Coronary Computed Tomography Angiography for the Detection of Cardiac Allograft Vasculopathy: A Meta-Analysis of Prospective Trials
How accurate is coronary CT angiography (CCTA) in identifying cardiac allograft vasculopathy (CAV)?
This meta-analysis examined 13 studies evaluating 615 adult patients with prior heart transplant undergoing both CCTA and invasive coronary angiography (ICA) with or without intravascular ultrasound (IVUS) to evaluate possible CAV. The accuracy of CCTA to identify any CAV (any stenosis) or significant CAV (≥50% stenosis) on ICA was assessed. Additional comparisons were performed to assess the accuracy of CCTA to identify CAV by IVUS, with CAV defined as a cutoff of >0.5 mm intimal thickening in three studies.
Mean age was 52 years, and 83% were males. On patient-based analyses, the weighted sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CCTA was 97%, 81%, 78%, and 97% for detection of any CAV (n = 203); and 94%, 92%, 67%, and 99% for detection of significant CAV (n = 392) as compared to ICA. In the three studies comparing CAV by CCTA to IVUS (n = 69) using a threshold of >0.5 mm intimal thickening, the patient-based weighted sensitivity, specificity, PPV, and NPV were 81%, 75%, 93%, and 50%, respectively.
The authors concluded that CCTA represents a noninvasive and accurate method to identify CAV in selected patients with prior heart transplant.
Yearly screening to identify CAV in patients with a heart transplant is recommended, and ICA is often used as a means to identify this at an early stage. Disadvantages of ICA include the need for an invasive procedure with its inherent risks and costs, and visualization that is limited to the vessel lumen, unless IVUS is also performed. CCTA represents a noninvasive means to assess luminal stenosis, and can also visualize the vessel wall and plaque in a manner similar to IVUS, although with a lower spatial resolution. The present study finds that CCTA has high accuracy to identify and exclude the presence of any stenosis or significant stenosis as compared to ICA, and has a moderate accuracy to identify intimal thickening in comparison to IVUS. Limitations of CCTA include the need for larger contrast volume as compared to ICA, which may be problematic in patients with renal insufficiency. Further, some of these studies excluded a proportion of patients with nondiagnostic CCTA studies from analyses, and individuals with significant cardiac arrhythmias were excluded from all studies. Finally, these studies excluded small segments, which are often poorly visualized on CCTA given the limits of spatial resolution, but which may demonstrate CAV in early stages. These findings suggest that CCTA may be a reasonable alternative in some patients who might otherwise undergo ICA, provided there is careful attention paid to appropriate patient selection.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Cardiac Surgery and Heart Failure, Heart Transplant, Interventions and Imaging, Angiography, Nuclear Imaging
Keywords: Renal Insufficiency, Coronary Angiography, Tomography, Transplantation, Homologous, Constriction, Pathologic, Tunica Intima, Heart Transplantation
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