The prevalence of potentially unstable coronary lesions in patients with coronary artery disease--virtual histology study.

Background: Histopathological studies indicate that coronary artery lesions with a thin fibrous cap and large necrotic core (thin-cap fibroatheromas, TCFA) are characterised by a high risk of rupture and can potentially trigger acute coronary syndrome (ACS). Atherosclerotic lesions with a well preserved fibrous cap (fibroatheromas, FA) are considered to be more stable ones. Intravascular ultrasound virtual histology (IVUS-VH) enables identification of FA and TCFA in vivo. There are no published data regarding IVUS-VH derived occurrence of both FA and TCFA in patients with different clinical presentation.

Aim: To determine IVUS-VH derived occurrence of FA and TCFA in coronary arteries of patients with chronic stable angina in comparison with recent or acute ACS subjects.

Methods: Intravascular ultrasound examination was performed in 60 patients, who were prospectively enrolled to three groups: group A--chronic stable angina, without a history of ACS within the previous 12 months; group B--recent ACS (4 weeks-3 months); group C--acute phase of ACS.

Results: The final analysis included 75 non-culprit lesions (group A: n=29 lesions; group B: n=22; group C: n=24). There were no significant differences in lesions' angiographic and ultrasound characteristics between the studied groups. There was no significant difference in the occurrence of FA lesions between the studied groups (20.7 vs. 22.7 vs. 4.2, respectively; NS). There was a significant difference in TCFA occurrence between the studied groups (31.0 vs. 50.0 vs. 79.2%; p <0.01).

Conclusions: The present study confirms higher occurrence of thin-cap fibroatheromas in patients with clinically confirmed coronary instability. It also indicates that IVUS-VH can be a valuable tool for rupture prone lesion identification, which might help in better risk stratification in coronary artery disease patients.