Role of Noninvasive Imaging in the Diagnosis of Cardiac Allograft Vasculopathy

Abstract

Cardiac allograft vasculopathy (CAV) is common, with a prevalence of 52% at 10 years after transplantation, and represents a leading cause of death beyond the first year, responsible for approximately 15% of deaths annually.1 It is characterized by diffuse and concentric intimal proliferation, typically involving the intramural as well as epicardial coronary arteries. Its diagnosis is difficult to establish clinically because of denervation of the transplanted heart. Consequently, it presents late with silent myocardial infarction, progressive heart failure, or arrhythmic sudden death.2 Screening is therefore required for its early detection. Although coronary intravascular ultrasound (IVUS) is considered the gold-standard technique for detecting the anatomic features of CAV (Table 1), its broad clinical use in this context is limited by cost and lack of widespread expertise, and its evaluation is limited to epicardial vessels.3 Coronary angiography, performed annually or biannually, remains the most common clinical screening method.4 However, because of the diffuse nature of CAV with a lack of normal reference segments and the relatively late occurring luminal narrowing, the sensitivity of angiography is as low as 30% when compared with IVUS (Figure 1).5 As a result, complications frequently occur before disease is evident angiographically.6 Furthermore, angiography is associated with significant albeit uncommon complications (overall complication rate, 7.4/1000 procedures, including rates of 0.65/1000, 1.6/1000, and 0.72/1000 for cerebrovascular accidents, vascular complications, and death, respectively), is disliked by transplant recipients, is costly, and repeated studies are associated with an important cumulative radiation dose.7 View this table: Table 1. Stanford Classification of CAV Severity on IVUS Figure 1. Invasive assessment of cardiac allograft vasculopathy (CAV) in a patient with severe disease, highlighting the limited sensitivity of conventional coronary angiography. Although no left anterior descending (LAD) flow-limiting stenoses are seen on angiography ( A ), intravascular ultrasound ( B ) shows significant intimal thickening, measuring up to …