Moderate Association of Coronary Artery Calcium and Cardiac Allograft Vasculopathy in Heart Transplant Recipients on Non-Gated CT

Abstract

<h3>Purpose</h3> Cardiac allograft vasculopathy (CAV) is common in patients who have undergone orthotopic heart transplant (OHT) and is associated with significant morbidity and mortality. Non-invasive methods for identifying CAV are an appealing alternative to standard clinical practice of routine invasive angiography. We explored the association of CAV with incidental coronary artery calcium (CAC) from non-ECG gated, clinically indicated chest CT scans. <h3>Methods</h3> This is a single-center, retrospective, observational study of OHT patients >1 year from transplant who underwent left heart catheterization between 2015 and 2019 and had a clinically indicated, non-ECG gated chest CT obtained for a variety of indications within 6 months of the catheterization. CAC was graded by a blinded reviewer in a semi-quantitative manner based on extent and distribution across the coronary tree. Angiographically significant CAV was obtained from left heart catheterizations results obtained per standard institutional protocol. <h3>Results</h3> 73 patients were included, 56 (77%) were male, mean age was 60±12 years and median time from heart transplant was 4 years [IQR 2, 8]. 34 patients (47%) were found to have CAC, of which 7 (21%) were found to have moderate or severe CAC. 38 patients (52%) were found to have CAV on angiography. In the CAC group, 25 were found to have CAV (74%). Of those with moderate to severe CAC, 7 (100%) were found to have CAV. In the no CAC group, 13 (33%) were found to have CAV. The presence of CAC had a sensitivity, specificity, positive predictive value and negative predictive value of 66%, 74%, 73%, and 67% respectively for the diagnosis of CAV. <h3>Conclusion</h3> The absence of CAC on non-ECG gated CT demonstrated a moderate ability to rule out CAV, while moderate to severe CAC was strongly associated with CAV. As chest CT scans are common in this population, informing clinical decision making with this "free" information is potentially beneficial.