Predicting Outcome of Heart Transplantation

Abstract

Heart transplantation has become the treatment of choice for patients with end-stage heart diseases. Originally, strict recipient and donor selection criteria were developed to minimize morbidity and mortality after heart transplantation. However, the increasing demand for heart transplantation has led to the liberalization of the traditional recipient selection criteria. There has been a gradual increase of recipient age. Patients at poor health status, e.g. pretransplant diagnosis of end-stage valvular heart disease and older recipients, are more likely to have a higher morbidity and mortality due to co-existing medical problems. The increased gap between the demand and supply of donor hearts results in significant prolonged waiting time and an increased mortality of recipients on the waiting list. To increase donor supply, acceptance criteria of donor hearts have been expanded to include the sub-optimal or marginal donor hearts. Nevertheless, the impact of these trends on the outcome of heart transplantation, in particular on long term, remains uncertain. Heart transplantation should be reserved for those patients most likely to benefit in terms of survival. To enable predicting the outcome for individual patient based on recipient and donor characteristics, and their match, a prediction model may play a crucial role in selection of a donor heart to a specific recipient. The focus of this thesis is on the impact of various recipient and donor baseline characteristics on the outcome after adult heart transplantation. This thesis also includes several models that have been developed and validated to predict mortality risk after adult heart transplantation. We demonstrated that despite changing in baseline risk profiles at different transplant periods, the survival of adult heart transplantation remains stable and encouraging. Moreover, we showed that prognosis after heart transplantation in patients with end-stage valvular disease is similar to patients with other indications, whereas a longer waiting time to heart transplantation significantly improved survival. Our results also demonstrated that the outcome of heart transplantation in older recipients is less favorable than in younger patients. Therefore, the decision to offer heart transplantation to recipients older than 55 years should be considered cautiously. Furthermore, we found that heart transplantation from donors with sodium level > 155 mmol/L and using donor hearts that have been subject to cardiopulmonary resuscitation do not adversely affect the outcome of heart transplantation. Accepting such donor hearts will add to the enlargement of the donor pool, and guidelines should be adjusted accordingly. Finally, we have shown that the 30-day, 1- and 5-year mortality risk after adult heart transplantation could be predicted with accuracy based on pretransplant clinical characteristics of recipients and donors as well as perioperative data. The prediction models which were converted to easy use nomograms provide easily applicable instruments for prediction of mortality risk after adult heart transplantation. Their use in clinical practice can support decisions on allocation of limited number of donor hearts to patients waiting for heart transplantation in an optimal manner.