A National Swedish Study Evaluating Dd-cfDNA for as a Diagnostic Biomarker for Rejection Surveillence in Heart Transplantation

The SweD-HTx-study is an observational, multicenter cohort study including adult HTx recipients from Skåne University Hospital (Lund), Sahlgrenska University Hospital (Gothenburg), and Karolinska University Hospital (Stockholm). The aim of the study is to establish a robust, nationwide protocol for dd-cfDNA-based rejection monitoring in Swedish HTx recipients and to enhance our understanding of rejection mechanisms and immune activation. All participants undergo endomyocardial biopsies as part of routine post-transplant surveillance. Heart transplantations are performed at Skåne University Hospital or Sahlgrenska University Hospital, with post-transplant follow-up conducted at the outpatient transplant clinics at the participating centers. Eligible participants are adults (≥18 years) who undergo orthotopic HTx. Exclusion criteria include pregnancy, multi-organ transplantation, or a history of other solid organ or hematopoietic stem cell transplantation. Peripheral blood samples are collected according to standardized operating procedures and transported at ambient temperature to the immunology laboratory for processing. A subset of samples is immediately cryopreserved upon collection. Clinical and demographic data are extracted from the electronic medical record (EMR) using standardized data collection forms. The main outcome is the correlation between analyzed dd-cfDNA fraction levels and biopsy-proven rejection, defined by International Society of Heart and Lung Transplantation (ISHLT)'s histopathological criteria. The longitudinal changes in dd-cfDNA fraction and DSA will be analyzed as well as the association between DSA and dd-cfDNA fraction.