Assessing the temporal course of neointimal hyperplasia formation after different generations of drug-eluting stents.

Objectives: This study sought to assess the temporal course of neointimal hyperplasia (NIH) formation following implantation of 2 different generations of drug-eluting stents (DES).

Background: The amount of NIH following DES implantation correlates with the potency of the antiproliferative drug, its kinetic release, as well as some individual characteristics, as the presence of diabetes mellitus (DM). Recently, some publications have suggested a continuous growth of NIH following DES, which in some cases, might result in late "catch-up."

Methods: Twenty-five patients with single, de novo lesions were treated with sirolimus-eluting stents (SES) (n = 12) and biolimus-eluting stents (BES) (n = 13) and underwent intravascular ultrasound evaluation immediately after the procedure and at 9-month and 5-year follow-ups. The primary endpoint was the comparison of the percentage of NIH obstruction between mid- and long-term follow-up.

Results: Mean age was 59 years and 28% of patients had DM. Overall, the percentage of NIH obstruction significantly increased from 9 months to 5 years (1.3% at first follow-up vs. 4.8% at second follow-up, p = 0.002). There was no significant difference in the variation of vessel volume (Δ = -0.70 mm(3)/mm BES vs. Δ = 0.18 mm(3)/mm SES, p = 0.56), lumen volume (Δ = 0.40 mm(3)/mm BES vs. Δ = -0.05 mm(3)/mm SES, p = 0.71), and percentage of NIH obstruction (Δ = 3.0% BES vs. Δ = 3.8% SES, p = 0.55) among DES. However, diabetic patients had a marked NIH increase along the years (NIH volume at second follow-up: 10.15 mm(3) DM vs. 5.11 mm(3) non-DM, p = 0.028).

Conclusions: The present serial intravascular ultrasound assessment supports the occurrence of continuous NIH growth following different generations of DES. These findings seem to be particularly more pronounced among patients with DM.