SAN FRANCISCO – Two sirolimus-eluting stents with differing elution an absorption kinetics were equally effective in the prospective, randomized PANDA III trial.
The sirolimus in the BuMA stent is completely absorbed in 3 months, while that in the Excel stent takes 6-9 months to be absorbed.
The target lesion failure rate, defined as a composite of cardiac death, target vessel myocardial infarction, or ischemia-driven target lesion revascularization, was the same at 6.4% in 1,175 patients randomized to receive the BuMA device, and 1,175 randomized to receive the Excel device. Cardiac death occurred in 1.2% and 1.3% of patients in the groups, respectively; target vessel myocardial infarction occurred in 4.3% and 4.9%; and ischemia-driven target lesion revascularization occurred in 1.9% and 1.2%, respectively, Dr. Bo Xu of Fu Wai Hospital, Beijing, explained at the Transcatheter Cardiovascular Therapeutics annual meeting.
However, the definite/probable stent thrombosis rate at 1 year was 0.5% in the BuMA patients, and 1.3% in the Excel patients in the intention to treat population. The difference was statistically significant.
BuMA and Excel – neither of which are available in the United States – are both bioresorbable, polymer-based metallic stents, but they have varying elution and absorption kinetics: The BuMA sirolimus-eluting stent (SES) is a poly lactic-co-glycolic acid (PLGA) polymer-based stent incorporating an electrografting base layer between the polymer and stent strut, securing adhesion for the PLGA coating. The BuMA sirolimus is 100% eluted within 30 days, and the polymer is completely absorbed within 3 months, Dr. Xu said at the meeting, which was sponsored by the Cardiovascular Research Foundation.
“In contrast, the [polylactic acid, or PLA] polymer-based Excel SES elutes sirolimus completely within 180 days, and the PLA polymer is completely absorbed within 6-9 months,” he said.
Both stents elute sirolimus from stainless steel platforms, which means that major differences in effects are likely attributable to the polymer and elution kinetics, he noted.
In a previous small study (the BuMA-OCT trial, EuroIntervention 2014;10:806-14) involving 80 patients who were randomized to receive either the BuMA or the Excel stent, the BuMA stent was found to be superior at 3 months (strut coverage proportion, 94.2% vs. 90.0%). The current study enrolled all comers to determine whether BuMA is noninferior or superior to the Excel SES for the primary endpoint of 1 year target lesion failure.
The findings demonstrate noninferiority of the BuMA SES. Further, the BuMA SES was associated with a lower incidence of stent thrombosis, compared with the Excel SES, consistent with the previous findings of enhanced strut coverage with this device, Dr. Xu said, adding that longer follow-up is needed to further understand the long-term effects of this emerging stent technology.
Discussant Dr. David J. Cohen of St. Luke’s Mid America Heart Institute, Kansas City, applauded the study design and inclusion of all comers, but noted that the findings don’t have immediate clinical implications in the United States since neither is available here. They do, however, shed some light on the two stents used in the trial, he said.
“The only difference was stent thrombosis, which was somewhat borderline in the intention-to-treat population, and has to at least be taken as a word of caution. We don’t know if this is because the new stent with the bioabsorbable polymer is better than other things we have, or if the comparator stent is worse, since it’s not a comparator that’s widely used, he said.
Panda III was funded by a research grant from SinoMed. Dr. Xu reported having no disclosures.