Highlights
- OCT guidance during PCI yields larger minimal stent areas (MSA) and reduces target-vessel failure (TVF) in patients with moderate to severely calcified coronary lesions.
- Post-PCI OCT-based virtual flow reserve (VFR) independently predicts 2-year clinical outcomes, providing incremental physiological assessment beyond anatomical imaging.
- OCT-guided stent implantation enhances safety and efficacy in complex lesions, including chronic total occlusions and in-stent restenosis, evidenced by reduced serious major adverse cardiac events (MACE).
- Suboptimal stent implantation parameters identifiable by OCT, such as minimal stent area <4.5 mm2 and proximal edge dissection, strongly predict adverse device-oriented cardiovascular events.
Background
Percutaneous coronary intervention (PCI) remains a cornerstone treatment modality for coronary artery disease, particularly when complex or calcified lesions are present. Traditional angiography-guided PCI provides limited insight into lesion morphology and stent optimization, which can compromise procedural success and long-term outcomes. Optical coherence tomography (OCT), with its superior resolution, offers detailed intravascular imaging facilitating precise stent deployment. The ILUMIEN IV trial and related studies substantially advance our understanding of the clinical utility of OCT-guided PCI, especially in high-risk patient populations and challenging lesion subsets such as calcified lesions, complex anatomies, and in-stent restenosis (ISR).
Key Content
1. Efficacy of OCT-Guided PCI in Calcified Lesions: The ILUMIEN IV Trial (Ali et al., Eur Heart J, 2025)
The ILUMIEN IV trial is a large-scale, randomized, multicenter study that compared OCT-guided versus angiography-guided stent implantation in 2,487 patients with diabetes or complex coronary artery lesions. In a subset analysis involving 2,114 patients, lesion calcification was graded angiographically, revealing 1,082 patients with moderate to severe calcification. OCT-guided PCI achieved significantly larger post-PCI minimal stent area (MSA) compared to angiography guidance (5.57 ± 1.86 mm2 vs 5.33 ± 1.78 mm2; P=0.03) in this subgroup.
At 2-year follow-up, TVF—composite of cardiac death, target-vessel myocardial infarction (TV-MI), or ischemia-driven target-vessel revascularization—occurred less frequently with OCT guidance in moderate/severe calcified lesions (6.8% vs 9.7%; adjusted hazard ratio [aHR] 0.62; 95% CI 0.40–0.96), but not in the no/mild calcification group. OCT guidance also reduced 2-year rates of serious MACE, TV-MI, and stent thrombosis, indicating the substantive clinical benefit in this challenging lesion subset.
2. Post-PCI Physiology Assessment via OCT-Based Virtual Flow Reserve (Johnson et al., JACC, 2025)
Building on anatomical imaging, the ILUMIEN IV substudy investigated OCT-based virtual flow reserve (VFR), a novel physiological surrogate, in 2,057 patients. Higher post-PCI VFR was independently predictive of reduced 2-year TVF, independent of MSA, highlighting the added prognostic value of integrating functional assessment with OCT imaging. The study supports immediate post-PCI physiology assessment using VFR as a complementary tool to optimize procedural success and patient outcomes.
3. OCT in Complex Lesions and In-Stent Restenosis Management
Another ILUMIEN IV substudy analyzed outcomes in patients with complex angiographic lesions, including long lesions, bifurcations, chronic total occlusions, and severe calcification. OCT-guided PCI yielded larger final MSA and a lower 2-year serious MACE rate (3.1% vs 4.9%; HR 0.63, P=0.04), though no significant difference in overall TVF was noted (Ali et al., JACC, 2024). Moreover, for treatment of ISR lesions, cobalt chromium everolimus-eluting stents (EES) demonstrated safety and efficacy with acceptable 1-year target lesion failure rates, albeit with smaller post-PCI MSA compared to non-ISR lesions (Ali et al., J Am Heart Assoc., 2025).
4. OCT-Derived Predictors of Clinical Outcomes Post-Stenting
A comprehensive analysis from ILUMIEN IV identified key OCT predictors of adverse events, including smaller minimal stent area, proximal edge dissection, smaller intra-stent flow area, and longer stent length. These parameters were strongly associated with target lesion failure, myocardial infarction, ischemia-driven target lesion revascularization, and stent thrombosis, underscoring the critical role of OCT in procedural optimization and risk stratification (Landmesser et al., Eur Heart J, 2024).
