Intravascular ultrasound to guide left main stem intervention: a NOBLE trial substudy

Aims: We aimed to investigate the association between the use and Findings of IVUS with clinical outcomes in the PCI arm of a randomised trial of LMS PCI. Methods and results: The NOBLE trial randomised patients with LMS disease to treatment by PCI or CABG. Of 603 patients treated by PCI, 435 (72%) underwent post-PCI IVUS assessment, 224 of which were analysed in a core laboratory. At five years, the composite of MACCE was 18.9% if post-PCI IVUS was performed versus 25.0% if it was not performed (p=0.45, after adjustment). Overall repeat revascularisation was not reduced (10.6% vs 16.5%, p=0.11); however, LMS TLR was (5.1% vs 11.6%, p=0.01) if IVUS was used. For comparison of stent expansion, LMS MSA was split into tertiles. We found no significant difference in MACCE, death, myocardial infarction or stent thrombosis between tertiles. There was a significant difference between the lower and upper tertiles for repeat revascularisation (17.6% vs 5.2%, p=0.02) and LMS TLR (12.2% vs 0%, p=0.002). Conclusions: Post-PCI IVUS assessment and adequate stent expansion are not associated with reduced MACCE; however, there is an association with reduced LMS TLR. The use of intracoronary imaging to prevent stent underexpansion in LMS PCI is likely to improve outcomes.