Computed tomography imaging of cardiac allograft vasculopathy

Cardiac allograft vasculopathy (CAV) is the main cause of morbidity and mortality beyond 1 year after heart transplantation. Ischemic symptoms are usually not present because of the denervated allograft and diffuse nature of the disease. Patients present with heart failure, ventricular arrhythmia, or sudden cardiac death as a result of advanced CAV. Therefore, clinical evaluation includes routine annual invasive coronary angiography (ICA) and transthoracic echocardiography to screen for CAV. Noninvasive imaging methods for the detection of CAV have not been widely adopted. Computed tomography (CT) permits detection of coronary stenoses and plaque in the nontransplant population. The strength of CT is its high negative predictive value. These attributes predispose CT to a role of a gatekeeper for further invasive testing in heart transplant recipients. We reviewed the available literature on CT evaluation of CAV. Technical challenges (eg, high heart rates, need for contrast and radiation, image quality) specific for patients who have received a heart transplant are emphasized, and solutions, including appropriate protocols and advances through the new CT technology, are summarized. We systematically analyze the results of studies that report the diagnostic performance of cardiac CT for the detection of coronary stenoses compared with ICA. Similar analysis is performed for the comparison between CT and intravascular ultrasound scanning for the detection of nonobstructive CAV. Finally, we suggest future directions in cardiac CT imaging research of CAV.