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To assess calcium growth with fused greyscale-IVUS, virtual histology-IVUS (VH-IVUS) and OCT from baseline to 5-year follow-up in patients treated with Bioresorbable Vascular Scaffolds (BVS).
Anatomic landmarks and endoluminal radiopaque markers were used to fuse OCT and IVUS images and match baseline and follow-up.
Seventy-two VH-IVUS and OCT paired matched cross-section in- and out-scaffold segments were fused at baseline and follow-up. In total, 46 calcified plaques at follow-up were detected by the fusion method (33 in-, 13 out-scaffold), showing either calcium progression (52.2%) or de novo calcifications(47.8%). On OCT, calcification volume increased from baseline to follow-up by 2.3±2.4 mm3 (p=0.001). The baseline VH tissue precursors of dense calcium (DC) at follow-up were necrotic core (NC) in 73.9% and Fibrous/Fibrofatty (F/FF) in 10.9%. In 15.2%, calcium was already present at baseline. Precursors on OCT were lipid pool in 71.2%, fibrous in 4.3%, and fibrocalcific plaque in 23.9%.
The use of OCT/IVUS fusion imaging shows similar calcium growth in-and out-scaffold segments. NC is the most frequent precursor of calcification. The scaffold resorption process creates a tissue layer that recaps the calcified plaques.