Frequency of vascular inflammation and impact on healing of 2^nd generation drug eluting stents in porcine coronary arteries

Background: We aimed to describe the frequency of vascular inflammatory reactions in 2^nd generation drug eluting stent as compared to 1 ^st generation technologies and analyze the impact on inflammation and neointimal proliferation in the porcine coronary model. Methods: A total of 26 stents (7 multi-link VISION, 6 CYPHER, 6 TAXUS and 7 XIENCE V) were deployed in coronary arteries of 10 domestic swine and followed up at 28 days. At termination, each stent was harvested and processed for histo-morphometric analysis. Results: A total of 202 histological segments were included. The mean neointimal thickness was significantly reduced in the Drug eluting stent group compared to the bare metal stent group. As a group, drug eluting stent displayed higher injury scores (0.99±0.79 versus 0.67±0.44, p<0.004), inflammatory scores (2.09±1.54 versus 0.64±0.98, p<0.001) and presence of para-strut granulomas (35% versus 2%, p<0.001), By logistic regression, the presence of para-strut granuloma correlated with area stenosis >50% (RR: 6.11, 95% CI: 2.97 to 12.59, p=0.001), Within the drug eluting stent group, the 2^nd generation stents demonstrated lower neointimal area (XIENCE V: 1.64 ± 0.90 mm²) compared to the 1 ^st generation stents (TAXUS: 2.36 ± 1.56 mm², p=0.005), (CYPHER 2.78 ± 1.82 mm², p=0.001). The XIENCE V stents had lower inflammatory scores and lower frequency of para-strut granuloma in comparison to TAXUS and CYPHER stents. Conclusions: Second generation drug eluting stent displayed lower incidence of vascular inflammatory reaction compared to 1^st generation drug eluting stent. This biological phenomenon appears to influence the patterns of neointimal formation and vascular healing.