Highlights
– The randomized multicentre OCCUPI trial (n=1604) found OCT guidance during PCI for complex lesions reduced 1‑year major adverse cardiac events (MACE) versus angiography alone (5% vs 7%; HR 0.62; p=0.023).
– An as‑treated OCT subanalysis (n=773 with post‑stent OCT) identified that achievement of predefined OCT optimization criteria (stent expansion, apposition, absence of major edge dissection) occurred in 71% and was associated with markedly lower 1‑year events (2.9% vs 9.4%; HR 0.30).
– Long lesions and small‑vessel disease predicted failure to achieve OCT optimization, highlighting both technical barriers and targets for procedural strategy.
Background
Percutaneous coronary intervention (PCI) with modern drug‑eluting stents (DES) is routine for obstructive coronary artery disease. Despite improvements in stent design, procedural factors — notably incomplete stent expansion, poor apposition, and edge dissections — remain determinants of stent thrombosis, restenosis and recurrent ischemic events. Intravascular imaging with optical coherence tomography (OCT) provides micron‑level resolution to detect these technical issues and to guide corrective measures (post‑dilation, additional stents or ballooning). Prior observational and smaller randomized studies suggested intravascular imaging may improve outcomes, but high‑quality randomized data in patients with complex lesions were limited.
Study design
OCCUPI was an investigator‑initiated, multicentre, randomized, open‑label, superiority trial in South Korea that enrolled patients with clinically indicated PCI for one or more complex coronary lesions. Key design elements:
- Population: Adults aged 19–85 requiring DES implantation for complex coronary lesions (study centres = 20 hospitals).
- Randomization: 1:1 to OCT‑guided PCI (n=803) versus angiography‑guided PCI (n=801); allocation via web‑response permuted blocks; outcome assessors were masked.
- Intervention: PCI performed with standard techniques using everolimus‑eluting stents; OCT guidance allowed pre‑ and post‑stent imaging and corrective maneuvers per operator judgment.
- Primary endpoint: 1‑year major adverse cardiac events (MACE) — composite of cardiac death, myocardial infarction (MI), definite/probable stent thrombosis, or ischemia‑driven target‑vessel revascularization (TVR).
- Key subanalysis: Among patients randomized to OCT, an as‑treated cohort with post‑stent OCT imaging (n=773) was classified by whether they achieved predefined OCT optimization criteria (OCCUPI‑OCT): stent expansion thresholds (minimal stent area relative to reference or absolute MSA >4.5 mm2), limited malapposition (malapposed distance <400 μm), and absence of major edge dissection.
Key findings
Primary randomized trial (Lancet, 2024)
Between January 2019 and September 2022, 1604 patients were randomized; 99% completed 1‑year follow‑up. The primary endpoint occurred in 37 of 803 patients (5%) in the OCT‑guided group versus 59 of 801 (7%) in the angiography group. The absolute difference was −2.8% (95% CI −5.1 to −0.4) and the hazard ratio was 0.62 (95% CI 0.41–0.93; p=0.023), meeting the prespecified superiority criterion. There were no significant differences in rates of stroke, bleeding, or contrast‑induced nephropathy between groups.
Interpretation: In patients with complex coronary lesions requiring DES, routine OCT guidance produced a modest but statistically significant reduction in 1‑year MACE compared with angiography alone.
OCT post‑stent optimization subanalysis (Eur Heart J, 2025)
Of the 803 patients randomized to OCT, 773 had post‑stent OCT and formed the analysis cohort. Using the OCCUPI‑OCT criteria, 549 patients (71.0%) met optimization targets (OCT Optimization) and 224 patients did not (OCT Sub‑Optimization).
Outcomes at 1 year differed substantially: the primary endpoint occurred in 2.9% of the OCT Optimization group versus 9.4% in the OCT Sub‑Optimization group (HR 0.30; 95% CI 0.16–0.58; P < .001). Compared with the angiography‑guided arm, the OCT Optimization group also had fewer events (7.5% in angiography; HR 0.38; 95% CI 0.22–0.66; P < .001).
On multivariable analysis, lesion length and small‑vessel disease were independent predictors of failing to achieve OCT optimization. Each component of the OCCUPI‑OCT criteria — adequate expansion (relative or absolute MSA thresholds), limited malapposition (<400 μm), and absence of major edge dissection — was individually associated with lower event rates (all P < .001).
Interpretation: Achieving specific OCT‑defined mechanical endpoints after stent implantation strongly correlated with better clinical outcomes. However, complex lesion anatomy (long lesions, small vessels) reduced the likelihood of meeting optimization goals.
Expert commentary: interpretation, mechanisms and limitations
Mechanistic plausibility: OCT provides high‑resolution cross‑sectional imaging that detects suboptimal stent expansion, residual malapposition, undertreated ostia, and edge dissections often occult on angiography. Identifying and correcting these issues (high‑pressure post‑dilation, further stenting, adjunctive devices) can logically reduce stent thrombosis and restenosis and thereby lower MACE.
