An optical coherence tomography study of two new generation stents with biodegradable polymer carrier, eluting paclitaxel vs. biolimus-A9.

BACKGROUND

Tissue coverage and strut apposition of drug eluting stents (DES), which can be assessed with optical coherence tomography (OCT), may be associated with late stent thrombosis (LST).

METHODS

Prospective observational angiographic and OCT follow-up at 6 months post-implantation of a biolimus-A9 eluting stent (BES) vs. a paclitaxel eluting stent (PES), with biodegradable polymer carriers. The primary outcome was the percent difference of uncovered struts between BESs and PESs.

RESULTS

A maximum likelihood model was used for analysis, to account for data clustering. Sixteen patients were treated with BES (28 lesions/4530 struts) and 16 with PES (23 lesions/4450 struts). Overall, BESs compared to PESs had more uncovered [0.41% vs. 0.21%, difference estimate (DE) 0.2 (95% CI, 0.06-0.34), p=0.006], malapposed [0.18% vs. 0.04%, DE 0.14 (95% CI 0.05-0.23), p=0.003], uncovered and malapposed [0.08% vs. 0.026%, DE 0.057 (95% CI 0.015-0.1), p=0.01] and protruding struts [0.23% vs. 0.04%, DE 0.185 (95% CI 0.1-0.27), p<0.001], and significantly lower neointimal thickness (59.3 ± 28.2 μm vs. 201.7 ± 97.5, p<0.001). None of the BESs was totally covered with neointima, in contrast to 5 (21.7%) PESs (p=0.01). Thrombus was detected in 1 (3.6%) BES and 5 (21.7%) PESs (p=0.05); however, no patient experienced clinical stent thrombosis.

CONCLUSION

Between two stents with biodegradable polymer, OCT demonstrated that BESs had more uncovered and malapposed struts compared to PESs at 6 months. This difference might be partly attributed to the more potent antiproliferative properties of biolimus-A9; however, its impact on clinical outcome and on the risk of LST is yet to be determined.