Abstract 6004: SPIRIT III Japan: Eight-Month IVUS Analysis of Everolimus-Eluting Stent Compared to the US Arm
Background: XIENCE™V, an everolimus-eluting cobalt chromium stent on a durable fluoropolymer (EES) has shown promise in improving clinical and angiographic outcomes in patients with coronary artery disease. The aim of this IVUS study was to evaluate vessel responses to EES implantation in SPIRIT III Japan and compare them with the SPIRIT III (US).
Methods: The SPIRIT III trial is a prospective, multicenter, randomized clinical trial in the US comparing EES to the paclitaxel-eluting stent. The SPIRIT III Japan is a prospective, multicenter, non-randomized arm using EES in the Japanese population. Data were obtained from SPIRIT III Japan, and the randomized EES arm in SPIRIT III (US). Volumetric IVUS data were available at 8 months in 194 lesions (79 Japan: 115 US). Volume index (volume/length) was calculated for vessel, lumen (LVI), plaque, stent (SVI) and neointima (NIV). Percent neointimal volume (%NIV) was calculated as (NIV/SVI) X100. Cross-sectional narrowing (CSN) was defined as neointimal area divided by stent area.
Results: Although no difference was observed in vessel size in the reference segment between the two arms, post procedure minimum lumen area (MLA) and SVI were significantly larger in the Japan arm (Table⇓). Baseline incomplete stent apposition (ISA) was less frequently observed in the Japan arm, possibly related to higher maximum balloon pressure (Japan 16.4 atm vs. US 15.0 atm, p=0.003) and/or more post dilatation (Japan 65% vs. US 42%, p=0.002), without excess tissue prolapse or edge dissection. In the Japan arm, %NIV and max %CSN were significantly lower at 8 months follow-up. Late acquired ISA was infrequent in both arms (Japan 1.2% vs. US 1.7%, p=0.78).
Conclusions: In the SPIRIT III trial, larger post procedure MLA and SVI in the Japan arm resulted in lower %NIV and max %CSN at follow-up. Lower post procedure ISA appear to represent different optimization strategies.