5. Defining and Impacting Suboptimal Stent Implantation by OCT
Romagnoli et al. (Eur Heart J Cardiovasc Imaging, 2023) assessed various OCT-based criteria for suboptimal stent implantation in a large registry. Minimum stent area <4.5 mm2, stent edge disease (<4.5 mm2 lumen), and stent edge dissection emerged as principal predictors of device-oriented cardiovascular events. This evidence supports the use of specific OCT-derived metrics as targets for achieving optimal stent deployment and favorable clinical outcomes.
6. Supporting Studies and Meta-Analyses
Recent meta-analyses have shown that intravascular imaging guidance, including OCT and intravascular ultrasound (IVUS), reduces major adverse cardiovascular events compared to angiography alone, with IVUS showing more robust evidence in older adults but OCT trending towards benefit. The expanding real-world use of imaging guidance is reflected in registry data, though underutilization in certain indications remains a challenge.
Expert Commentary
The ILUMIEN IV trial and its substudies represent critical contributions establishing OCT as a superior guidance modality over angiography alone, especially in complex and calcified lesions. The improvement in minimal stent area—an established surrogate for stent optimization—translates into meaningful reductions in ischemic complications such as stent thrombosis and myocardial infarction.
The addition of novel OCT-based physiological assessments such as VFR offers a promising integrative strategy to combine anatomical and functional evaluation immediately post-PCI, potentially refining real-time decision-making. This could complement the limitations of angiography and standard OCT alone. However, wider adoption requires technical facilitation and operator training.
Despite these benefits, areas warranting further investigation include optimal treatment strategies for ISR, the interplay of OCT findings with lesion preparation techniques (especially in severe calcification), and long-term comparative effectiveness with IVUS-guided PCI, especially considering cost-effectiveness and accessibility.
Clinical guidelines increasingly endorse intravascular imaging for complex PCI, but real-world utilization remains suboptimal, partly due to resource constraints. Integrating standardized OCT optimization criteria could enhance procedural consistency and clinical outcomes.
Conclusion
OCT-guided PCI markedly improves procedural stent deployment and clinical outcomes in patients with complex and calcified coronary lesions, as corroborated by the ILUMIEN IV trial and associated analyses. Post-PCI OCT-based physiological parameters further enhance prognostic accuracy. Establishing OCT-guided strategies as standard practice offers a pathway to optimize PCI safety and efficacy, particularly in high-risk populations. Future research should focus on expanding OCT applications, refining optimization metrics, and exploring complementary imaging and physiology tools to further individualize coronary interventions.
References
- Ali ZA et al. Optical coherence tomography- vs angiography-guided coronary stent implantation in calcified lesions: the ILUMIEN IV trial. Eur Heart J. 2025;46(32):3201-3210. doi:10.1093/eurheartj/ehaf331. PMID:40470719.
- Johnson TW et al. Impact of Optical Coherence Tomography-Based Post-PCI Physiology Assessment to Predict Clinical Outcomes: An ILUMIEN-IV Substudy. J Am Coll Cardiol. 2025;86(2):93-102. doi:10.1016/j.jacc.2025.05.019. PMID:40406943.
- Ali ZA et al. Safety and Efficacy of Cobalt Chromium Everolimus-Eluting Stents for Treatment of In-Stent Restenosis: An ILUMIEN IV Substudy. J Am Heart Assoc. 2025;14(11):e039482. doi:10.1161/JAHA.124.039482. PMID:40401609.
- Landmesser U et al. Optical coherence tomography predictors of clinical outcomes after stent implantation: the ILUMIEN IV trial. Eur Heart J. 2024;45(43):4630-4643. doi:10.1093/eurheartj/ehae521. PMID:39196989.
- Ali ZA et al. OCT-Guided vs Angiography-Guided Coronary Stent Implantation in Complex Lesions: An ILUMIEN IV Substudy. J Am Coll Cardiol. 2024;84(4):368-378. doi:10.1016/j.jacc.2024.04.037. PMID:38759907.
- Romagnoli E et al. Clinical impact of OCT-derived suboptimal stent implantation parameters and definitions. Eur Heart J Cardiovasc Imaging. 2023 Dec 21;25(1):48-57. doi:10.1093/ehjci/jead172. PMID:37463223.
- Ali ZA et al. Optical Coherence Tomography-Guided versus Angiography-Guided PCI. N Engl J Med. 2023 Oct 19;389(16):1466-1476. doi:10.1056/NEJMoa2305861. PMID:37634188.
