AIMS OF THE PROJECT The aim of this study is to use OCT imaging for identification of patients with early rapid progression of cardiac allograft vasculopathy (rapid progressors) and to identify the critical risk factors responsible for CAV progression. The impact of conventional and HTx-specific risk factors, such as donor-specific antibodies (using the most sensitive methods for its measurement) or rapid heart rate (using repeated Holter monitoring) will be studied in a prospective, national-level cohort study. The implication of OCT results will lead to adjustment of immunosuppressive therapy in one year after heart transplant to prevent further progression of the disease in CAV rapid progressors.