Abstract 17259: Differential Changes in Plaque Behind the Stent After Bare-Metal and Drug-Eluting Stent Implantation in Humans: Implications for In-Stent Restenosis?

Background: The natural history and the role of the atherosclerotic plaque located behind the stent (PBS) are still poorly understood. We evaluated the serial changes in PBS following bare-metal (BMS) compared with first-generation drug-eluting stent (DES) implantation and the impact of these changes on in-stent neointimal hyperplasia (NIH). Methods: 3D coronary reconstruction by angiography and intravascular ultrasound were serially performed after intervention and at 6- to 10-month follow-up in 157 Japanese patients treated with BMS (n=90) and DES (n=98; 68 sirolimus-eluting and 30 paclitaxel-eluting stents) included in the PREDICTION Study. Each reconstructed stented coronary artery was divided into consecutive 1.5-mm segments. External elastic lamina, lumen, stent, and PBS area were measured for each segment at both baseline and follow-up. At follow-up NIH area was assessed. Due to the very low rate of events in our population we used significant NIH (defined as NIH area >50% of stent area) as a binary anatomic outcome. Results: Patient, lesion, and stent characteristics were comparable between BMS and DES. There was a significant decrease in PBS area after BMS (median relative change: -7.2%, IQR -19.3 to 5.2%, p<0.001) and a significant increase after DES implantation (median relative change: 6.1%, IQR -5.7 to 20.5%, p<0.001). The decrease in PBS area significantly predicted NIH area at follow-up after controlling for baseline lumen area and baseline PBS area in both BMS (β 0.15, 95% CI 0.1 to 0.2, p<0.001) and DES (β 0.09, 95% CI 0.07 to 0.11, p<0.001). The decrease in PBS area was the most powerful predictor of significant NIH in both BMS (OR 1.13, 95% CI 1.02 to 1.26, p=0.017) and DES (OR 1.65, 95% CI 1.16 to 2.36, p=0.005). Conclusions: The PBS significantly decreased 6 to 10 months after BMS implantation, whereas after DES it increased. The decrease in PBS area was significantly associated with the development of NIH at follow-up in both stent types. These findings raise the possibility of a communication between the lesion within the stent and the underlying native atherosclerotic plaque, and may have important implications regarding the pathobiology of in-stent restenosis.