Impact of out-stent plaque volume on in-stent intimal hyperplasia: results from serial volumetric analysis with high-gain intravascular ultrasound.

BACKGROUND

Changes in out-stent plaque volume can be related to in-stent intimal hyperplasia. However, few data exist regarding the impact of out-stent plaque volume on in-stent intimal hyperplasia.

METHODS

We prospectively performed volumetric intravascular ultrasound in 46 stable coronary patients (34 males, mean age of 66 years) immediately as well as 18 months after stenting. From the high-gain ultrasound images, out-stent plaque volume was calculated by extracting the stent volume from the external elastic membrane volume. Volumes of in-stent intimal hyperplasia and reference plaque were also evaluated.

RESULTS

Out-stent plaque volume increased from 177.3 ± 100.8mm(3) to 190.7 ± 111.1mm(3) (p<0.05) in correlation with increases in-stent intimal hyperplasia (r=0.536, p<0.05). Under these conditions, changes in reference plaque volume correlated with those in LDL-C, which decreased from 121.2 ± 48.0mg/dl to 103.3 ± 48.9 mg/dl (r=0.43, p<0.05). Interestingly, increases in out-stent plaque volume in the silorimus-eluting stent (2.7 ± 1.2%) were lesser than those in the bare-metal stent (14.0 ± 11.0%, p<0.05).

CONCLUSIONS

These results indicate that irrespective of LDL-C level, changes in out-stent plaque volume correlate with those in in-stent intimal hyperplasia. We suggest that silorimus-eluting stent can suppress in-stent intimal hyperplasia partially by affecting out-stent plaque, although further large-scale studies are required to define the role of out-stent plaque in the occurrence of in-stent intimal hyperplasia.