Evaluation of plaque stabilization by fluvastatin with carotid intima-medial elasticity measured by a transcutaneous ultrasonic-based tissue characterization system

Aim: As an approach to tissue characterization, we attempted to classify in vivo carotid plaque tissues in terms of arterial wall elasticity instead of echogenicity on B-mode scanning and investigated whether the effect of fluvastatin on carotid elasticity can be detected in hypercholesterolemic patients. Methods: In 170 subjects, simultaneous measurements of intima-media thickness (IMT) and elastic modulus in the circumferential direction (E _θ) were performed using a new transcutaneous high-resolution Doppler technique. Results: From the observation of various tissues, an elasticity library was obtained as follows: lipid core, 22 ± 15 kPa; calcification, 674 ± 384 kPa; lipid core- and calcification-free plaques, 173 ± 69 kPa; smooth muscle, 104 ± 32 kPa; blood clot, 85 ± 68 kPa; fibrosis, 273 ± 173 kPa. The effect of fluvastatin (30 mg/day, n = 62) was assessed over 12 months using the elasticity distribution and serum markers. The statin reduced low-density lipoprotein cholesterol, high-sensitivity CRP, mean IMT and mean E_θ, and increased nitrite/nitrate. In the max IMT ≥ 1.1 mm group, both E_θ and IMT decreased significantly. On the other hand, in the max IMT <1.1 mm group, E_θ but not IMT decreased significantly. The histogram of the subgroups showing increased E_θ with max IMT ≥ 1.1 mm revealed a decrease in areas corresponding to E_θ of 20-200 kPa (lipid/smooth muscle-rich tissue) and an increase in relatively hardened areas of <250 kPa (collagen fibers). Conclusion: Non-invasive echographic carotid arterial elasticity measurement is useful for the classification of atherosclerotic plaques and evaluation of chronological and histopathological changes.