Progression of atherosclerosis at one-year follow-up seen with volumetric intravascular ultrasound in femoropopliteal arteries

Volume measurements derived from intravascular ultrasound (IVUS) images assessed with an automated contour analysis system are accurate and reproducible. However, it is unknown to what extent plaque volume may change at follow-up. Therefore, the purpose of this longitudinal study is to examine whether IVUS is a sensitive means to identify progression of atherosclerosis and its derived primary end point plaque volume at 1-year follow-up. Patients (n = 11) undergoing percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery were studied with IVUS immediately after PTA in the same session and at 1-year follow-up. Matched, well-identified vascular segments (3 to 4 cm in length), not subjected to PTA, imaged at baseline and after 1-year follow-up, were used for calculation of the longitudinal change in lumen, vessel and plaque volume, and mean plaque thickness. The median length of the selected vascular segments was 4 cm. At follow-up (12 ± 2 months) a nonsignificant increase in lumen volume (2.3 ± 11%), vessel volume (2.0 ± 7.0%), and plaque volume (3.0 ± 5.1%) was seen; the mean plaque thickness increase was 2.2 ± 5.6%. In conclusion, progression of atherosclerosis implies changes in plaque and vessel volume, resulting in lumen volume change. This observation has important implications for future clinical trials aimed at monitoring the effect of pharmacologic agents on the progression and/or regression of atherosclerosis.