Donor-derived Cell Free DNA as a New Biomarker in Cardiac Acute Rejection

All patients will be enrolled immediately after HT, and will undergo undergo routine surveillance EMB at 15 days, 1 month, 2, 3, 4, 6 and 12 months after HT. Simultaneously with each EMB, dd-cfDNA will be measured in plasma.

• Donor-derived cell Free DNA (Diagnostic test): Measurement of dd-cfDNA and comparison against grade of rejection as determined by endomyocardial biopsy, taken simultaneously

Primary outcomes

• Association between dd-cfDNA levels and the presence of acute cellular rejection [1 year]: Association between dd-cfDNA levels above a certain cut-point and the presence of treatable acute cellular rejection as determined by endomyocardial biopsy (graded by International Society of Heart and Lung Transplantation 2010 classification, grade > 1R).

Secondary outcomes

• Area under curve for dd-cfDNA [1 year]: To define a cutt-off point of dd-cfDNA level with a high negative predictive value that could obviate the need to perform surveillance endomyocardial biopsies
• Correlation between dd-cfDNA and antibody mediated rejection (AMR) [1 year]: Correlation between dd-cfDNA and antibody mediated rejection (AMR)
• Association between dd-cfDNA and immunosuppressive (IS) treatment [1 year]: Subanalysis of association between dd-cfDNA and rejection stratified by IS regimen (type and dose of drug).
• Association between dd-cfDNA (%) and left ventricular ejection fraction [1 year]: Association between dd-cfDNA and left ventricular ejection fraction (LVEF). All echocardiograms will be performed on the same day of EMB.
• Determine the biomarker's kinetics at 15 days post-transplant [15 days]: Determine dd-cfDNA levels at 15 days post-transplant in absence of rejection
• Association between dd-cfDNA levels and cytomegalovirus (CMV) infection [1 year]: Association between dd-cfDNA levels and CMV infection as determined by CMV polymerase chain reaction (number of copies per ml)
• Determine a cut-off point of dd-cfDNA that allows to differentiate between acute cellular rejection (ACR) and antibody mediated rejection (AMR) [1 year]: Determine a cut-off point of dd-cfDNA that allows to differentiate between acute cellular rejection (ACR) and antibody mediated rejection (AMR)

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Patients > 18 years old who undergo heart transplant during the recruiting period

Exclusion Criteria:

* Patients with moderate or severe Primary Graft Dysfunction
* Patients on invasive mechanical ventilation 15 days after heart transplant
* Patients on renal replacement therapy, continuous or periodic, 15 days after heart transplant
* Heart Transplant due to a cardiomyopathy that could potentially recur on the graft (cardiac amyloidosis, Chagas disease or sarcoidosis, amongst others)
* Multiorgan transplant

• Results publication: Jimenez-Blanco M, Crespo-Leiro MG, Garcia-Cosio Carmena MD, Gomez Bueno M, Lopez-Vilella R, Ortiz-Bautista C, Farrero-Torres M, Zegri-Reiriz I, Diaz-Molina B, Garcia-Romero E, Rangel-Sousa D, Salterain N, Garrido Bravo I, Segovia-Cubero J. Donor-derived cell-free DNA as a new biomarker for cardiac allograft rejection: A prospective study (FreeDNA-CAR). J Heart Lung Transplant. 2025 Apr;44(4):560-569. doi: 10.1016/j.healun.2024.11.009. Epub 2024 Nov 20. PMID 39577511