PANDA III: BuMA SES Noninferior to Excel SES for TLF at 1 Year
Two sirolimus-eluting bioresorbable-polymer-based metallic stents with varying elution and absorption kinetics showed comparable rates of target lesion failure at 1 year, but each device carried distinct risks of stent thrombosis, according to results of the PANDA III trial presented at TCT 2015.
Bo Xu, MD, of Fu Wai Hospital, China, reported data on 2,350 patients (mean age, 61 years; 70% men) enrolled at 46 centers in China with symptomatic CAD, silent ischemia or ACS. Patients were randomized to PCI using the PLGA polymer-based BuMA sirolimus-eluting stent (SinoMed; n = 1,174) or the PLA polymer-based Excel SES (JW Medical Systems; n = 1,174). Baseline characteristics between groups were well matched, except that the Excel group had a higher rate of prior PCI.
At 1-year follow-up, BuMA met noinferiority criteria compared with Excel for the primary endpoint of TLF, a composite of cardiac death, target-vessel MI or ischemia-driven target lesion revascularization (Figure).
Individual components of the primary outcome also were similar between the two stents. Cardiac death was 1.2% with BuMA vs. 1.3% with Excel (P = .86), target-vessel MI was 4.3% vs. 4.9%, respectively (P = .49) and ischemia-driven TLR was 1.9% vs. 1.2%, respectively (P = .18). A patient-oriented composite endpoint of death, MI or any revascularization at 1 year yielded equivalent results for both devices.
Stent thrombosis differed
The BuMA SES, however, was associated with a lower rate of definite or probable stent thrombosis compared with Excel: 0.5% vs. 1.3% (P = .047).
Given that the cumulative incidence of stent thrombosis was low overall, Xu called for caution, noting that PANDA III “was not powered adequately to evaluate low-frequency safety endpoints such as stent thrombosis.” Nonetheless, he concluded that the decreased stent thrombosis for BuMA seen here is consistent with the BuMA-OCT trial, which showed better strut coverage at 3 months with BuMA vs Excel.
“It’s fascinating” that less strut coverage could be linked with a greater rate of stent thrombosis, commented session moderator and TCT Course Director Gregg W. Stone, MD, of NewYork-Presbyterian Hospital/Columbia University Medical Center, N.Y. “We’ve never had that linkage before.”
SES drug elution, polymer absorption
The trial was designed to determine whether drug elution and polymer absorption rates of SES affect clinical outcomes of biodegradable polymer-based DES, Xu explained.
BuMA incorporates an electro-grafting base layer between the polymer and stent strut to secure adhesion of the PLGA coating. Sirolimus is eluted completely within 30 days and the PLGA polymer is completely absorbed within 3 months. In contrast, Excel elutes sirolimus completely within 180 days and the PLA polymer is completely absorbed within 6 to 9 months. Both DES elute sirolimus from a stainless-steel platform, isolating major differences to the polymer and elution kinetics, Xu said.
- Xu reports no relevant conflicts of interest.