Non-Invasive Assessment of Coronary Microcirculation in Heart Transplantation

Abstract

Heart transplantation (HT) is an accepted treatment for end-stage heart failure (HF). Heart transplantation significantly increases survival, exercise capacity, quality of life and return to work in selected patients with advanced heart failure compared with conventional treatment. The survival rates have improved with the use of new immunosuppressive drugs, with a median survival after transplantation of approximately 11 years. The shortage of donor hearts represents a major limitation in this field. In addition many are the consequences of the limited effectiveness and complications of immunosuppressive therapy (i.e. antibody-mediated rejection, infection, hypertension, renal failure, malignancy and coronary artery vasculopathy). In particular, chronic rejection may occur months to years after the transplantation and is referred to as cardiac allograft vasculopathy (CAV). CAV occurs in 32% of the patients after 5 years and ensuing allograft failure from CAV eventually accounts for 30% of recipient deaths after transplantation. Cardiac allograft vasculopathy, involving coronary macro-and microcirculation, is caused by complicated interplay between immunologic and non-immunologic factors resulting in repetitive endothelial injury and localized sustained inflammatory response. Early diagnosis of microvascular dysfunction is substantial. In this review we analyze signs and symptoms of CAV presentation and the different methodologies to achieve an early and precise diagnosis. We will discuss invasive and non-invasive diagnostic tools and their specific role in evaluating graft's function, morphology, the presence of coronary artery disease and possible microcirculation involvement.