Abstract 909: Natural History of Coronary Artery Lesion Morphology Assessed by Serial VH-IVUS Tissue Characterization
Plaque stability is related to its histological composition. We used Virtual Histology -intravascular ultrasound (VH-IVUS) to investigate the natural history of coronary artery lesion morphology.
Methods & Results: We performed serial (baseline and follow-up @11 mos) VH-IVUS studies and examined non-culprit plaque morphology in 221 lesions (plaque burden>40%) in 106 pts. Lesions were classified into 6 types based on plaque composition; pathological intimal thickening (PIT), thick-capped fibroatheroma without calcification (ThCFA-Ca), thick-capped fibroatheroma with calcification (ThCFA+Ca), thin-capped fibroatheroma (TCFA), fibrocalcific, and fibrotic. During follow-up, 14% of PIT at baseline changed to ThCFA-Ca, 3% changed to ThCFA+Ca, and 9% changed to TCFA. During follow-up, 19% of ThCFA-Ca at baseline changed to ThCFA+Ca, and 4% changed to TCFA. No ThCFA+Ca changed to TCFA. Although 62% of TCFA changed to ThCFA (±Ca), 24% of TCFA were still present at follow-up. Overall, plaque area increased and lumen area decreased during follow-up in all 6 lesion types; however, Δplaque area (p<0.05) and lumen area (p<0.05) were significantly greater in PIT compared to other lesion types. Overall, 38 plaques underwent percutaneous coronary intervention (PCI) at follow-up. The incidence of PCI in PIT was similar to ThCFA (±Ca) and TCFA, but it was significantly higher than in fibrocalcific plaque (p<0.05) and fibrotic plaque (p<0.05).
Conclusions: VH-IVUS is useful to assess the natural history of atherosclerotic lesions. In particular, lesions classified as PIT show the greatest plaque progression ad requirement for PCI. Conversely, most TCFAs seem to stabilize.