated the impact of anthropometrics donor–recipient mismatch on short-term outcomes of transplant recipients. Evaluated outcomes were death, graft rejection, right ventricular failure, renal failure, need for ECMO, inotrope dependency, duration of intubation, and length of ICU stay during the first month after transplantation.
The results of this study showed that the weight mismatch between donor and recipient did not affect the mentioned outcomes in patients. As in the univariate correlation analysis, none of the studied variables were associated with the donor-to-recipient weight mismatch as well as with the donor-to-recipient BSA mismatch. In other words, after dividing the patients based on the donor-to-recipient weight into three groups (between 0.8 and 1.5, between 1.5 and 2.5, and above 2.5), none of the outcomes were significantly different between these three groups. These results are in line with other studies that have been conducted on this field. As shown by Jayarajan et al., the use of low donor-to-recipient weight ratio did not influence median survival, but in female donor-to-male recipient group, lower donor-to-recipient weight ratio was associated with decreased median survival . Tang et al. also found that in patients with low donor-to-recipient weight ratio, acute rejection during the first month after transplantation is less common; however, infants with donor-to-recipient weight ratio between 0.5 and 0.59 had lower 1-month survival.
There was no difference in survival of patients with donor-to-recipient weight ratio 0.6–0.79 and donor-to-recipient weight ratio 0.8–2.0, and thus they suggested that donor-to-recipient weight ratio between 0.6 and 0.8 has no adverse outcome on the survival of pediatric heart transplantation . A similar result to the current study was observed in adult patients. In a study by Patel et al. performed on 15,284 patients receiving heart transplants, patients were divided into three groups based on donor-to-recipient weight ratio, less than 0.8, between 0.8 and 1.2, and above 1.2. In this study, among patients with a donor-to-recipient weight ratio of less than 0.8, 5-year survival was lower in recipients with high pulmonary vascular resistance, and similar results were observed in other patients .
On the other hand, in the current study if the donor-to-recipient weight ratio was less than 0.8, the donated tissue was not used for heart transplantation. This policy is due to the fact that in previous studies, the donor-to-recipient weight ratio of less than 0.8 is one of the risk factors for transplant rejection and donor heart failure. Tamisier et al. indicated that donor-to-recipient weight ratio less than 1 is a risk factor for donor heart failure and early mortality. In this study, from 1987 to 1994, 73 patients who underwent heart transplantation were retrospectively evaluated. Pulmonary hypertension before the transplantation, major inotropic support of the donor, and the donor-to-recipient weight ratio were risk factors for donor heart failure. Donor heart failure was seen in 50% of patients whom donor-to-recipient weight ratio was less than 1, 33% of patients with donor-to-recipient weight ratio between 1 and 1.6, and 7% of patients with donor-to-recipient weight ratio more than 1.6. They also concluded that patients, particularly with pulmonary hypertension, may benefit from the use of grafts with greater donor-to-recipient weight ratio .
In another study by Conway et al., a lower donor-to-recipient ratio was a risk factor for transplant rejection , whereas some studies have shown that undersized allografts with weight mismatch between donor and recipient more than 20% did not relate to increased mortality .
Sethi et al. showed that early and late mortality of patients who had received smaller allograft with donor and recipient weight difference of 30% to 46% were not different from other patients with donor and recipient weight difference less than 30% ; thus, data on the use of small allografts are conflicting.
Whereas matching donated tissue with the recipient is a complex process, race, age, and size of the donor are important determinants in this area. Our study showed that in patients who are candidates for heart transplantation, allografts which are not matched with the recipient in terms of weight can be used, especially allografts which are larger in size. Since most cases of brain death occur in adults who have a larger heart in size, this size mismatch has limited the number of heart transplantations. The results of this study will reduce this limitation; however, this study examined only early outcomes, and more studies are needed to evaluate the late consequences of using a larger allograft.