Background: Virtual histology (VH) uses intravascular ultrasound (IVUS) radiofrequency spectral analysis to locally identify the morphology and composition of atherosclerotic plaques. We sought to explore in vivo the relation between IVUS-derived thin cap fibro-atheroma (IDTCFA) and remodelling index in patients with acute coronary syndromes using IVUS-VH.
Methods and results: Twenty-one patients (63 vessels) were enrolled. When compared to cross sectional areas (CSAs) without necrotic core in contact with the lumen (NCCL), CSAs with NCCL had a larger plaque burden 42.8+/-11.5% vs. 32.8+/-11.5%, p<0.001; higher overall necrotic core content [13.8+/-10.7% vs. 2.3+/-7.9% (p<0.001)] and calcified tissue [4.7+/-6.5 vs. 0.66+/-2.1% (p<0.001)]. On average there were 2 IVUS-derived thin cap fibro-atheroma (IDTCFA) per patient. Nearly half of the IDTCFAs had positive remodelling.
Conclusions: CSAs with NCCL had worse morphological profiles than those with no NCCL. The simultaneous and more detailed assessment of IDTCFA and remodelling index identifies a reduced number of allegedly high-risk plaques. The findings of this study may have important clinical implications, since they shed light into a possible method of identiying potentially high-risk plaques suitable for pharmacological and/or local treatment.