Real‐life use of letermovir prophylaxis for cytomegalovirus in heart transplant recipients

Abstract Introduction Cytomegalovirus (CMV) remains the predominant opportunistic infection following solid organ transplantation (SOT). While valganciclovir is the drug of choice for CMV prophylaxis, its utility can be compromised due to the risk of cytopenia. Letermovir, a novel agent approved for CMV prophylaxis in allogeneic hematopoietic stem cell transplant recipients and high‐risk kidney transplant recipients, exhibits reduced toxicity. This study aims to present the practical application of letermovir as both primary and secondary prophylaxis against CMV in heart transplant recipients (HTR). Methods In this observational, retrospective, single‐center study, we included all consecutive adult HTRs from June 2020 to January 2022 who were administered letermovir for CMV prophylaxis. We documented instances of CMV breakthrough infections, side effects related to letermovir, changes in neutropenia following the switch from valganciclovir to letermovir, and any drug interactions with the immunosuppressive regimen. Results The study comprised 10 patients: two received primary prophylaxis with letermovir due to a high risk of CMV infection (donor‐positive, recipient‐negative serostatus), and eight received it as secondary prophylaxis following a CMV infection. The median duration of letermovir administration was 8 months (range 3–12 months). No CMV breakthrough infections were reported while on prophylaxis. However, three patients experienced CMV breakthrough infections after discontinuing letermovir prophylaxis (30%). No significant side effects were observed, although one patient reported digestive intolerance. Among the nine patients on tacrolimus, six needed reduced doses after switching to letermovir. Conclusion This real‐life study appears to support the effectiveness of letermovir prophylaxis in HTR. Nonetheless, the risk of CMV infection post‐treatment cessation is notable. Further drug monitoring and research on the efficacy of letermovir for CMV prophylaxis in SOT patients is warranted.