Strengths of the OCCUPI program: The randomized design, large sample size for a complex‑lesion population, high follow‑up completeness and clinically meaningful endpoints strengthen the inference that OCT guidance confers benefit. The complementary subanalysis illuminating the relationship between achieving concrete OCT targets and outcomes adds actionable detail for operators.
Limitations and cautions:
- Open‑label design: Operators were unblinded, which could influence procedural intensity or decisions unrelated to OCT findings, though outcome assessors were masked.
- Generalizability: The trial was conducted in South Korea with experienced operators and near‑universal use of a single DES type; results may not fully generalize to other healthcare systems, different operators, or different device mixes.
- As‑treated subanalysis selection bias: The optimization analysis included only patients with post‑stent OCT and is subject to selection effects; lesions that are easier to optimize may be inherently lower risk despite adjustment attempts.
- Implementation costs and logistics: OCT requires additional equipment, contrast and procedural time. The trial did not report a formal cost‑effectiveness analysis or time/contrast penalties, and these will influence uptake.
- Operator learning curve: Outcomes likely depend on operators’ experience interpreting OCT and translating findings into corrective maneuvers; real‑world effectiveness may vary.
Clinical implications and practical takeaways
For interventional cardiologists treating complex coronary lesions, OCCUPI provides randomized evidence that OCT guidance reduces 1‑year MACE compared with angiography alone. The subanalysis emphasizes that benefit appears to be concentrated when prespecified OCT optimization targets are achieved — expansion, low malapposition and no major edge dissection. Practically, this suggests:
- Consider routine use of OCT for complex lesions (multivessel disease, long lesions, bifurcations, heavily calcified segments, ostial or left main disease) where detection of mechanical problems may alter therapy.
- Define and aim for objective post‑stent benchmarks (minimal stent area relative to reference or absolute thresholds, limited malapposition, no major edge dissection) rather than only angiographic appearance.
- Prepare for adjunctive strategies when OCT reveals suboptimal results: high‑pressure non‑compliant balloon post‑dilation, additional stenting, atherectomy or scoring balloons for resistant calcified segments.
- Recognize lesion‑specific challenges: long lesions and small vessels are less likely to reach optimization thresholds and may require tailored planning (staged strategies, optimized device selection).
Research gaps and future directions
Outstanding questions include cost‑effectiveness and health‑system impact of routine OCT in complex PCI, replication of findings in diverse populations and healthcare settings, evaluation of long‑term outcomes beyond 1 year, head‑to‑head comparisons with intravascular ultrasound (IVUS) for complex lesions, and structured training pathways to shorten the operator learning curve. Additionally, trials that randomize on the basis of achieving OCT optimization (an OCT‑guided optimization strategy vs OCT without mandated correction) would clarify causality beyond the associations reported in the subanalysis.
Conclusion
The OCCUPI randomized trial established that OCT guidance during PCI for complex coronary lesions reduces 1‑year MACE compared with angiography alone. A focused OCT post‑stent optimization analysis further showed that reaching predefined mechanical goals for expansion, apposition and edge integrity is strongly associated with superior clinical outcomes. These results support a more systematic use of OCT in complex PCI and encourage operators to adopt objective optimization targets, while recognizing the need to evaluate cost, training and generalizability in broader practice.
Funding and trial registration
OCCUPI was funded by Abbott Vascular and the Cardiovascular Research Center. The randomized trial is registered at ClinicalTrials.gov (NCT03625908).
Selected references
1. Hong SJ, Lee SJ, Lee SH, et al; OCCUPI investigators. Optical coherence tomography‑guided versus angiography‑guided percutaneous coronary intervention for patients with complex lesions (OCCUPI): an investigator‑initiated, multicentre, randomised, open‑label, superiority trial in South Korea. Lancet. 2024 Sep 14;404(10457):1029–1039. doi:10.1016/S0140-6736(24)01454-5.
2. Lee SJ, Lee SJ, Hong SJ, et al. Optical coherence tomography‑guided stent optimization for complex coronary lesions: the OCCUPI trial. Eur Heart J. 2025 Nov 19:ehaf884. doi:10.1093/eurheartj/ehaf884. Epub ahead of print.
3. Neumann FJ, Sousa‑Uva M, Ahlsson A, et al. 2018 ESC/EACTS Guidelines on myocardial revascularization. Eur Heart J. 2019;40(2):87–165. (Guideline recommendation on intravascular imaging to optimize PCI in selected scenarios.)
AI thumbnail prompt
Photorealistic cath lab scene: close‑up of an interventional cardiologist viewing an intravascular OCT pullback on a high‑resolution monitor showing stent struts and cross‑sectional vessel images; sterile field, angiography monitors in the background, cool clinical lighting, emphasis on clarity of OCT image and focused clinician (16:9, cinematic, high detail).