Mechanical versus medical bridge to transplantation in children. What is the best timing for mechanical bridge?

Objective: Precise timing of mechanical circulatory support as a bridge to transplantation is crucial for successful outcome. In our practice, increasing metabolic injury resulting from third organ (renal/gut) dysfunction is an indication for mechanical circulatory support. It is not known how metabolic injury would influence the outcomes in these patients. In this study we compared biochemical and clinical parameters between children who received mechanical circulatory support and those who were treated with medical management alone as a bridge to transplantation.

Methods: Data from 24 patients were retrospectively analysed from their records. There were 11 patients in the mechanical group. In this group, five patients received biventricular assist device, five received veno arterial extra corporeal membrane oxygenation and one received left ventricular assist device. In the medical group, there were 13 patients who received various levels of inotropic support before transplantation. Five clinical and three biochemical parameters were identified and compared between the mechanical and medical groups. Mortality prior to transplantation was also compared between the two groups. Transplantation was the end point of the study.

Results: Serum creatinine and serum lactate levels were significantly higher in the mechanical group (P=0.006 and 0.001, respectively), reflecting advanced metabolic injury in these patients. Mean fractional shortening in the mechanical group was 8.4%, compared to 14.5% in the medical group which was statistically significant (P=0.02). All of the 11 patients in the mechanical group were ventilated compared to 7 of the 13 (53.8%) in the medical group. Need for renal support was higher in the mechanical group (83.3%) in comparison to none in the medical group (P=0.023). Mortality in both groups was comparable with two patients in each group. 11 patients in the medical group (84.6%) and 9 in the mechanical group (81.8%) reached transplantation.

Conclusion: This study confirmed that patients in the mechanical group were considerably worse in metabolic terms when compared to the medical group. Final outcome of bridging them to transplantation was comparable. This study seem to support the justification of reserving the mechanical circulatory support to those who are metabolically more injured without adversely affecting their outcomes.