An interim analysis of the Japanese CASTLE study suggests the thin-strut bioabsorbable-polymer sirolimus-eluting stents (BP-SES) may have similar clinical outcomes in percutaneous coronary intervention (PCI) to the durable-polymer everolimus-eluting stents (DP-EES) when the procedure is performed under intracoronary imaging guidance.
The findings came were reported in a late-breaking session Tuesday morning at the EuroPCR conference by Masato Nakamura, MD, Toho University, Tokyo, based on 70% of the follow-up.
Modern second-generation drug-eluting stents (DES) have significantly improved clinical outcomes for patients undergoing PCI, although further improvements are being tested for even better clinical outcomes, including thinner stents, bioabsorbable polymers and image-guided stent deployment.
Previous clinical trials such as BIOFLOW-V and BIOSTEMI suggest that ultrathin-strut BP-SES could result in lower target lesion failure than DP-EES, for example, the researchers noted.
However, there has been mixed evidence, with other randomized studies such as BIOSCIENCE showing neutral results for BP-SES versus DP-EES, for instance.
The researchers hypothesized that one possible explanation for the contradictory findings is the use of intracoronary imaging, which has shown to reduce the risk of stent thrombosis and late restenosis.
They, therefore, set out to compare the efficacy of Biotronik’s Orsiro – an ultrathin-strut (60 µm) BP-SES believed to be able to potentially reduce vessel inflammation and thrombogenicity – with “the most standard” second-generation DES, Abbott’s Xience Sierra, a DP-EES, with all procedures done under image guidance.
CASTLE – a prospective, investigator-initiated, single-blind study – ran in 66 centers in Japan between May 2019 and March 2020, randomizing 1,440 all-comer acute and chronic coronary syndrome patients in a 1:1 fashion (722 to Osiro, 718 to Xience) to test non-inferiority between the devices.
There were no significant differences between the two groups in terms of clinical and procedural characteristics, with the majority of the overall population being chronic coronary syndrome patients (85%) receiving a stent of 3 mm in diameter or less (66%). Imaging guidance was performed in at least 97.5% of the patients.
The prespecified margin for non-inferiority was 3.3%.
The primary outcome measure, target lesion failure at 12-months – defined by cardiovascular death, target vessel myocardial infarction, and clinically driven target lesion revascularization – occurred in 5.9% of the Osiro group and 6.1% of the Xience population (hazard ratio [HR] 0.97; 95% confidence interval [CI]: 0.63 – 1.49; p = 0.88), Nakamura noted during his presentation.
The researchers also did not find a significant difference in target lesion failure or its components between the groups at 30 days.
CASTLE, therefore, demonstrated non-inferiority of Orsiro with respect to target lesion failure over the contemporary benchmark DES, Xience. However, “We cannot find the superiority,” Nakamura said during a press conference.
Target lesion revascularization (0.8% vs 1.3%) and target vessel revascularization (2.0% vs 2.7%) were both at least numerically lower in Orsiro group, according to the accompanying press release.
The data suggest that BP-SES and DP-EES may have similar clinical outcomes when PCI is performed under intracoronary imaging guidance, the press release adds. However, it warns that the complete follow-up is yet to be performed to fully understand potential differences between the two devices.