Intravascular Imaging for Assessment of Cardiac Allograft Vasculopathy Following Heart Transplantation

Purpose of Review Cardiac allograft vasculopathy (CAV) is a significant cause of morbidity and mortality in the post-cardiac transplant patient population. Current guidelines recommend annual angiographic surveillance for CAV; however, angiography alone has several limitations and can lead to systematic underestimation of disease burden and the inability to sensitively track disease progression. We provide an overview of intravascular imaging in the initial and longitudinal evaluation of CAV, with a focus on the use of intravascular ultrasound (IVUS). Recent Findings Multiple studies have demonstrated that progression of maximal intimal thickness (MIT) on serial IVUS evaluation, particularly >= 0.5 mm over the first year, post-transplant, is predictive of both future development of angiographically significant CAV as well as major adverse cardiac events, including graft loss and mortality. There are also emerging data that in vivo plaque characterization, as assessed by the attenuated-signal plaque score or by virtual histology intravascular ultrasound (VH-IVUS), may provide prognostic value in this population. OCT-derived intimal measurements have been noted to correlate well with IVUS findings and may also aid in early identification of CAV. In addition to early identification and prognostication, several studies have used intravascular imaging to assess therapeutic impact of various immunosuppressive regimens on progression of established CAV. Intravascular ultrasound, and more recently, optical coherence tomography (OCT) have emerged as valuable adjuncts to angiography in the evaluation of CAV, particularly with regard to early detection, objective prognostication, and differentiation of CAV from donor-derived coronary artery disease (CAD). Furthermore, intravascular imaging may guide changes to the immunosuppressive regimen and/or percutaneous coronary intervention, when necessary.