Coronary allograft vasculopathy represents one of the major limiting factors of long-term survival in heart transplant recipients. While extensively researched, the underlying mechanisms of coronary allograft vasculopathy (CAV) after heart transplantation remain incompletely understood. As CD34+ cells represent one of the key determinants of coronary vascular homeostasis we investigated the potential association between CAV and CD34+ cell count in heart transplant recipients.

In a single-center prospective pilot cohort study, we aim to enroll 55 adult heart transplant recipients. All patients will undergo coronary CT angiography and the presence of CAV will be defined in accordance with the ISHLT criteria. At the time of CT angiography, patient will undergo detailed clinical evaluation, cardiac echo and we will also collect blood samples, perform extensive biochemical analysis and measure CD34+ cell count in peripheral venous blood using Beckman-Coulter Navios EX flow cytometry with standard antibodies according to ISAGE protocol. Biomarkers of angiogenesis will be evaluated using Luminex assay kit.

Inclusion Criteria:

• heart transplant recipient
• age > 18 years
• signed informed consent

Exclusion Criteria:

• multiorgan transplantation
• eGFR < 30 ml/min
• known hypersensitivity to the contrast media
• history of any malignancy treated with radiation or chemotherapy
• therapy with mTOR inhibitors
• rejection > 1R within 90 days before enrollment
• G-CSF therapy within 30 days of enrollment

Patients after heart transplantation, treated at Advanced Heart Failure and Transplantation Center, University Medical Center Ljubljana, Slovenia