ILLUMIEN IV Study: New Metric Predicts Long-Term PCI Success

A novel substudy of the ILUMIEN-IV trial demonstrates that optical coherence tomography (OCT)-derived virtual flow reserve (VFR) independently predicts 2-year target vessel failure (TVF) after percutaneous coronary intervention (PCI), complementing traditional intravascular imaging-derived anatomic measures, such as minimal stent area (MSA). The findings, published in the Journal of the American College of Cardiology, support the integration of physiology assessment into OCT-guided PCI to optimize procedural outcomes.

Despite advances in intracoronary imaging, up to 59% of PCI procedures fail to meet optimal OCT criteria, leaving room for improved risk stratification. While post-PCI fractional flow reserve (FFR) has prognostic value, its adoption is limited by cost and workflow disruptions. VFR, a computational model using OCT lumen geometry to estimate hyperemic pressure ratios, offers a rapid, wire-free alternative. This analysis evaluated the predictive value of VFR in 2,057 patients from ILUMIEN-IV who underwent single-lesion PCI with post-procedure OCT.

The median post-PCI VFR was 0.90 (IQR, 0.86–0.92), with slightly higher values in OCT-guided versus angiography-guided PCI (0.90 vs 0.89; P<0.001). Multivariable analysis revealed both VFR (per 0.1-unit increase: HR, 0.70; 95% CI, 0.0–0.95; P=0.021) and MSA (per 1 mm² increase; HR, 0.84; 95% CI, 0.76–0.94; P=0.002) as independent predictors of 2-year TVF (composite of cardiac death, target vessel MI, or revascularization). For target lesion failure (TLF), proximal edge dissection (HR, 1.69; 95% CI 1.14–2.52; P=0.009) also emerged as a key factor. Patients with both low VFR (≤0.90) and small MSA (≤5.26 mm²) had the highest TVF risk, underscoring the synergy of anatomic and physiologic assessments.

The weak correlation between VFR and MSA (r=0.305) highlights VFR’s ability to capture residual ischemia beyond the stent segment, including untreated proximal/diffuse disease. Case examples illustrated how low VFR identified missed optimization opportunities, such as under-expansion or focal lesions, even with acceptable MSA.

These findings suggest that real-time VFR could enhance OCT-guided PCI by providing immediate physiologic feedback, potentially reducing early adverse events. Future studies should investigate its utility in pre-PCI planning and assessing diffuse disease.