The effect of shear stress on neointimal response following sirolimus- and paclitaxel-eluting stent implantation compared with bare-metal stents in humans.

OBJECTIVES: We aimed to explore the relationship of neointimal thickness (NT) to shear stress (SS) after implantation of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) compared with bare-metal stents (BMS). We then tested the hypothesis that drug elution attenuates the SS effect.
BACKGROUND: Neointimal thickness after BMS implantation has been associated with SS; pertinent data for drug-eluting stents (DES) are limited.
METHODS: Three-dimensional coronary artery and stent reconstruction was performed in 30 patients at 6-month follow-up after SES (n = 10), PES (n = 10), or BMS (n = 10) implantation. Baseline SS at the stent surface was calculated using computational fluid dynamics and NT at follow-up was computed in 3-dimensional space.
RESULTS: Neointimal thickness was lower in DES versus BMS (0.03 ± 0.07 mm vs. 0.16 ± 0.08 mm, p < 0.001) and maximum NT was reduced in SES versus PES (0.33 ± 0.13 mm vs. 0.46 ± 0.13 mm, p = 0.025). In the total population, both SS (slope: -0.05 mm/Pa, p < 0.001) and DES (coefficient for DES vs. BMS: -0.17 mm, p = 0.003) were independent predictors of NT. Subgroup analysis demonstrated a significant negative relationship of NT to SS in PES (slope: -0.05 mm/Pa, p = 0.016) and BMS (slope: -0.05 mm/Pa, p = 0.001). Sirolimus elution significantly attenuated the effect of SS on NT (interaction coefficient for SES vs. BMS: 0.04 mm/Pa, p = 0.023), whereas the SS effect remained unchanged in PES (interaction coefficient for PES vs. BMS: 0.01 mm/Pa, p = 0.71).
CONCLUSIONS: Neointimal thickness is significantly correlated (inversely) to SS in PES as in BMS. Sirolimus elution abrogates the SS effect on the neointimal response following stent implantation, whereas the SS effect is unchanged in PES.