Monotherapy Immunosuppression in Pediatric Heart Transplant Recipients

Background Although dual‐drug immunosuppression is standard for rejection prophylaxis in pediatric heart transplant (HT), single‐drug immunosuppression (monotherapy) may be appropriate for certain patients. We describe the experience with monotherapy in select patients at a single institution. Methods Retrospective review of HT patients at a pediatric transplant center who underwent HT between 1/2001–12/2020 and were treated with calcineurin‐inhibitor monotherapy for > 1 month. Patients were transitioned to monotherapy due to concerns for over‐immune suppression, including recurrent infection, neutropenia, or post‐transplant lymphoproliferative disorder (PTLD). Clinical characteristics and patient outcomes were analyzed. Results During the study period, 16/318 (5%) HT patients were placed on monotherapy at a median of 4.6 years post‐HT (IQR 1.8–6.9 years). Most patients on monotherapy were transplanted as infants (81%, 13/16), 56% (9/16) were male, and 50% (8/16) underwent HT for congenital heart disease (CHD). Most (81%) were on tacrolimus monotherapy. The indication for monotherapy was recurrent infection in 50%, PTLD in 31%, and neutropenia in 19%. At a median follow‐up of 1.5 years (IQR 1.1–2.2 years), there were no episodes of moderate or greater rejection and no evidence of coronary allograft vasculopathy. At last follow‐up, 87% of patients remain on monotherapy, and 94% of patients are alive and well, including one patient who has continued monotherapy for over 15 years. Conclusions Monotherapy immunosuppression with calcineurin inhibitors may be preferred in a subset of pediatric HT patients with evidence of over‐immune suppression without conferring increased risk of rejection.