Key Points
- IVUS-guided PCI was not superior to angiography-guided PCI for the primary composite endpoint of cardiac death, target-vessel myocardial infarction, or clinically indicated target-vessel revascularization at a median follow-up of 19 months (13.9% vs. 11.1%; HR 1.25; 95% CI, 0.97–1.60; p=0.08).
- Definite stent thrombosis was significantly lower with IVUS guidance (0.2% vs. 1.0%; HR 0.20; 95% CI, 0.04–0.90), suggesting a mechanistic benefit in stent optimization despite the neutral primary outcome.
- IVUS-guided PCI was associated with longer procedure duration (88.8 vs. 66.2 minutes), greater total stent length (64.0 vs. 59.6 mm), and larger maximum stent diameter (3.50 vs. 3.38 mm), yet stent-optimization criteria were met in only 48% of lesions.
Intravascular ultrasound guidance during percutaneous coronary intervention has been associated with improved stent optimization and reduced adverse events in observational studies and trials conducted predominantly in Asian populations. However, adoption in Western countries remains low, and randomized evidence from contemporary European practice has been limited. The IVUS-CHIP trial (NCT04854070), presented at ACC.26 and simultaneously published in the New England Journal of Medicine, tested whether routine IVUS-guided PCI with prespecified stent-optimization criteria would reduce target-vessel failure compared with standard angiography-guided PCI in patients undergoing complex high-risk procedures.
IVUS-CHIP was an investigator-initiated, international, multicenter, open-label, event-driven, randomized superiority trial enrolling 2,020 patients across 37 European centers. Patients presenting with stable ischemic heart disease or non–ST-elevation acute coronary syndrome and at least one complex coronary lesion—defined as severe calcification, ostial lesion, true bifurcation with side branch ≥2.5 mm, left main disease, chronic total occlusion, in-stent restenosis, or lesion length >28 mm-were randomized 1:1 to IVUS-guided PCI (n=1,010) or angiography-guided PCI (n=1,009). The primary endpoint was target-vessel failure, a composite of cardiac death, target-vessel myocardial infarction, or clinically indicated target-vessel revascularization.
The population was high-risk: mean age was 69 years, 79.4% were male, and 27.4% presented with acute coronary syndrome. Diabetes was present in approximately 31%, prior PCI in 47%, and prior myocardial infarction in 30%. The mean anatomical SYNTAX score was 25±14 in both groups, and severe calcification was present in 45.8% and 42.2% of lesions in the IVUS and angiography groups, respectively.
At a median follow-up of 19.0 months, the primary endpoint occurred in 140 patients (13.9%) in the IVUS-guided group and 112 patients (11.1%) in the angiography-guided group (HR 1.25; 95% CI, 0.97–1.60; p=0.08). Individual components showed similar patterns: cardiac death occurred in 3.4% versus 2.7% (HR 1.24; 95% CI, 0.75–2.05), target-vessel myocardial infarction in 6.5% versus 5.7% (HR 1.13; 95% CI, 0.80–1.61) and clinically indicated target-vessel revascularization in 7.4% versus 6.0% (HR 1.22; 95% CI, 0.87–1.71).
Notably, IVUS guidance was associated with a marked reduction in stent thrombosis. Definite stent thrombosis occurred in 2 patients (0.2%) in the IVUS group versus 10 patients (1.0%) in the angiography group (HR 0.20; 95% CI, 0.04–0.90). Definite or probable stent thrombosis showed a similar pattern (0.5% vs. 1.5%; HR 0.33; 95% CI, 0.12–0.90).
Procedural characteristics reflected the impact of IVUS guidance on operator behavior. Post-dilation was performed more frequently in the IVUS group (91.3% vs. 84.5%), with larger maximum balloon diameters (3.90 vs. 3.72 mm) and stent diameters (3.50 vs. 3.38 mm). Total stent length was also greater with IVUS guidance (64.0 vs. 59.6 mm). However, mean procedure duration was substantially longer (88.8 vs. 66.2 minutes), and contrast volume was modestly higher (185.0 vs. 175.7 mL). Procedural complications occurred at similar rates (11.3% vs. 10.2%).
Core laboratory analysis revealed that prespecified stent-optimization criteria were met in only 48% of lesions in the IVUS group, with residual plaque burden exceeding 50% at stent edges being the most common reason for not meeting criteria. This finding suggests that even with IVUS guidance, achieving optimal results in severely diseased vessels remains challenging.
These findings contrast with previous trials, particularly the RENOVATE-COMPLEX-PCI trial conducted in Asia, which demonstrated benefit with intravascular imaging guidance. The IVUS-CHIP population had substantially higher anatomical complexity, including a threefold higher rate of severe calcification (42% vs. 14% in control groups), which may have limited the ability to achieve stent optimization despite imaging guidance. The results align with the ILUMIEN IV trial of optical coherence tomography–guided PCI, which also showed no benefit for the primary endpoint but a reduction in stent thrombosis.
Dr. Roberto Diletti, the study’s lead investigator, stated: “The use of IVUS was not improving clinical outcomes in this group of patients… The stent thrombosis was less, but the overall clinical outcome of those patients was not improved as per the primary endpoint of this trial.”