Long-Term Changes in the Coronary Artery Structure After Heart Transplantation: A Prospective Optical Coherence Tomography Study

Abstract

<h3>Purpose</h3> Optical coherence tomography (OCT) enables detailed characterization of plaque composition in cardiac allograft vasculopathy (CAV) after heart transplantation (HTx). Using serial OCT scans, our research group previously demonstrated that early CAV is characterized by intimal thickening strongly associated with layered fibrotic plaques (LFPs) progression. Early changes after HTx are well-described, whereas no serial OCT studies in long-term HTx patients have been performed. We aimed to describe and characterize late changes in the coronary artery microstructure after HTx. <h3>Methods</h3> In 134 vessels from 56 long-term HTx patients (median 8.3 years), we performed OCT scans of the major coronary arteries in relation to routine annual coronary angiography at baseline and after 12 months. We contoured the vessel layers for absolute and relative measurements. Lipid plaques, calcified plaques, bright spots, and LFPs were analyzed by delineating circumferential borders and measuring angulation of total circumference. <h3>Results</h3> A total of 15.634 frames were analyzed. Mean intima area increased significantly (2.8 [1.9 to 4.4] mm² vs. 3.0 [2.0 to 4.5] mm², <i>p</i> <0.01) and mean lumen area decreased significantly (8.7 [6.9 to 10.3] mm² vs. 8.4 [6.8 to 10.3] mm², <i>p</i><0.05) during follow-up. A high prevalence of LFPs was observed and the extent increased 14 % during follow-up (38.0 [22.7 to 65.9] % vs. 43.4 [25.1 to 67.7] %, <i>p</i><0.0001). A low prevalence of lipid plaques was observed (0.65% [0.34% to 1.48%] vs. 0.71% [0.16% to 2.27%], <i>p</i>=0.11). We found no difference in the extent of bright spots (<i>p</i>=0.99), calcified plaques (<i>p</i>=0.60) or mean media area (<i>p</i>=0.23) during follow-up. <h3>Conclusion</h3> LFPs are highly prevalent in long-term HTx patients. Late progression of CAV is similar to the findings early after HTx with intimal thickening primarily characterized by progression of LFPs. In contrast, the extent of bright spots and calcified plaques remained stable, and lipid plaques were rarely observed.