Coronary Computed Tomography Angiography in Heart Transplant Patients: Current Insights and Future Directions

Abstract

Cardiac allograft vasculopathy (CAV) remains a significant challenge after heart transplantation, necessitating effective surveillance methods. This review centers around the role of coronary computed tomography angiography (CCTA) in CAV surveillance, given its unique capabilities to visualize and quantify CAV in comparison with other imaging modalities, including invasive coronary angiography and intravascular ultrasound. CCTA has shown good diagnostic performance for detecting and monitoring CAV, exemplified by a higher sensitivity and negative predictive value compared with invasive coronary angiography. Additionally, CCTA can provide valuable functional insights with fractional flow reserve integration. An additional, considerable benefit of CCTA is that it allows for the opportunity to assess other imaging markers of cardiometabolic and general health, including coronary artery calcium score, epicardial fat volume, liver fat, vertebral bone density, and lung density, which allows for a comprehensive assessment of the overall health of the patient.

FIGURE 1.

ISHLT recommended standardized CAV grading. CAV, cardiac allograft vasculopathy; ISHLT, International Society for Heart and Lung Transplantation; LVEF, left ventricular ejection fraction.

FIGURE 2.

CAD-RADS 2.0 scoring for stenosis grading. CAD-RADS, Coronary Artery Disease Reporting and Data System; ICA, invasive coronary angiography.

FIGURE 3.

Assessments derived from coronary computed tomography (noncontrast and contrast-enhanced) angiography from an HTx patient. A, Diffuse thickening of the intima as seen in CAV. B, CAV plaque formation along the whole length of the coronary. C, Soft plaque and calcium are shown in the LAD coronary artery (yellow markers). D, Corresponding intersection of LAD with soft plaque and calcium. E, Plaque analysis of the corresponding intersection of the LAD: lumen (green), soft plaque (grey), coronary calcium (red and black). F, Fractional flow reserve CT from an HTx patient. G, Cardiometabolic and general health markers, as seen on a noncontrast CT scan: coronary artery calcium (purple), epicardial fat (green), left liver lobe (yellow), thoracic vertebra (red), and lung tissue (blue). CAV, cardiac allograft vasculopathy; CT, computed tomography; HTx, heart transplant; LAD, left anterior descending.

FIGURE 4.

Imaging markers on a noncontrast coronary calcium scan with, in color, different tissues from which the potential imaging markers may be obtained.

FIGURE 5.

Clinical relevance of cardiometabolic health markers that can be found on CCTA. *There are multiple potential interventions available. These interventions have been proven effective in the general population beyond the context of transplantation. CAV, cardiac allograft vasculopathy; CCTA, coronary computed tomography angiography; GLP-1, glucagon-like peptide-1; SGLT2, sodium-glucose cotransporter 2.

FIGURE 6.

Comparison of CCTA to other imaging modalities. CCTA, coronary computed tomography angiography; CMR, cardiovascular magnetic resonance; DSE, dobutamine stress echocardiography; ICA, invasive coronary angiography; IVUS, intravascular ultrasound; OCT, optimal coherence tomography; PET, positron emission tomography; SPECT, single-photon emission computed tomography.