Impact of Intravascular Ultrasound–Guided Optimal Stent Expansion on 3-Year Hard Clinical Outcomes

Background: Although stent underexpansion on intravascular ultrasound (IVUS) has been a major predictor for adverse outcomes in previous studies, these studies have primarily focused on angiographic restenosis or repeat revascularization with short-term follow-up. This study sought to evaluate the long-term benefit of different criteria for IVUS-defined optimal stent expansion on hard clinical outcomes. Methods: From the pooled data of 2 randomized trials, IVUS-XPL (Impact of Intravascular Ultrasound Guidance on the Outcomes of Xience Prime Stents in Long Lesions) and ULTIMATE (Intravascular Ultrasound Guided Drug Eluting Stents Implantation in All-Comers Coronary Lesions) that compared IVUS- versus angiography-guided drug-eluting stent implantation, a total of 1254 patients with IVUS-guided drug-eluting stent implantation into 1484 long lesions (implanted stent length, ≥28 mm) were included. Different criteria for IVUS-defined optimal stent expansion based on minimum stent area (MSA) as an absolute measure or MSA relative to reference lumen area were applied and validated. The primary end point was composite of cardiac death, target lesion–related myocardial infarction, or stent thrombosis at 3 years. Results: The rate of the primary end point was lower in patients with optimal stent expansion versus those without optimal stent expansion according to 3 IVUS-defined optimal stent expansion criteria: MSA >5.5 mm 2 (0.5% versus 2.2%; hazard ratio, 0.21 [95% CI, 0.06–0.75]; P =0.008), MSA >5.0 mm 2 (0.6% versus 2.6%; hazard ratio, 0.24 [95% CI, 0.09–0.68]; P =0.003), and MSA/distal reference lumen area >90% (0.5% versus 2.4%; hazard ratio, 0.32 [95% CI, 0.12–0.88]; P =0.019). Achieving other relative expansion criteria, MSA/distal reference lumen area >100% or 80% or MSA/average reference lumen area >90% or 80%, was not associated with a reduction in hard clinical events. Conclusions: In patients undergoing IVUS-guided drug-eluting stent implantation for long lesions, achieving optimal stent expansion of MSA >5.5 mm 2 , >5.0 mm 2 , or MSA/distal reference lumen area >90% was associated with improved long-term hard clinical outcomes.